[ruby/json] Resync

18 files changed, 2167 insertions, 866 deletions

diff --git a/ext/json/fbuffer/fbuffer.h b/ext/json/fbuffer/fbuffer.h
index 367ebd89ff..3e154a5fa8 100644
--- a/ext/json/fbuffer/fbuffer.h
+++ b/ext/json/fbuffer/fbuffer.h
@@ -4,9 +4,40 @@
 #include "ruby.h"
 #include "ruby/encoding.h"
 
+/* shims */
+/* This is the fallback definition from Ruby 3.4 */
+
+#ifndef RBIMPL_STDBOOL_H
+#if defined(__cplusplus)
+# if defined(HAVE_STDBOOL_H) && (__cplusplus >= 201103L)
+#  include <cstdbool>
+# endif
+#elif defined(HAVE_STDBOOL_H)
+# include <stdbool.h>
+#elif !defined(HAVE__BOOL)
+typedef unsigned char _Bool;
+# define bool  _Bool
+# define true  ((_Bool)+1)
+# define false ((_Bool)+0)
+# define __bool_true_false_are_defined
+#endif
+#endif
+
+#ifndef RB_UNLIKELY
+#define RB_UNLIKELY(expr) expr
+#endif
+
+#ifndef RB_LIKELY
+#define RB_LIKELY(expr) expr
+#endif
+
+#ifndef MAYBE_UNUSED
+# define MAYBE_UNUSED(x) x
+#endif
+
 enum fbuffer_type {
-    HEAP = 0,
-    STACK = 1,
+    FBUFFER_HEAP_ALLOCATED = 0,
+    FBUFFER_STACK_ALLOCATED = 1,
 };
 
 typedef struct FBufferStruct {
@@ -38,19 +69,11 @@ static inline void fbuffer_append_char(FBuffer *fb, char newchr);
 static VALUE fbuffer_to_s(FBuffer *fb);
 #endif
 
-#ifndef RB_UNLIKELY
-#define RB_UNLIKELY(expr) expr
-#endif
-
-#ifndef RB_LIKELY
-#define RB_LIKELY(expr) expr
-#endif
-
 static void fbuffer_stack_init(FBuffer *fb, unsigned long initial_length, char *stack_buffer, long stack_buffer_size)
 {
     fb->initial_length = (initial_length > 0) ? initial_length : FBUFFER_INITIAL_LENGTH_DEFAULT;
     if (stack_buffer) {
-        fb->type = STACK;
+        fb->type = FBUFFER_STACK_ALLOCATED;
         fb->ptr = stack_buffer;
         fb->capa = stack_buffer_size;
     }
@@ -58,7 +81,7 @@ static void fbuffer_stack_init(FBuffer *fb, unsigned long initial_length, char *
 
 static void fbuffer_free(FBuffer *fb)
 {
-    if (fb->ptr && fb->type == HEAP) {
+    if (fb->ptr && fb->type == FBUFFER_HEAP_ALLOCATED) {
         ruby_xfree(fb->ptr);
     }
 }
@@ -82,10 +105,10 @@ static void fbuffer_do_inc_capa(FBuffer *fb, unsigned long requested)
     for (required = fb->capa; requested > required - fb->len; required <<= 1);
 
     if (required > fb->capa) {
-        if (fb->type == STACK) {
+        if (fb->type == FBUFFER_STACK_ALLOCATED) {
             const char *old_buffer = fb->ptr;
             fb->ptr = ALLOC_N(char, required);
-            fb->type = HEAP;
+            fb->type = FBUFFER_HEAP_ALLOCATED;
             MEMCPY(fb->ptr, old_buffer, char, fb->len);
         } else {
             REALLOC_N(fb->ptr, char, required);
diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index c32b5ce093..80539af6c8 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -1,5 +1,27 @@
+#include "ruby.h"
 #include "../fbuffer/fbuffer.h"
-#include "generator.h"
+
+#include <math.h>
+#include <ctype.h>
+
+/* ruby api and some helpers */
+
+typedef struct JSON_Generator_StateStruct {
+    VALUE indent;
+    VALUE space;
+    VALUE space_before;
+    VALUE object_nl;
+    VALUE array_nl;
+
+    long max_nesting;
+    long depth;
+    long buffer_initial_length;
+
+    bool allow_nan;
+    bool ascii_only;
+    bool script_safe;
+    bool strict;
+} JSON_Generator_State;
 
 #ifndef RB_UNLIKELY
 #define RB_UNLIKELY(cond) (cond)
@@ -31,6 +53,7 @@ struct generate_json_data {
     generator_func func;
 };
 
+static VALUE cState_from_state_s(VALUE self, VALUE opts);
 static VALUE cState_partial_generate(VALUE self, VALUE obj, generator_func);
 static void generate_json(FBuffer *buffer, struct generate_json_data *data, JSON_Generator_State *state, VALUE obj);
 static void generate_json_object(FBuffer *buffer, struct generate_json_data *data, JSON_Generator_State *state, VALUE obj);
@@ -1013,6 +1036,10 @@ static VALUE generate_json_rescue(VALUE d, VALUE exc)
     struct generate_json_data *data = (struct generate_json_data *)d;
     fbuffer_free(data->buffer);
 
+    if (RBASIC_CLASS(exc) == rb_path2class("Encoding::UndefinedConversionError")) {
+        exc = rb_exc_new_str(eGeneratorError, rb_funcall(exc, rb_intern("message"), 0));
+    }
+
     rb_exc_raise(exc);
 
     return Qundef;
diff --git a/ext/json/generator/generator.h b/ext/json/generator/generator.h
deleted file mode 100644
index 749a627a10..0000000000
--- a/ext/json/generator/generator.h
+++ /dev/null
@@ -1,91 +0,0 @@
-#ifndef _GENERATOR_H_
-#define _GENERATOR_H_
-
-#include <math.h>
-#include <ctype.h>
-
-#include "ruby.h"
-
-/* This is the fallback definition from Ruby 3.4 */
-#ifndef RBIMPL_STDBOOL_H
-#if defined(__cplusplus)
-# if defined(HAVE_STDBOOL_H) && (__cplusplus >= 201103L)
-#  include <cstdbool>
-# endif
-#elif defined(HAVE_STDBOOL_H)
-# include <stdbool.h>
-#elif !defined(HAVE__BOOL)
-typedef unsigned char _Bool;
-# define bool  _Bool
-# define true  ((_Bool)+1)
-# define false ((_Bool)+0)
-# define __bool_true_false_are_defined
-#endif
-#endif
-
-/* ruby api and some helpers */
-
-typedef struct JSON_Generator_StateStruct {
-    VALUE indent;
-    VALUE space;
-    VALUE space_before;
-    VALUE object_nl;
-    VALUE array_nl;
-
-    long max_nesting;
-    long depth;
-    long buffer_initial_length;
-
-    bool allow_nan;
-    bool ascii_only;
-    bool script_safe;
-    bool strict;
-} JSON_Generator_State;
-
-static VALUE mHash_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mArray_to_json(int argc, VALUE *argv, VALUE self);
-#ifdef RUBY_INTEGER_UNIFICATION
-static VALUE mInteger_to_json(int argc, VALUE *argv, VALUE self);
-#else
-static VALUE mFixnum_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mBignum_to_json(int argc, VALUE *argv, VALUE self);
-#endif
-static VALUE mFloat_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mString_included_s(VALUE self, VALUE modul);
-static VALUE mString_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mString_to_json_raw_object(VALUE self);
-static VALUE mString_to_json_raw(int argc, VALUE *argv, VALUE self);
-static VALUE mString_Extend_json_create(VALUE self, VALUE o);
-static VALUE mTrueClass_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mFalseClass_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mNilClass_to_json(int argc, VALUE *argv, VALUE self);
-static VALUE mObject_to_json(int argc, VALUE *argv, VALUE self);
-static void State_free(void *state);
-static VALUE cState_s_allocate(VALUE klass);
-
-static VALUE cState_generate(VALUE self, VALUE obj);
-static VALUE cState_from_state_s(VALUE self, VALUE opts);
-static VALUE cState_indent(VALUE self);
-static VALUE cState_indent_set(VALUE self, VALUE indent);
-static VALUE cState_space(VALUE self);
-static VALUE cState_space_set(VALUE self, VALUE space);
-static VALUE cState_space_before(VALUE self);
-static VALUE cState_space_before_set(VALUE self, VALUE space_before);
-static VALUE cState_object_nl(VALUE self);
-static VALUE cState_object_nl_set(VALUE self, VALUE object_nl);
-static VALUE cState_array_nl(VALUE self);
-static VALUE cState_array_nl_set(VALUE self, VALUE array_nl);
-static VALUE cState_max_nesting(VALUE self);
-static VALUE cState_max_nesting_set(VALUE self, VALUE depth);
-static VALUE cState_allow_nan_p(VALUE self);
-static VALUE cState_ascii_only_p(VALUE self);
-static VALUE cState_depth(VALUE self);
-static VALUE cState_depth_set(VALUE self, VALUE depth);
-static VALUE cState_script_safe(VALUE self);
-static VALUE cState_script_safe_set(VALUE self, VALUE depth);
-static VALUE cState_strict(VALUE self);
-static VALUE cState_strict_set(VALUE self, VALUE strict);
-
-static const rb_data_type_t JSON_Generator_State_type;
-
-#endif
diff --git a/ext/json/lib/json.rb b/ext/json/lib/json.rb
index c28e853e13..dfd9b7dfc2 100644
--- a/ext/json/lib/json.rb
+++ b/ext/json/lib/json.rb
@@ -583,10 +583,5 @@ require 'json/common'
 #
 module JSON
   require 'json/version'
-
-  begin
-    require 'json/ext'
-  rescue LoadError
-    require 'json/pure'
-  end
+  require 'json/ext'
 end
diff --git a/ext/json/lib/json/common.rb b/ext/json/lib/json/common.rb
index 546b6ec801..2269896ba8 100644
--- a/ext/json/lib/json/common.rb
+++ b/ext/json/lib/json/common.rb
@@ -32,9 +32,7 @@ module JSON
       JSON.generate(object, opts)
     end
 
-    # Returns the JSON parser class that is used by JSON. This is either
-    # JSON::Ext::Parser or JSON::Pure::Parser:
-    #   JSON.parser # => JSON::Ext::Parser
+    # Returns the JSON parser class that is used by JSON.
     attr_reader :parser
 
     # Set the JSON parser class _parser_ to be used by JSON.
@@ -97,14 +95,10 @@ module JSON
       )
     end
 
-    # Returns the JSON generator module that is used by JSON. This is
-    # either JSON::Ext::Generator or JSON::Pure::Generator:
-    #   JSON.generator # => JSON::Ext::Generator
+    # Returns the JSON generator module that is used by JSON.
     attr_reader :generator
 
-    # Sets or Returns the JSON generator state class that is used by JSON. This is
-    # either JSON::Ext::Generator::State or JSON::Pure::Generator::State:
-    #   JSON.state # => JSON::Ext::Generator::State
+    # Sets or Returns the JSON generator state class that is used by JSON.
     attr_accessor :state
   end
 
@@ -207,16 +201,7 @@ module JSON
   #   JSON.parse('')
   #
   def parse(source, opts = nil)
-    if opts.nil?
-      Parser.new(source).parse
-    else
-      # NB: The ** shouldn't be required, but we have to deal with
-      # different versions of the `json` and `json_pure` gems being
-      # loaded concurrently.
-      # Prior to 2.7.3, `JSON::Ext::Parser` would only take kwargs.
-      # Ref: https://github.com/ruby/json/issues/650
-      Parser.new(source, **opts).parse
-    end
+    Parser.parse(source, opts)
   end
 
   # :call-seq:
diff --git a/ext/json/lib/json/ext.rb b/ext/json/lib/json/ext.rb
index 92ef61eaec..2082cae68f 100644
--- a/ext/json/lib/json/ext.rb
+++ b/ext/json/lib/json/ext.rb
@@ -8,14 +8,12 @@ module JSON
   module Ext
     if RUBY_ENGINE == 'truffleruby'
       require 'json/ext/parser'
-      require 'json/pure'
-      $DEBUG and warn "Using Ext extension for JSON parser and Pure library for JSON generator."
+      require 'json/truffle_ruby/generator'
       JSON.parser = Parser
-      JSON.generator = JSON::Pure::Generator
+      JSON.generator = ::JSON::TruffleRuby::Generator
     else
       require 'json/ext/parser'
       require 'json/ext/generator'
-      $DEBUG and warn "Using Ext extension for JSON."
       JSON.parser = Parser
       JSON.generator = Generator
     end
diff --git a/lib/json/ext/generator/state.rb b/ext/json/lib/json/ext/generator/state.rb
index 6cd9496e67..6cd9496e67 100644
--- a/lib/json/ext/generator/state.rb
+++ b/ext/json/lib/json/ext/generator/state.rb
diff --git a/ext/json/parser/extconf.rb b/ext/json/parser/extconf.rb
index c3c23d2cb4..f9104de12d 100644
--- a/ext/json/parser/extconf.rb
+++ b/ext/json/parser/extconf.rb
@@ -2,7 +2,10 @@
 require 'mkmf'
 
 have_func("rb_enc_interned_str", "ruby.h") # RUBY_VERSION >= 3.0
-have_func("rb_gc_mark_locations") # Missing on TruffleRuby
+have_func("rb_hash_new_capa", "ruby.h") # RUBY_VERSION >= 3.2
+have_func("rb_gc_mark_locations", "ruby.h") # Missing on TruffleRuby
+have_func("rb_hash_bulk_insert", "ruby.h") # Missing on TruffleRuby
+
 append_cflags("-std=c99")
 
