1 files changed, 69 insertions, 32 deletions
diff --git a/prism/node.h b/prism/node.h
index 3e15d18552..75bc3c9b2d 100644
--- a/prism/node.h
+++ b/prism/node.h
@@ -6,52 +6,89 @@
 #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.
- *
- * @param list The list to append to.
- * @param node The node to append.
- */
-void pm_node_list_append(pm_node_list_t *list, pm_node_t *node);
+#include "prism/ast.h"
 
 /**
- * Deallocate a node and all of its children.
- *
- * @param parser The parser that owns the node.
- * @param node The node to deallocate.
+ * Loop through each node in the node list, writing each node to the given
+ * pm_node_t pointer.
  */
-PRISM_EXPORTED_FUNCTION void pm_node_destroy(pm_parser_t *parser, struct pm_node *node);
+#define PM_NODE_LIST_FOREACH(list, index, node) \
+    for (size_t index = 0; index < (list)->size && ((node) = (list)->nodes[index]); index++)
 
 /**
- * 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.
+ * 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.
  */
-typedef struct {
-    /** The total memory footprint of the node and all of its children. */
-    size_t memsize;
-
-    /** The number of children the node has. */
-    size_t node_count;
-} pm_memsize_t;
+PRISM_EXPORTED_FUNCTION const char * pm_node_type(pm_node_type_t node_type);
 
 /**
- * Calculates the memory footprint of a given node.
+ * 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));
  *
- * @param node The node to calculate the memory footprint of.
- * @param memsize The memory footprint of the node and all of its children.
+ *     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_node_memsize(pm_node_t *node, pm_memsize_t *memsize);
+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);
 
 /**
- * Returns a string representation of the given node type.
+ * 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_type The node type to convert to a string.
- * @return A string representation of the given node type.
+ * @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 const char * pm_node_type_to_str(pm_node_type_t node_type);
+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);
 
 #endif