coregex

package module

v0.1.3 Latest Latest Go to latest Published: Nov 27, 2025 License: MIT Imports: 1 Imported by: 0

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Tagged version
Stable version
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Repository

github.com/coregx/coregex

Links

Open Source Insights

README ¶

coregex - Production-Grade Regex Engine for Go

5-50x faster than stdlib through multi-engine architecture and SIMD optimizations

A production-grade regex engine for Go with dramatic performance improvements over the standard library. Inspired by Rust's regex crate, coregex uses a multi-engine architecture with SIMD-accelerated prefilters to achieve 5-50x speedup on typical workloads.

Features

⚡ Performance

🚀 5-50x faster than Go's regexp package through intelligent prefiltering
🎯 SIMD-accelerated search with AVX2/SSSE3 assembly (10-15x faster substring search)
📊 Multi-pattern search (Teddy SIMD algorithm for 2-8 literals)
🔍 Aho-Corasick for many literals
💾 Zero allocations in hot paths through object pooling

🏗️ Architecture

🧠 Meta-engine orchestrates strategy selection (DFA/NFA/bounded backtracking)
⚡ Lazy DFA with configurable caching (on-demand state construction)
🔄 Pike VM (Thompson's NFA) for guaranteed O(n×m) performance
🎭 One-pass DFA for simple patterns (no backtracking needed)
📌 Prefilter coordination (memchr/memmem/teddy/aho-corasick)

🎯 API Design

Simple, drop-in replacement for regexp package
Configuration system for performance tuning
Thread-safe with concurrent compilation support
Comprehensive error handling

Installation

go get github.com/coregx/coregex

Requirements:

Go 1.25 or later
Zero external dependencies (except golang.org/x/sys for CPU feature detection)

Quick Start

Basic Usage

package main

import (
	"fmt"
	"log"

	"github.com/coregx/coregex"
)

func main() {
	// Compile a regex pattern
	re, err := coregex.Compile(`\b\w+@\w+\.\w+\b`)
	if err != nil {
		log.Fatal(err)
	}

	// Find first match
	text := []byte("Contact us at support@example.com for help")
	if match := re.Find(text); match != nil {
		fmt.Printf("Found email: %s\n", match)
	}

	// Find all matches
	matches := re.FindAll(text, -1)
	for _, m := range matches {
		fmt.Printf("Match: %s\n", m)
	}
}

Advanced Configuration

package main

import (
	"log"

	"github.com/coregx/coregex"
)

func main() {
	// Create custom configuration for performance tuning
	config := coregex.DefaultConfig()
	config.DFAMaxStates = 10000        // Limit DFA cache size
	config.EnablePrefilter = true       // Use SIMD prefilters (default)
	config.UseObjectPools = true        // Zero-allocation mode (default)

	// Compile with custom config
	re, err := coregex.CompileWithConfig(`pattern`, config)
	if err != nil {
		log.Fatal(err)
	}

	// Use regex...
	text := []byte("search this text")
	match := re.Find(text)
	if match != nil {
		log.Printf("Found: %s", match)
	}
}

Performance Example

package main

import (
	"fmt"
	"regexp"
	"time"

	"github.com/coregx/coregex"
)

func benchmarkSearch(pattern string, text []byte) {
	// stdlib regexp
	start := time.Now()
	reStdlib := regexp.MustCompile(pattern)
	for i := 0; i < 10000; i++ {
		reStdlib.Find(text)
	}
	stdlibTime := time.Since(start)

	// coregex
	start = time.Now()
	reGoregex := coregex.MustCompile(pattern)
	for i := 0; i < 10000; i++ {
		reGoregex.Find(text)
	}
	coregexTime := time.Since(start)

	speedup := float64(stdlibTime) / float64(coregexTime)
	fmt.Printf("Speedup: %.1fx faster\n", speedup)
}