 create_makefile 'json/ext/parser'
diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index 758dba4694..382e21e12d 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -1,7 +1,310 @@
 /* This file is automatically generated from parser.rl by using ragel */
 #line 1 "parser.rl"
+#include "ruby.h"
 #include "../fbuffer/fbuffer.h"
-#include "parser.h"
+
+static VALUE mJSON, mExt, cParser, eNestingError, Encoding_UTF_8;
+static VALUE CNaN, CInfinity, CMinusInfinity;
+
+static ID i_json_creatable_p, i_json_create, i_create_id,
+          i_chr, i_deep_const_get, i_match, i_aset, i_aref,
+          i_leftshift, i_new, i_try_convert, i_uminus, i_encode;
+
+static VALUE sym_max_nesting, sym_allow_nan, sym_allow_trailing_comma, sym_symbolize_names, sym_freeze,
+             sym_create_additions, sym_create_id, sym_object_class, sym_array_class,
+             sym_decimal_class, sym_match_string;
+
+static int binary_encindex;
+static int utf8_encindex;
+
+#ifndef HAVE_RB_GC_MARK_LOCATIONS
+// For TruffleRuby
+void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+{
+    VALUE *value = start;
+
+    while (value < end) {
+        rb_gc_mark(*value);
+        value++;
+    }
+}
+#endif
+
+#ifndef HAVE_RB_HASH_BULK_INSERT
+// For TruffleRuby
+void rb_hash_bulk_insert(long count, const VALUE *pairs, VALUE hash)
+{
+    long index = 0;
+    while (index < count) {
+        VALUE name = pairs[index++];
+        VALUE value = pairs[index++];
+        rb_hash_aset(hash, name, value);
+    }
+    RB_GC_GUARD(hash);
+}
+#endif
+
+/* name cache */
+
+#include <string.h>
+#include <ctype.h>
+
+// Object names are likely to be repeated, and are frozen.
+// As such we can re-use them if we keep a cache of the ones we've seen so far,
+// and save much more expensive lookups into the global fstring table.
+// This cache implementation is deliberately simple, as we're optimizing for compactness,
+// to be able to fit safely on the stack.
+// As such, binary search into a sorted array gives a good tradeoff between compactness and
+// performance.
+#define JSON_RVALUE_CACHE_CAPA 63
+typedef struct rvalue_cache_struct {
+    int length;
+    VALUE entries[JSON_RVALUE_CACHE_CAPA];
+} rvalue_cache;
+
+static rb_encoding *enc_utf8;
+
+#define JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH 55
+
+static inline VALUE build_interned_string(const char *str, const long length)
+{
+# ifdef HAVE_RB_ENC_INTERNED_STR
+    return rb_enc_interned_str(str, length, enc_utf8);
+# else
+    VALUE rstring = rb_utf8_str_new(str, length);
+    return rb_funcall(rb_str_freeze(rstring), i_uminus, 0);
+# endif
+}
+
+static inline VALUE build_symbol(const char *str, const long length)
+{
+    return rb_str_intern(build_interned_string(str, length));
+}
+
+static void rvalue_cache_insert_at(rvalue_cache *cache, int index, VALUE rstring)
+{
+    MEMMOVE(&cache->entries[index + 1], &cache->entries[index], VALUE, cache->length - index);
+    cache->length++;
+    cache->entries[index] = rstring;
+}
+
+static inline int rstring_cache_cmp(const char *str, const long length, VALUE rstring)
+{
+    long rstring_length = RSTRING_LEN(rstring);
+    if (length == rstring_length) {
+        return memcmp(str, RSTRING_PTR(rstring), length);
+    } else {
+        return (int)(length - rstring_length);
+    }
+}
+
+static VALUE rstring_cache_fetch(rvalue_cache *cache, const char *str, const long length)
+{
+    if (RB_UNLIKELY(length > JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH)) {
+        // Common names aren't likely to be very long. So we just don't
+        // cache names above an arbitrary threshold.
+        return Qfalse;
+    }
+
+    if (RB_UNLIKELY(!isalpha(str[0]))) {
+        // Simple heuristic, if the first character isn't a letter,
+        // we're much less likely to see this string again.
+        // We mostly want to cache strings that are likely to be repeated.
+        return Qfalse;
+    }
+
+    int low = 0;
+    int high = cache->length - 1;
+    int mid = 0;
+    int last_cmp = 0;
+
+    while (low <= high) {
+        mid = (high + low) >> 1;
+        VALUE entry = cache->entries[mid];
+        last_cmp = rstring_cache_cmp(str, length, entry);
+
+        if (last_cmp == 0) {
+            return entry;
+        } else if (last_cmp > 0) {
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+    }
+
+    if (RB_UNLIKELY(memchr(str, '\\', length))) {
+        // We assume the overwhelming majority of names don't need to be escaped.
+        // But if they do, we have to fallback to the slow path.
+        return Qfalse;
+    }
+
+    VALUE rstring = build_interned_string(str, length);
+
+    if (cache->length < JSON_RVALUE_CACHE_CAPA) {
+        if (last_cmp > 0) {
+            mid += 1;
+        }
+
+        rvalue_cache_insert_at(cache, mid, rstring);
+    }
+    return rstring;
+}
+
+static VALUE rsymbol_cache_fetch(rvalue_cache *cache, const char *str, const long length)
+{
+    if (RB_UNLIKELY(length > JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH)) {
+        // Common names aren't likely to be very long. So we just don't
+        // cache names above an arbitrary threshold.
+        return Qfalse;
+    }
+
+    if (RB_UNLIKELY(!isalpha(str[0]))) {
+        // Simple heuristic, if the first character isn't a letter,
+        // we're much less likely to see this string again.
+        // We mostly want to cache strings that are likely to be repeated.
+        return Qfalse;
+    }
+
+    int low = 0;
+    int high = cache->length - 1;
+    int mid = 0;
+    int last_cmp = 0;
+
+    while (low <= high) {
+        mid = (high + low) >> 1;
+        VALUE entry = cache->entries[mid];
+        last_cmp = rstring_cache_cmp(str, length, rb_sym2str(entry));
+
+        if (last_cmp == 0) {
+            return entry;
+        } else if (last_cmp > 0) {
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+    }
+
+    if (RB_UNLIKELY(memchr(str, '\\', length))) {
+        // We assume the overwhelming majority of names don't need to be escaped.
+        // But if they do, we have to fallback to the slow path.
+        return Qfalse;
+    }
+
+    VALUE rsymbol = build_symbol(str, length);
+
+    if (cache->length < JSON_RVALUE_CACHE_CAPA) {
+        if (last_cmp > 0) {
+            mid += 1;
+        }
+
+        rvalue_cache_insert_at(cache, mid, rsymbol);
+    }
+    return rsymbol;
+}
+
+/* rvalue stack */
+
+#define RVALUE_STACK_INITIAL_CAPA 128
+
+enum rvalue_stack_type {
+    RVALUE_STACK_HEAP_ALLOCATED = 0,
+    RVALUE_STACK_STACK_ALLOCATED = 1,
+};
+
+typedef struct rvalue_stack_struct {
+    enum rvalue_stack_type type;
+    long capa;
+    long head;
+    VALUE *ptr;
+} rvalue_stack;
+
+static rvalue_stack *rvalue_stack_spill(rvalue_stack *old_stack, VALUE *handle, rvalue_stack **stack_ref);
+
+static rvalue_stack *rvalue_stack_grow(rvalue_stack *stack, VALUE *handle, rvalue_stack **stack_ref)
+{
+    long required = stack->capa * 2;
+
+    if (stack->type == RVALUE_STACK_STACK_ALLOCATED) {
+        stack = rvalue_stack_spill(stack, handle, stack_ref);
+    } else {
+        REALLOC_N(stack->ptr, VALUE, required);
+        stack->capa = required;
+    }
+    return stack;
+}
+
+static void rvalue_stack_push(rvalue_stack *stack, VALUE value, VALUE *handle, rvalue_stack **stack_ref)
+{
+    if (RB_UNLIKELY(stack->head >= stack->capa)) {
+        stack = rvalue_stack_grow(stack, handle, stack_ref);
+    }
+    stack->ptr[stack->head] = value;
+    stack->head++;
+}
+
+static inline VALUE *rvalue_stack_peek(rvalue_stack *stack, long count)
+{
+    return stack->ptr + (stack->head - count);
+}
+
+static inline void rvalue_stack_pop(rvalue_stack *stack, long count)
+{
+    stack->head -= count;
+}
+
+static void rvalue_stack_mark(void *ptr)
+{
+    rvalue_stack *stack = (rvalue_stack *)ptr;
+    rb_gc_mark_locations(stack->ptr, stack->ptr + stack->head);
+}
+
+static void rvalue_stack_free(void *ptr)
+{
+    rvalue_stack *stack = (rvalue_stack *)ptr;
+    if (stack) {
+        ruby_xfree(stack->ptr);
+        ruby_xfree(stack);
+    }
+}
+
+static size_t rvalue_stack_memsize(const void *ptr)
+{
+    const rvalue_stack *stack = (const rvalue_stack *)ptr;
+    return sizeof(rvalue_stack) + sizeof(VALUE) * stack->capa;
+}
+
+static const rb_data_type_t JSON_Parser_rvalue_stack_type = {
+    "JSON::Ext::Parser/rvalue_stack",
+    {
+        .dmark = rvalue_stack_mark,
+        .dfree = rvalue_stack_free,
+        .dsize = rvalue_stack_memsize,
+    },
+    0, 0,
+    RUBY_TYPED_FREE_IMMEDIATELY,
+};
+
+static rvalue_stack *rvalue_stack_spill(rvalue_stack *old_stack, VALUE *handle, rvalue_stack **stack_ref)
+{
+    rvalue_stack *stack;
+    *handle = TypedData_Make_Struct(0, rvalue_stack, &JSON_Parser_rvalue_stack_type, stack);
+    *stack_ref = stack;
+    MEMCPY(stack, old_stack, rvalue_stack, 1);
+
+    stack->capa = old_stack->capa << 1;
+    stack->ptr = ALLOC_N(VALUE, stack->capa);
+    stack->type = RVALUE_STACK_HEAP_ALLOCATED;
+    MEMCPY(stack->ptr, old_stack->ptr, VALUE, old_stack->head);
+    return stack;
+}
+
+static void rvalue_stack_eagerly_release(VALUE handle)
+{
+    rvalue_stack *stack;
+    TypedData_Get_Struct(handle, rvalue_stack, &JSON_Parser_rvalue_stack_type, stack);
+    RTYPEDDATA_DATA(handle) = NULL;
+    rvalue_stack_free(stack);
+}
 
 /* unicode */
 
@@ -69,6 +372,50 @@ static int convert_UTF32_to_UTF8(char *buf, uint32_t ch)
     return len;
 }
 
+typedef struct JSON_ParserStruct {
+    VALUE Vsource;
+    char *source;
+    long len;
+    char *memo;
+    VALUE create_id;
+    VALUE object_class;
+    VALUE array_class;
+    VALUE decimal_class;
+    VALUE match_string;
+    FBuffer fbuffer;
+    int max_nesting;
+    bool allow_nan;
+    bool allow_trailing_comma;
+    bool parsing_name;
+    bool symbolize_names;
+    bool freeze;
+    bool create_additions;
+    bool deprecated_create_additions;
+    rvalue_cache name_cache;
+    rvalue_stack *stack;
+    VALUE stack_handle;
+} JSON_Parser;
+
+#define GET_PARSER                          \
+    GET_PARSER_INIT;                        \
+    if (!json->Vsource) rb_raise(rb_eTypeError, "uninitialized instance")
+
+#define GET_PARSER_INIT                     \
+    JSON_Parser *json;                      \
+    TypedData_Get_Struct(self, JSON_Parser, &JSON_Parser_type, json)
+
+#define MinusInfinity "-Infinity"
+#define EVIL 0x666
+
+static const rb_data_type_t JSON_Parser_type;
+static char *JSON_parse_string(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+static char *JSON_parse_integer(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_array(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+
+
 #define PARSE_ERROR_FRAGMENT_LEN 32
 #ifdef RBIMPL_ATTR_NORETURN
 RBIMPL_ATTR_NORETURN()
@@ -86,60 +433,49 @@ static void raise_parse_error(const char *format, const char *start)
         ptr = buffer;
     }
 
-    rb_enc_raise(rb_utf8_encoding(), rb_path2class("JSON::ParserError"), format, ptr);
+    rb_enc_raise(enc_utf8, rb_path2class("JSON::ParserError"), format, ptr);
 }
 
-static VALUE mJSON, mExt, cParser, eNestingError, Encoding_UTF_8;
-static VALUE CNaN, CInfinity, CMinusInfinity;
-
-static ID i_json_creatable_p, i_json_create, i_create_id, i_create_additions,
-          i_chr, i_max_nesting, i_allow_nan, i_symbolize_names,
-          i_object_class, i_array_class, i_decimal_class,
-          i_deep_const_get, i_match, i_match_string, i_aset, i_aref,
-          i_leftshift, i_new, i_try_convert, i_freeze, i_uminus, i_encode;
 
-static int binary_encindex;
-static int utf8_encindex;
 
+#line 464 "parser.rl"
 
 
-#line 129 "parser.rl"
 
-
-
-#line 111 "parser.c"
+#line 446 "parser.c"
 enum {JSON_object_start = 1};
-enum {JSON_object_first_final = 27};
+enum {JSON_object_first_final = 32};
 enum {JSON_object_error = 0};
 
 enum {JSON_object_en_main = 1};
 
 
-#line 171 "parser.rl"
+#line 504 "parser.rl"
+
 
+#define PUSH(result) rvalue_stack_push(json->stack, result, &json->stack_handle, &json->stack)
 
 static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting)
 {
     int cs = EVIL;
-    VALUE last_name = Qnil;
-    VALUE object_class = json->object_class;
 
     if (json->max_nesting && current_nesting > json->max_nesting) {
         rb_raise(eNestingError, "nesting of %d is too deep", current_nesting);
     }
 
-    *result = NIL_P(object_class) ? rb_hash_new() : rb_class_new_instance(0, 0, object_class);
+    long stack_head = json->stack->head;
 
 
-#line 135 "parser.c"
+#line 470 "parser.c"
 	{
 	cs = JSON_object_start;
 	}
 
-#line 186 "parser.rl"
+#line 519 "parser.rl"
 
-#line 142 "parser.c"
+#line 477 "parser.c"
 	{
+	short _widec;
 	if ( p == pe )
 		goto _test_eof;
 	switch ( cs )
@@ -159,27 +495,30 @@ case 2:
 		case 13: goto st2;
 		case 32: goto st2;
 		case 34: goto tr2;
-		case 47: goto st23;
+		case 47: goto st28;
 		case 125: goto tr4;
 	}
 	if ( 9 <= (*p) && (*p) <= 10 )
 		goto st2;
 	goto st0;
 tr2:
-#line 153 "parser.rl"
+#line 483 "parser.rl"
 	{
         char *np;
-        json->parsing_name = 1;
-        np = JSON_parse_string(json, p, pe, &last_name);
-        json->parsing_name = 0;
-        if (np == NULL) { p--; {p++; cs = 3; goto _out;} } else {p = (( np))-1;}
+        json->parsing_name = true;
+        np = JSON_parse_string(json, p, pe, result);
+        json->parsing_name = false;
+        if (np == NULL) { p--; {p++; cs = 3; goto _out;} } else {
+            PUSH(*result);
+            {p = (( np))-1;}
+         }
     }
 	goto st3;
 st3:
 	if ( ++p == pe )
 		goto _test_eof3;
 case 3:
-#line 183 "parser.c"
+#line 522 "parser.c"
 	switch( (*p) ) {
 		case 13: goto st3;
 		case 32: goto st3;
@@ -230,7 +569,7 @@ case 8:
 		case 32: goto st8;
 		case 34: goto tr11;
 		case 45: goto tr11;
-		case 47: goto st19;
+		case 47: goto st24;
 		case 73: goto tr11;
 		case 78: goto tr11;
 		case 91: goto tr11;
@@ -246,19 +585,12 @@ case 8:
 		goto st8;
 	goto st0;
 tr11:
-#line 137 "parser.rl"
+#line 472 "parser.rl"
 	{
-        VALUE v = Qnil;
-        char *np = JSON_parse_value(json, p, pe, &v, current_nesting);
+        char *np = JSON_parse_value(json, p, pe, result, current_nesting);
         if (np == NULL) {
             p--; {p++; cs = 9; goto _out;}
         } else {
-            if (NIL_P(json->object_class)) {
-                OBJ_FREEZE(last_name);
-                rb_hash_aset(*result, last_name, v);
-            } else {
-                rb_funcall(*result, i_aset, 2, last_name, v);
-            }
             {p = (( np))-1;}
         }
     }
@@ -267,16 +599,75 @@ st9:
 	if ( ++p == pe )
 		goto _test_eof9;
 case 9:
-#line 271 "parser.c"
-	switch( (*p) ) {
-		case 13: goto st9;
-		case 32: goto st9;
-		case 44: goto st10;
-		case 47: goto st15;
+#line 603 "parser.c"
+	_widec = (*p);
+	if ( (*p) < 13 ) {
+		if ( (*p) > 9 ) {
+			if ( 10 <= (*p) && (*p) <= 10 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) >= 9 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 13 ) {
+		if ( (*p) < 44 ) {
+			if ( 32 <= (*p) && (*p) <= 32 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) > 44 ) {
+			if ( 47 <= (*p) && (*p) <= 47 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
 		case 125: goto tr4;
-	}
-	if ( 9 <= (*p) && (*p) <= 10 )
-		goto st9;
+		case 269: goto st10;
+		case 288: goto st10;
+		case 300: goto st11;
+		case 303: goto st16;
+		case 525: goto st9;
+		case 544: goto st9;
+		case 556: goto st2;
+		case 559: goto st20;
+	}
+	if ( _widec > 266 ) {
+		if ( 521 <= _widec && _widec <= 522 )
+			goto st9;
+	} else if ( _widec >= 265 )
+		goto st10;
+	goto st0;
+tr4:
+#line 494 "parser.rl"
+	{ p--; {p++; cs = 32; goto _out;} }
+	goto st32;
+st32:
+	if ( ++p == pe )
+		goto _test_eof32;
+case 32:
+#line 671 "parser.c"
 	goto st0;
 st10:
 	if ( ++p == pe )
@@ -285,8 +676,9 @@ case 10:
 	switch( (*p) ) {
 		case 13: goto st10;
 		case 32: goto st10;
-		case 34: goto tr2;
-		case 47: goto st11;
+		case 44: goto st11;
+		case 47: goto st16;
+		case 125: goto tr4;
 	}
 	if ( 9 <= (*p) && (*p) <= 10 )
 		goto st10;
@@ -296,139 +688,288 @@ st11:
 		goto _test_eof11;
 case 11:
 	switch( (*p) ) {
-		case 42: goto st12;
-		case 47: goto st14;
+		case 13: goto st11;
+		case 32: goto st11;
+		case 34: goto tr2;
+		case 47: goto st12;
 	}
+	if ( 9 <= (*p) && (*p) <= 10 )
+		goto st11;
 	goto st0;
 st12:
 	if ( ++p == pe )
 		goto _test_eof12;
 case 12:
-	if ( (*p) == 42 )
-		goto st13;
-	goto st12;
+	switch( (*p) ) {
+		case 42: goto st13;
+		case 47: goto st15;
+	}
+	goto st0;
 st13:
 	if ( ++p == pe )
 		goto _test_eof13;
 case 13:
-	switch( (*p) ) {
-		case 42: goto st13;
-		case 47: goto st10;
-	}
-	goto st12;
+	if ( (*p) == 42 )
+		goto st14;
+	goto st13;
 st14:
 	if ( ++p == pe )
 		goto _test_eof14;
 case 14:
-	if ( (*p) == 10 )
-		goto st10;
-	goto st14;
+	switch( (*p) ) {
+		case 42: goto st14;
+		case 47: goto st11;
+	}
+	goto st13;
 st15:
 	if ( ++p == pe )
 		goto _test_eof15;
 case 15:
-	switch( (*p) ) {
-		case 42: goto st16;
-		case 47: goto st18;
-	}
-	goto st0;
+	if ( (*p) == 10 )
+		goto st11;
+	goto st15;
 st16:
 	if ( ++p == pe )
 		goto _test_eof16;
 case 16:
-	if ( (*p) == 42 )
-		goto st17;
-	goto st16;
+	switch( (*p) ) {
+		case 42: goto st17;
+		case 47: goto st19;
+	}
+	goto st0;
 st17:
 	if ( ++p == pe )
 		goto _test_eof17;
 case 17:
-	switch( (*p) ) {
-		case 42: goto st17;
-		case 47: goto st9;
-	}
-	goto st16;
+	if ( (*p) == 42 )
+		goto st18;
+	goto st17;
 st18:
 	if ( ++p == pe )
 		goto _test_eof18;
 case 18:
-	if ( (*p) == 10 )
-		goto st9;
-	goto st18;
-tr4:
-#line 161 "parser.rl"
-	{ p--; {p++; cs = 27; goto _out;} }
-	goto st27;
-st27:
-	if ( ++p == pe )
-		goto _test_eof27;
-case 27:
-#line 367 "parser.c"
-	goto st0;
+	switch( (*p) ) {
+		case 42: goto st18;
+		case 47: goto st10;
+	}
+	goto st17;
 st19:
 	if ( ++p == pe )
 		goto _test_eof19;
 case 19:
-	switch( (*p) ) {
-		case 42: goto st20;
-		case 47: goto st22;
-	}
-	goto st0;
+	if ( (*p) == 10 )
+		goto st10;
+	goto st19;
 st20:
 	if ( ++p == pe )
 		goto _test_eof20;
 case 20:
-	if ( (*p) == 42 )
-		goto st21;
-	goto st20;
+	_widec = (*p);
+	if ( (*p) > 42 ) {
+		if ( 47 <= (*p) && (*p) <= 47 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) >= 42 ) {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st17;
+		case 303: goto st19;
+		case 554: goto st21;
+		case 559: goto st23;
+	}
+	goto st0;
 st21:
 	if ( ++p == pe )
 		goto _test_eof21;
 case 21:
-	switch( (*p) ) {
-		case 42: goto st21;
-		case 47: goto st8;
-	}
-	goto st20;
+	_widec = (*p);
+	if ( (*p) < 42 ) {
+		if ( (*p) <= 41 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 42 ) {
+		if ( 43 <= (*p) )
+ {			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st18;
+		case 554: goto st22;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st21;
+	} else if ( _widec >= 128 )
+		goto st17;
+	goto st0;
 st22:
 	if ( ++p == pe )
 		goto _test_eof22;
 case 22:
-	if ( (*p) == 10 )
-		goto st8;
-	goto st22;
+	_widec = (*p);
+	if ( (*p) < 43 ) {
+		if ( (*p) > 41 ) {
+			if ( 42 <= (*p) && (*p) <= 42 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 46 ) {
+		if ( (*p) > 47 ) {
+			if ( 48 <= (*p) )
+ {				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) >= 47 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st18;
+		case 303: goto st10;
+		case 554: goto st22;
+		case 559: goto st9;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st21;
+	} else if ( _widec >= 128 )
+		goto st17;
+	goto st0;
 st23:
 	if ( ++p == pe )
 		goto _test_eof23;
 case 23:
-	switch( (*p) ) {
-		case 42: goto st24;
-		case 47: goto st26;
-	}
+	_widec = (*p);
+	if ( (*p) < 10 ) {
+		if ( (*p) <= 9 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 10 ) {
+		if ( 11 <= (*p) )
+ {			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 481 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 266: goto st10;
+		case 522: goto st9;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st23;
+	} else if ( _widec >= 128 )
+		goto st19;
 	goto st0;
 st24:
 	if ( ++p == pe )
 		goto _test_eof24;
 case 24:
-	if ( (*p) == 42 )
-		goto st25;
-	goto st24;
+	switch( (*p) ) {
+		case 42: goto st25;
+		case 47: goto st27;
+	}
+	goto st0;
 st25:
 	if ( ++p == pe )
 		goto _test_eof25;
 case 25:
-	switch( (*p) ) {
-		case 42: goto st25;
-		case 47: goto st2;
-	}
-	goto st24;
+	if ( (*p) == 42 )
+		goto st26;
+	goto st25;
 st26:
 	if ( ++p == pe )
 		goto _test_eof26;
 case 26:
+	switch( (*p) ) {
+		case 42: goto st26;
+		case 47: goto st8;
+	}
+	goto st25;
+st27:
+	if ( ++p == pe )
+		goto _test_eof27;
+case 27:
+	if ( (*p) == 10 )
+		goto st8;
+	goto st27;
+st28:
+	if ( ++p == pe )
+		goto _test_eof28;
+case 28:
+	switch( (*p) ) {
+		case 42: goto st29;
+		case 47: goto st31;
+	}
+	goto st0;
+st29:
+	if ( ++p == pe )
+		goto _test_eof29;
+case 29:
+	if ( (*p) == 42 )
+		goto st30;
+	goto st29;
+st30:
+	if ( ++p == pe )
+		goto _test_eof30;
+case 30:
+	switch( (*p) ) {
+		case 42: goto st30;
+		case 47: goto st2;
+	}
+	goto st29;
+st31:
+	if ( ++p == pe )
+		goto _test_eof31;
+case 31:
 	if ( (*p) == 10 )
 		goto st2;
-	goto st26;
+	goto st31;
 	}
 	_test_eof2: cs = 2; goto _test_eof;
 	_test_eof3: cs = 3; goto _test_eof;
@@ -438,6 +979,7 @@ case 26:
 	_test_eof7: cs = 7; goto _test_eof;
 	_test_eof8: cs = 8; goto _test_eof;
 	_test_eof9: cs = 9; goto _test_eof;
+	_test_eof32: cs = 32; goto _test_eof;
 	_test_eof10: cs = 10; goto _test_eof;
 	_test_eof11: cs = 11; goto _test_eof;
 	_test_eof12: cs = 12; goto _test_eof;
@@ -447,7 +989,6 @@ case 26:
 	_test_eof16: cs = 16; goto _test_eof;
 	_test_eof17: cs = 17; goto _test_eof;
 	_test_eof18: cs = 18; goto _test_eof;
-	_test_eof27: cs = 27; goto _test_eof;
 	_test_eof19: cs = 19; goto _test_eof;
 	_test_eof20: cs = 20; goto _test_eof;
 	_test_eof21: cs = 21; goto _test_eof;
@@ -456,20 +997,49 @@ case 26:
 	_test_eof24: cs = 24; goto _test_eof;
 	_test_eof25: cs = 25; goto _test_eof;
 	_test_eof26: cs = 26; goto _test_eof;
+	_test_eof27: cs = 27; goto _test_eof;
+	_test_eof28: cs = 28; goto _test_eof;
+	_test_eof29: cs = 29; goto _test_eof;
+	_test_eof30: cs = 30; goto _test_eof;
+	_test_eof31: cs = 31; goto _test_eof;
 
