From e2d1035924a06072cc938e25609ce68d0808b6d3 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 28 Oct 2021 16:36:09 +0300
Subject: Make HTML renderer not to use empty attribute syntax

---
 libcmark-gfm/libcmark-gfm/src/html.c | 486 +++++++++++++++++++++++++++++++++++
 1 file changed, 486 insertions(+)
 create mode 100644 libcmark-gfm/libcmark-gfm/src/html.c

(limited to 'libcmark-gfm/libcmark-gfm/src/html.c')

diff --git a/libcmark-gfm/libcmark-gfm/src/html.c b/libcmark-gfm/libcmark-gfm/src/html.c
new file mode 100644
index 0000000..f662aa3
--- /dev/null
+++ b/libcmark-gfm/libcmark-gfm/src/html.c
@@ -0,0 +1,486 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include "cmark_ctype.h"
+#include "config.h"
+#include "cmark-gfm.h"
+#include "houdini.h"
+#include "scanners.h"
+#include "syntax_extension.h"
+#include "html.h"
+#include "render.h"
+
+// Functions to convert cmark_nodes to HTML strings.
+
+static void escape_html(cmark_strbuf *dest, const unsigned char *source,
+                        bufsize_t length) {
+  houdini_escape_html0(dest, source, length, 0);
+}
+
+static void filter_html_block(cmark_html_renderer *renderer, uint8_t *data, size_t len) {
+  cmark_strbuf *html = renderer->html;
+  cmark_llist *it;
+  cmark_syntax_extension *ext;
+  bool filtered;
+  uint8_t *match;
+
+  while (len) {
+    match = (uint8_t *) memchr(data, '<', len);
+    if (!match)
+      break;
+
+    if (match != data) {
+      cmark_strbuf_put(html, data, (bufsize_t)(match - data));
+      len -= (match - data);
+      data = match;
+    }
+
+    filtered = false;
+    for (it = renderer->filter_extensions; it; it = it->next) {
+      ext = ((cmark_syntax_extension *) it->data);
+      if (!ext->html_filter_func(ext, data, len)) {
+        filtered = true;
+        break;
+      }
+    }
+
+    if (!filtered) {
+      cmark_strbuf_putc(html, '<');
+    } else {
+      cmark_strbuf_puts(html, "&lt;");
+    }
+
+    ++data;
+    --len;
+  }
+
+  if (len)
+    cmark_strbuf_put(html, data, (bufsize_t)len);
+}
+
+static bool S_put_footnote_backref(cmark_html_renderer *renderer, cmark_strbuf *html, cmark_node *node) {
+  if (renderer->written_footnote_ix >= renderer->footnote_ix)
+    return false;
+  renderer->written_footnote_ix = renderer->footnote_ix;
+
+  cmark_strbuf_puts(html, "<a href=\"#fnref-");
+  houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
+  cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref=\"\" aria-label=\"Back to content\">↩</a>");
+
+  if (node->footnote.def_count > 1)
+  {
+    for(int i = 2; i <= node->footnote.def_count; i++) {
+      char n[32];
+      snprintf(n, sizeof(n), "%d", i);
+
+      cmark_strbuf_puts(html, " <a href=\"#fnref-");
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
+      cmark_strbuf_puts(html, "-");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "\" class=\"footnote-backref\" data-footnote-backref=\"\" aria-label=\"Back to content\">↩<sup class=\"footnote-ref\">");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "</sup></a>");
+    }
+  }
+
+  return true;
+}
+
+static int S_render_node(cmark_html_renderer *renderer, cmark_node *node,
+                         cmark_event_type ev_type, int options) {
+  cmark_node *parent;
+  cmark_node *grandparent;
+  cmark_strbuf *html = renderer->html;
+  cmark_llist *it;
+  cmark_syntax_extension *ext;
+  char start_heading[] = "<h0";
+  char end_heading[] = "</h0";
+  bool tight;
+  bool filtered;
+  char buffer[BUFFER_SIZE];
+
+  bool entering = (ev_type == CMARK_EVENT_ENTER);
+
+  if (renderer->plain == node) { // back at original node
+    renderer->plain = NULL;
+  }
+
+  if (renderer->plain != NULL) {
+    switch (node->type) {
+    case CMARK_NODE_TEXT:
+    case CMARK_NODE_CODE:
+    case CMARK_NODE_HTML_INLINE:
+      escape_html(html, node->as.literal.data, node->as.literal.len);
+      break;
+
+    case CMARK_NODE_LINEBREAK:
+    case CMARK_NODE_SOFTBREAK:
