Add continuecomment.js utility add-on

Author: marijnh

doc/manual.html

@@ -355,7 +355,7 @@ <h2 id="keymaps">Keymaps</h2>
     also contains the <code>"default"</code> keymap holding the
     default bindings.</p>
 
-    <p>The values of properties in keymaps can be either functions of
+    <p id="commands">The values of properties in keymaps can be either functions of
     a single argument (the CodeMirror instance), strings, or
     <code>false</code>. Such strings refer to properties of the
     <code>CodeMirror.commands</code> object, which defines a number of
@@ -993,6 +993,11 @@ <h2 id="addons">Add-ons</h2>
       which will ensure the given mode is loaded and cause the given
       editor instance to refresh its mode when the loading
       succeeded. See the <a href="../demo/loadmode.html">demo</a>.</dd>
+      <dt id="util_continuecomment"><a href="../lib/util/continuecomment.js"><code>continuecomment.js</code></a></dt>
+      <dd>Adds a <a href="#commands">command</a>
+      called <code>newlineAndIndentContinueComment</code> that you can
+      bind <code>Enter</code> to in order to have the editor prefix
+      new lines inside C-like block comments with an asterisk.</dd>
     </dl>
 
     <h2 id="modeapi">Writing CodeMirror Modes</h2>

lib/util/continuecomment.js

@@ -0,0 +1,36 @@
+(function() {
+  var modes = ["clike", "css", "javascript"];
+  for (var i = 0; i < modes.length; ++i)
+    CodeMirror.extendMode(modes[i], {blockCommentStart: "/*",
+                                     blockCommentEnd: "*/",
+                                     blockCommentContinue: " * "});
+
+  CodeMirror.commands.newlineAndIndentContinueComment = function(cm) {
+    var pos = cm.getCursor(), token = cm.getTokenAt(pos);
+    var mode = CodeMirror.innerMode(cm.getMode(), token.state).mode;
+    var space;
+
+    if (token.className == "comment" && mode.blockCommentStart) {
+      var end = token.string.indexOf(mode.blockCommentEnd);
+      var full = cm.getRange({line: pos.line, ch: 0}, {line: pos.line, ch: token.end}), found;
+      if (end != -1 && end == token.string.length - mode.blockCommentEnd.length) {
+        // Comment ended, don't continue it
+      } else if (token.string.indexOf(mode.blockCommentStart) == 0) {
+        space = full.slice(0, token.start);
+        if (!/^\s*$/.test(space)) {
+          space = "";
+          for (var i = 0; i < token.start; ++i) space += " ";
+        }
+      } else if ((found = full.indexOf(mode.blockCommentContinue)) != -1 &&
+                 found + mode.blockCommentContinue.length > token.start &&
+                 /^\s*$/.test(full.slice(0, found))) {
+        space = full.slice(0, found);
+      }
+    }
+
+    if (space != null)
+      cm.replaceSelection("\n" + space + mode.blockCommentContinue, "end");
+    else
+      cm.execCommand("newlineAndIndent");
+  };
+})();

mode/javascript/index.html

@@ -5,6 +5,7 @@
     <title>CodeMirror: JavaScript mode</title>
     <link rel="stylesheet" href="../../lib/codemirror.css">
     <script src="../../lib/codemirror.js"></script>
+    <script src="../../lib/util/continuecomment.js"></script>
     <script src="javascript.js"></script>
     <link rel="stylesheet" href="../../doc/docs.css">
     <style type="text/css">.CodeMirror {border-top: 1px solid black; border-bottom: 1px solid black;}</style>
@@ -65,7 +66,8 @@ <h1>CodeMirror: JavaScript mode</h1>
     <script>
       var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
         lineNumbers: true,
-        matchBrackets: true
+        matchBrackets: true,
+        extraKeys: {"Enter": "newlineAndIndentContinueComment"}
       });
     </script>