 	_test_eof: {}
 	_out: {}
 	}
 
-#line 187 "parser.rl"
+#line 520 "parser.rl"
 
     if (cs >= JSON_object_first_final) {
-        if (json->create_additions) {
+        long count = json->stack->head - stack_head;
+
+        if (RB_UNLIKELY(json->object_class)) {
+            VALUE object = rb_class_new_instance(0, 0, json->object_class);
+            long index = 0;
+            VALUE *items = rvalue_stack_peek(json->stack, count);
+            while (index < count) {
+                VALUE name = items[index++];
+                VALUE value = items[index++];
+                rb_funcall(object, i_aset, 2, name, value);
+            }
+            *result = object;
+        } else {
+            VALUE hash;
+#ifdef HAVE_RB_HASH_NEW_CAPA
+            hash = rb_hash_new_capa(count >> 1);
+#else
+            hash = rb_hash_new();
+#endif
+            rb_hash_bulk_insert(count, rvalue_stack_peek(json->stack, count), hash);
+            *result = hash;
+        }
+        rvalue_stack_pop(json->stack, count);
+
+        if (RB_UNLIKELY(json->create_additions)) {
             VALUE klassname;
-            if (NIL_P(json->object_class)) {
-              klassname = rb_hash_aref(*result, json->create_id);
+            if (json->object_class) {
+                klassname = rb_funcall(*result, i_aref, 1, json->create_id);
             } else {
-              klassname = rb_funcall(*result, i_aref, 1, json->create_id);
+                klassname = rb_hash_aref(*result, json->create_id);
             }
             if (!NIL_P(klassname)) {
                 VALUE klass = rb_funcall(mJSON, i_deep_const_get, 1, klassname);
@@ -488,8 +1058,7 @@ case 26:
 }
 
 
-
-#line 493 "parser.c"
+#line 1062 "parser.c"
 enum {JSON_value_start = 1};
 enum {JSON_value_first_final = 29};
 enum {JSON_value_error = 0};
@@ -497,7 +1066,7 @@ enum {JSON_value_error = 0};
 enum {JSON_value_en_main = 1};
 
 
-#line 290 "parser.rl"
+#line 655 "parser.rl"
 
 
 static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting)
@@ -505,14 +1074,14 @@ static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *resul
     int cs = EVIL;
 
 
-#line 509 "parser.c"
+#line 1078 "parser.c"
 	{
 	cs = JSON_value_start;
 	}
 
-#line 297 "parser.rl"
+#line 662 "parser.rl"
 
-#line 516 "parser.c"
+#line 1085 "parser.c"
 	{
 	if ( p == pe )
 		goto _test_eof;
@@ -546,14 +1115,19 @@ st0:
 cs = 0;
 	goto _out;
 tr2:
-#line 242 "parser.rl"
+#line 598 "parser.rl"
 	{
         char *np = JSON_parse_string(json, p, pe, result);
-        if (np == NULL) { p--; {p++; cs = 29; goto _out;} } else {p = (( np))-1;}
+        if (np == NULL) {
+            p--;
+            {p++; cs = 29; goto _out;}
+        } else {
+            {p = (( np))-1;}
+        }
     }
 	goto st29;
 tr3:
-#line 247 "parser.rl"
+#line 608 "parser.rl"
 	{
         char *np;
         if(pe > p + 8 && !strncmp(MinusInfinity, p, 9)) {
@@ -566,14 +1140,18 @@ tr3:
             }
         }
         np = JSON_parse_float(json, p, pe, result);
-        if (np != NULL) {p = (( np))-1;}
+        if (np != NULL) {
+            {p = (( np))-1;}
+        }
         np = JSON_parse_integer(json, p, pe, result);
-        if (np != NULL) {p = (( np))-1;}
+        if (np != NULL) {
+            {p = (( np))-1;}
+        }
         p--; {p++; cs = 29; goto _out;}
     }
 	goto st29;
 tr7:
-#line 265 "parser.rl"
+#line 630 "parser.rl"
 	{
         char *np;
         np = JSON_parse_array(json, p, pe, result, current_nesting + 1);
@@ -581,7 +1159,7 @@ tr7:
     }
 	goto st29;
 tr11:
-#line 271 "parser.rl"
+#line 636 "parser.rl"
 	{
         char *np;
         np =  JSON_parse_object(json, p, pe, result, current_nesting + 1);
@@ -589,7 +1167,7 @@ tr11:
     }
 	goto st29;
 tr25:
-#line 235 "parser.rl"
+#line 591 "parser.rl"
 	{
         if (json->allow_nan) {
             *result = CInfinity;
@@ -599,7 +1177,7 @@ tr25:
     }
 	goto st29;
 tr27:
-#line 228 "parser.rl"
+#line 584 "parser.rl"
 	{
         if (json->allow_nan) {
             *result = CNaN;
@@ -609,19 +1187,19 @@ tr27:
     }
 	goto st29;
 tr31:
-#line 222 "parser.rl"
+#line 578 "parser.rl"
 	{
         *result = Qfalse;
     }
 	goto st29;
 tr34:
-#line 219 "parser.rl"
+#line 575 "parser.rl"
 	{
         *result = Qnil;
     }
 	goto st29;
 tr37:
-#line 225 "parser.rl"
+#line 581 "parser.rl"
 	{
         *result = Qtrue;
     }
@@ -630,9 +1208,9 @@ st29:
 	if ( ++p == pe )
 		goto _test_eof29;
 case 29:
-#line 277 "parser.rl"
+#line 642 "parser.rl"
 	{ p--; {p++; cs = 29; goto _out;} }
-#line 636 "parser.c"
+#line 1214 "parser.c"
 	switch( (*p) ) {
 		case 13: goto st29;
 		case 32: goto st29;
@@ -873,13 +1451,14 @@ case 28:
 	_out: {}
 	}
 
-#line 298 "parser.rl"
+#line 663 "parser.rl"
 
     if (json->freeze) {
         OBJ_FREEZE(*result);
     }
 
     if (cs >= JSON_value_first_final) {
+        PUSH(*result);
         return p;
     } else {
         return NULL;
@@ -887,7 +1466,7 @@ case 28:
 }
 
 
-#line 891 "parser.c"
+#line 1470 "parser.c"
 enum {JSON_integer_start = 1};
 enum {JSON_integer_first_final = 3};
 enum {JSON_integer_error = 0};
@@ -895,7 +1474,7 @@ enum {JSON_integer_error = 0};
 enum {JSON_integer_en_main = 1};
 
 
-#line 318 "parser.rl"
+#line 684 "parser.rl"
 
 
 static char *JSON_parse_integer(JSON_Parser *json, char *p, char *pe, VALUE *result)
@@ -903,15 +1482,15 @@ static char *JSON_parse_integer(JSON_Parser *json, char *p, char *pe, VALUE *res
     int cs = EVIL;
 
 
-#line 907 "parser.c"
+#line 1486 "parser.c"
 	{
 	cs = JSON_integer_start;
 	}
 
-#line 325 "parser.rl"
+#line 691 "parser.rl"
     json->memo = p;
 
-#line 915 "parser.c"
+#line 1494 "parser.c"
 	{
 	if ( p == pe )
 		goto _test_eof;
@@ -945,14 +1524,14 @@ case 3:
 		goto st0;
 	goto tr4;
 tr4:
-#line 315 "parser.rl"
+#line 681 "parser.rl"
 	{ p--; {p++; cs = 4; goto _out;} }
 	goto st4;
 st4:
 	if ( ++p == pe )
 		goto _test_eof4;
 case 4:
-#line 956 "parser.c"
+#line 1535 "parser.c"
 	goto st0;
 st5:
 	if ( ++p == pe )
@@ -971,7 +1550,7 @@ case 5:
 	_out: {}
 	}
 
-#line 327 "parser.rl"
+#line 693 "parser.rl"
 
     if (cs >= JSON_integer_first_final) {
         long len = p - json->memo;
@@ -986,7 +1565,7 @@ case 5:
 }
 
 
-#line 990 "parser.c"
+#line 1569 "parser.c"
 enum {JSON_float_start = 1};
 enum {JSON_float_first_final = 8};
 enum {JSON_float_error = 0};
@@ -994,7 +1573,7 @@ enum {JSON_float_error = 0};
 enum {JSON_float_en_main = 1};
 
 
-#line 352 "parser.rl"
+#line 718 "parser.rl"
 
 
 static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *result)
@@ -1002,15 +1581,15 @@ static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *resul
     int cs = EVIL;
 
 
-#line 1006 "parser.c"
+#line 1585 "parser.c"
 	{
 	cs = JSON_float_start;
 	}
 
-#line 359 "parser.rl"
+#line 725 "parser.rl"
     json->memo = p;
 
-#line 1014 "parser.c"
+#line 1593 "parser.c"
 	{
 	if ( p == pe )
 		goto _test_eof;
@@ -1068,14 +1647,14 @@ case 8:
 		goto st0;
 	goto tr9;
 tr9:
-#line 346 "parser.rl"
+#line 712 "parser.rl"
 	{ p--; {p++; cs = 9; goto _out;} }
 	goto st9;
 st9:
 	if ( ++p == pe )
 		goto _test_eof9;
 case 9:
-#line 1079 "parser.c"
+#line 1658 "parser.c"
 	goto st0;
 st5:
 	if ( ++p == pe )
@@ -1136,12 +1715,12 @@ case 7:
 	_out: {}
 	}
 
-#line 361 "parser.rl"
+#line 727 "parser.rl"
 
     if (cs >= JSON_float_first_final) {
         VALUE mod = Qnil;
         ID method_id = 0;
-        if (!NIL_P(json->decimal_class)) {
+        if (json->decimal_class) {
             if (rb_respond_to(json->decimal_class, i_try_convert)) {
                 mod = json->decimal_class;
                 method_id = i_try_convert;
@@ -1189,37 +1768,37 @@ case 7:
 
 
 
-#line 1193 "parser.c"
+#line 1772 "parser.c"
 enum {JSON_array_start = 1};
-enum {JSON_array_first_final = 17};
+enum {JSON_array_first_final = 22};
 enum {JSON_array_error = 0};
 
 enum {JSON_array_en_main = 1};
 
 
-#line 441 "parser.rl"
+#line 804 "parser.rl"
 
 
 static char *JSON_parse_array(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting)
 {
     int cs = EVIL;
-    VALUE array_class = json->array_class;
 
     if (json->max_nesting && current_nesting > json->max_nesting) {
         rb_raise(eNestingError, "nesting of %d is too deep", current_nesting);
     }
-    *result = NIL_P(array_class) ? rb_ary_new() : rb_class_new_instance(0, 0, array_class);
+    long stack_head = json->stack->head;
 
 
-#line 1215 "parser.c"
+#line 1793 "parser.c"
 	{
 	cs = JSON_array_start;
 	}
 
-#line 454 "parser.rl"
+#line 816 "parser.rl"
 
