Merge pull request commonmark#322 from kevinbackhouse/list-item-index

Fix quadratic list indexing in commonmark/man/plaintext output formats

Author: kevinbackhouse

src/cmark-gfm.h

@@ -423,6 +423,17 @@ CMARK_GFM_EXPORT int cmark_node_get_list_tight(cmark_node *node);
  */
 CMARK_GFM_EXPORT int cmark_node_set_list_tight(cmark_node *node, int tight);
 
+/**
+ * Returns item index of 'node'. This is only used when rendering output
+ * formats such as commonmark, which need to output the index. It is not
+ * required for formats such as html or latex.
+ */
+CMARK_GFM_EXPORT int cmark_node_get_item_index(cmark_node *node);
+
+/** Sets item index of 'node'. Returns 1 on success, 0 on failure.
+ */
+CMARK_GFM_EXPORT int cmark_node_set_item_index(cmark_node *node, int idx);
+
 /** Returns the info string from a fenced code block.
  */
 CMARK_GFM_EXPORT const char *cmark_node_get_fence_info(cmark_node *node);

src/commonmark.c

@@ -216,14 +216,13 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
       LIT("<!-- end list -->");
       BLANKLINE();
     }
-    renderer->list_number = cmark_node_get_list_start(node);
     break;
 
   case CMARK_NODE_ITEM:
     if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
       marker_width = 4;
     } else {
-      list_number = renderer->list_number++;
+      list_number = cmark_node_get_item_index(node);
       list_delim = cmark_node_get_list_delim(node->parent);
       // we ensure a width of at least 4 so
       // we get nice transition from single digits

src/man.c

@@ -113,7 +113,6 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     break;
 
   case CMARK_NODE_LIST:
-    renderer->list_number = cmark_node_get_list_start(node);
     break;
 
   case CMARK_NODE_ITEM:
@@ -123,7 +122,7 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
       if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
         LIT("\\[bu] 2");
       } else {
-        list_number = renderer->list_number++;
+        list_number = cmark_node_get_item_index(node);
         char list_number_s[LIST_NUMBER_SIZE];
         snprintf(list_number_s, LIST_NUMBER_SIZE, "\"%d.\" 4", list_number);
         LIT(list_number_s);

src/node.c

@@ -564,6 +564,31 @@ int cmark_node_set_list_tight(cmark_node *node, int tight) {
   }
 }
 
+int cmark_node_get_item_index(cmark_node *node) {
+  if (node == NULL) {
+    return 0;
+  }
+
+  if (node->type == CMARK_NODE_ITEM) {
+    return node->as.list.start;
+  } else {
+    return 0;
+  }
+}
+
+int cmark_node_set_item_index(cmark_node *node, int idx) {
+  if (node == NULL || idx < 0) {
+    return 0;
+  }
+
+  if (node->type == CMARK_NODE_ITEM) {
+    node->as.list.start = idx;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
 const char *cmark_node_get_fence_info(cmark_node *node) {
   if (node == NULL) {
     return NULL;

src/plaintext.c

@@ -61,14 +61,13 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
                                     node->next->type == CMARK_NODE_LIST)) {
       CR();
     }
-    renderer->list_number = cmark_node_get_list_start(node);
     break;
 
   case CMARK_NODE_ITEM:
     if (cmark_node_get_list_type(node->parent) == CMARK_BULLET_LIST) {
       marker_width = 4;
     } else {
-      list_number = renderer->list_number++;
+      list_number = cmark_node_get_item_index(node);
       list_delim = cmark_node_get_list_delim(node->parent);
       // we ensure a width of at least 4 so
       // we get nice transition from single digits

src/render.c

@@ -171,8 +171,8 @@ char *cmark_render(cmark_mem *mem, cmark_node *root, int options, int width,
 
   cmark_renderer renderer = {mem,   &buf, &pref, 0,           width,
                              0,     0,    true,  true,        false,
-                             false, 0,    outc,  S_cr,        S_blankline,
-                             S_out, 0};
+                             false, outc, S_cr,  S_blankline, S_out,
+                             0};
 
   while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
     cur = cmark_iter_get_node(iter);
@@ -181,6 +181,15 @@ char *cmark_render(cmark_mem *mem, cmark_node *root, int options, int width,
     } else if (cur->parent) {
       cur->ancestor_extension = cur->parent->ancestor_extension;
     }
+    if (cur->type == CMARK_NODE_ITEM) {
+      // Calculate the list item's index, for the benefit of output formats
+      // like commonmark and plaintext.
+      if (cur->prev) {
+        cmark_node_set_item_index(cur, 1 + cmark_node_get_item_index(cur->prev));
+      } else {
+        cmark_node_set_item_index(cur, cmark_node_get_list_start(cur->parent));
+      }
+    }
     if (!render_node(&renderer, cur, ev_type, options)) {
       // a false value causes us to skip processing
       // the node's contents.  this is used for

src/render.h

@@ -23,7 +23,6 @@ struct cmark_renderer {
   bool begin_content;
   bool no_linebreaks;
   bool in_tight_list_item;
-  int list_number;
   void (*outc)(struct cmark_renderer *, cmark_node *, cmark_escaping, int32_t, unsigned char);
   void (*cr)(struct cmark_renderer *);
   void (*blankline)(struct cmark_renderer *);