Add my own highlight extension

lib/commonmarker/extensions/CMakeLists.txt

@@ -10,6 +10,7 @@ set (LIBRARY_SOURCES
   ext_scanners.re
   ext_scanners.h
   tasklist.c
+  highlight.c
 )
 
 set_property(GLOBAL PROPERTY COMMONMARKER_EXTENSIONS_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})

lib/commonmarker/extensions/core-extensions.c

@@ -4,6 +4,7 @@
 #include "table.h"
 #include "tagfilter.h"
 #include "tasklist.h"
+#include "highlight.h"
 #include "registry.h"
 #include "plugin.h"
 
@@ -14,6 +15,7 @@ static int core_extensions_registration(cmark_plugin *plugin) {
   cmark_plugin_register_syntax_extension(plugin, create_autolink_extension());
   cmark_plugin_register_syntax_extension(plugin, create_tagfilter_extension());
   cmark_plugin_register_syntax_extension(plugin, create_tasklist_extension());
+  cmark_plugin_register_syntax_extension(plugin, create_highlight_extension());
   return 1;
 }
 

lib/commonmarker/extensions/highlight.c

@@ -0,0 +1,128 @@
+#include "highlight.h"
+#include <parser.h>
+#include <render.h>
+
+cmark_node_type CMARK_NODE_HIGHLIGHT;
+
+static cmark_node *match(cmark_syntax_extension *self, cmark_parser *parser,
+                         cmark_node *parent, unsigned char character,
+                         cmark_inline_parser *inline_parser) {
+  cmark_node *res = NULL;
+  int left_flanking, right_flanking, punct_before, punct_after, delims;
+  char buffer[101] = {0};
+
+  if (character != '=')
+    return NULL;
+
+  delims = cmark_inline_parser_scan_delimiters(
+      inline_parser, sizeof(buffer) - 1, '=',
+      &left_flanking,
+      &right_flanking, &punct_before, &punct_after);
+
+  memset(buffer, '=', delims);
+  buffer[delims] = 0;
+
+  res = cmark_node_new_with_mem(CMARK_NODE_TEXT, parser->mem);
+  cmark_node_set_literal(res, buffer);
+  res->start_line = res->end_line = cmark_inline_parser_get_line(inline_parser);
+  res->start_column = cmark_inline_parser_get_column(inline_parser) - delims;
+
+  // '=' char needs to be matched 2x
+  if ((left_flanking || right_flanking) && (delims == 2)) {
+    cmark_inline_parser_push_delimiter(inline_parser, character, left_flanking,
+                                       right_flanking, res);
+  }
+
+  return res;
+}
+
+static delimiter *insert(cmark_syntax_extension *self, cmark_parser *parser,
+                         cmark_inline_parser *inline_parser, delimiter *opener,
+                         delimiter *closer) {
+  cmark_node *highlight;
+  cmark_node *tmp, *next;
+  delimiter *delim, *tmp_delim;
+  delimiter *res = closer->next;
+
+  highlight = opener->inl_text;
+
+  if (opener->inl_text->as.literal.len != closer->inl_text->as.literal.len)
+    goto done;
+
+  if (!cmark_node_set_type(highlight, CMARK_NODE_HIGHLIGHT))
+    goto done;
+
+  cmark_node_set_syntax_extension(highlight, self);
+
+  tmp = cmark_node_next(opener->inl_text);
+
+  while (tmp) {
+    if (tmp == closer->inl_text)
+      break;
+    next = cmark_node_next(tmp);
+    cmark_node_append_child(highlight, tmp);
+    tmp = next;
+  }
+
+  highlight->end_column = closer->inl_text->start_column + closer->inl_text->as.literal.len - 1;
+  cmark_node_free(closer->inl_text);
+
+  delim = closer;
+  while (delim != NULL && delim != opener) {
+    tmp_delim = delim->previous;
+    cmark_inline_parser_remove_delimiter(inline_parser, delim);
+    delim = tmp_delim;
+  }
+
+  cmark_inline_parser_remove_delimiter(inline_parser, opener);
+
+done:
+  return res;
+}
+
+static const char *get_type_string(cmark_syntax_extension *extension,
+                                   cmark_node *node) {
+  return node->type == CMARK_NODE_HIGHLIGHT ? "highlight" : "<unknown>";
+}
+
+static int can_contain(cmark_syntax_extension *extension, cmark_node *node,
+                       cmark_node_type child_type) {
+  if (node->type != CMARK_NODE_HIGHLIGHT)
+    return false;
+
+  return CMARK_NODE_TYPE_INLINE_P(child_type);
+}
+
+static void commonmark_render(cmark_syntax_extension *extension,
+                              cmark_renderer *renderer, cmark_node *node,
+                              cmark_event_type ev_type, int options) {
+  renderer->out(renderer, node, "==", false, LITERAL);
+}
+
+static void plaintext_render(cmark_syntax_extension *extension,
+                             cmark_renderer *renderer, cmark_node *node,
+                             cmark_event_type ev_type, int options) {
+  renderer->out(renderer, node, "=", false, LITERAL);
+}
+
+cmark_syntax_extension *create_highlight_extension(void) {
+  cmark_syntax_extension *ext = cmark_syntax_extension_new("highlight");
+  cmark_llist *special_chars = NULL;
+
+  cmark_syntax_extension_set_get_type_string_func(ext, get_type_string);
+  cmark_syntax_extension_set_can_contain_func(ext, can_contain);
+  cmark_syntax_extension_set_commonmark_render_func(ext, commonmark_render);
+  cmark_syntax_extension_set_plaintext_render_func(ext, plaintext_render);
+  CMARK_NODE_HIGHLIGHT = cmark_syntax_extension_add_node(1);
+
+  cmark_syntax_extension_set_match_inline_func(ext, match);
+  cmark_syntax_extension_set_inline_from_delim_func(ext, insert);
+
+  cmark_mem *mem = cmark_get_default_mem_allocator();
+  special_chars = cmark_llist_append(mem, special_chars, (void *)'=');
+  cmark_syntax_extension_set_special_inline_chars(ext, special_chars);
+
+  cmark_syntax_extension_set_emphasis(ext, 1);
+
+  return ext;
+}