-#line 1222 "parser.c"
+#line 1800 "parser.c"
 	{
+	short _widec;
 	if ( p == pe )
 		goto _test_eof;
 	switch ( cs )
@@ -1240,7 +1819,7 @@ case 2:
 		case 32: goto st2;
 		case 34: goto tr2;
 		case 45: goto tr2;
-		case 47: goto st13;
+		case 47: goto st18;
 		case 73: goto tr2;
 		case 78: goto tr2;
 		case 91: goto tr2;
@@ -1257,18 +1836,13 @@ case 2:
 		goto st2;
 	goto st0;
 tr2:
-#line 418 "parser.rl"
+#line 784 "parser.rl"
 	{
         VALUE v = Qnil;
         char *np = JSON_parse_value(json, p, pe, &v, current_nesting);
         if (np == NULL) {
             p--; {p++; cs = 3; goto _out;}
         } else {
-            if (NIL_P(json->array_class)) {
-                rb_ary_push(*result, v);
-            } else {
-                rb_funcall(*result, i_leftshift, 1, v);
-            }
             {p = (( np))-1;}
         }
     }
@@ -1277,15 +1851,23 @@ st3:
 	if ( ++p == pe )
 		goto _test_eof3;
 case 3:
-#line 1281 "parser.c"
-	switch( (*p) ) {
+#line 1855 "parser.c"
+	_widec = (*p);
+	if ( 44 <= (*p) && (*p) <= 44 ) {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
 		case 13: goto st3;
 		case 32: goto st3;
-		case 44: goto st4;
-		case 47: goto st9;
+		case 47: goto st4;
 		case 93: goto tr4;
+		case 300: goto st8;
+		case 556: goto st13;
 	}
-	if ( 9 <= (*p) && (*p) <= 10 )
+	if ( 9 <= _widec && _widec <= 10 )
 		goto st3;
 	goto st0;
 st4:
@@ -1293,57 +1875,67 @@ st4:
 		goto _test_eof4;
 case 4:
 	switch( (*p) ) {
-		case 13: goto st4;
-		case 32: goto st4;
-		case 34: goto tr2;
-		case 45: goto tr2;
-		case 47: goto st5;
-		case 73: goto tr2;
-		case 78: goto tr2;
-		case 91: goto tr2;
-		case 102: goto tr2;
-		case 110: goto tr2;
-		case 116: goto tr2;
-		case 123: goto tr2;
+		case 42: goto st5;
+		case 47: goto st7;
 	}
-	if ( (*p) > 10 ) {
-		if ( 48 <= (*p) && (*p) <= 57 )
-			goto tr2;
-	} else if ( (*p) >= 9 )
-		goto st4;
 	goto st0;
 st5:
 	if ( ++p == pe )
 		goto _test_eof5;
 case 5:
-	switch( (*p) ) {
-		case 42: goto st6;
-		case 47: goto st8;
-	}
-	goto st0;
+	if ( (*p) == 42 )
+		goto st6;
+	goto st5;
 st6:
 	if ( ++p == pe )
 		goto _test_eof6;
 case 6:
-	if ( (*p) == 42 )
-		goto st7;
-	goto st6;
+	switch( (*p) ) {
+		case 42: goto st6;
+		case 47: goto st3;
+	}
+	goto st5;
 st7:
 	if ( ++p == pe )
 		goto _test_eof7;
 case 7:
-	switch( (*p) ) {
-		case 42: goto st7;
-		case 47: goto st4;
-	}
-	goto st6;
+	if ( (*p) == 10 )
+		goto st3;
+	goto st7;
+tr4:
+#line 796 "parser.rl"
+	{ p--; {p++; cs = 22; goto _out;} }
+	goto st22;
+st22:
+	if ( ++p == pe )
+		goto _test_eof22;
+case 22:
+#line 1914 "parser.c"
+	goto st0;
 st8:
 	if ( ++p == pe )
 		goto _test_eof8;
 case 8:
-	if ( (*p) == 10 )
-		goto st4;
-	goto st8;
+	switch( (*p) ) {
+		case 13: goto st8;
+		case 32: goto st8;
+		case 34: goto tr2;
+		case 45: goto tr2;
+		case 47: goto st9;
+		case 73: goto tr2;
+		case 78: goto tr2;
+		case 91: goto tr2;
+		case 102: goto tr2;
+		case 110: goto tr2;
+		case 116: goto tr2;
+		case 123: goto tr2;
+	}
+	if ( (*p) > 10 ) {
+		if ( 48 <= (*p) && (*p) <= 57 )
+			goto tr2;
+	} else if ( (*p) >= 9 )
+		goto st8;
+	goto st0;
 st9:
 	if ( ++p == pe )
 		goto _test_eof9;
@@ -1366,7 +1958,7 @@ st11:
 case 11:
 	switch( (*p) ) {
 		case 42: goto st11;
-		case 47: goto st3;
+		case 47: goto st8;
 	}
 	goto st10;
 st12:
@@ -1374,50 +1966,252 @@ st12:
 		goto _test_eof12;
 case 12:
 	if ( (*p) == 10 )
-		goto st3;
+		goto st8;
 	goto st12;
-tr4:
-#line 433 "parser.rl"
-	{ p--; {p++; cs = 17; goto _out;} }
-	goto st17;
-st17:
-	if ( ++p == pe )
-		goto _test_eof17;
-case 17:
-#line 1388 "parser.c"
-	goto st0;
 st13:
 	if ( ++p == pe )
 		goto _test_eof13;
 case 13:
-	switch( (*p) ) {
-		case 42: goto st14;
-		case 47: goto st16;
-	}
+	_widec = (*p);
+	if ( (*p) < 13 ) {
+		if ( (*p) > 9 ) {
+			if ( 10 <= (*p) && (*p) <= 10 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) >= 9 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 13 ) {
+		if ( (*p) > 32 ) {
+			if ( 47 <= (*p) && (*p) <= 47 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) >= 32 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 34: goto tr2;
+		case 45: goto tr2;
+		case 73: goto tr2;
+		case 78: goto tr2;
+		case 91: goto tr2;
+		case 93: goto tr4;
+		case 102: goto tr2;
+		case 110: goto tr2;
+		case 116: goto tr2;
+		case 123: goto tr2;
+		case 269: goto st8;
+		case 288: goto st8;
+		case 303: goto st9;
+		case 525: goto st13;
+		case 544: goto st13;
+		case 559: goto st14;
+	}
+	if ( _widec < 265 ) {
+		if ( 48 <= _widec && _widec <= 57 )
+			goto tr2;
+	} else if ( _widec > 266 ) {
+		if ( 521 <= _widec && _widec <= 522 )
+			goto st13;
+	} else
+		goto st8;
 	goto st0;
 st14:
 	if ( ++p == pe )
 		goto _test_eof14;
 case 14:
-	if ( (*p) == 42 )
-		goto st15;
-	goto st14;
+	_widec = (*p);
+	if ( (*p) > 42 ) {
+		if ( 47 <= (*p) && (*p) <= 47 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) >= 42 ) {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st10;
+		case 303: goto st12;
+		case 554: goto st15;
+		case 559: goto st17;
+	}
+	goto st0;
 st15:
 	if ( ++p == pe )
 		goto _test_eof15;
 case 15:
-	switch( (*p) ) {
-		case 42: goto st15;
-		case 47: goto st2;
-	}
-	goto st14;
+	_widec = (*p);
+	if ( (*p) < 42 ) {
+		if ( (*p) <= 41 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 42 ) {
+		if ( 43 <= (*p) )
+ {			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st11;
+		case 554: goto st16;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st15;
+	} else if ( _widec >= 128 )
+		goto st10;
+	goto st0;
 st16:
 	if ( ++p == pe )
 		goto _test_eof16;
 case 16:
+	_widec = (*p);
+	if ( (*p) < 43 ) {
+		if ( (*p) > 41 ) {
+			if ( 42 <= (*p) && (*p) <= 42 ) {
+				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 46 ) {
+		if ( (*p) > 47 ) {
+			if ( 48 <= (*p) )
+ {				_widec = (short)(128 + ((*p) - -128));
+				if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+			}
+		} else if ( (*p) >= 47 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 298: goto st11;
+		case 303: goto st8;
+		case 554: goto st16;
+		case 559: goto st13;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st15;
+	} else if ( _widec >= 128 )
+		goto st10;
+	goto st0;
+st17:
+	if ( ++p == pe )
+		goto _test_eof17;
+case 17:
+	_widec = (*p);
+	if ( (*p) < 10 ) {
+		if ( (*p) <= 9 ) {
+			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else if ( (*p) > 10 ) {
+		if ( 11 <= (*p) )
+ {			_widec = (short)(128 + ((*p) - -128));
+			if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+		}
+	} else {
+		_widec = (short)(128 + ((*p) - -128));
+		if (
+#line 794 "parser.rl"
+ json->allow_trailing_comma  ) _widec += 256;
+	}
+	switch( _widec ) {
+		case 266: goto st8;
+		case 522: goto st13;
+	}
+	if ( _widec > 383 ) {
+		if ( 384 <= _widec && _widec <= 639 )
+			goto st17;
+	} else if ( _widec >= 128 )
+		goto st12;
+	goto st0;
+st18:
+	if ( ++p == pe )
+		goto _test_eof18;
+case 18:
+	switch( (*p) ) {
+		case 42: goto st19;
+		case 47: goto st21;
+	}
+	goto st0;
+st19:
+	if ( ++p == pe )
+		goto _test_eof19;
+case 19:
+	if ( (*p) == 42 )
+		goto st20;
+	goto st19;
+st20:
+	if ( ++p == pe )
+		goto _test_eof20;
+case 20:
+	switch( (*p) ) {
+		case 42: goto st20;
+		case 47: goto st2;
+	}
+	goto st19;
+st21:
+	if ( ++p == pe )
+		goto _test_eof21;
+case 21:
 	if ( (*p) == 10 )
 		goto st2;
-	goto st16;
+	goto st21;
 	}
 	_test_eof2: cs = 2; goto _test_eof;
 	_test_eof3: cs = 3; goto _test_eof;
@@ -1425,24 +2219,45 @@ case 16:
 	_test_eof5: cs = 5; goto _test_eof;
 	_test_eof6: cs = 6; goto _test_eof;
 	_test_eof7: cs = 7; goto _test_eof;
+	_test_eof22: cs = 22; goto _test_eof;
 	_test_eof8: cs = 8; goto _test_eof;
 	_test_eof9: cs = 9; goto _test_eof;
 	_test_eof10: cs = 10; goto _test_eof;
 	_test_eof11: cs = 11; goto _test_eof;
 	_test_eof12: cs = 12; goto _test_eof;
-	_test_eof17: cs = 17; goto _test_eof;
 	_test_eof13: cs = 13; goto _test_eof;
 	_test_eof14: cs = 14; goto _test_eof;
 	_test_eof15: cs = 15; goto _test_eof;
 	_test_eof16: cs = 16; goto _test_eof;
+	_test_eof17: cs = 17; goto _test_eof;
+	_test_eof18: cs = 18; goto _test_eof;
+	_test_eof19: cs = 19; goto _test_eof;
+	_test_eof20: cs = 20; goto _test_eof;
+	_test_eof21: cs = 21; goto _test_eof;
 
 	_test_eof: {}
 	_out: {}
 	}
 
-#line 455 "parser.rl"
+#line 817 "parser.rl"
 
     if(cs >= JSON_array_first_final) {
+        long count = json->stack->head - stack_head;
+
+        if (RB_UNLIKELY(json->array_class)) {
+            VALUE array = rb_class_new_instance(0, 0, json->array_class);
+            VALUE *items = rvalue_stack_peek(json->stack, count);
+            long index;
+            for (index = 0; index < count; index++) {
+                rb_funcall(array, i_leftshift, 1, items[index]);
+            }
+            *result = array;
+        } else {
+            VALUE array = rb_ary_new_from_values(count, rvalue_stack_peek(json->stack, count));
+            *result = array;
+        }
+        rvalue_stack_pop(json->stack, count);
+
         return p + 1;
     } else {
         raise_parse_error("unexpected token at '%s'", p);
@@ -1458,7 +2273,7 @@ static inline VALUE build_string(const char *start, const char *end, bool intern
     VALUE result;
 # ifdef HAVE_RB_ENC_INTERNED_STR
     if (intern) {
-      result = rb_enc_interned_str(start, (long)(end - start), rb_utf8_encoding());
+      result = rb_enc_interned_str(start, (long)(end - start), enc_utf8);
     } else {
       result = rb_utf8_str_new(start, (long)(end - start));
     }
@@ -1476,13 +2291,26 @@ static inline VALUE build_string(const char *start, const char *end, bool intern
     return result;
 }
 
-static VALUE json_string_unescape(char *string, char *stringEnd, bool intern, bool symbolize)
+static VALUE json_string_unescape(JSON_Parser *json, char *string, char *stringEnd, bool is_name, bool intern, bool symbolize)
 {
     size_t bufferSize = stringEnd - string;
     char *p = string, *pe = string, *unescape, *bufferStart, *buffer;
     int unescape_len;
     char buf[4];
 
+    if (is_name) {
+        VALUE cached_key;
+        if (RB_UNLIKELY(symbolize)) {
+            cached_key = rsymbol_cache_fetch(&json->name_cache, string, bufferSize);
+        } else {
+            cached_key = rstring_cache_fetch(&json->name_cache, string, bufferSize);
+        }
+
+        if (RB_LIKELY(cached_key)) {
+            return cached_key;
+        }
+    }
+
     pe = memchr(p, '\\', bufferSize);
     if (RB_LIKELY(pe == NULL)) {
         return build_string(string, stringEnd, intern, symbolize);
@@ -1585,7 +2413,7 @@ static VALUE json_string_unescape(char *string, char *stringEnd, bool intern, bo
 }
 
 
-#line 1589 "parser.c"
+#line 2417 "parser.c"
 enum {JSON_string_start = 1};
 enum {JSON_string_first_final = 8};
 enum {JSON_string_error = 0};
@@ -1593,7 +2421,7 @@ enum {JSON_string_error = 0};
 enum {JSON_string_en_main = 1};
 
 
-#line 617 "parser.rl"
+#line 1008 "parser.rl"
 
 
 static int
@@ -1614,15 +2442,15 @@ static char *JSON_parse_string(JSON_Parser *json, char *p, char *pe, VALUE *resu
     VALUE match_string;
 
 
-#line 1618 "parser.c"
+#line 2446 "parser.c"
 	{
 	cs = JSON_string_start;
 	}
 
-#line 637 "parser.rl"
+#line 1028 "parser.rl"
     json->memo = p;
 
-#line 1626 "parser.c"
+#line 2454 "parser.c"
 	{
 	if ( p == pe )
 		goto _test_eof;
@@ -1647,9 +2475,9 @@ case 2:
 		goto st0;
 	goto st2;
 tr2:
-#line 604 "parser.rl"
+#line 995 "parser.rl"
 	{
-        *result = json_string_unescape(json->memo + 1, p, json->parsing_name || json-> freeze, json->parsing_name && json->symbolize_names);
+        *result = json_string_unescape(json, json->memo + 1, p, json->parsing_name, json->parsing_name || json-> freeze, json->parsing_name && json->symbolize_names);
         if (NIL_P(*result)) {
             p--;
             {p++; cs = 8; goto _out;}
@@ -1657,14 +2485,14 @@ tr2:
             {p = (( p + 1))-1;}
         }
     }
-#line 614 "parser.rl"
+#line 1005 "parser.rl"
 	{ p--; {p++; cs = 8; goto _out;} }
 	goto st8;
 st8:
 	if ( ++p == pe )
 		goto _test_eof8;
 case 8:
-#line 1668 "parser.c"
+#line 2496 "parser.c"
 	goto st0;
 st3:
 	if ( ++p == pe )
@@ -1740,7 +2568,7 @@ case 7:
 	_out: {}
 	}
 
-#line 639 "parser.rl"
+#line 1030 "parser.rl"
 
     if (json->create_additions && RTEST(match_string = json->match_string)) {
           VALUE klass;
@@ -1776,7 +2604,7 @@ static VALUE convert_encoding(VALUE source)
 {
   int encindex = RB_ENCODING_GET(source);
 
-  if (encindex == utf8_encindex) {
+  if (RB_LIKELY(encindex == utf8_encindex)) {
     return source;
   }
 
@@ -1788,6 +2616,68 @@ static VALUE convert_encoding(VALUE source)
   return rb_funcall(source, i_encode, 1, Encoding_UTF_8);
 }
 
+static int configure_parser_i(VALUE key, VALUE val, VALUE data)
+{
+    JSON_Parser *json = (JSON_Parser *)data;
+
+         if (key == sym_max_nesting)          { json->max_nesting = RTEST(val) ? FIX2INT(val) : 0; }
+    else if (key == sym_allow_nan)            { json->allow_nan = RTEST(val); }
+    else if (key == sym_allow_trailing_comma) { json->allow_trailing_comma = RTEST(val); }
+    else if (key == sym_symbolize_names)      { json->symbolize_names = RTEST(val); }
+    else if (key == sym_freeze)               { json->freeze = RTEST(val); }
+    else if (key == sym_create_id)            { json->create_id = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_object_class)         { json->object_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_array_class)          { json->array_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_decimal_class)        { json->decimal_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_match_string)         { json->match_string = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_create_additions)     {
+        if (NIL_P(val)) {
+            json->create_additions = true;
+            json->deprecated_create_additions = true;
+        } else {
+            json->create_additions = RTEST(val);
+            json->deprecated_create_additions = false;
+        }
+    }
+
+    return ST_CONTINUE;
+}
+
+static void parser_init(JSON_Parser *json, VALUE source, VALUE opts)
+{
+    if (json->Vsource) {
+        rb_raise(rb_eTypeError, "already initialized instance");
+    }
+
+    json->fbuffer.initial_length = FBUFFER_INITIAL_LENGTH_DEFAULT;
+    json->max_nesting = 100;
+
+    if (!NIL_P(opts)) {
+        Check_Type(opts, T_HASH);
+        if (RHASH_SIZE(opts) > 0) {
+            // We assume in most cases few keys are set so it's faster to go over
+            // the provided keys than to check all possible keys.
+            rb_hash_foreach(opts, configure_parser_i, (VALUE)json);
+
+            if (json->symbolize_names && json->create_additions) {
+                rb_raise(rb_eArgError,
+                    "options :symbolize_names and :create_additions cannot be "
+                    " used in conjunction");
+            }
+
+            if (json->create_additions && !json->create_id) {
+                json->create_id = rb_funcall(mJSON, i_create_id, 0);
+            }
+        }
+
+    }
+    source = convert_encoding(StringValue(source));
+    StringValue(source);
+    json->len = RSTRING_LEN(source);
+    json->source = RSTRING_PTR(source);
+    json->Vsource = source;
+}
+
 /*
  * call-seq: new(source, opts => {})
  *
@@ -1822,122 +2712,16 @@ static VALUE convert_encoding(VALUE source)
  */
 static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self)
 {
-    VALUE source, opts;
     GET_PARSER_INIT;
 
