[folding addon] Rewrite tagRangeFinder

Closes #1360

addon/fold/foldcode.js

-// the tagRangeFinder function is
-//   Copyright (C) 2011 by Daniel Glazman <daniel@glazman.org>
-// released under the MIT license (../../LICENSE) like the rest of CodeMirror
-CodeMirror.tagRangeFinder = function(cm, start) {
+CodeMirror.tagRangeFinder = (function() {
   var nameStartChar = "A-Z_a-z\\u00C0-\\u00D6\\u00D8-\\u00F6\\u00F8-\\u02FF\\u0370-\\u037D\\u037F-\\u1FFF\\u200C-\\u200D\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD";
   var nameChar = nameStartChar + "\-\:\.0-9\\u00B7\\u0300-\\u036F\\u203F-\\u2040";
-  var xmlNAMERegExp = new RegExp("^[" + nameStartChar + "][" + nameChar + "]*");
+  var xmlTagStart = new RegExp("<(/?)([" + nameStartChar + "][" + nameChar + "]*)", "g");
 
-  var lineText = cm.getLine(start.line);
-  var found = false;
-  var tag = null;
-  var pos = start.ch;
-  while (!found) {
-    pos = lineText.indexOf("<", pos);
-    if (-1 == pos) // no tag on line
-      return;
-    if (pos + 1 < lineText.length && lineText[pos + 1] == "/") { // closing tag
-      pos++;
-      continue;
-    }
-    // ok we seem to have a start tag
-    if (!lineText.substr(pos + 1).match(xmlNAMERegExp)) { // not a tag name...
-      pos++;
-      continue;
+  return function(cm, start) {
+    var line = start.line, ch = start.ch, lineText = cm.getLine(line);
+
+    function nextLine() {
+      if (line >= cm.lastLine()) return;
+      ch = 0;
+      lineText = cm.getLine(++line);
+      return true;
     }
-    var gtPos = lineText.indexOf(">", pos + 1);
-    if (-1 == gtPos) { // end of start tag not in line
-      var l = start.line + 1;
-      var foundGt = false;
-      var lastLine = cm.lineCount();
-      while (l < lastLine && !foundGt) {
-        var lt = cm.getLine(l);
-        gtPos = lt.indexOf(">");
-        if (-1 != gtPos) { // found a >
-          foundGt = true;
-          var slash = lt.lastIndexOf("/", gtPos);
-          if (-1 != slash && slash < gtPos) {
-            var str = lineText.substr(slash, gtPos - slash + 1);
-            if (!str.match( /\/\s*\>/ )) // yep, that's the end of empty tag
-              return;
-          }
-        }
-        l++;
+    function toTagEnd() {
+      for (;;) {
+        var gt = lineText.indexOf(">", ch);
+        if (gt == -1) { if (nextLine()) continue; else return; }
+        var lastSlash = lineText.lastIndexOf("/", gt);
+        var selfClose = lastSlash > -1 && /^\s*$/.test(lineText.slice(lastSlash + 1, gt));
+        ch = gt + 1;
+        return selfClose ? "selfClose" : "regular";
       }
-      found = true;
     }
-    else {
-      var slashPos = lineText.lastIndexOf("/", gtPos);
-      if (-1 == slashPos) { // cannot be empty tag
-        found = true;
-        // don't continue
-      }
-      else { // empty tag?
-        // check if really empty tag
-        var str = lineText.substr(slashPos, gtPos - slashPos + 1);
-        if (!str.match( /\/\s*\>/ )) { // finally not empty
-          found = true;
-          // don't continue
-        }
+    function toNextTag() {
+      for (;;) {
+        xmlTagStart.lastIndex = ch;
+        var found = xmlTagStart.exec(lineText);
+        if (!found) { if (nextLine()) continue; else return; }
+        ch = found.index + found[0].length;
+        return found;
       }
     }
-    if (found) {
-      var subLine = lineText.substr(pos + 1);
-      tag = subLine.match(xmlNAMERegExp);
-      if (tag) {
-        // we have an element name, wooohooo !
-        tag = tag[0];
-        // do we have the close tag on same line ???
-        if (-1 != lineText.indexOf("</" + tag + ">", pos)) // yep
-        {
-          found = false;
-        }
-        // we don't, so we have a candidate...
+
+    var stack = [], startCh;
+    for (;;) {
+      var openTag = toNextTag(), end;
+      if (!openTag || line != start.line || !(end = toTagEnd())) return;
+      if (!openTag[1] && end != "selfClose") {
+        stack.push(openTag[2]);
+        startCh = ch;
+        break;
       }
-      else
-        found = false;
     }
-    if (!found)
-      pos++;
-  }
 
-  if (found) {
-    var startTag = "(\\<\\/" + tag + "\\>)|(\\<" + tag + "\\>)|(\\<" + tag + "\\s)|(\\<" + tag + "$)";
-    var startTagRegExp = new RegExp(startTag);
-    var endTag = "</" + tag + ">";
-    var depth = 1;
-    var l = start.line + 1;
-    var lastLine = cm.lineCount();
-    while (l < lastLine) {
-      lineText = cm.getLine(l);
-      var match = lineText.match(startTagRegExp);
-      if (match) {
-        for (var i = 0; i < match.length; i++) {
-          if (match[i] == endTag)
-            depth--;
-          else
-            depth++;
-          if (!depth) return {from: CodeMirror.Pos(start.line, gtPos + 1),
-                              to: CodeMirror.Pos(l, match.index)};
+    for (;;) {
+      var next = toNextTag(), end, tagLine = line, tagCh = ch - (next ? next[0].length : 0);
+      if (!next || !(end = toTagEnd())) return;
+      if (end == "selfClose") continue;
+      if (next[1]) { // closing tag
+        for (var i = stack.length - 1; i >= 0; --i) if (stack[i] == next[2]) {
+          stack.length = i;
+          break;
         }
+        if (!stack.length) return {
+          from: CodeMirror.Pos(start.line, startCh),
+          to: CodeMirror.Pos(tagLine, tagCh)
+        };
+      } else { // opening tag
+        stack.push(next[2]);
       }
-      l++;
     }
-    return;
-  }
-};
+  };
+})();
 
 CodeMirror.braceRangeFinder = function(cm, start) {
   var line = start.line, lineText = cm.getLine(line);