Performance Benchmarks

SIMD Primitives (vs stdlib):

memchr (single byte): 12.3x faster (64KB input)
memmem (substring): 14.2x faster (64KB input, short needle)
teddy (multi-pattern): 8.5x faster (2-8 patterns)

Regex Search (vs regexp):

Pattern Type	Input Size	stdlib	coregex	Speedup
Literal (case-sensitive)	32KB	3,654 ns	4,375 ns	~1x (on par)
Literal (case-insensitive)	32KB	842,422 ns	5,883 ns	143x faster
Email extraction	-	-	-	15-25x faster
URL matching	-	-	-	10-20x faster
Log parsing	-	-	-	30-50x faster

Key insight: Case-insensitive patterns ((?i)...) are where coregex truly shines - stdlib uses backtracking which becomes very slow, while our DFA handles it with the same speed as case-sensitive patterns.

See benchmark/ for detailed comparisons.

Supported Features

v0.1.0 (Current)

Feature	Status	Notes
SIMD Primitives	✅	memchr, memchr2/3, memmem, teddy
Literal Extraction	✅	Prefix/suffix/inner literals
Prefilter System	✅	Automatic strategy selection
Meta-Engine	✅	DFA/NFA orchestration
Lazy DFA	✅	On-demand state construction
Pike VM (NFA)	✅	Thompson's construction
One-pass DFA	✅	For simple patterns
Unicode support	✅	Via `regexp/syntax`
Captures	✅	Numbered groups
Named captures	📅 v0.2.0	Planned
Look-around	📅 v0.3.0	Lookahead/lookbehind
Backreferences	❌	Incompatible with O(n) guarantee

Regex Syntax

coregex uses Go's regexp/syntax for pattern parsing, supporting:

✅ Character classes [a-z], \d, \w, \s
✅ Quantifiers *, +, ?, {n,m}
✅ Anchors ^, $, \b, \B
✅ Groups (...) and alternation |
✅ Unicode categories \p{L}, \P{N}
✅ Case-insensitive matching (?i)
✅ Non-capturing groups (?:...)
❌ Backreferences (not supported - O(n) performance guarantee)

Known Limitations

v0.1.0 (Experimental)

What Works:

✅ All standard regex syntax (except backreferences)
✅ Unicode support via regexp/syntax
✅ SIMD acceleration on AMD64 (AVX2/SSSE3)
✅ Cross-platform (fallback to pure Go on other architectures)
✅ Thread-safe compilation and execution
✅ Zero external dependencies

Current Limitations:

⚠️ Experimental API - May change in v0.2+
⚠️ No named capture groups yet (planned v0.2.0)
⚠️ No look-around assertions yet (planned v0.3.0)
⚠️ SIMD only on AMD64 (ARM NEON planned v0.4.0)

Performance Notes:

🚀 Best speedup on patterns with literal prefixes/suffixes
🚀 Excellent for log parsing, email/URL extraction
⚡ May be slower than stdlib on trivial patterns (overhead)
⚡ First match slower (compilation cost), repeated matches faster

See CHANGELOG.md for detailed version history.

Documentation

Getting Started - Usage examples and tutorials
API Reference - Full API documentation
CHANGELOG.md - Version history
ROADMAP.md - Future plans and development timeline
SECURITY.md - Security policy and ReDoS prevention

Development

Building

# Clone repository
git clone https://github.com/coregx/coregex.git
cd coregex

# Build all packages
go build ./...

# Run tests
go test ./...

# Run tests with race detector
go test -race ./...

# Run benchmarks
go test -bench=. -benchmem ./simd/
go test -bench=. -benchmem ./prefilter/

Testing

# Run all tests
go test ./...

# Run specific package tests
go test ./simd/ -v
go test ./meta/ -v

# Run with coverage
go test -cover ./...

# Run linter (golangci-lint required)
golangci-lint run

Pre-release Check

Before creating a release, run the comprehensive validation script:

bash scripts/pre-release-check.sh

This checks:

✅ Go version (1.25+)
✅ Code formatting (gofmt)
✅ go vet passes
✅ All tests pass (with race detector)
✅ Test coverage >70%
✅ golangci-lint passes
✅ Documentation present

Contributing

Contributions are welcome! This is an experimental project and we'd love your help.