-    if (json->Vsource) {
-        rb_raise(rb_eTypeError, "already initialized instance");
-    }
-
     rb_check_arity(argc, 1, 2);
-    source = argv[0];
-    opts = Qnil;
-    if (argc == 2) {
-        opts = argv[1];
-        Check_Type(argv[1], T_HASH);
-        if (RHASH_SIZE(argv[1]) > 0) {
-            opts = argv[1];
-        }
-    }
 
-    if (!NIL_P(opts)) {
-        VALUE tmp = ID2SYM(i_max_nesting);
-        if (option_given_p(opts, tmp)) {
-            VALUE max_nesting = rb_hash_aref(opts, tmp);
-            if (RTEST(max_nesting)) {
-                Check_Type(max_nesting, T_FIXNUM);
-                json->max_nesting = FIX2INT(max_nesting);
-            } else {
-                json->max_nesting = 0;
-            }
-        } else {
-            json->max_nesting = 100;
-        }
-        tmp = ID2SYM(i_allow_nan);
-        if (option_given_p(opts, tmp)) {
-            json->allow_nan = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->allow_nan = 0;
-        }
-        tmp = ID2SYM(i_symbolize_names);
-        if (option_given_p(opts, tmp)) {
-            json->symbolize_names = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->symbolize_names = 0;
-        }
-        tmp = ID2SYM(i_freeze);
-        if (option_given_p(opts, tmp)) {
-            json->freeze = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->freeze = 0;
-        }
-        tmp = ID2SYM(i_create_additions);
-        if (option_given_p(opts, tmp)) {
-            tmp = rb_hash_aref(opts, tmp);
-            if (NIL_P(tmp)) {
-                json->create_additions = 1;
-                json->deprecated_create_additions = 1;
-            } else {
-                json->create_additions = RTEST(tmp);
-                json->deprecated_create_additions = 0;
-            }
-        }
-
-        if (json->symbolize_names && json->create_additions) {
-            rb_raise(rb_eArgError,
-                "options :symbolize_names and :create_additions cannot be "
-                " used in conjunction");
-        }
-        tmp = ID2SYM(i_create_id);
-        if (option_given_p(opts, tmp)) {
-            json->create_id = rb_hash_aref(opts, tmp);
-        } else {
-            json->create_id = rb_funcall(mJSON, i_create_id, 0);
-        }
-        tmp = ID2SYM(i_object_class);
-        if (option_given_p(opts, tmp)) {
-            json->object_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->object_class = Qnil;
-        }
-        tmp = ID2SYM(i_array_class);
-        if (option_given_p(opts, tmp)) {
-            json->array_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->array_class = Qnil;
-        }
-        tmp = ID2SYM(i_decimal_class);
-        if (option_given_p(opts, tmp)) {
-            json->decimal_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->decimal_class = Qnil;
-        }
-        tmp = ID2SYM(i_match_string);
-        if (option_given_p(opts, tmp)) {
-            VALUE match_string = rb_hash_aref(opts, tmp);
-            json->match_string = RTEST(match_string) ? match_string : Qnil;
-        } else {
-            json->match_string = Qnil;
-        }
-    } else {
-        json->max_nesting = 100;
-        json->allow_nan = 0;
-        json->create_additions = 0;
-        json->create_id = Qnil;
-        json->object_class = Qnil;
-        json->array_class = Qnil;
-        json->decimal_class = Qnil;
-    }
-    source = convert_encoding(StringValue(source));
-    StringValue(source);
-    json->len = RSTRING_LEN(source);
-    json->source = RSTRING_PTR(source);
-    json->Vsource = source;
+    parser_init(json, argv[0], argc == 2 ? argv[1] : Qnil);
     return self;
 }
 
 
-#line 1941 "parser.c"
+#line 2725 "parser.c"
 enum {JSON_start = 1};
 enum {JSON_first_final = 10};
 enum {JSON_error = 0};
@@ -1945,7 +2729,7 @@ enum {JSON_error = 0};
 enum {JSON_en_main = 1};
 
 
-#line 849 "parser.rl"
+#line 1196 "parser.rl"
 
 
 /*
@@ -1962,17 +2746,28 @@ static VALUE cParser_parse(VALUE self)
     VALUE result = Qnil;
     GET_PARSER;
 
+    char stack_buffer[FBUFFER_STACK_SIZE];
+    fbuffer_stack_init(&json->fbuffer, FBUFFER_INITIAL_LENGTH_DEFAULT, stack_buffer, FBUFFER_STACK_SIZE);
+
+    VALUE rvalue_stack_buffer[RVALUE_STACK_INITIAL_CAPA];
+    rvalue_stack stack = {
+        .type = RVALUE_STACK_STACK_ALLOCATED,
+        .ptr = rvalue_stack_buffer,
+        .capa = RVALUE_STACK_INITIAL_CAPA,
+    };
+    json->stack = &stack;
 
-#line 1967 "parser.c"
+
+#line 2762 "parser.c"
 	{
 	cs = JSON_start;
 	}
 
-#line 866 "parser.rl"
+#line 1224 "parser.rl"
     p = json->source;
     pe = p + json->len;
 
-#line 1976 "parser.c"
+#line 2771 "parser.c"
 	{
 	if ( p == pe )
 		goto _test_eof;
@@ -2006,7 +2801,7 @@ st0:
 cs = 0;
 	goto _out;
 tr2:
-#line 841 "parser.rl"
+#line 1188 "parser.rl"
 	{
         char *np = JSON_parse_value(json, p, pe, &result, 0);
         if (np == NULL) { p--; {p++; cs = 10; goto _out;} } else {p = (( np))-1;}
@@ -2016,7 +2811,7 @@ st10:
 	if ( ++p == pe )
 		goto _test_eof10;
 case 10:
-#line 2020 "parser.c"
+#line 2815 "parser.c"
 	switch( (*p) ) {
 		case 13: goto st10;
 		case 32: goto st10;
@@ -2105,7 +2900,11 @@ case 9:
 	_out: {}
 	}
 
-#line 869 "parser.rl"
+#line 1227 "parser.rl"
+
+    if (json->stack_handle) {
+        rvalue_stack_eagerly_release(json->stack_handle);
+    }
 
     if (cs >= JSON_first_final && p == pe) {
         return result;
@@ -2115,18 +2914,183 @@ case 9:
     }
 }
 
-#ifndef HAVE_RB_GC_MARK_LOCATIONS
-// For TruffleRuby
-void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+static VALUE cParser_m_parse(VALUE klass, VALUE source, VALUE opts)
 {
-    VALUE *value = start;
+    char *p, *pe;
+    int cs = EVIL;
+    VALUE result = Qnil;
 
-    while (value < end) {
-        rb_gc_mark(*value);
-        value++;
+    JSON_Parser _parser = {0};
+    JSON_Parser *json = &_parser;
+    parser_init(json, source, opts);
+
+    char stack_buffer[FBUFFER_STACK_SIZE];
+    fbuffer_stack_init(&json->fbuffer, FBUFFER_INITIAL_LENGTH_DEFAULT, stack_buffer, FBUFFER_STACK_SIZE);
+
+    VALUE rvalue_stack_buffer[RVALUE_STACK_INITIAL_CAPA];
+    rvalue_stack stack = {
+        .type = RVALUE_STACK_STACK_ALLOCATED,
+        .ptr = rvalue_stack_buffer,
+        .capa = RVALUE_STACK_INITIAL_CAPA,
+    };
+    json->stack = &stack;
+
+
+#line 2940 "parser.c"
+	{
+	cs = JSON_start;
+	}
+
+#line 1262 "parser.rl"
+    p = json->source;
+    pe = p + json->len;
+
+#line 2949 "parser.c"
+	{
+	if ( p == pe )
+		goto _test_eof;
+	switch ( cs )
+	{
+st1:
+	if ( ++p == pe )
+		goto _test_eof1;
+case 1:
+	switch( (*p) ) {
+		case 13: goto st1;
+		case 32: goto st1;
+		case 34: goto tr2;
+		case 45: goto tr2;
+		case 47: goto st6;
+		case 73: goto tr2;
+		case 78: goto tr2;
+		case 91: goto tr2;
+		case 102: goto tr2;
+		case 110: goto tr2;
+		case 116: goto tr2;
+		case 123: goto tr2;
+	}
+	if ( (*p) > 10 ) {
+		if ( 48 <= (*p) && (*p) <= 57 )
+			goto tr2;
+	} else if ( (*p) >= 9 )
+		goto st1;
+	goto st0;
+st0:
+cs = 0;
+	goto _out;
+tr2:
+#line 1188 "parser.rl"
+	{
+        char *np = JSON_parse_value(json, p, pe, &result, 0);
+        if (np == NULL) { p--; {p++; cs = 10; goto _out;} } else {p = (( np))-1;}
+    }
+	goto st10;
+st10:
+	if ( ++p == pe )
+		goto _test_eof10;
+case 10:
+#line 2993 "parser.c"
+	switch( (*p) ) {
+		case 13: goto st10;
+		case 32: goto st10;
+		case 47: goto st2;
+	}
+	if ( 9 <= (*p) && (*p) <= 10 )
+		goto st10;
+	goto st0;
+st2:
+	if ( ++p == pe )
+		goto _test_eof2;
+case 2:
+	switch( (*p) ) {
+		case 42: goto st3;
+		case 47: goto st5;
+	}
+	goto st0;
+st3:
+	if ( ++p == pe )
+		goto _test_eof3;
+case 3:
+	if ( (*p) == 42 )
+		goto st4;
+	goto st3;
+st4:
+	if ( ++p == pe )
+		goto _test_eof4;
+case 4:
+	switch( (*p) ) {
+		case 42: goto st4;
+		case 47: goto st10;
+	}
+	goto st3;
+st5:
+	if ( ++p == pe )
+		goto _test_eof5;
+case 5:
+	if ( (*p) == 10 )
+		goto st10;
+	goto st5;
+st6:
+	if ( ++p == pe )
+		goto _test_eof6;
+case 6:
+	switch( (*p) ) {
+		case 42: goto st7;
+		case 47: goto st9;
+	}
+	goto st0;
+st7:
+	if ( ++p == pe )
+		goto _test_eof7;
+case 7:
+	if ( (*p) == 42 )
+		goto st8;
+	goto st7;
+st8:
+	if ( ++p == pe )
+		goto _test_eof8;
+case 8:
+	switch( (*p) ) {
+		case 42: goto st8;
+		case 47: goto st1;
+	}
+	goto st7;
+st9:
+	if ( ++p == pe )
+		goto _test_eof9;
+case 9:
+	if ( (*p) == 10 )
+		goto st1;
+	goto st9;
+	}
+	_test_eof1: cs = 1; goto _test_eof;
+	_test_eof10: cs = 10; goto _test_eof;
+	_test_eof2: cs = 2; goto _test_eof;
+	_test_eof3: cs = 3; goto _test_eof;
+	_test_eof4: cs = 4; goto _test_eof;
+	_test_eof5: cs = 5; goto _test_eof;
+	_test_eof6: cs = 6; goto _test_eof;
+	_test_eof7: cs = 7; goto _test_eof;
+	_test_eof8: cs = 8; goto _test_eof;
+	_test_eof9: cs = 9; goto _test_eof;
+
+	_test_eof: {}
+	_out: {}
+	}
+
+#line 1265 "parser.rl"
+
+    if (json->stack_handle) {
+        rvalue_stack_eagerly_release(json->stack_handle);
+    }
+
+    if (cs >= JSON_first_final && p == pe) {
+        return result;
+    } else {
+        raise_parse_error("unexpected token at '%s'", p);
+        return Qnil;
     }
 }
-#endif
 
 static void JSON_mark(void *ptr)
 {
@@ -2137,6 +3101,8 @@ static void JSON_mark(void *ptr)
     rb_gc_mark(json->array_class);
     rb_gc_mark(json->decimal_class);
     rb_gc_mark(json->match_string);
+    rb_gc_mark(json->stack_handle);
+
     const VALUE *name_cache_entries = &json->name_cache.entries[0];
     rb_gc_mark_locations(name_cache_entries, name_cache_entries + json->name_cache.length);
 }
@@ -2199,6 +3165,8 @@ void Init_parser(void)
     rb_define_method(cParser, "parse", cParser_parse, 0);
     rb_define_method(cParser, "source", cParser_source, 0);
 
+    rb_define_singleton_method(cParser, "parse", cParser_m_parse, 2);
+
     CNaN = rb_const_get(mJSON, rb_intern("NaN"));
     rb_gc_register_mark_object(CNaN);
 
@@ -2211,31 +3179,35 @@ void Init_parser(void)
     rb_global_variable(&Encoding_UTF_8);
     Encoding_UTF_8 = rb_const_get(rb_path2class("Encoding"), rb_intern("UTF_8"));
 
+    sym_max_nesting = ID2SYM(rb_intern("max_nesting"));
+    sym_allow_nan = ID2SYM(rb_intern("allow_nan"));
+    sym_allow_trailing_comma = ID2SYM(rb_intern("allow_trailing_comma"));
+    sym_symbolize_names = ID2SYM(rb_intern("symbolize_names"));
+    sym_freeze = ID2SYM(rb_intern("freeze"));
+    sym_create_additions = ID2SYM(rb_intern("create_additions"));
+    sym_create_id = ID2SYM(rb_intern("create_id"));
+    sym_object_class = ID2SYM(rb_intern("object_class"));
+    sym_array_class = ID2SYM(rb_intern("array_class"));
+    sym_decimal_class = ID2SYM(rb_intern("decimal_class"));
+    sym_match_string = ID2SYM(rb_intern("match_string"));
+
+    i_create_id = rb_intern("create_id");
     i_json_creatable_p = rb_intern("json_creatable?");
     i_json_create = rb_intern("json_create");
-    i_create_id = rb_intern("create_id");
-    i_create_additions = rb_intern("create_additions");
     i_chr = rb_intern("chr");
-    i_max_nesting = rb_intern("max_nesting");
-    i_allow_nan = rb_intern("allow_nan");
-    i_symbolize_names = rb_intern("symbolize_names");
-    i_object_class = rb_intern("object_class");
-    i_array_class = rb_intern("array_class");
-    i_decimal_class = rb_intern("decimal_class");
     i_match = rb_intern("match");
-    i_match_string = rb_intern("match_string");
     i_deep_const_get = rb_intern("deep_const_get");
     i_aset = rb_intern("[]=");
     i_aref = rb_intern("[]");
     i_leftshift = rb_intern("<<");
     i_new = rb_intern("new");
     i_try_convert = rb_intern("try_convert");
-    i_freeze = rb_intern("freeze");
     i_uminus = rb_intern("-@");
     i_encode = rb_intern("encode");
 
     binary_encindex = rb_ascii8bit_encindex();
     utf8_encindex = rb_utf8_encindex();
+    enc_utf8 = rb_utf8_encoding();
 }
 
