API improvements: cmark_event_type parameter for walk handlers.

Added cmark_event_type enum, which is used as the second
parameter of the handler passed to cmark_walk.

See #224.

3 files changed, 20 insertions, 9 deletions

diff --git a/src/cmark.h b/src/cmark.h
index 224ef3a..a43703a 100644
--- a/src/cmark.h
+++ b/src/cmark.h
@@ -85,7 +85,14 @@ typedef enum {
 typedef struct cmark_node cmark_node;
 typedef struct cmark_parser cmark_parser;
 
-typedef int (*cmark_node_handler)(cmark_node*, int, void*);
+typedef enum {
+	CMARK_EVENT_DONE,
+	CMARK_EVENT_ENTER,
+	CMARK_EVENT_EXIT
+} cmark_event_type;
+
+typedef int (*cmark_node_handler)(cmark_node *node, cmark_event_type ev_type,
+				  void *state);
 
 /**
  * .SH CREATING AND DESTROYING NODES
@@ -311,7 +318,7 @@ char *cmark_render_html(cmark_node *root);
 /** Walks the tree starting from root, applying handler to each node.
  * Nodes that can have children are visited twice, once on the way in
  * and once on the way out.  handler is a function that takes a node
- * pointer, an integer direction (1 for entering, 0 for leaving),
+ * pointer, a cmark_event_type,
  * and a pointer to a state structure that can be consulted and
  * updated by the handler.  The handler should return 1 on success,
  * 0 on failure.  cmark_walk returns 1 if it traversed the entire
diff --git a/src/html.c b/src/html.c
index 12d4659..1ccb57a 100644
--- a/src/html.c
+++ b/src/html.c
@@ -39,7 +39,7 @@ struct render_state {
 };
 
 static int
-S_render_node(cmark_node *node, int entering, void *vstate)
+S_render_node(cmark_node *node, cmark_event_type ev_type, void *vstate)
 {
 	struct render_state *state = vstate;
 	cmark_node *parent;
@@ -50,6 +50,8 @@ S_render_node(cmark_node *node, int entering, void *vstate)
 	strbuf *info;
 	bool tight;
 
+	bool entering = (ev_type == CMARK_EVENT_ENTER);
+
 	if (state->plain == node) { // back at original node
 		state->plain = NULL;
 	}
diff --git a/src/node.c b/src/node.c
index a7083ca..72eb619 100644
--- a/src/node.c
+++ b/src/node.c
@@ -786,7 +786,7 @@ int S_is_leaf_node(cmark_node *current_node)
 
 int cmark_walk(cmark_node *root, cmark_node_handler handler, void *state)
 {
-	int begin = 1;
+	int ev_type = CMARK_EVENT_ENTER;
 	cmark_node *current_node = root;
 	int depth = 0;
 	cmark_node *next, *parent, *first_child;
@@ -796,14 +796,15 @@ int cmark_walk(cmark_node *root, cmark_node_handler handler, void *state)
 		next = current_node->next;
 		parent = current_node->parent;
 
-		if (!handler(current_node, begin, state)) {
+		if (!handler(current_node, ev_type, state)) {
 			return 0;
 		}
 
-		if (begin && !S_is_leaf_node(current_node)) {
+		if (ev_type == CMARK_EVENT_ENTER &&
+		    !S_is_leaf_node(current_node)) {
 			first_child = current_node->first_child;
 			if (first_child == NULL) {
-				begin = 0; // stay on this node
+				ev_type = CMARK_EVENT_EXIT; // stay on this node
 			} else {
 				depth += 1;
 				current_node = first_child;
@@ -816,13 +817,14 @@ int cmark_walk(cmark_node *root, cmark_node_handler handler, void *state)
 			if (next) {
 				// don't go past root:
 				if (current_node == root) {
+					ev_type = CMARK_EVENT_DONE;
 					return 1;
 				} else {
-					begin = 1;
+					ev_type = CMARK_EVENT_ENTER;
 					current_node = next;
 				}
 			} else {
-				begin = 0;
+				ev_type = CMARK_EVENT_EXIT;
 				depth -= 1;
 				current_node = parent;
 			}