+      cmark_strbuf_putc(html, ' ');
+      break;
+
+    default:
+      break;
+    }
+    return 1;
+  }
+
+  if (node->extension && node->extension->html_render_func) {
+    node->extension->html_render_func(node->extension, renderer, node, ev_type, options);
+    return 1;
+  }
+
+  switch (node->type) {
+  case CMARK_NODE_DOCUMENT:
+    break;
+
+  case CMARK_NODE_BLOCK_QUOTE:
+    if (entering) {
+      cmark_html_render_cr(html);
+      cmark_strbuf_puts(html, "<blockquote");
+      cmark_html_render_sourcepos(node, html, options);
+      cmark_strbuf_puts(html, ">\n");
+    } else {
+      cmark_html_render_cr(html);
+      cmark_strbuf_puts(html, "</blockquote>\n");
+    }
+    break;
+
+  case CMARK_NODE_LIST: {
+    cmark_list_type list_type = node->as.list.list_type;
+    int start = node->as.list.start;
+
+    if (entering) {
+      cmark_html_render_cr(html);
+      if (list_type == CMARK_BULLET_LIST) {
+        cmark_strbuf_puts(html, "<ul");
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_puts(html, ">\n");
+      } else if (start == 1) {
+        cmark_strbuf_puts(html, "<ol");
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_puts(html, ">\n");
+      } else {
+        snprintf(buffer, BUFFER_SIZE, "<ol start=\"%d\"", start);
+        cmark_strbuf_puts(html, buffer);
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_puts(html, ">\n");
+      }
+    } else {
+      cmark_strbuf_puts(html,
+                        list_type == CMARK_BULLET_LIST ? "</ul>\n" : "</ol>\n");
+    }
+    break;
+  }
+
+  case CMARK_NODE_ITEM:
+    if (entering) {
+      cmark_html_render_cr(html);
+      cmark_strbuf_puts(html, "<li");
+      cmark_html_render_sourcepos(node, html, options);
+      cmark_strbuf_putc(html, '>');
+    } else {
+      cmark_strbuf_puts(html, "</li>\n");
+    }
+    break;
+
+  case CMARK_NODE_HEADING:
+    if (entering) {
+      cmark_html_render_cr(html);
+      start_heading[2] = (char)('0' + node->as.heading.level);
+      cmark_strbuf_puts(html, start_heading);
+      cmark_html_render_sourcepos(node, html, options);
+      cmark_strbuf_putc(html, '>');
+    } else {
+      end_heading[3] = (char)('0' + node->as.heading.level);
+      cmark_strbuf_puts(html, end_heading);
+      cmark_strbuf_puts(html, ">\n");
+    }
+    break;
+
+  case CMARK_NODE_CODE_BLOCK:
+    cmark_html_render_cr(html);
+
+    if (node->as.code.info.len == 0) {
+      cmark_strbuf_puts(html, "<pre");
+      cmark_html_render_sourcepos(node, html, options);
+      cmark_strbuf_puts(html, "><code>");
+    } else {
+      bufsize_t first_tag = 0;
+      while (first_tag < node->as.code.info.len &&
+             !cmark_isspace(node->as.code.info.data[first_tag])) {
+        first_tag += 1;
+      }
+
+      if (options & CMARK_OPT_GITHUB_PRE_LANG) {
+        cmark_strbuf_puts(html, "<pre");
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_puts(html, " lang=\"");
+        escape_html(html, node->as.code.info.data, first_tag);
+        if (first_tag < node->as.code.info.len && (options & CMARK_OPT_FULL_INFO_STRING)) {
+          cmark_strbuf_puts(html, "\" data-meta=\"");
+          escape_html(html, node->as.code.info.data + first_tag + 1, node->as.code.info.len - first_tag - 1);
+        }
+        cmark_strbuf_puts(html, "\"><code>");
+      } else {
+        cmark_strbuf_puts(html, "<pre");
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_puts(html, "><code class=\"language-");
+        escape_html(html, node->as.code.info.data, first_tag);
+        if (first_tag < node->as.code.info.len && (options & CMARK_OPT_FULL_INFO_STRING)) {
+          cmark_strbuf_puts(html, "\" data-meta=\"");
+          escape_html(html, node->as.code.info.data + first_tag + 1, node->as.code.info.len - first_tag - 1);
+        }
+        cmark_strbuf_puts(html, "\">");
+      }
+    }
+
+    escape_html(html, node->as.code.literal.data, node->as.code.literal.len);
