Add indentRangeFinder function to lib/util/foldcode.js

doc/manual.html

@@ -712,8 +712,8 @@ <h2 id="addons">Add-ons</h2>
       of <a href="#util_dialog"><code>openDialog</code></a> when
       available to make prompting for search queries less ugly.</dd>
       <dt id="util_foldcode"><a href="../lib/util/foldcode.js"><code>foldcode.js</code></a></dt>
-      <dd>Helps with code folding. See <a href="../demo/folding.html">the
-      demo</a> for an example.
+      <dd>Helps with code folding.
+      See <a href="../demo/folding.html">the demo</a> for an example.
       Call <code>CodeMirror.newFoldFunction</code> with a range-finder
       helper function to create a function that will, when applied to
       a CodeMirror instance and a line number, attempt to fold or
@@ -722,7 +722,11 @@ <h2 id="addons">Add-ons</h2>
       line number, and returns an end line for the block, or null if
       no block is started on that line. This file
       provides <code>CodeMirror.braceRangeFinder</code>, which finds
-      blocks in brace languages (JavaScript, C, Java, etc).</dd>
+      blocks in brace languages (JavaScript, C, Java,
+      etc), <code>CodeMirror.indentRangeFinder</code>, for languages
+      where indentation determines block structure (Python, Haskell),
+      and <code>CodeMirror.tagRangeFinder</code>, for XML-style
+      languages.</dd>
       <dt id="util_runmode"><a href="../lib/util/runmode.js"><code>runmode.js</code></a></dt>
       <dd>Can be used to run a CodeMirror mode over text without
       actually opening an editor instance.

lib/util/foldcode.js

@@ -130,6 +130,19 @@ CodeMirror.braceRangeFinder = function(cm, line) {
   return end;
 };
 
+CodeMirror.indentRangeFinder = function(cm, line) {
+  var tabSize = cm.getOption("tabSize");
+  var myIndent = cm.getLineHandle(line).indentation(tabSize), last;
+  for (var i = line + 1, end = cm.lineCount(); i < end; ++i) {
+    var handle = cm.getLineHandle(i);
+    if (!/^\s*$/.test(handle.text)) {
+      if (handle.indentation(tabSize) <= myIndent) break;
+      last = i;
+    }
+  }
+  if (!last) return null;
+  return last + 1;
+};
 
 CodeMirror.newFoldFunction = function(rangeFinder, markText) {
   var folded = [];