 /*
diff --git a/ext/json/parser/parser.h b/ext/json/parser/parser.h
deleted file mode 100644
index d1863a2b9a..0000000000
--- a/ext/json/parser/parser.h
+++ /dev/null
@@ -1,78 +0,0 @@
-#ifndef _PARSER_H_
-#define _PARSER_H_
-
-#include "ruby.h"
-
-/* This is the fallback definition from Ruby 3.4 */
-#ifndef RBIMPL_STDBOOL_H
-#if defined(__cplusplus)
-# if defined(HAVE_STDBOOL_H) && (__cplusplus >= 201103L)
-#  include <cstdbool>
-# endif
-#elif defined(HAVE_STDBOOL_H)
-# include <stdbool.h>
-#elif !defined(HAVE__BOOL)
-typedef unsigned char _Bool;
-# define bool  _Bool
-# define true  ((_Bool)+1)
-# define false ((_Bool)+0)
-# define __bool_true_false_are_defined
-#endif
-#endif
-
-#ifndef MAYBE_UNUSED
-# define MAYBE_UNUSED(x) x
-#endif
-
-#define option_given_p(opts, key) (rb_hash_lookup2(opts, key, Qundef) != Qundef)
-
-typedef struct JSON_ParserStruct {
-    VALUE Vsource;
-    char *source;
-    long len;
-    char *memo;
-    VALUE create_id;
-    VALUE object_class;
-    VALUE array_class;
-    VALUE decimal_class;
-    VALUE match_string;
-    FBuffer fbuffer;
-    int max_nesting;
-    char allow_nan;
-    char parsing_name;
-    char symbolize_names;
-    char freeze;
-    char create_additions;
-    char deprecated_create_additions;
-} JSON_Parser;
-
-#define GET_PARSER                          \
-    GET_PARSER_INIT;                        \
-    if (!json->Vsource) rb_raise(rb_eTypeError, "uninitialized instance")
-#define GET_PARSER_INIT                     \
-    JSON_Parser *json;                      \
-    TypedData_Get_Struct(self, JSON_Parser, &JSON_Parser_type, json)
-
-#define MinusInfinity "-Infinity"
-#define EVIL 0x666
-
-static uint32_t unescape_unicode(const unsigned char *p);
-static int convert_UTF32_to_UTF8(char *buf, uint32_t ch);
-static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
-static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
-static char *JSON_parse_integer(JSON_Parser *json, char *p, char *pe, VALUE *result);
-static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *result);
-static char *JSON_parse_array(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
-static VALUE json_string_unescape(char *string, char *stringEnd, bool intern, bool symbolize);
-static char *JSON_parse_string(JSON_Parser *json, char *p, char *pe, VALUE *result);
-static VALUE convert_encoding(VALUE source);
-static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self);
-static VALUE cParser_parse(VALUE self);
-static void JSON_mark(void *json);
-static void JSON_free(void *json);
-static VALUE cJSON_parser_s_allocate(VALUE klass);
-static VALUE cParser_source(VALUE self);
-
-static const rb_data_type_t JSON_Parser_type;
-
-#endif
diff --git a/ext/json/parser/parser.rl b/ext/json/parser/parser.rl
index 15ec2b6843..6d4cc7a5b0 100644
--- a/ext/json/parser/parser.rl
+++ b/ext/json/parser/parser.rl
@@ -1,5 +1,308 @@
+#include "ruby.h"
 #include "../fbuffer/fbuffer.h"
-#include "parser.h"
+
+static VALUE mJSON, mExt, cParser, eNestingError, Encoding_UTF_8;
+static VALUE CNaN, CInfinity, CMinusInfinity;
+
+static ID i_json_creatable_p, i_json_create, i_create_id,
+          i_chr, i_deep_const_get, i_match, i_aset, i_aref,
+          i_leftshift, i_new, i_try_convert, i_uminus, i_encode;
+
+static VALUE sym_max_nesting, sym_allow_nan, sym_allow_trailing_comma, sym_symbolize_names, sym_freeze,
+             sym_create_additions, sym_create_id, sym_object_class, sym_array_class,
+             sym_decimal_class, sym_match_string;
+
+static int binary_encindex;
+static int utf8_encindex;
+
+#ifndef HAVE_RB_GC_MARK_LOCATIONS
+// For TruffleRuby
+void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+{
+    VALUE *value = start;
+
+    while (value < end) {
+        rb_gc_mark(*value);
+        value++;
+    }
+}
+#endif
+
+#ifndef HAVE_RB_HASH_BULK_INSERT
+// For TruffleRuby
+void rb_hash_bulk_insert(long count, const VALUE *pairs, VALUE hash)
+{
+    long index = 0;
+    while (index < count) {
+        VALUE name = pairs[index++];
+        VALUE value = pairs[index++];
+        rb_hash_aset(hash, name, value);
+    }
+    RB_GC_GUARD(hash);
+}
+#endif
+
+/* name cache */
+
+#include <string.h>
+#include <ctype.h>
+
+// Object names are likely to be repeated, and are frozen.
+// As such we can re-use them if we keep a cache of the ones we've seen so far,
+// and save much more expensive lookups into the global fstring table.
+// This cache implementation is deliberately simple, as we're optimizing for compactness,
+// to be able to fit safely on the stack.
+// As such, binary search into a sorted array gives a good tradeoff between compactness and
+// performance.
+#define JSON_RVALUE_CACHE_CAPA 63
+typedef struct rvalue_cache_struct {
+    int length;
+    VALUE entries[JSON_RVALUE_CACHE_CAPA];
+} rvalue_cache;
+
+static rb_encoding *enc_utf8;
+
+#define JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH 55
+
+static inline VALUE build_interned_string(const char *str, const long length)
+{
+# ifdef HAVE_RB_ENC_INTERNED_STR
+    return rb_enc_interned_str(str, length, enc_utf8);
+# else
+    VALUE rstring = rb_utf8_str_new(str, length);
+    return rb_funcall(rb_str_freeze(rstring), i_uminus, 0);
+# endif
+}
+
+static inline VALUE build_symbol(const char *str, const long length)
+{
+    return rb_str_intern(build_interned_string(str, length));
+}
+
+static void rvalue_cache_insert_at(rvalue_cache *cache, int index, VALUE rstring)
+{
+    MEMMOVE(&cache->entries[index + 1], &cache->entries[index], VALUE, cache->length - index);
+    cache->length++;
+    cache->entries[index] = rstring;
+}
+
+static inline int rstring_cache_cmp(const char *str, const long length, VALUE rstring)
+{
+    long rstring_length = RSTRING_LEN(rstring);
+    if (length == rstring_length) {
+        return memcmp(str, RSTRING_PTR(rstring), length);
+    } else {
+        return (int)(length - rstring_length);
+    }
+}
+
+static VALUE rstring_cache_fetch(rvalue_cache *cache, const char *str, const long length)
+{
+    if (RB_UNLIKELY(length > JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH)) {
+        // Common names aren't likely to be very long. So we just don't
+        // cache names above an arbitrary threshold.
+        return Qfalse;
+    }
+
+    if (RB_UNLIKELY(!isalpha(str[0]))) {
+        // Simple heuristic, if the first character isn't a letter,
+        // we're much less likely to see this string again.
+        // We mostly want to cache strings that are likely to be repeated.
+        return Qfalse;
+    }
+
+    int low = 0;
+    int high = cache->length - 1;
+    int mid = 0;
+    int last_cmp = 0;
+
+    while (low <= high) {
+        mid = (high + low) >> 1;
+        VALUE entry = cache->entries[mid];
+        last_cmp = rstring_cache_cmp(str, length, entry);
+
+        if (last_cmp == 0) {
+            return entry;
+        } else if (last_cmp > 0) {
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+    }
+
+    if (RB_UNLIKELY(memchr(str, '\\', length))) {
+        // We assume the overwhelming majority of names don't need to be escaped.
+        // But if they do, we have to fallback to the slow path.
+        return Qfalse;
+    }
+
+    VALUE rstring = build_interned_string(str, length);
+
+    if (cache->length < JSON_RVALUE_CACHE_CAPA) {
+        if (last_cmp > 0) {
+            mid += 1;
+        }
+
+        rvalue_cache_insert_at(cache, mid, rstring);
+    }
+    return rstring;
+}
+
+static VALUE rsymbol_cache_fetch(rvalue_cache *cache, const char *str, const long length)
+{
+    if (RB_UNLIKELY(length > JSON_RVALUE_CACHE_MAX_ENTRY_LENGTH)) {
+        // Common names aren't likely to be very long. So we just don't
+        // cache names above an arbitrary threshold.
+        return Qfalse;
+    }
+
+    if (RB_UNLIKELY(!isalpha(str[0]))) {
+        // Simple heuristic, if the first character isn't a letter,
+        // we're much less likely to see this string again.
+        // We mostly want to cache strings that are likely to be repeated.
+        return Qfalse;
+    }
+
+    int low = 0;
+    int high = cache->length - 1;
+    int mid = 0;
+    int last_cmp = 0;
+
+    while (low <= high) {
+        mid = (high + low) >> 1;
+        VALUE entry = cache->entries[mid];
+        last_cmp = rstring_cache_cmp(str, length, rb_sym2str(entry));
+
+        if (last_cmp == 0) {
+            return entry;
+        } else if (last_cmp > 0) {
+            low = mid + 1;
+        } else {
+            high = mid - 1;
+        }
+    }
+
+    if (RB_UNLIKELY(memchr(str, '\\', length))) {
+        // We assume the overwhelming majority of names don't need to be escaped.
+        // But if they do, we have to fallback to the slow path.
+        return Qfalse;
+    }
+
+    VALUE rsymbol = build_symbol(str, length);
+
+    if (cache->length < JSON_RVALUE_CACHE_CAPA) {
+        if (last_cmp > 0) {
+            mid += 1;
+        }
+
+        rvalue_cache_insert_at(cache, mid, rsymbol);
+    }
+    return rsymbol;
+}
+
+/* rvalue stack */
+
+#define RVALUE_STACK_INITIAL_CAPA 128
+
+enum rvalue_stack_type {
+    RVALUE_STACK_HEAP_ALLOCATED = 0,
+    RVALUE_STACK_STACK_ALLOCATED = 1,
+};
+
+typedef struct rvalue_stack_struct {
+    enum rvalue_stack_type type;
+    long capa;
+    long head;
+    VALUE *ptr;
+} rvalue_stack;
+
+static rvalue_stack *rvalue_stack_spill(rvalue_stack *old_stack, VALUE *handle, rvalue_stack **stack_ref);
+
+static rvalue_stack *rvalue_stack_grow(rvalue_stack *stack, VALUE *handle, rvalue_stack **stack_ref)
+{
+    long required = stack->capa * 2;
+
+    if (stack->type == RVALUE_STACK_STACK_ALLOCATED) {
+        stack = rvalue_stack_spill(stack, handle, stack_ref);
+    } else {
+        REALLOC_N(stack->ptr, VALUE, required);
+        stack->capa = required;
+    }
+    return stack;
+}
+
+static void rvalue_stack_push(rvalue_stack *stack, VALUE value, VALUE *handle, rvalue_stack **stack_ref)
+{
+    if (RB_UNLIKELY(stack->head >= stack->capa)) {
+        stack = rvalue_stack_grow(stack, handle, stack_ref);
+    }
+    stack->ptr[stack->head] = value;
+    stack->head++;
+}
+
+static inline VALUE *rvalue_stack_peek(rvalue_stack *stack, long count)
+{
+    return stack->ptr + (stack->head - count);
+}
+
+static inline void rvalue_stack_pop(rvalue_stack *stack, long count)
+{
+    stack->head -= count;
+}
+
+static void rvalue_stack_mark(void *ptr)
+{
+    rvalue_stack *stack = (rvalue_stack *)ptr;
+    rb_gc_mark_locations(stack->ptr, stack->ptr + stack->head);
+}
+
+static void rvalue_stack_free(void *ptr)
+{
+    rvalue_stack *stack = (rvalue_stack *)ptr;
+    if (stack) {
+        ruby_xfree(stack->ptr);
+        ruby_xfree(stack);
+    }
+}
+
+static size_t rvalue_stack_memsize(const void *ptr)
+{
+    const rvalue_stack *stack = (const rvalue_stack *)ptr;
+    return sizeof(rvalue_stack) + sizeof(VALUE) * stack->capa;
+}
+
+static const rb_data_type_t JSON_Parser_rvalue_stack_type = {
+    "JSON::Ext::Parser/rvalue_stack",
+    {
+        .dmark = rvalue_stack_mark,
+        .dfree = rvalue_stack_free,
+        .dsize = rvalue_stack_memsize,
+    },
+    0, 0,
+    RUBY_TYPED_FREE_IMMEDIATELY,
+};
+
+static rvalue_stack *rvalue_stack_spill(rvalue_stack *old_stack, VALUE *handle, rvalue_stack **stack_ref)
+{
+    rvalue_stack *stack;
+    *handle = TypedData_Make_Struct(0, rvalue_stack, &JSON_Parser_rvalue_stack_type, stack);
+    *stack_ref = stack;
+    MEMCPY(stack, old_stack, rvalue_stack, 1);
+
+    stack->capa = old_stack->capa << 1;
+    stack->ptr = ALLOC_N(VALUE, stack->capa);
+    stack->type = RVALUE_STACK_HEAP_ALLOCATED;
+    MEMCPY(stack->ptr, old_stack->ptr, VALUE, old_stack->head);
+    return stack;
+}
+
+static void rvalue_stack_eagerly_release(VALUE handle)
+{
+    rvalue_stack *stack;
+    TypedData_Get_Struct(handle, rvalue_stack, &JSON_Parser_rvalue_stack_type, stack);
+    RTYPEDDATA_DATA(handle) = NULL;
+    rvalue_stack_free(stack);
+}
 
 /* unicode */
 
@@ -67,6 +370,50 @@ static int convert_UTF32_to_UTF8(char *buf, uint32_t ch)
     return len;
 }
 
+typedef struct JSON_ParserStruct {
+    VALUE Vsource;
+    char *source;
+    long len;
+    char *memo;
+    VALUE create_id;
+    VALUE object_class;
+    VALUE array_class;
+    VALUE decimal_class;
+    VALUE match_string;
+    FBuffer fbuffer;
+    int max_nesting;
+    bool allow_nan;
+    bool allow_trailing_comma;
+    bool parsing_name;
+    bool symbolize_names;
+    bool freeze;
+    bool create_additions;
+    bool deprecated_create_additions;
+    rvalue_cache name_cache;
+    rvalue_stack *stack;
+    VALUE stack_handle;
+} JSON_Parser;
+
+#define GET_PARSER                          \
+    GET_PARSER_INIT;                        \
+    if (!json->Vsource) rb_raise(rb_eTypeError, "uninitialized instance")
+
+#define GET_PARSER_INIT                     \
+    JSON_Parser *json;                      \
+    TypedData_Get_Struct(self, JSON_Parser, &JSON_Parser_type, json)
+
+#define MinusInfinity "-Infinity"
+#define EVIL 0x666
+
+static const rb_data_type_t JSON_Parser_type;
+static char *JSON_parse_string(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+static char *JSON_parse_integer(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *result);
+static char *JSON_parse_array(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting);
+
+
 #define PARSE_ERROR_FRAGMENT_LEN 32
 #ifdef RBIMPL_ATTR_NORETURN
 RBIMPL_ATTR_NORETURN()
@@ -84,21 +431,9 @@ static void raise_parse_error(const char *format, const char *start)
         ptr = buffer;
     }
 
-    rb_enc_raise(rb_utf8_encoding(), rb_path2class("JSON::ParserError"), format, ptr);
+    rb_enc_raise(enc_utf8, rb_path2class("JSON::ParserError"), format, ptr);
 }
 
-static VALUE mJSON, mExt, cParser, eNestingError, Encoding_UTF_8;
-static VALUE CNaN, CInfinity, CMinusInfinity;
-
-static ID i_json_creatable_p, i_json_create, i_create_id, i_create_additions,
-          i_chr, i_max_nesting, i_allow_nan, i_symbolize_names,
-          i_object_class, i_array_class, i_decimal_class,
-          i_deep_const_get, i_match, i_match_string, i_aset, i_aref,
-          i_leftshift, i_new, i_try_convert, i_freeze, i_uminus, i_encode;
-
-static int binary_encindex;
-static int utf8_encindex;
-
 
 %%{
     machine JSON_common;
@@ -135,27 +470,25 @@ static int utf8_encindex;
     write data;
 
     action parse_value {
-        VALUE v = Qnil;
-        char *np = JSON_parse_value(json, fpc, pe, &v, current_nesting);
+        char *np = JSON_parse_value(json, fpc, pe, result, current_nesting);
         if (np == NULL) {
             fhold; fbreak;
         } else {
-            if (NIL_P(json->object_class)) {
-                OBJ_FREEZE(last_name);
-                rb_hash_aset(*result, last_name, v);
-            } else {
-                rb_funcall(*result, i_aset, 2, last_name, v);
-            }
             fexec np;
         }
     }
 
+    action allow_trailing_comma { json->allow_trailing_comma }
+
     action parse_name {
         char *np;
-        json->parsing_name = 1;
-        np = JSON_parse_string(json, fpc, pe, &last_name);
-        json->parsing_name = 0;
-        if (np == NULL) { fhold; fbreak; } else fexec np;
+        json->parsing_name = true;
+        np = JSON_parse_string(json, fpc, pe, result);
+        json->parsing_name = false;
+        if (np == NULL) { fhold; fbreak; } else {
+            PUSH(*result);
+            fexec np;
+         }
     }
 
     action exit { fhold; fbreak; }
@@ -165,33 +498,57 @@ static int utf8_encindex;
 
     main := (
       begin_object
-      (pair (next_pair)*)? ignore*
+      (pair (next_pair)*((ignore* value_separator) when allow_trailing_comma)?)? ignore*
       end_object
     ) @exit;
 }%%
 
+#define PUSH(result) rvalue_stack_push(json->stack, result, &json->stack_handle, &json->stack)
+
 static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting)
 {
     int cs = EVIL;
-    VALUE last_name = Qnil;
-    VALUE object_class = json->object_class;
 
     if (json->max_nesting && current_nesting > json->max_nesting) {
         rb_raise(eNestingError, "nesting of %d is too deep", current_nesting);
     }
 
-    *result = NIL_P(object_class) ? rb_hash_new() : rb_class_new_instance(0, 0, object_class);
+    long stack_head = json->stack->head;
 