Before contributing:

Read CONTRIBUTING.md - Git Flow workflow and guidelines
Check open issues
Join GitHub Discussions

Ways to contribute:

🐛 Report bugs and edge cases
💡 Suggest features
📝 Improve documentation
🔧 Submit pull requests
⭐ Star the project
🧪 Benchmark against stdlib and report results

Priority areas:

ARM NEON SIMD implementation (v0.4.0)
Named capture groups (v0.2.0)
Look-around assertions (v0.3.0)
More comprehensive benchmarks
Real-world performance testing

Comparison with Other Libraries

Feature	coregex	stdlib `regexp`	regexp2
Performance	🚀 5-50x faster	Baseline	Slower (backtracking)
SIMD acceleration	✅ AVX2/SSSE3	❌ No	❌ No
Prefilters	✅ Automatic	❌ No	❌ No
Multi-engine	✅ DFA/NFA/PikeVM	❌ Single	❌ Backtracking only
O(n) guarantee	✅ Yes	✅ Yes	❌ No (exponential worst-case)
Backreferences	❌ Not supported	❌ Not supported	✅ Supported
Named captures	📅 v0.2.0	✅ Supported	✅ Supported
Look-around	📅 v0.3.0	❌ Limited	✅ Supported
API compatibility	⚠️ Similar	-	Different
Maintained	✅ Active	✅ Stdlib	✅ Active

When to use coregex:

✅ Performance-critical applications (log parsing, text processing)
✅ Patterns with literal prefixes/suffixes
✅ Multi-pattern search (email/URL extraction)
✅ When you need O(n) performance guarantee

When to use stdlib regexp:

✅ Simple patterns where performance doesn't matter
✅ You need named captures NOW (coming in v0.2.0)
✅ Maximum stability and API compatibility

When to use regexp2:

✅ You need backreferences (not supported by coregex)
✅ Complex look-around assertions (v0.3.0 for coregex)
⚠️ Accept exponential worst-case performance

Architecture Overview

┌─────────────────────────────────────────────────────────────┐
│                        Meta-Engine                          │
│  (Strategy Selection: DFA/NFA/One-pass)                     │
└────────────┬────────────────────────────────────────────────┘
             │
     ┌───────┴───────┐
     │  Prefilter    │ ──► memchr (single byte)
     │  Coordinator  │ ──► memmem (substring)
     └───────┬───────┘ ──► teddy (2-8 patterns, SIMD)
             │         ──► aho-corasick (many patterns)
     ┌───────┴─────────────────────────────────┐
     │                                         │
┌────┴────┐  ┌──────────┐  ┌────────────┐  ┌───┴────┐
│ Lazy    │  │ Pike VM  │  │ One-pass   │  │ Literal│
│ DFA     │  │ (NFA)    │  │ DFA        │  │Extract │
└─────────┘  └──────────┘  └────────────┘  └────────┘
     │             │              │             │
     └─────────────┴──────────────┴─────────────┘
                       │
              ┌────────┴────────┐
              │ SIMD Primitives │
              │ (AVX2/SSSE3)    │
              └─────────────────┘

Key components:

Meta-Engine - Intelligent strategy selection based on pattern analysis
Prefilter System - Fast rejection of non-matching candidates
Multi-Engine Execution - DFA for speed, NFA for correctness
SIMD Primitives - 10-15x faster byte/substring search

See package documentation on pkg.go.dev for API details.

Part of the CoreGX (Core Go eXtensions) ecosystem:

More projects coming soon!

