Formatter re-think/updates.

pkg/analyzer_experimental/lib/src/services/writer.dart

+// Copyright (c) 2013, 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 source_writer;
+
+
+class Line {
+
+  final int lineLength;
+  final tokens = <LineToken>[];
+  final bool useTabs;
+  final int spacesPerIndent;
+
+  Line({indent: 0, this.lineLength: 80, this.useTabs: false,
+        this.spacesPerIndent: 2}) {
+    if (indent > 0) {
+      _indent(indent);
+    }
+  }
+
+  addSpace() {
+    addSpaces(1);
+  }
+
+  addSpaces(int n) {
+    if (n > 0) {
+      tokens.add(new SpaceToken(n));
+    }
+  }
+
+  addToken(LineToken token) {
+    tokens.add(token);
+  }
+
+  _indent(int n) {
+    tokens.add(useTabs ? new TabToken(n) : new SpaceToken(n * spacesPerIndent));
+  }
+
+  String toString() {
+    var buffer = new StringBuffer();
+    for (var tok in tokens) {
+      buffer.write(tok.toString());
+    }
+    return buffer.toString();
+  }
+
+}
+
+
+class LineToken {
+
+  final String value;
+
+  LineToken(this.value);
+
+  String toString() => value;
+}
+
+class SpaceToken extends LineToken {
+
+  SpaceToken(int n) : super(getSpaces(n));
+}
+
+class TabToken extends LineToken {
+
+  TabToken(int n) : super(getTabs(n));
+}
+
+
+class NewlineToken extends LineToken {
+
+  NewlineToken(String value) : super(value);
+}
+
+
+
+class SourceWriter {
+
+  final StringBuffer buffer = new StringBuffer();
+  Line currentLine = new Line();
+
+  final String lineSeparator;
+  int indentCount = 0;
+
+  SourceWriter({int initialIndent: 0, this.lineSeparator: '\n'}) :
+    indentCount = initialIndent;
+
+  indent() {
+    ++indentCount;
+  }
+
+  unindent() {
+    --indentCount;
+  }
+
+  print(x) {
+    currentLine.addToken(new LineToken(x));
+  }
+
+  newline() {
+    currentLine.addToken(new NewlineToken(this.lineSeparator));
+    buffer.write(currentLine.toString());
+    currentLine = new Line(indent: indentCount);
+  }
+
+  space() {
+    spaces(1);
+  }
+
+  spaces(n) {
+    currentLine.addSpaces(n);
+  }
+
+  println(String s) {
+    print(s);
+    newline();
+  }
+
+  String toString() {
+    var source = new StringBuffer(buffer.toString());
+    source.write(currentLine);
+    return source.toString();
+  }
+}
+
+
+const SPACE = ' ';
+final SPACES = [
+          '',
+          ' ',
+          '  ',
+          '   ',
+          '    ',
+          '     ',
+          '      ',
+          '       ',
+          '        ',
+          '         ',
+          '          ',
+          '           ',
+          '            ',
+          '             ',
+          '              ',
+          '               ',
+          '                ',
+];
+final TABS = [
+          '',
+          '\t',
+          '\t\t',
+          '\t\t\t',
+          '\t\t\t\t',
+          '\t\t\t\t\t',
+          '\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t\t\t\t\t',
+          '\t\t\t\t\t\t\t\t\t\t\t\t\t\t',
+];
+
+
+String getIndentString(int indentWidth, {bool useTabs: false}) =>
+    useTabs ? getTabs(indentWidth) : getSpaces(indentWidth);
+
+String getSpaces(int n) => n < SPACES.length ? SPACES[n] : repeat(' ', n);
+
+String getTabs(int n) => n < TABS.length ? TABS[n] : repeat('\t', n);
+
+String repeat(String ch, int times) {
+  var sb = new StringBuffer();
+  for (var i = 0; i < times; ++i) {
+    sb.write(ch);
+  }
+  return sb.toString();
+}