     %% write init;
     %% write exec;
 
     if (cs >= JSON_object_first_final) {
-        if (json->create_additions) {
+        long count = json->stack->head - stack_head;
+
+        if (RB_UNLIKELY(json->object_class)) {
+            VALUE object = rb_class_new_instance(0, 0, json->object_class);
+            long index = 0;
+            VALUE *items = rvalue_stack_peek(json->stack, count);
+            while (index < count) {
+                VALUE name = items[index++];
+                VALUE value = items[index++];
+                rb_funcall(object, i_aset, 2, name, value);
+            }
+            *result = object;
+        } else {
+            VALUE hash;
+#ifdef HAVE_RB_HASH_NEW_CAPA
+            hash = rb_hash_new_capa(count >> 1);
+#else
+            hash = rb_hash_new();
+#endif
+            rb_hash_bulk_insert(count, rvalue_stack_peek(json->stack, count), hash);
+            *result = hash;
+        }
+        rvalue_stack_pop(json->stack, count);
+
+        if (RB_UNLIKELY(json->create_additions)) {
             VALUE klassname;
-            if (NIL_P(json->object_class)) {
-              klassname = rb_hash_aref(*result, json->create_id);
+            if (json->object_class) {
+                klassname = rb_funcall(*result, i_aref, 1, json->create_id);
             } else {
-              klassname = rb_funcall(*result, i_aref, 1, json->create_id);
+                klassname = rb_hash_aref(*result, json->create_id);
             }
             if (!NIL_P(klassname)) {
                 VALUE klass = rb_funcall(mJSON, i_deep_const_get, 1, klassname);
@@ -209,7 +566,6 @@ static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *resu
     }
 }
 
-
 %%{
     machine JSON_value;
     include JSON_common;
@@ -241,7 +597,12 @@ static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *resu
     }
     action parse_string {
         char *np = JSON_parse_string(json, fpc, pe, result);
-        if (np == NULL) { fhold; fbreak; } else fexec np;
+        if (np == NULL) {
+            fhold;
+            fbreak;
+        } else {
+            fexec np;
+        }
     }
 
     action parse_number {
@@ -256,9 +617,13 @@ static char *JSON_parse_object(JSON_Parser *json, char *p, char *pe, VALUE *resu
             }
         }
         np = JSON_parse_float(json, fpc, pe, result);
-        if (np != NULL) fexec np;
+        if (np != NULL) {
+            fexec np;
+        }
         np = JSON_parse_integer(json, fpc, pe, result);
-        if (np != NULL) fexec np;
+        if (np != NULL) {
+            fexec np;
+        }
         fhold; fbreak;
     }
 
@@ -301,6 +666,7 @@ static char *JSON_parse_value(JSON_Parser *json, char *p, char *pe, VALUE *resul
     }
 
     if (cs >= JSON_value_first_final) {
+        PUSH(*result);
         return p;
     } else {
         return NULL;
@@ -362,7 +728,7 @@ static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *resul
     if (cs >= JSON_float_first_final) {
         VALUE mod = Qnil;
         ID method_id = 0;
-        if (!NIL_P(json->decimal_class)) {
+        if (json->decimal_class) {
             if (rb_respond_to(json->decimal_class, i_try_convert)) {
                 mod = json->decimal_class;
                 method_id = i_try_convert;
@@ -421,39 +787,51 @@ static char *JSON_parse_float(JSON_Parser *json, char *p, char *pe, VALUE *resul
         if (np == NULL) {
             fhold; fbreak;
         } else {
-            if (NIL_P(json->array_class)) {
-                rb_ary_push(*result, v);
-            } else {
-                rb_funcall(*result, i_leftshift, 1, v);
-            }
             fexec np;
         }
     }
 
+    action allow_trailing_comma { json->allow_trailing_comma }
+
     action exit { fhold; fbreak; }
 
     next_element  = value_separator ignore* begin_value >parse_value;
 
     main := begin_array ignore*
           ((begin_value >parse_value ignore*)
-           (ignore* next_element ignore*)*)?
+          (ignore* next_element ignore*)*((value_separator ignore*) when allow_trailing_comma)?)?
           end_array @exit;
 }%%
 
 static char *JSON_parse_array(JSON_Parser *json, char *p, char *pe, VALUE *result, int current_nesting)
 {
     int cs = EVIL;
-    VALUE array_class = json->array_class;
 
     if (json->max_nesting && current_nesting > json->max_nesting) {
         rb_raise(eNestingError, "nesting of %d is too deep", current_nesting);
     }
-    *result = NIL_P(array_class) ? rb_ary_new() : rb_class_new_instance(0, 0, array_class);
+    long stack_head = json->stack->head;
 
     %% write init;
     %% write exec;
 
     if(cs >= JSON_array_first_final) {
+        long count = json->stack->head - stack_head;
+
+        if (RB_UNLIKELY(json->array_class)) {
+            VALUE array = rb_class_new_instance(0, 0, json->array_class);
+            VALUE *items = rvalue_stack_peek(json->stack, count);
+            long index;
+            for (index = 0; index < count; index++) {
+                rb_funcall(array, i_leftshift, 1, items[index]);
+            }
+            *result = array;
+        } else {
+            VALUE array = rb_ary_new_from_values(count, rvalue_stack_peek(json->stack, count));
+            *result = array;
+        }
+        rvalue_stack_pop(json->stack, count);
+
         return p + 1;
     } else {
         raise_parse_error("unexpected token at '%s'", p);
@@ -469,7 +847,7 @@ static inline VALUE build_string(const char *start, const char *end, bool intern
     VALUE result;
 # ifdef HAVE_RB_ENC_INTERNED_STR
     if (intern) {
-      result = rb_enc_interned_str(start, (long)(end - start), rb_utf8_encoding());
+      result = rb_enc_interned_str(start, (long)(end - start), enc_utf8);
     } else {
       result = rb_utf8_str_new(start, (long)(end - start));
     }
@@ -487,13 +865,26 @@ static inline VALUE build_string(const char *start, const char *end, bool intern
     return result;
 }
 
-static VALUE json_string_unescape(char *string, char *stringEnd, bool intern, bool symbolize)
+static VALUE json_string_unescape(JSON_Parser *json, char *string, char *stringEnd, bool is_name, bool intern, bool symbolize)
 {
     size_t bufferSize = stringEnd - string;
     char *p = string, *pe = string, *unescape, *bufferStart, *buffer;
     int unescape_len;
     char buf[4];
 
+    if (is_name) {
+        VALUE cached_key;
+        if (RB_UNLIKELY(symbolize)) {
+            cached_key = rsymbol_cache_fetch(&json->name_cache, string, bufferSize);
+        } else {
+            cached_key = rstring_cache_fetch(&json->name_cache, string, bufferSize);
+        }
+
+        if (RB_LIKELY(cached_key)) {
+            return cached_key;
+        }
+    }
+
     pe = memchr(p, '\\', bufferSize);
     if (RB_LIKELY(pe == NULL)) {
         return build_string(string, stringEnd, intern, symbolize);
@@ -602,7 +993,7 @@ static VALUE json_string_unescape(char *string, char *stringEnd, bool intern, bo
     write data;
 
     action parse_string {
-        *result = json_string_unescape(json->memo + 1, p, json->parsing_name || json-> freeze, json->parsing_name && json->symbolize_names);
+        *result = json_string_unescape(json, json->memo + 1, p, json->parsing_name, json->parsing_name || json-> freeze, json->parsing_name && json->symbolize_names);
         if (NIL_P(*result)) {
             fhold;
             fbreak;
@@ -671,7 +1062,7 @@ static VALUE convert_encoding(VALUE source)
 {
   int encindex = RB_ENCODING_GET(source);
 
-  if (encindex == utf8_encindex) {
+  if (RB_LIKELY(encindex == utf8_encindex)) {
     return source;
   }
 
@@ -683,6 +1074,68 @@ static VALUE convert_encoding(VALUE source)
   return rb_funcall(source, i_encode, 1, Encoding_UTF_8);
 }
 
+static int configure_parser_i(VALUE key, VALUE val, VALUE data)
+{
+    JSON_Parser *json = (JSON_Parser *)data;
+
+         if (key == sym_max_nesting)          { json->max_nesting = RTEST(val) ? FIX2INT(val) : 0; }
+    else if (key == sym_allow_nan)            { json->allow_nan = RTEST(val); }
+    else if (key == sym_allow_trailing_comma) { json->allow_trailing_comma = RTEST(val); }
+    else if (key == sym_symbolize_names)      { json->symbolize_names = RTEST(val); }
+    else if (key == sym_freeze)               { json->freeze = RTEST(val); }
+    else if (key == sym_create_id)            { json->create_id = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_object_class)         { json->object_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_array_class)          { json->array_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_decimal_class)        { json->decimal_class = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_match_string)         { json->match_string = RTEST(val) ? val : Qfalse; }
+    else if (key == sym_create_additions)     {
+        if (NIL_P(val)) {
+            json->create_additions = true;
+            json->deprecated_create_additions = true;
+        } else {
+            json->create_additions = RTEST(val);
+            json->deprecated_create_additions = false;
+        }
+    }
+
+    return ST_CONTINUE;
+}
+
+static void parser_init(JSON_Parser *json, VALUE source, VALUE opts)
+{
+    if (json->Vsource) {
+        rb_raise(rb_eTypeError, "already initialized instance");
+    }
+
+    json->fbuffer.initial_length = FBUFFER_INITIAL_LENGTH_DEFAULT;
+    json->max_nesting = 100;
+
+    if (!NIL_P(opts)) {
+        Check_Type(opts, T_HASH);
+        if (RHASH_SIZE(opts) > 0) {
+            // We assume in most cases few keys are set so it's faster to go over
+            // the provided keys than to check all possible keys.
+            rb_hash_foreach(opts, configure_parser_i, (VALUE)json);
+
+            if (json->symbolize_names && json->create_additions) {
+                rb_raise(rb_eArgError,
+                    "options :symbolize_names and :create_additions cannot be "
+                    " used in conjunction");
+            }
+
+            if (json->create_additions && !json->create_id) {
+                json->create_id = rb_funcall(mJSON, i_create_id, 0);
+            }
+        }
+
+    }
+    source = convert_encoding(StringValue(source));
+    StringValue(source);
+    json->len = RSTRING_LEN(source);
+    json->source = RSTRING_PTR(source);
+    json->Vsource = source;
+}
+
 /*
  * call-seq: new(source, opts => {})
  *
@@ -717,117 +1170,11 @@ static VALUE convert_encoding(VALUE source)
  */
 static VALUE cParser_initialize(int argc, VALUE *argv, VALUE self)
 {
-    VALUE source, opts;
     GET_PARSER_INIT;
 
-    if (json->Vsource) {
-        rb_raise(rb_eTypeError, "already initialized instance");
-    }
-
     rb_check_arity(argc, 1, 2);
-    source = argv[0];
-    opts = Qnil;
-    if (argc == 2) {
-        opts = argv[1];
-        Check_Type(argv[1], T_HASH);
-        if (RHASH_SIZE(argv[1]) > 0) {
-            opts = argv[1];
-        }
-    }
-
-    if (!NIL_P(opts)) {
-        VALUE tmp = ID2SYM(i_max_nesting);
-        if (option_given_p(opts, tmp)) {
-            VALUE max_nesting = rb_hash_aref(opts, tmp);
-            if (RTEST(max_nesting)) {
-                Check_Type(max_nesting, T_FIXNUM);
-                json->max_nesting = FIX2INT(max_nesting);
-            } else {
-                json->max_nesting = 0;
-            }
-        } else {
-            json->max_nesting = 100;
-        }
-        tmp = ID2SYM(i_allow_nan);
-        if (option_given_p(opts, tmp)) {
-            json->allow_nan = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->allow_nan = 0;
-        }
-        tmp = ID2SYM(i_symbolize_names);
-        if (option_given_p(opts, tmp)) {
-            json->symbolize_names = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->symbolize_names = 0;
-        }
-        tmp = ID2SYM(i_freeze);
-        if (option_given_p(opts, tmp)) {
-            json->freeze = RTEST(rb_hash_aref(opts, tmp)) ? 1 : 0;
-        } else {
-            json->freeze = 0;
-        }
-        tmp = ID2SYM(i_create_additions);
-        if (option_given_p(opts, tmp)) {
-            tmp = rb_hash_aref(opts, tmp);
-            if (NIL_P(tmp)) {
-                json->create_additions = 1;
-                json->deprecated_create_additions = 1;
-            } else {
-                json->create_additions = RTEST(tmp);
-                json->deprecated_create_additions = 0;
-            }
-        }
 
-        if (json->symbolize_names && json->create_additions) {
-            rb_raise(rb_eArgError,
-                "options :symbolize_names and :create_additions cannot be "
-                " used in conjunction");
-        }
-        tmp = ID2SYM(i_create_id);
-        if (option_given_p(opts, tmp)) {
-            json->create_id = rb_hash_aref(opts, tmp);
-        } else {
-            json->create_id = rb_funcall(mJSON, i_create_id, 0);
-        }
-        tmp = ID2SYM(i_object_class);
-        if (option_given_p(opts, tmp)) {
-            json->object_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->object_class = Qnil;
-        }
-        tmp = ID2SYM(i_array_class);
-        if (option_given_p(opts, tmp)) {
-            json->array_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->array_class = Qnil;
-        }
-        tmp = ID2SYM(i_decimal_class);
-        if (option_given_p(opts, tmp)) {
-            json->decimal_class = rb_hash_aref(opts, tmp);
-        } else {
-            json->decimal_class = Qnil;
-        }
-        tmp = ID2SYM(i_match_string);
-        if (option_given_p(opts, tmp)) {
-            VALUE match_string = rb_hash_aref(opts, tmp);
-            json->match_string = RTEST(match_string) ? match_string : Qnil;
-        } else {
-            json->match_string = Qnil;
-        }
-    } else {
-        json->max_nesting = 100;
-        json->allow_nan = 0;
-        json->create_additions = 0;
-        json->create_id = Qnil;
-        json->object_class = Qnil;
-        json->array_class = Qnil;
-        json->decimal_class = Qnil;
-    }
-    source = convert_encoding(StringValue(source));
-    StringValue(source);
-    json->len = RSTRING_LEN(source);
-    json->source = RSTRING_PTR(source);
-    json->Vsource = source;
+    parser_init(json, argv[0], argc == 2 ? argv[1] : Qnil);
     return self;
 }
 
@@ -862,11 +1209,26 @@ static VALUE cParser_parse(VALUE self)
     VALUE result = Qnil;
     GET_PARSER;
 
+    char stack_buffer[FBUFFER_STACK_SIZE];
+    fbuffer_stack_init(&json->fbuffer, FBUFFER_INITIAL_LENGTH_DEFAULT, stack_buffer, FBUFFER_STACK_SIZE);
+
+    VALUE rvalue_stack_buffer[RVALUE_STACK_INITIAL_CAPA];
+    rvalue_stack stack = {
+        .type = RVALUE_STACK_STACK_ALLOCATED,
+        .ptr = rvalue_stack_buffer,
+        .capa = RVALUE_STACK_INITIAL_CAPA,
+    };
+    json->stack = &stack;
+
     %% write init;
     p = json->source;
     pe = p + json->len;
     %% write exec;
 
+    if (json->stack_handle) {
+        rvalue_stack_eagerly_release(json->stack_handle);
+    }
+
     if (cs >= JSON_first_final && p == pe) {
         return result;
     } else {
@@ -875,18 +1237,43 @@ static VALUE cParser_parse(VALUE self)
     }
 }
 
-#ifndef HAVE_RB_GC_MARK_LOCATIONS
-// For TruffleRuby
-void rb_gc_mark_locations(const VALUE *start, const VALUE *end)
+static VALUE cParser_m_parse(VALUE klass, VALUE source, VALUE opts)
 {
-    VALUE *value = start;
+    char *p, *pe;
+    int cs = EVIL;
+    VALUE result = Qnil;
 
-    while (value < end) {
-        rb_gc_mark(*value);
-        value++;
+    JSON_Parser _parser = {0};
+    JSON_Parser *json = &_parser;
+    parser_init(json, source, opts);
+
+    char stack_buffer[FBUFFER_STACK_SIZE];
+    fbuffer_stack_init(&json->fbuffer, FBUFFER_INITIAL_LENGTH_DEFAULT, stack_buffer, FBUFFER_STACK_SIZE);
+
+    VALUE rvalue_stack_buffer[RVALUE_STACK_INITIAL_CAPA];
+    rvalue_stack stack = {
+        .type = RVALUE_STACK_STACK_ALLOCATED,
+        .ptr = rvalue_stack_buffer,
+        .capa = RVALUE_STACK_INITIAL_CAPA,
+    };
+    json->stack = &stack;
+
+    %% write init;
+    p = json->source;
+    pe = p + json->len;
+    %% write exec;
+
+    if (json->stack_handle) {
+        rvalue_stack_eagerly_release(json->stack_handle);
+    }
+
+    if (cs >= JSON_first_final && p == pe) {
+        return result;
+    } else {
+        raise_parse_error("unexpected token at '%s'", p);
+        return Qnil;
     }
 }
-#endif
 
 static void JSON_mark(void *ptr)
 {
@@ -897,6 +1284,8 @@ static void JSON_mark(void *ptr)
     rb_gc_mark(json->array_class);
     rb_gc_mark(json->decimal_class);
     rb_gc_mark(json->match_string);
+    rb_gc_mark(json->stack_handle);
+
     const VALUE *name_cache_entries = &json->name_cache.entries[0];
     rb_gc_mark_locations(name_cache_entries, name_cache_entries + json->name_cache.length);
 }
@@ -959,6 +1348,8 @@ void Init_parser(void)
     rb_define_method(cParser, "parse", cParser_parse, 0);
     rb_define_method(cParser, "source", cParser_source, 0);
 
