1 files changed, 85 insertions, 40 deletions
diff --git a/prism/node.h b/prism/node.h
index 403e84e0d3..75bc3c9b2d 100644
--- a/prism/node.h
+++ b/prism/node.h
@@ -1,49 +1,94 @@
+/**
+ * @file node.h
+ *
+ * Functions related to nodes in the AST.
+ */
 #ifndef PRISM_NODE_H
 #define PRISM_NODE_H
 
-#include "prism/defines.h"
-#include "prism/parser.h"
+#include "prism/compiler/exported.h"
+#include "prism/compiler/nonnull.h"
 
-// Append a new node onto the end of the node list.
-void pm_node_list_append(pm_node_list_t *list, pm_node_t *node);
+#include "prism/ast.h"
 
-// Clear the node but preserves the location.
-void pm_node_clear(pm_node_t *node);
+/**
+ * Loop through each node in the node list, writing each node to the given
+ * pm_node_t pointer.
+ */
+#define PM_NODE_LIST_FOREACH(list, index, node) \
+    for (size_t index = 0; index < (list)->size && ((node) = (list)->nodes[index]); index++)
 
-// Deallocate a node and all of its children.
-PRISM_EXPORTED_FUNCTION void pm_node_destroy(pm_parser_t *parser, struct pm_node *node);
+/**
+ * Returns a string representation of the given node type.
+ *
+ * @param node_type The node type to convert to a string.
+ * @returns A string representation of the given node type.
+ */
+PRISM_EXPORTED_FUNCTION const char * pm_node_type(pm_node_type_t node_type);
 
-// This struct stores the information gathered by the pm_node_memsize function.
-// It contains both the memory footprint and additionally metadata about the
-// shape of the tree.
-typedef struct {
-    size_t memsize;
-    size_t node_count;
-} pm_memsize_t;
+/**
+ * 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(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_arena_t *arena = pm_arena_new();
+ *     pm_options_t *options = pm_options_new();
+ *
+ *     pm_parser_t *parser = pm_parser_new(arena, (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_parser_free(parser);
+ *     pm_options_free(options);
+ *     pm_arena_free(arena);
+ *
+ *     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) PRISM_NONNULL(1);
 
-// Calculates the memory footprint of a given node.
-PRISM_EXPORTED_FUNCTION void pm_node_memsize(pm_node_t *node, pm_memsize_t *memsize);
+/**
+ * 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) PRISM_NONNULL(1);
 
-// Returns a string representation of the given node type.
-PRISM_EXPORTED_FUNCTION const char * pm_node_type_to_str(pm_node_type_t node_type);
-
-#define PM_EMPTY_NODE_LIST ((pm_node_list_t) { .nodes = NULL, .size = 0, .capacity = 0 })
-
-// ScopeNodes are helper nodes, and will never be part of the AST. We manually
-// declare them here to avoid generating them.
-typedef struct pm_scope_node {
-    pm_node_t base;
-    struct pm_scope_node *previous;
-    pm_node_t *ast_node;
-    struct pm_parameters_node *parameters;
-    pm_node_t *body;
-    pm_constant_id_list_t locals;
-    pm_parser_t *parser;
-
-    // We don't have the CRuby types ID and st_table within Prism
-    // so we use void *
-    void *constants; // ID *constants
-    void *index_lookup_table; // st_table *index_lookup_table
-} pm_scope_node_t;
-
-#endif // PRISM_NODE_H
+#endif