+    cmark_strbuf_puts(html, "</code></pre>\n");
+    break;
+
+  case CMARK_NODE_HTML_BLOCK:
+    cmark_html_render_cr(html);
+    if (!(options & CMARK_OPT_UNSAFE)) {
+      cmark_strbuf_puts(html, "<!-- raw HTML omitted -->");
+    } else if (renderer->filter_extensions) {
+      filter_html_block(renderer, node->as.literal.data, node->as.literal.len);
+    } else {
+      cmark_strbuf_put(html, node->as.literal.data, node->as.literal.len);
+    }
+    cmark_html_render_cr(html);
+    break;
+
+  case CMARK_NODE_CUSTOM_BLOCK:
+    cmark_html_render_cr(html);
+    if (entering) {
+      cmark_strbuf_put(html, node->as.custom.on_enter.data,
+                       node->as.custom.on_enter.len);
+    } else {
+      cmark_strbuf_put(html, node->as.custom.on_exit.data,
+                       node->as.custom.on_exit.len);
+    }
+    cmark_html_render_cr(html);
+    break;
+
+  case CMARK_NODE_THEMATIC_BREAK:
+    cmark_html_render_cr(html);
+    cmark_strbuf_puts(html, "<hr");
+    cmark_html_render_sourcepos(node, html, options);
+    cmark_strbuf_puts(html, " />\n");
+    break;
+
+  case CMARK_NODE_PARAGRAPH:
+    parent = cmark_node_parent(node);
+    grandparent = cmark_node_parent(parent);
+    if (grandparent != NULL && grandparent->type == CMARK_NODE_LIST) {
+      tight = grandparent->as.list.tight;
+    } else {
+      tight = false;
+    }
+    if (!tight) {
+      if (entering) {
+        cmark_html_render_cr(html);
+        cmark_strbuf_puts(html, "<p");
+        cmark_html_render_sourcepos(node, html, options);
+        cmark_strbuf_putc(html, '>');
+      } else {
+        if (parent->type == CMARK_NODE_FOOTNOTE_DEFINITION && node->next == NULL) {
+          cmark_strbuf_putc(html, ' ');
+          S_put_footnote_backref(renderer, html, parent);
+        }
+        cmark_strbuf_puts(html, "</p>\n");
+      }
+    }
+    break;
+
+  case CMARK_NODE_TEXT:
+    escape_html(html, node->as.literal.data, node->as.literal.len);
+    break;
+
+  case CMARK_NODE_LINEBREAK:
+    cmark_strbuf_puts(html, "<br />\n");
+    break;
+
+  case CMARK_NODE_SOFTBREAK:
+    if (options & CMARK_OPT_HARDBREAKS) {
+      cmark_strbuf_puts(html, "<br />\n");
+    } else if (options & CMARK_OPT_NOBREAKS) {
+      cmark_strbuf_putc(html, ' ');
+    } else {
+      cmark_strbuf_putc(html, '\n');
+    }
+    break;
+
+  case CMARK_NODE_CODE:
+    cmark_strbuf_puts(html, "<code>");
+    escape_html(html, node->as.literal.data, node->as.literal.len);
+    cmark_strbuf_puts(html, "</code>");
+    break;
+
+  case CMARK_NODE_HTML_INLINE:
+    if (!(options & CMARK_OPT_UNSAFE)) {
+      cmark_strbuf_puts(html, "<!-- raw HTML omitted -->");
+    } else {
+      filtered = false;
+      for (it = renderer->filter_extensions; it; it = it->next) {
+        ext = (cmark_syntax_extension *) it->data;
+        if (!ext->html_filter_func(ext, node->as.literal.data, node->as.literal.len)) {
+          filtered = true;
+          break;
+        }
+      }
+      if (!filtered) {
+        cmark_strbuf_put(html, node->as.literal.data, node->as.literal.len);
+      } else {
+        cmark_strbuf_puts(html, "&lt;");
+        cmark_strbuf_put(html, node->as.literal.data + 1, node->as.literal.len - 1);
+      }
+    }
+    break;
+
+  case CMARK_NODE_CUSTOM_INLINE:
+    if (entering) {
+      cmark_strbuf_put(html, node->as.custom.on_enter.data,
+                       node->as.custom.on_enter.len);
+    } else {
+      cmark_strbuf_put(html, node->as.custom.on_exit.data,
+                       node->as.custom.on_exit.len);
+    }
+    break;
+
+  case CMARK_NODE_STRONG:
+    if (entering) {
+      cmark_strbuf_puts(html, "<strong>");
+    } else {
+      cmark_strbuf_puts(html, "</strong>");
+    }
+    break;
+
+  case CMARK_NODE_EMPH:
+    if (entering) {
+      cmark_strbuf_puts(html, "<em>");
+    } else {
+      cmark_strbuf_puts(html, "</em>");
+    }
+    break;
+
+  case CMARK_NODE_LINK:
+    if (entering) {