Inspired by:

Rust regex crate - Architecture and design
RE2 - O(n) performance guarantees
Hyperscan - SIMD multi-pattern matching

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

Rust regex crate team for architectural inspiration
Russ Cox for Thompson's NFA articles and RE2
Intel for Hyperscan and Teddy algorithm
Go team for regexp/syntax parser
All contributors to this project

Support

📖 API Reference - Full documentation
🐛 Issue Tracker - Report bugs
💬 Discussions - Ask questions

Status: ⚠️ EXPERIMENTAL - v0.1.0 released, API may change in 0.x versions

Current Version: v0.1.0 (2025-01-26)

Ready for: Testing, benchmarking, feedback, and experimental use Production readiness: API stability expected in v1.0.0

Next Release: v0.2.0 (Q1 2025) - Named captures, API refinements

Built with performance and correctness in mind by the CoreGX community 🚀

Documentation ¶

Overview ¶

Package coregex provides a high-performance regex engine for Go.

coregex achieves 5-50x speedup over Go's stdlib regexp through:

Multi-engine architecture (NFA, Lazy DFA, prefilters)
SIMD-accelerated primitives (memchr, memmem, teddy)
Literal extraction and prefiltering
Automatic strategy selection

The public API is compatible with stdlib regexp where possible, making it easy to migrate existing code.

Basic usage:

// Compile a pattern
re, err := coregex.Compile(`\d+`)
if err != nil {
    log.Fatal(err)
}

// Find first match
match := re.Find([]byte("hello 123 world"))
fmt.Println(string(match)) // "123"

// Check if matches
if re.Match([]byte("hello 123")) {
    fmt.Println("matched!")
}

Advanced usage:

// Custom configuration
config := coregex.DefaultConfig()
config.MaxDFAStates = 50000
re, err := coregex.CompileWithConfig("(a|b|c)*", config)

Performance characteristics:

Patterns with literals: 5-50x faster (prefilter optimization)
Simple patterns: comparable to stdlib
Complex patterns: 2-10x faster (DFA avoids backtracking)
Worst case: guaranteed O(m*n) (ReDoS safe)

Limitations (v1.0):

No capture groups (coming in v1.1)
No replace functions (coming in v1.1)
No multiline/case-insensitive flags (coming in v1.1)

Examples ¶

Compile
CompileWithConfig
MustCompile
Regex.Find
Regex.FindAll
Regex.FindAllString
Regex.FindIndex
Regex.FindString

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

func DefaultConfig ¶

func DefaultConfig() meta.Config

DefaultConfig returns the default configuration for compilation.

Users can customize this and pass to CompileWithConfig.

Example:

config := coregex.DefaultConfig()
config.EnableDFA = false // Use NFA only
re, _ := coregex.CompileWithConfig("pattern", config)

Types ¶

type Regex ¶

type Regex struct {
	// contains filtered or unexported fields
}

Regex represents a compiled regular expression.

A Regex is safe to use concurrently from multiple goroutines, except for methods that modify internal state (like ResetStats).

Example:

re := coregex.MustCompile(`hello`)
if re.Match([]byte("hello world")) {
    println("matched!")
}

func Compile ¶

func Compile(pattern string) (*Regex, error)

Compile compiles a regular expression pattern.

Syntax is Perl-compatible (same as Go's stdlib regexp). Returns an error if the pattern is invalid.

Example:

re, err := coregex.Compile(`\d{3}-\d{4}`)
if err != nil {
    log.Fatal(err)
}

Example ¶

ExampleCompile demonstrates basic pattern compilation and matching.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re, err := coregex.Compile(`\d+`)
	if err != nil {
		panic(err)
	}

	fmt.Println(re.Match([]byte("hello 123")))
}

Output:

true

func CompileWithConfig ¶

func CompileWithConfig(pattern string, config meta.Config) (*Regex, error)

CompileWithConfig compiles a pattern with custom configuration.

This allows fine-tuning of performance characteristics.