lib/commonmarker/extensions/highlight.h

@@ -0,0 +1,13 @@
+/**
+ * Markdown Highlight extension by Melroy van den Berg
+ * Usage: ==Highlight text==
+ */
+#ifndef CMARK_GFM_HIGHLIGHT_H
+#define CMARK_GFM_HIGHLIGHT_H
+
+#include "cmark-gfm-core-extensions.h"
+
+extern cmark_node_type CMARK_NODE_HIGHLIGHT;
+cmark_syntax_extension *create_highlight_extension(void);
+
+#endif

src/draw.cc

@@ -29,6 +29,7 @@ Draw::Draw(MainWindow &mainWindow)
       isBold(false),
       isItalic(false),
       isStrikethrough(false),
+      isHighlight(false),
       bulletListLevel(0),
       orderedListLevel(0),
       isOrderedList(false),
@@ -52,13 +53,13 @@ Draw::Draw(MainWindow &mainWindow)
     set_app_paintable(true);
 
     defaultFont.set_size(fontSize);
+    boldItalic.set_size(fontSize);
+    boldItalic.set_weight(Pango::WEIGHT_BOLD);
+    boldItalic.set_style(Pango::Style::STYLE_ITALIC);
     bold.set_size(fontSize);
     bold.set_weight(Pango::WEIGHT_BOLD);
     italic.set_size(fontSize);
     italic.set_style(Pango::Style::STYLE_ITALIC);
-    boldItalic.set_size(fontSize);
-    boldItalic.set_weight(Pango::WEIGHT_BOLD);
-    boldItalic.set_style(Pango::Style::STYLE_ITALIC);
 
     heading1.set_size(fontSize * PANGO_SCALE_XXX_LARGE);
     heading1.set_weight(Pango::WEIGHT_BOLD);
@@ -617,8 +618,13 @@ void Draw::processNode(cmark_node *node, cmark_event_type ev_type)
         if (strcmp(node->extension->name, "strikethrough") == 0)
         {
             isStrikethrough = entering;
+            return;
+        }
+        else if (strcmp(node->extension->name, "highlight") == 0)
+        {
+            isHighlight = entering;
+            return;
         }
-        return;
     }
 
     switch (node->type)
@@ -635,6 +641,7 @@ void Draw::processNode(cmark_node *node, cmark_event_type ev_type)
             isBold = false;
             isItalic = false;
             isStrikethrough = false;
+            isHighlight = false;
         }
         break;
 
@@ -821,6 +828,10 @@ void Draw::processNode(cmark_node *node, cmark_event_type ev_type)
         {
             insertStrikethrough(text);
         }
+        else if (isHighlight)
+        {
+            insertHighlight(text);
+        }
         // URL
         else if (isLink)
         {
@@ -969,6 +980,11 @@ void Draw::insertStrikethrough(const std::string &text)
     insertMarkupTextOnThread("<span font_desc=\"" + defaultFont.to_string() + "\" strikethrough=\"true\">" + text + "</span>");
 }
 
+void Draw::insertHighlight(const std::string &text)
+{
+    insertMarkupTextOnThread("<span font_desc=\"" + defaultFont.to_string() + "\" foreground=\"black\" background=\"#FFFF00\">" + text + "</span>");
+}
+
 /******************************************************
  * Helper functions below
  *****************************************************/

src/draw.h

@@ -76,6 +76,7 @@ private:
     void insertItalic(const std::string &text);
     void insertBold(const std::string &text);
     void insertStrikethrough(const std::string &text);
+    void insertHighlight(const std::string &text);
 
     void insertMarkupTextOnThread(const std::string &text);
     void clearOnThread();
@@ -94,6 +95,7 @@ private:
     bool isBold;
     bool isItalic;
     bool isStrikethrough;
+    bool isHighlight;
     int bulletListLevel;
     int orderedListLevel;
     bool isOrderedList;
@@ -102,9 +104,9 @@ private:
     std::map<int,int> orderedListCounters;
 
     Pango::FontDescription defaultFont;
+    Pango::FontDescription boldItalic;
     Pango::FontDescription bold;
     Pango::FontDescription italic;
-    Pango::FontDescription boldItalic;
     Pango::FontDescription heading1;
     Pango::FontDescription heading2;
     Pango::FontDescription heading3;

src/md-parser.cc

@@ -40,6 +40,7 @@ cmark_node *Parser::parseContent(const std::string &content)
     cmark_node *document;
     // Add extensions
     addMarkdownExtension(parser, "strikethrough");
+    addMarkdownExtension(parser, "highlight");
     addMarkdownExtension(parser, "table");
 
     cmark_parser_feed(parser, data, strlen(data));