+      cmark_strbuf_puts(html, "<a href=\"");
+      if ((options & CMARK_OPT_UNSAFE) ||
+            !(scan_dangerous_url(&node->as.link.url, 0))) {
+        houdini_escape_href(html, node->as.link.url.data,
+                            node->as.link.url.len);
+      }
+      if (node->as.link.title.len) {
+        cmark_strbuf_puts(html, "\" title=\"");
+        escape_html(html, node->as.link.title.data, node->as.link.title.len);
+      }
+      cmark_strbuf_puts(html, "\">");
+    } else {
+      cmark_strbuf_puts(html, "</a>");
+    }
+    break;
+
+  case CMARK_NODE_IMAGE:
+    if (entering) {
+      cmark_strbuf_puts(html, "<img src=\"");
+      if ((options & CMARK_OPT_UNSAFE) ||
+            !(scan_dangerous_url(&node->as.link.url, 0))) {
+        houdini_escape_href(html, node->as.link.url.data,
+                            node->as.link.url.len);
+      }
+      cmark_strbuf_puts(html, "\" alt=\"");
+      renderer->plain = node;
+    } else {
+      if (node->as.link.title.len) {
+        cmark_strbuf_puts(html, "\" title=\"");
+        escape_html(html, node->as.link.title.data, node->as.link.title.len);
+      }
+
+      cmark_strbuf_puts(html, "\" />");
+    }
+    break;
+
+  case CMARK_NODE_FOOTNOTE_DEFINITION:
+    if (entering) {
+      if (renderer->footnote_ix == 0) {
+        cmark_strbuf_puts(html, "<section class=\"footnotes\" data-footnotes=\"\">\n<ol>\n");
+      }
+      ++renderer->footnote_ix;
+
+      cmark_strbuf_puts(html, "<li id=\"fn-");
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
+      cmark_strbuf_puts(html, "\">\n");
+    } else {
+      if (S_put_footnote_backref(renderer, html, node)) {
+        cmark_strbuf_putc(html, '\n');
+      }
+      cmark_strbuf_puts(html, "</li>\n");
+    }
+    break;
+
+  case CMARK_NODE_FOOTNOTE_REFERENCE:
+    if (entering) {
+      cmark_strbuf_puts(html, "<sup class=\"footnote-ref\"><a href=\"#fn-");
+      houdini_escape_href(html, node->parent_footnote_def->as.literal.data, node->parent_footnote_def->as.literal.len);
+      cmark_strbuf_puts(html, "\" id=\"fnref-");
+      houdini_escape_href(html, node->parent_footnote_def->as.literal.data, node->parent_footnote_def->as.literal.len);
+
+      if (node->footnote.ref_ix > 1) {
+        char n[32];
+        snprintf(n, sizeof(n), "%d", node->footnote.ref_ix);
+        cmark_strbuf_puts(html, "-");
+        cmark_strbuf_puts(html, n);
+      }
+
+      cmark_strbuf_puts(html, "\" data-footnote-ref=\"\">");
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
+      cmark_strbuf_puts(html, "</a></sup>");
+    }
+    break;
+
+  default:
+    assert(false);
+    break;
+  }
+
+  return 1;
+}
+
+char *cmark_render_html(cmark_node *root, int options, cmark_llist *extensions) {
+  return cmark_render_html_with_mem(root, options, extensions, cmark_node_mem(root));
+}
+
+char *cmark_render_html_with_mem(cmark_node *root, int options, cmark_llist *extensions, cmark_mem *mem) {
+  char *result;
+  cmark_strbuf html = CMARK_BUF_INIT(mem);
+  cmark_event_type ev_type;
+  cmark_node *cur;
+  cmark_html_renderer renderer = {&html, NULL, NULL, 0, 0, NULL};
+  cmark_iter *iter = cmark_iter_new(root);
+
+  for (; extensions; extensions = extensions->next)
+    if (((cmark_syntax_extension *) extensions->data)->html_filter_func)
+      renderer.filter_extensions = cmark_llist_append(
+          mem,
+          renderer.filter_extensions,
+          (cmark_syntax_extension *) extensions->data);
+
+  while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
+    cur = cmark_iter_get_node(iter);
+    S_render_node(&renderer, cur, ev_type, options);
+  }
+
+  if (renderer.footnote_ix) {
+    cmark_strbuf_puts(&html, "</ol>\n</section>\n");
+  }
+
+  result = (char *)cmark_strbuf_detach(&html);
+
+  cmark_llist_free(mem, renderer.filter_extensions);
+
+  cmark_iter_free(iter);
+  return result;
+}
-- 
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