Example:

config := coregex.DefaultConfig()
config.MaxDFAStates = 100000 // Larger cache
re, err := coregex.CompileWithConfig("(a|b|c)*", config)

Example ¶

ExampleCompileWithConfig demonstrates custom configuration.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	config := coregex.DefaultConfig()
	config.MaxDFAStates = 50000 // Increase cache size

	re, err := coregex.CompileWithConfig("(a|b|c)*", config)
	if err != nil {
		panic(err)
	}

	fmt.Println(re.MatchString("abcabc"))
}

Output:

true

func MustCompile ¶

func MustCompile(pattern string) *Regex

MustCompile compiles a regular expression pattern and panics if it fails.

This is useful for patterns known to be valid at compile time.

Example:

var emailRegex = coregex.MustCompile(`[a-z]+@[a-z]+\.[a-z]+`)

Example ¶

ExampleMustCompile demonstrates panic-on-error compilation.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`hello`)
	fmt.Println(re.MatchString("hello world"))
}

Output:

true

func (*Regex) Find ¶

func (r *Regex) Find(b []byte) []byte

Find returns a slice holding the text of the leftmost match in b. Returns nil if no match is found.

Example:

re := coregex.MustCompile(`\d+`)
match := re.Find([]byte("age: 42"))
println(string(match)) // "42"

Example ¶

ExampleRegex_Find demonstrates finding the first match.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`\d+`)
	match := re.Find([]byte("age: 42 years"))
	fmt.Println(string(match))
}

Output:

42

func (*Regex) FindAll ¶

func (r *Regex) FindAll(b []byte, n int) [][]byte

FindAll returns a slice of all successive matches of the pattern in b. If n > 0, it returns at most n matches. If n <= 0, it returns all matches.

Example:

re := coregex.MustCompile(`\d+`)
matches := re.FindAll([]byte("1 2 3"), -1)
// matches = [[]byte("1"), []byte("2"), []byte("3")]

Example ¶

ExampleRegex_FindAll demonstrates finding all matches.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`\d`)
	matches := re.FindAll([]byte("a1b2c3"), -1)
	for _, m := range matches {
		fmt.Print(string(m), " ")
	}
	fmt.Println()
}

Output:

1 2 3

func (*Regex) FindAllString ¶

func (r *Regex) FindAllString(s string, n int) []string

FindAllString returns a slice of all successive matches of the pattern in s. If n > 0, it returns at most n matches. If n <= 0, it returns all matches.

Example:

re := coregex.MustCompile(`\d+`)
matches := re.FindAllString("1 2 3", -1)
// matches = ["1", "2", "3"]

Example ¶

ExampleRegex_FindAllString demonstrates finding all string matches.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`\w+`)
	words := re.FindAllString("hello world test", -1)
	for _, word := range words {
		fmt.Print(word, " ")
	}
	fmt.Println()
}

Output:

hello world test

func (*Regex) FindIndex ¶

func (r *Regex) FindIndex(b []byte) []int

FindIndex returns a two-element slice of integers defining the location of the leftmost match in b. The match is at b[loc[0]:loc[1]]. Returns nil if no match is found.

Example:

re := coregex.MustCompile(`\d+`)
loc := re.FindIndex([]byte("age: 42"))
println(loc[0], loc[1]) // 5, 7

Example ¶

ExampleRegex_FindIndex demonstrates finding match positions.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`\d+`)
	loc := re.FindIndex([]byte("age: 42"))
	fmt.Printf("Match at [%d:%d]\n", loc[0], loc[1])
}

Output:

Match at [5:7]

func (*Regex) FindString ¶

func (r *Regex) FindString(s string) string

FindString returns a string holding the text of the leftmost match in s. Returns empty string if no match is found.

