[indent-fold addon] Ignore comment lines

Closes #4548

addon/fold/indent-fold.js

@@ -11,32 +11,36 @@
 })(function(CodeMirror) {
 "use strict";
 
+function lineIndent(cm, lineNo) {
+  var text = cm.getLine(lineNo)
+  var spaceTo = text.search(/\S/)
+  if (spaceTo == -1 || /\bcomment\b/.test(cm.getTokenTypeAt(CodeMirror.Pos(lineNo, spaceTo + 1))))
+    return -1
+  return CodeMirror.countColumn(text, null, cm.getOption("tabSize"))
+}
+               !
 CodeMirror.registerHelper("fold", "indent", function(cm, start) {
-  var tabSize = cm.getOption("tabSize"), firstLine = cm.getLine(start.line);
-  if (!/\S/.test(firstLine)) return;
-  var getIndent = function(line) {
-    return CodeMirror.countColumn(line, null, tabSize);
-  };
-  var myIndent = getIndent(firstLine);
-  var lastLineInFold = null;
+  var myIndent = lineIndent(cm, start.line)
+  if (myIndent < 0) return
+  var lastLineInFold = null
+
   // Go through lines until we find a line that definitely doesn't belong in
   // the block we're folding, or to the end.
   for (var i = start.line + 1, end = cm.lastLine(); i <= end; ++i) {
-    var curLine = cm.getLine(i);
-    var curIndent = getIndent(curLine);
-    if (curIndent > myIndent) {
+    var indent = lineIndent(cm, i)
+    if (indent == -1) {
+    } else if (indent > myIndent) {
       // Lines with a greater indent are considered part of the block.
       lastLineInFold = i;
-    } else if (!/\S/.test(curLine)) {
-      // Empty lines might be breaks within the block we're trying to fold.
     } else {
-      // A non-empty line at an indent equal to or less than ours marks the
-      // start of another block.
+      // If this line has non-space, non-comment content, and is
+      // indented less or equal to the start line, it is the start of
+      // another block.
       break;
     }
   }
   if (lastLineInFold) return {
-    from: CodeMirror.Pos(start.line, firstLine.length),
+    from: CodeMirror.Pos(start.line, cm.getLine(start.line).length),
     to: CodeMirror.Pos(lastLineInFold, cm.getLine(lastLineInFold).length)
   };
 });

demo/folding.html

@@ -12,10 +12,12 @@
   <script src="../addon/fold/foldgutter.js"></script>
   <script src="../addon/fold/brace-fold.js"></script>
   <script src="../addon/fold/xml-fold.js"></script>
+  <script src="../addon/fold/indent-fold.js"></script>
   <script src="../addon/fold/markdown-fold.js"></script>
   <script src="../addon/fold/comment-fold.js"></script>
   <script src="../mode/javascript/javascript.js"></script>
   <script src="../mode/xml/xml.js"></script>
+  <script src="../mode/python/python.js"></script>
   <script src="../mode/markdown/markdown.js"></script>
   <style type="text/css">
     .CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}
@@ -43,6 +45,24 @@
     <textarea id="code" name="code"></textarea></div>
     <div style="max-width: 50em; margin-bottom: 1em">HTML:<br>
     <textarea id="code-html" name="code-html"></textarea></div>
+    <div style="max-width: 50em">Python:<br>
+    <textarea id="code-python" name="code">
+def foo():
+  do_some_stuff()
+  here
+  return None
+
+class Bar:
+  __init__(self):
+    if True:
+      print("True")
+    else:
+      print("False")
+
+  this_code_makes_no_sense():
+    pass
+
+# A comment</textarea></div>
     <div style="max-width: 50em">Markdown:<br>
     <textarea id="code-markdown" name="code"></textarea></div>
   </form>
@@ -57,6 +77,7 @@ window.onload = function() {
   sc.innerHTML = "";
   var te_html = document.getElementById("code-html");
   te_html.value = document.documentElement.innerHTML;
+  var te_python = document.getElementById("code-python");
   var te_markdown = document.getElementById("code-markdown");
   te_markdown.value = "# Foo\n## Bar\n\nblah blah\n\n## Baz\n\nblah blah\n\n# Quux\n\nblah blah\n"
 
@@ -81,6 +102,14 @@ window.onload = function() {
   editor_html.foldCode(CodeMirror.Pos(0, 0));
   editor_html.foldCode(CodeMirror.Pos(21, 0));
 
+  window.editor_python = CodeMirror.fromTextArea(te_python, {
+    mode: "python",
+    lineNumbers: true,
+    extraKeys: {"Ctrl-Q": function(cm){ cm.foldCode(cm.getCursor()); }},
+    foldGutter: true,
+    gutters: ["CodeMirror-linenumbers", "CodeMirror-foldgutter"]
+  });
+
   window.editor_markdown = CodeMirror.fromTextArea(te_markdown, {
     mode: "markdown",
     lineNumbers: true,