Added iterator interface to API, removed cmark_walk.

* Added `iterator.c`, `iterator.h`.
* Removed `cmark_walk`.
* Replaced `cmark_walk` with iterator in HTML renderer.
* Replaced API test for `cmark_walk` with simple iterator test.

1 files changed, 86 insertions, 0 deletions

diff --git a/src/iterator.c b/src/iterator.c
new file mode 100644
index 0000000..a9e6d20
--- /dev/null
+++ b/src/iterator.c
@@ -0,0 +1,86 @@
+#include <stdlib.h>
+
+#include "config.h"
+#include "node.h"
+#include "cmark.h"
+#include "iterator.h"
+
+cmark_iter*
+cmark_iter_new(cmark_node *root)
+{
+	cmark_iter *iter = (cmark_iter*)malloc(sizeof(cmark_iter));
+	if (iter == NULL) {
+		return NULL;
+	} else {
+		iter->root = root;
+		iter->current = root;
+		iter->event_type = CMARK_EVENT_ENTER;
+		return iter;
+	}
+}
+
+void
+cmark_iter_free(cmark_iter *iter)
+{
+	free(iter);
+}
+
+cmark_event_type
+cmark_iter_next(cmark_iter *iter)
+{
+	return iter->event_type;
+}
+
+int S_is_leaf(cmark_node *node)
+{
+	switch (cmark_node_get_type(node)) {
+	case CMARK_NODE_HTML:
+	case CMARK_NODE_HRULE:
+	case CMARK_NODE_CODE_BLOCK:
+	case CMARK_NODE_TEXT:
+	case CMARK_NODE_SOFTBREAK:
+	case CMARK_NODE_LINEBREAK:
+	case CMARK_NODE_INLINE_CODE:
+	case CMARK_NODE_INLINE_HTML:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+cmark_node*
+cmark_iter_get_node(cmark_iter *iter)
+{
+	/* we'll return current */
+	cmark_node *cur = iter->current;
+
+	if (cur == NULL || iter->event_type == CMARK_EVENT_DONE) {
+		return NULL;
+	}
+
+	/* roll forward to next item, setting both fields */
+	if (iter->event_type == CMARK_EVENT_ENTER && !S_is_leaf(cur)) {
+		if (cur->first_child == NULL) {
+			/* stay on this node but exit */
+			iter->event_type = CMARK_EVENT_EXIT;
+		} else {
+			iter->current = cur->first_child;
+			iter->event_type = CMARK_EVENT_ENTER;
+		}
+	} else if (cur == iter->root) {
+		/* don't move past root */
+		iter->event_type = CMARK_EVENT_DONE;
+		iter->current = NULL;
+	} else if (cur->next) {
+		iter->event_type = CMARK_EVENT_ENTER;
+		iter->current = cur->next;
+	} else if (cur->parent) {
+		iter->event_type = CMARK_EVENT_EXIT;
+		iter->current = cur->parent;
+	} else {
+		iter->event_type = CMARK_EVENT_DONE;
+		iter->current = NULL;
+	}
+
+	return cur;
+}