1 files changed, 62 insertions, 0 deletions
diff --git a/prism/node.h b/prism/node.h
index 76eb720978..a001b4a9e4 100644
--- a/prism/node.h
+++ b/prism/node.h
@@ -82,4 +82,66 @@ PRISM_EXPORTED_FUNCTION void pm_node_memsize(pm_node_t *node, pm_memsize_t *mems
  */
 PRISM_EXPORTED_FUNCTION const char * pm_node_type_to_str(pm_node_type_t node_type);
 
+/**
+ * Visit each of the nodes in this subtree using the given visitor callback. The
+ * callback function will be called for each node in the subtree. If it returns
+ * false, then that node's children will not be visited. If it returns true,
+ * then the children will be visited. The data parameter is treated as an opaque
+ * pointer and is passed to the visitor callback for consumers to use as they
+ * see fit.
+ *
+ * As an example:
+ *
+ * ```c
+ * #include "prism.h"
+ *
+ * bool visit(const pm_node_t *node, void *data) {
+ *     size_t *indent = (size_t *) data;
+ *     for (size_t i = 0; i < *indent * 2; i++) putc(' ', stdout);
+ *     printf("%s\n", pm_node_type_to_str(node->type));
+ *
+ *     size_t next_indent = *indent + 1;
+ *     size_t *next_data = &next_indent;
+ *     pm_visit_child_nodes(node, visit, next_data);
+ *
+ *     return false;
+ * }
+ *
+ * int main(void) {
+ *     const char *source = "1 + 2; 3 + 4";
+ *     size_t size = strlen(source);
+ *
+ *     pm_parser_t parser;
+ *     pm_options_t options = { 0 };
+ *     pm_parser_init(&parser, (const uint8_t *) source, size, &options);
+ *
+ *     size_t indent = 0;
+ *     pm_node_t *node = pm_parse(&parser);
+ *
+ *     size_t *data = &indent;
+ *     pm_visit_node(node, visit, data);
+ *
+ *     pm_node_destroy(&parser, node);
+ *     pm_parser_free(&parser);
+ *     return EXIT_SUCCESS;
+ * }
+ * ```
+ *
+ * @param node The root node to start visiting from.
+ * @param visitor The callback to call for each node in the subtree.
+ * @param data An opaque pointer that is passed to the visitor callback.
+ */
+PRISM_EXPORTED_FUNCTION void pm_visit_node(const pm_node_t *node, bool (*visitor)(const pm_node_t *node, void *data), void *data);
+
+/**
+ * Visit the children of the given node with the given callback. This is the
+ * default behavior for walking the tree that is called from pm_visit_node if
+ * the callback returns true.
+ *
+ * @param node The node to visit the children of.
+ * @param visitor The callback to call for each child node.
+ * @param data An opaque pointer that is passed to the visitor callback.
+ */
+PRISM_EXPORTED_FUNCTION void pm_visit_child_nodes(const pm_node_t *node, bool (*visitor)(const pm_node_t *node, void *data), void *data);
+
 #endif