+    rb_define_singleton_method(cParser, "parse", cParser_m_parse, 2);
+
     CNaN = rb_const_get(mJSON, rb_intern("NaN"));
     rb_gc_register_mark_object(CNaN);
 
@@ -971,31 +1362,35 @@ void Init_parser(void)
     rb_global_variable(&Encoding_UTF_8);
     Encoding_UTF_8 = rb_const_get(rb_path2class("Encoding"), rb_intern("UTF_8"));
 
+    sym_max_nesting = ID2SYM(rb_intern("max_nesting"));
+    sym_allow_nan = ID2SYM(rb_intern("allow_nan"));
+    sym_allow_trailing_comma = ID2SYM(rb_intern("allow_trailing_comma"));
+    sym_symbolize_names = ID2SYM(rb_intern("symbolize_names"));
+    sym_freeze = ID2SYM(rb_intern("freeze"));
+    sym_create_additions = ID2SYM(rb_intern("create_additions"));
+    sym_create_id = ID2SYM(rb_intern("create_id"));
+    sym_object_class = ID2SYM(rb_intern("object_class"));
+    sym_array_class = ID2SYM(rb_intern("array_class"));
+    sym_decimal_class = ID2SYM(rb_intern("decimal_class"));
+    sym_match_string = ID2SYM(rb_intern("match_string"));
+
+    i_create_id = rb_intern("create_id");
     i_json_creatable_p = rb_intern("json_creatable?");
     i_json_create = rb_intern("json_create");
-    i_create_id = rb_intern("create_id");
-    i_create_additions = rb_intern("create_additions");
     i_chr = rb_intern("chr");
-    i_max_nesting = rb_intern("max_nesting");
-    i_allow_nan = rb_intern("allow_nan");
-    i_symbolize_names = rb_intern("symbolize_names");
-    i_object_class = rb_intern("object_class");
-    i_array_class = rb_intern("array_class");
-    i_decimal_class = rb_intern("decimal_class");
     i_match = rb_intern("match");
-    i_match_string = rb_intern("match_string");
     i_deep_const_get = rb_intern("deep_const_get");
     i_aset = rb_intern("[]=");
     i_aref = rb_intern("[]");
     i_leftshift = rb_intern("<<");
     i_new = rb_intern("new");
     i_try_convert = rb_intern("try_convert");
-    i_freeze = rb_intern("freeze");
     i_uminus = rb_intern("-@");
     i_encode = rb_intern("encode");
 
     binary_encindex = rb_ascii8bit_encindex();
     utf8_encindex = rb_utf8_encindex();
+    enc_utf8 = rb_utf8_encoding();
 }
 
 /*
diff --git a/test/json/fixtures/fail4.json b/test/json/fixtures/fail4.json
deleted file mode 100644
index 9de168bf34..0000000000
--- a/test/json/fixtures/fail4.json
+++ /dev/null
@@ -1 +0,0 @@
-["extra comma",]
\ No newline at end of file
diff --git a/test/json/fixtures/fail9.json b/test/json/fixtures/fail9.json
deleted file mode 100644
index 5815574f36..0000000000
--- a/test/json/fixtures/fail9.json
+++ /dev/null
@@ -1 +0,0 @@
-{"Extra comma": true,}
\ No newline at end of file
diff --git a/test/json/json_common_interface_test.rb b/test/json/json_common_interface_test.rb
index e552412bfd..6165cc0411 100644
--- a/test/json/json_common_interface_test.rb
+++ b/test/json/json_common_interface_test.rb
@@ -52,11 +52,11 @@ class JSONCommonInterfaceTest < Test::Unit::TestCase
   end
 
   def test_generator
-    assert_match(/::Generator\z/, JSON.generator.name)
+    assert_match(/::(TruffleRuby)?Generator\z/, JSON.generator.name)
   end
 
   def test_state
-    assert_match(/::Generator::State\z/, JSON.state.name)
+    assert_match(/::(TruffleRuby)?Generator::State\z/, JSON.state.name)
   end
 
   def test_create_id
diff --git a/test/json/json_ext_parser_test.rb b/test/json/json_ext_parser_test.rb
index 9db8ae772f..da61504989 100644
--- a/test/json/json_ext_parser_test.rb
+++ b/test/json/json_ext_parser_test.rb
@@ -2,53 +2,51 @@
 require_relative 'test_helper'
 
 class JSONExtParserTest < Test::Unit::TestCase
-  if defined?(JSON::Ext::Parser)
-    include JSON
-
-    def test_allocate
-      parser = JSON::Ext::Parser.new("{}")
-      assert_raise(TypeError, '[ruby-core:35079]') do
-        parser.__send__(:initialize, "{}")
-      end
-      parser = JSON::Ext::Parser.allocate
-      assert_raise(TypeError, '[ruby-core:35079]') { parser.source }
-    end
+  include JSON
 
-    def test_error_messages
-      ex = assert_raise(ParserError) { parse('Infinity') }
-      assert_equal "unexpected token at 'Infinity'", ex.message
+  def test_allocate
+    parser = JSON::Ext::Parser.new("{}")
+    assert_raise(TypeError, '[ruby-core:35079]') do
+      parser.__send__(:initialize, "{}")
+    end
+    parser = JSON::Ext::Parser.allocate
+    assert_raise(TypeError, '[ruby-core:35079]') { parser.source }
+  end
 
-      unless RUBY_PLATFORM =~ /java/
-        ex = assert_raise(ParserError) { parse('-Infinity') }
-        assert_equal "unexpected token at '-Infinity'", ex.message
-      end
+  def test_error_messages
+    ex = assert_raise(ParserError) { parse('Infinity') }
+    assert_equal "unexpected token at 'Infinity'", ex.message
 
-      ex = assert_raise(ParserError) { parse('NaN') }
-      assert_equal "unexpected token at 'NaN'", ex.message
+    unless RUBY_PLATFORM =~ /java/
+      ex = assert_raise(ParserError) { parse('-Infinity') }
+      assert_equal "unexpected token at '-Infinity'", ex.message
     end
 
-    if GC.respond_to?(:stress=)
-      def test_gc_stress_parser_new
-        payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
-
-        previous_stress = GC.stress
-        JSON::Parser.new(payload).parse
-      ensure
-        GC.stress = previous_stress
-      end
+    ex = assert_raise(ParserError) { parse('NaN') }
+    assert_equal "unexpected token at 'NaN'", ex.message
+  end
 
-      def test_gc_stress
-        payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
+  if GC.respond_to?(:stress=)
+    def test_gc_stress_parser_new
+      payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
 
-        previous_stress = GC.stress
-        JSON.parse(payload)
-      ensure
-        GC.stress = previous_stress
-      end
+      previous_stress = GC.stress
+      JSON::Parser.new(payload).parse
+    ensure
+      GC.stress = previous_stress
     end
 
-    def parse(json)
-      JSON::Ext::Parser.new(json).parse
+    def test_gc_stress
+      payload = JSON.dump([{ foo: 1, bar: 2, baz: 3, egg: { spam: 4 } }] * 10)
+
+      previous_stress = GC.stress
+      JSON.parse(payload)
+    ensure
+      GC.stress = previous_stress
     end
   end
+
+  def parse(json)
+    JSON::Ext::Parser.new(json).parse
+  end
 end
diff --git a/test/json/json_generator_test.rb b/test/json/json_generator_test.rb
index 112c03b220..700220a152 100755
--- a/test/json/json_generator_test.rb
+++ b/test/json/json_generator_test.rb
@@ -343,27 +343,25 @@ class JSONGeneratorTest < Test::Unit::TestCase
     assert_equal '2', state.indent
   end
 
-  if defined?(JSON::Ext::Generator)
-    def test_broken_bignum # [ruby-core:38867]
-      pid = fork do
-        x = 1 << 64
-        x.class.class_eval do
-          def to_s
-          end
-        end
-        begin
-          JSON::Ext::Generator::State.new.generate(x)
-          exit 1
-        rescue TypeError
-          exit 0
+  def test_broken_bignum # [ruby-core:38867]
+    pid = fork do
+      x = 1 << 64
+      x.class.class_eval do
+        def to_s
         end
       end
-      _, status = Process.waitpid2(pid)
-      assert status.success?
-    rescue NotImplementedError
-      # forking to avoid modifying core class of a parent process and
-      # introducing race conditions of tests are run in parallel
+      begin
+        JSON::Ext::Generator::State.new.generate(x)
+        exit 1
+      rescue TypeError
+        exit 0
+      end
     end
+    _, status = Process.waitpid2(pid)
+    assert status.success?
+  rescue NotImplementedError
+    # forking to avoid modifying core class of a parent process and
+    # introducing race conditions of tests are run in parallel
   end
 
   def test_hash_likeness_set_symbol
@@ -477,12 +475,20 @@ class JSONGeneratorTest < Test::Unit::TestCase
     end
     assert_includes error.message, "source sequence is illegal/malformed utf-8"
 
-    assert_raise(Encoding::UndefinedConversionError) do
+    assert_raise(JSON::GeneratorError) do
+      JSON.dump("\x82\xAC\xEF".b)
+    end
+
+    assert_raise(JSON::GeneratorError) do
       "\x82\xAC\xEF".b.to_json
     end
 
-    assert_raise(Encoding::UndefinedConversionError) do
-      JSON.dump("\x82\xAC\xEF".b)
+    assert_raise(JSON::GeneratorError) do
+      ["\x82\xAC\xEF".b].to_json
+    end
+
+    assert_raise(JSON::GeneratorError) do
+      { foo: "\x82\xAC\xEF".b }.to_json
     end
   end
 
diff --git a/test/json/json_parser_test.rb b/test/json/json_parser_test.rb
index adff91674d..8759ccd262 100644
--- a/test/json/json_parser_test.rb
+++ b/test/json/json_parser_test.rb
@@ -40,7 +40,7 @@ class JSONParserTest < Test::Unit::TestCase
     }
     assert_equal(Encoding::UTF_8, e.message.encoding, bug10705)
     assert_include(e.message, json, bug10705)
-  end if defined?(JSON::Ext::Parser)
+  end
 
   def test_parsing
     parser = JSON::Parser.new('"test"')
@@ -180,7 +180,93 @@ class JSONParserTest < Test::Unit::TestCase
     assert parse('NaN', :allow_nan => true).nan?
     assert parse('Infinity', :allow_nan => true).infinite?
     assert parse('-Infinity', :allow_nan => true).infinite?
-    assert_raise(JSON::ParserError) { parse('[ 1, ]') }
+  end
+
+  def test_parse_arrays_with_allow_trailing_comma
+    assert_equal([], parse('[]', allow_trailing_comma: true))
+    assert_equal([], parse('[]', allow_trailing_comma: false))
+    assert_raise(JSON::ParserError) { parse('[,]', allow_trailing_comma: true) }
+    assert_raise(JSON::ParserError) { parse('[,]', allow_trailing_comma: false) }
+
+    assert_equal([1], parse('[1]', allow_trailing_comma: true))
+    assert_equal([1], parse('[1]', allow_trailing_comma: false))
+    assert_equal([1], parse('[1,]', allow_trailing_comma: true))
+    assert_raise(JSON::ParserError) { parse('[1,]', allow_trailing_comma: false) }
+
+    assert_equal([1, 2, 3], parse('[1,2,3]', allow_trailing_comma: true))
+    assert_equal([1, 2, 3], parse('[1,2,3]', allow_trailing_comma: false))
+    assert_equal([1, 2, 3], parse('[1,2,3,]', allow_trailing_comma: true))
+    assert_raise(JSON::ParserError) { parse('[1,2,3,]', allow_trailing_comma: false) }
+
+    assert_equal([1, 2, 3], parse('[  1  ,  2  ,  3  ]', allow_trailing_comma: true))
+    assert_equal([1, 2, 3], parse('[  1  ,  2  ,  3  ]', allow_trailing_comma: false))
+    assert_equal([1, 2, 3], parse('[  1  ,  2  ,  3  ,  ]', allow_trailing_comma: true))
+    assert_raise(JSON::ParserError) { parse('[  1  ,  2  ,  3  ,  ]', allow_trailing_comma: false) }
+
+    assert_equal({'foo' => [1, 2, 3]}, parse('{ "foo": [1,2,3] }', allow_trailing_comma: true))
+    assert_equal({'foo' => [1, 2, 3]}, parse('{ "foo": [1,2,3] }', allow_trailing_comma: false))
+    assert_equal({'foo' => [1, 2, 3]}, parse('{ "foo": [1,2,3,] }', allow_trailing_comma: true))
+    assert_raise(JSON::ParserError) { parse('{ "foo": [1,2,3,] }', allow_trailing_comma: false) }
+  end
+
+  def test_parse_object_with_allow_trailing_comma
+    assert_equal({}, parse('{}', allow_trailing_comma: true))
+    assert_equal({}, parse('{}', allow_trailing_comma: false))
+    assert_raise(JSON::ParserError) { parse('{,}', allow_trailing_comma: true) }
+    assert_raise(JSON::ParserError) { parse('{,}', allow_trailing_comma: false) }
+    
+    assert_equal({'foo'=>'bar'}, parse('{"foo":"bar"}', allow_trailing_comma: true))
+    assert_equal({'foo'=>'bar'}, parse('{"foo":"bar"}', allow_trailing_comma: false))
+    assert_equal({'foo'=>'bar'}, parse('{"foo":"bar",}', allow_trailing_comma: true))
+    assert_raise(JSON::ParserError) { parse('{"foo":"bar",}', allow_trailing_comma: false) }
+    
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{"foo":"bar","baz":"qux","quux":"garply"}', allow_trailing_comma: true)
+    )
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{"foo":"bar","baz":"qux","quux":"garply"}', allow_trailing_comma: false)
+    )
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{"foo":"bar","baz":"qux","quux":"garply",}', allow_trailing_comma: true)
+    )
+    assert_raise(JSON::ParserError) {
+      parse('{"foo":"bar","baz":"qux","quux":"garply",}', allow_trailing_comma: false)
+    }
+    
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{  "foo":"bar"  ,  "baz":"qux"  ,  "quux":"garply"  }', allow_trailing_comma: true)
+    )
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{  "foo":"bar"  ,  "baz":"qux"  ,  "quux":"garply"  }', allow_trailing_comma: false)
+    )
+    assert_equal(
+      {'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'},
+      parse('{  "foo":"bar"  ,  "baz":"qux"  ,  "quux":"garply"  ,  }', allow_trailing_comma: true)
+    )
+    assert_raise(JSON::ParserError) {
+      parse('{  "foo":"bar"  ,  "baz":"qux"  ,  "quux":"garply"  ,  }', allow_trailing_comma: false)
+    }
+    
+    assert_equal(
+      [{'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'}],
+      parse('[{"foo":"bar","baz":"qux","quux":"garply"}]', allow_trailing_comma: true)
+    )
+    assert_equal(
+      [{'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'}],
+      parse('[{"foo":"bar","baz":"qux","quux":"garply"}]', allow_trailing_comma: false)
+    )
+    assert_equal(
+      [{'foo'=>'bar', 'baz'=>'qux', 'quux'=>'garply'}],
+      parse('[{"foo":"bar","baz":"qux","quux":"garply",}]', allow_trailing_comma: true)
+    )
+    assert_raise(JSON::ParserError) {
+      parse('[{"foo":"bar","baz":"qux","quux":"garply",}]', allow_trailing_comma: false)
+    }
   end
 
   def test_parse_some_strings
@@ -533,7 +619,7 @@ class JSONParserTest < Test::Unit::TestCase
     error = assert_raise(JSON::ParserError) do
       JSON.parse('{"input":{"firstName":"Bob","lastName":"Mob","email":"[email protected]"}')
     end
-    if RUBY_ENGINE == "ruby" && defined?(JSON::Ext)
+    if RUBY_ENGINE == "ruby"
       assert_equal %(unexpected token at '{"input":{"firstName":"Bob","las'), error.message
     end
   end
diff --git a/test/json/test_helper.rb b/test/json/test_helper.rb
index 6fcb76edf8..11bb8ba8c2 100644
--- a/test/json/test_helper.rb
+++ b/test/json/test_helper.rb
@@ -1,30 +1,14 @@
-case ENV['JSON']
-when 'pure'
-  $LOAD_PATH.unshift(File.expand_path('../../../lib', __FILE__))
-  $stderr.puts("Testing JSON::Pure")
-  require 'json/pure'
-when 'ext'
-  $stderr.puts("Testing JSON::Ext")
-  $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
-  require 'json/ext'
-else
-  $LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
-  $stderr.puts("Testing JSON")
-  require 'json'
-end
+$LOAD_PATH.unshift(File.expand_path('../../../ext', __FILE__), File.expand_path('../../../lib', __FILE__))
 
+require 'json'
 require 'test/unit'
-begin
-  require 'byebug'
-rescue LoadError
-end
 
 if GC.respond_to?(:verify_compaction_references)
   # This method was added in Ruby 3.0.0. Calling it this way asks the GC to
   # move objects around, helping to find object movement bugs.
   begin
-    GC.verify_compaction_references(double_heap: true, toward: :empty)
-  rescue NotImplementedError
+    GC.verify_compaction_references(expand_heap: true, toward: :empty)
+  rescue NotImplementedError, ArgumentError
     # Some platforms don't support compaction
   end
 end