Example:

re := coregex.MustCompile(`\d+`)
match := re.FindString("age: 42")
println(match) // "42"

Example ¶

ExampleRegex_FindString demonstrates finding a match in a string.

package main

import (
	"fmt"

	"github.com/coregx/coregex"
)

func main() {
	re := coregex.MustCompile(`\w+@\w+\.\w+`)
	email := re.FindString("Contact: user@example.com")
	fmt.Println(email)
}

Output:

user@example.com

func (*Regex) FindStringIndex ¶

func (r *Regex) FindStringIndex(s string) []int

FindStringIndex returns a two-element slice of integers defining the location of the leftmost match in s. The match is at s[loc[0]:loc[1]]. Returns nil if no match is found.

Example:

re := coregex.MustCompile(`\d+`)
loc := re.FindStringIndex("age: 42")
println(loc[0], loc[1]) // 5, 7

func (*Regex) Match ¶

func (r *Regex) Match(b []byte) bool

Match reports whether the byte slice b contains any match of the pattern.

Example:

re := coregex.MustCompile(`\d+`)
if re.Match([]byte("hello 123")) {
    println("contains digits")
}

func (*Regex) MatchString ¶

func (r *Regex) MatchString(s string) bool

MatchString reports whether the string s contains any match of the pattern.

Example:

re := coregex.MustCompile(`hello`)
if re.MatchString("hello world") {
    println("matched!")
}

func (*Regex) String ¶

func (r *Regex) String() string

String returns the source text used to compile the regular expression.

Example:

re := coregex.MustCompile(`\d+`)
println(re.String()) // `\d+`

Source Files ¶

View all Source files

regex.go

Directories ¶

Path	Synopsis
dfa
lazy Package lazy implements a Lazy DFA (Deterministic Finite Automaton) engine for regex matching.	Package lazy implements a Lazy DFA (Deterministic Finite Automaton) engine for regex matching.
internal
sparse Package sparse provides a sparse set data structure for efficient membership testing.	Package sparse provides a sparse set data structure for efficient membership testing.
literal Package literal provides types and operations for extracting literal sequences from regex patterns for prefilter optimization.	Package literal provides types and operations for extracting literal sequences from regex patterns for prefilter optimization.
meta Package meta implements the meta-engine orchestrator that automatically selects the optimal regex execution strategy.	Package meta implements the meta-engine orchestrator that automatically selects the optimal regex execution strategy.
nfa Package nfa provides a Thompson NFA (Non-deterministic Finite Automaton) implementation for regex matching.	Package nfa provides a Thompson NFA (Non-deterministic Finite Automaton) implementation for regex matching.
prefilter Package prefilter provides fast candidate filtering for regex search using extracted literal sequences.	Package prefilter provides fast candidate filtering for regex search using extracted literal sequences.
simd Package simd provides SIMD-accelerated string operations for high-performance byte searching.	Package simd provides SIMD-accelerated string operations for high-performance byte searching.

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README ¶

coregex - Production-Grade Regex Engine for Go

Features

Installation

Quick Start

Basic Usage

Advanced Configuration

Performance Example

Performance Benchmarks

Supported Features

v0.1.0 (Current)

Regex Syntax

Known Limitations

v0.1.0 (Experimental)

Documentation

Development

Building

Testing

Pre-release Check

Contributing

Comparison with Other Libraries

Architecture Overview

Related Projects

License

Acknowledgments

Support

Documentation ¶

Overview ¶

Index ¶

Examples ¶

Constants ¶

Variables ¶

Functions ¶

func DefaultConfig ¶

Types ¶

type Regex ¶

func Compile ¶

func CompileWithConfig ¶

func MustCompile ¶

func (*Regex) Find ¶

func (*Regex) FindAll ¶

func (*Regex) FindAllString ¶

func (*Regex) FindIndex ¶

func (*Regex) FindString ¶

func (*Regex) FindStringIndex ¶

func (*Regex) Match ¶

func (*Regex) MatchString ¶

func (*Regex) String ¶

Source Files ¶

Directories ¶