Simplify content rewriting.

dart/site/try/src/html_to_text.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library trydart.htmlToText;
+
+import 'dart:math' show
+    max;
+
+import 'dart:html';
+
+/// Returns true if [node] is a block element, that is, not inline.
+bool isBlockElement(Node node) {
+  if (node is! Element) return false;
+  Element element = node;
+  return element.getComputedStyle().display != 'inline';
+}
+
+/// Position [walker] at the last predecessor (that is, child of child of
+/// child...) of [node]. The next call to walker.nextNode will return the first
+/// node after [node].
+void skip(Node node, TreeWalker walker) {
+  if (walker.nextSibling() != null) {
+    walker.previousNode();
+    return;
+  }
+  for (Node current = walker.nextNode();
+       current != null;
+       current = walker.nextNode()) {
+    if (!node.contains(current)) {
+      walker.previousNode();
+      return;
+    }
+  }
+}
+
+/// Writes the text of [root] to [buffer]. Keeps track of [selection] and
+/// returns the new anchorOffset from beginning of [buffer] or -1 if the
+/// selection isn't in [root].
+int htmlToText(Node root, StringBuffer buffer, Selection selection) {
+  int selectionOffset = -1;
+  TreeWalker walker = new TreeWalker(root, NodeFilter.SHOW_ALL);
+
+  for (Node node = root; node != null; node = walker.nextNode()) {
+    switch (node.nodeType) {
+      case Node.CDATA_SECTION_NODE:
+      case Node.TEXT_NODE:
+        if (selection.isCollapsed && selection.anchorNode == node) {
+          selectionOffset = selection.anchorOffset + buffer.length;
+        }
+        Text text = node;
+        buffer.write(text.data.replaceAll('\xA0', ' '));
+        break;
+
+      default:
+        if (node.nodeName == 'BR') {
+          buffer.write('\n');
+        } else if (node != root && isBlockElement(node)) {
+          selectionOffset =
+              max(selectionOffset, htmlToText(node, buffer, selection));
+          skip(node, walker);
+        }
+        break;
+    }
+  }
+
+  if (isBlockElement(root)) {
+    buffer.write('\n');
+  }
+
+  return selectionOffset;
+}