Add node constructor and accessors to the public API

The approach I'm taking is to copy inline literals internally to
NULL-terminated C strings if requested by an accessor. This allows to
return a 'const char *' that doesn't have to be freed by the caller.

3 files changed, 139 insertions, 17 deletions

diff --git a/src/chunk.h b/src/chunk.h
index 9dd56b6..7a1dbc3 100644
--- a/src/chunk.h
+++ b/src/chunk.h
@@ -8,15 +8,15 @@
 #include "buffer.h"
 
 typedef struct {
-	const unsigned char *data;
+	unsigned char *data;
 	int len;
-	int alloc;
+	int alloc;  // also implies a NULL-terminated string
 } cmark_chunk;
 
 static inline void cmark_chunk_free(cmark_chunk *c)
 {
 	if (c->alloc)
-		free((char *)c->data);
+		free(c->data);
 
 	c->data = NULL;
 	c->alloc = 0;
@@ -55,21 +55,38 @@ static inline int cmark_chunk_strchr(cmark_chunk *ch, int c, int offset)
 	return p ? (int)(p - ch->data) : ch->len;
 }
 
-static inline unsigned char *cmark_chunk_to_cstr(cmark_chunk *c)
+static inline const char *cmark_chunk_to_cstr(cmark_chunk *c)
 {
 	unsigned char *str;
 
-	str = (unsigned char *)calloc(c->len + 1, sizeof(*str));
-    if(str != NULL) {
-    	memcpy(str, c->data, c->len);
-	    str[c->len] = 0;
-    }
-	return str;
+	if (c->alloc) {
+		return (char *)c->data;
+	}
+	str = (unsigned char *)malloc(c->len + 1);
+	if(str != NULL) {
+		memcpy(str, c->data, c->len);
+		str[c->len] = 0;
+	}
+	c->data  = str;
+	c->alloc = 1;
+
+	return (char *)str;
+}
+
+static inline void cmark_chunk_set_cstr(cmark_chunk *c, const char *str)
+{
+	if (c->alloc) {
+		free(c->data);
+	}
+	c->len   = strlen(str);
+	c->data  = (unsigned char *)malloc(c->len + 1);
+	c->alloc = 1;
+	memcpy(c->data, str, c->len + 1);
 }
 
 static inline cmark_chunk cmark_chunk_literal(const char *data)
 {
-	cmark_chunk c = {(const unsigned char *)data, data ? strlen(data) : 0, 0};
+	cmark_chunk c = {(unsigned char *)data, data ? strlen(data) : 0, 0};
 	return c;
 }
 
diff --git a/src/cmark.h b/src/cmark.h
index c5ddd5b..522e77e 100644
--- a/src/cmark.h
+++ b/src/cmark.h
@@ -56,8 +56,16 @@ typedef enum {
 typedef struct cmark_node cmark_node;
 typedef struct cmark_doc_parser cmark_doc_parser;
 
-CMARK_EXPORT cmark_node_type
-cmark_node_get_type(cmark_node *node);
+// Construction and destruction
+
+CMARK_EXPORT cmark_node*
+cmark_node_new(cmark_node_type type);
+
+CMARK_EXPORT void
+cmark_node_destroy(cmark_node *node);
+
+CMARK_EXPORT void
+cmark_free_nodes(cmark_node *e);
 
 // Tree traversal
 
@@ -76,6 +84,23 @@ cmark_node_first_child(cmark_node *node);
 CMARK_EXPORT cmark_node*
 cmark_node_last_child(cmark_node *node);
 
+// Accessors
+
+CMARK_EXPORT cmark_node_type
+cmark_node_get_type(cmark_node *node);
+
+CMARK_EXPORT const char*
+cmark_node_get_content(cmark_node *node);
+
+CMARK_EXPORT int
+cmark_node_set_content(cmark_node *node, const char *content);
+
+CMARK_EXPORT const char*
+cmark_node_get_url(cmark_node *node);
+
+CMARK_EXPORT int
+cmark_node_set_url(cmark_node *node, const char *url);
+
 // Tree manipulation
 
 CMARK_EXPORT void
@@ -124,9 +149,6 @@ unsigned char *cmark_render_html(cmark_node *root);
 CMARK_EXPORT
 unsigned char *cmark_markdown_to_html(unsigned char *text, int len);
 
-CMARK_EXPORT
-void cmark_free_nodes(cmark_node *e);
-
 #ifndef CMARK_NO_SHORT_NAMES
   #define NODE_DOCUMENT             CMARK_NODE_DOCUMENT
   #define NODE_BQUOTE               CMARK_NODE_BQUOTE
diff --git a/src/node.c b/src/node.c
index 489ac7c..c5ce642 100644
--- a/src/node.c
+++ b/src/node.c
@@ -1,8 +1,26 @@
-#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "config.h"
 #include "node.h"
 
+static void
+S_node_unlink(cmark_node *node);
+
+cmark_node*
+cmark_node_new(cmark_node_type type) {
+	cmark_node *node = (cmark_node *)calloc(1, sizeof(*node));
+	node->type = type;
+	return node;
+}
+
+void
+cmark_node_destroy(cmark_node *node) {
+	S_node_unlink(node);
+	node->next = NULL;
+	cmark_free_nodes(node);
+}
+
 cmark_node_type
 cmark_node_get_type(cmark_node *node)
 {
@@ -69,6 +87,71 @@ cmark_node_last_child(cmark_node *node)
 	return node->last_child;
 }
 
+static char*
+S_strdup(const char *str) {
+	size_t size = strlen(str) + 1;
+	char *dup = (char *)malloc(size);
+	memcpy(dup, str, size);
+	return dup;
+}
+
+const char*
+cmark_node_get_content(cmark_node *node) {
+	switch (node->type) {
+	case NODE_STRING:
+	case NODE_INLINE_HTML:
+	case NODE_INLINE_CODE:
+		return cmark_chunk_to_cstr(&node->as.literal);
+	default:
+		break;
+	}
+
+	return NULL;
+}
+
+int
+cmark_node_set_content(cmark_node *node, const char *content) {
+	switch (node->type) {
+	case NODE_STRING:
+	case NODE_INLINE_HTML:
+	case NODE_INLINE_CODE:
+		cmark_chunk_set_cstr(&node->as.literal, content);
+		return 1;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+const char*
+cmark_node_get_url(cmark_node *node) {
+	switch (node->type) {
+	case NODE_LINK:
+	case NODE_IMAGE:
+		return (char *)node->as.link.url;
+	default:
+		break;
+	}
+
+	return NULL;
+}
+
+int
+cmark_node_set_url(cmark_node *node, const char *url) {
+	switch (node->type) {
+	case NODE_LINK:
+	case NODE_IMAGE:
+		free(node->as.link.url);
+		node->as.link.url = (unsigned char *)S_strdup(url);
+		return 1;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 static inline bool
 S_is_block(cmark_node *node) {
 	return node->type >= CMARK_NODE_FIRST_BLOCK