New, simpler and faster line splitter.

example/format.dart

Index: example/format.dart
diff --git a/example/format.dart b/example/format.dart
index f41327f1879dde264855b0218871b44ab9d6f536..4eec856e6d1528540f1c9cc48a1625acc52f2074 100644
--- a/example/format.dart
+++ b/example/format.dart
@@ -2,34 +2,34 @@
 // 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.
 
-import 'package:dart_style/dart_style.dart';
+library dart_style.example.format;
+
+import 'dart:io';
+import 'dart:mirrors';
+
+import 'package:path/path.dart' as p;
 
+import 'package:dart_style/dart_style.dart';
 import 'package:dart_style/src/debug.dart' as debug;
 
 void main(List<String> args) {
   // Enable debugging so you can see some of the formatter's internal state.
   // Normal users do not do this.
   debug.traceChunkBuilder = true;
-  //debug.traceLineWriter = true;
-  //debug.traceSplitter = true;
+  debug.traceLineWriter = true;
+  debug.traceSplitter = true;
   debug.useAnsiColors = true;
 
-  formatStmt("""
-  init({@Option(
-      help: 'The git Uri containing the jefe.yaml.',
-      abbr: 'g') String gitUri, @Option(
-      help: 'The directory to install into',
-      abbr: 'd') String installDirectory: '.', @Flag(
-      help: 'Skips the checkout of the develop branch',
-      abbr: 's') bool skipCheckout: false}) async {}
-""", 80);
+  runTest("regression/0000/0068.stmt", 14);
+
+  formatStmt("hello(world);");
 }
 
-void formatStmt(String source, [int pageWidth = 40]) {
+void formatStmt(String source, [int pageWidth = 80]) {
   runFormatter(source, pageWidth, isCompilationUnit: false);
 }
 
-void formatUnit(String source, [int pageWidth = 40]) {
+void formatUnit(String source, [int pageWidth = 80]) {
   runFormatter(source, pageWidth, isCompilationUnit: true);
 }
 
@@ -61,3 +61,109 @@ void drawRuler(String label, int width) {
   var padding = " " * (width - label.length - 1);
   print("$label:$padding|");
 }
+
+/// Runs the formatter test starting on [line] at [path] inside the "test"
+/// directory.
+void runTest(String path, int line) {
+  var indentPattern = new RegExp(r"^\(indent (\d+)\)\s*");
+
+  // Locate the "test" directory. Use mirrors so that this works with the test
+  // package, which loads this suite into an isolate.
+  var testDir = p.join(
+      p.dirname(currentMirrorSystem()
+          .findLibrary(#dart_style.example.format)
+          .uri
+          .path),
+      "../test");
+
+  var lines = new File(p.join(testDir, path)).readAsLinesSync();
+
+  // The first line may have a "|" to indicate the page width.
+  var pageWidth = 80;
+  if (lines[0].endsWith("|")) {
+    pageWidth = lines[0].indexOf("|");
+    lines = lines.skip(1).toList();
+  }
+
+  var i = 0;
+  while (i < lines.length) {
+    var description = lines[i++].replaceAll(">>>", "").trim();
+
+    // Let the test specify a leading indentation. This is handy for
+    // regression tests which often come from a chunk of nested code.
+    var leadingIndent = 0;
+    var indentMatch = indentPattern.firstMatch(description);
+    if (indentMatch != null) {
+      leadingIndent = int.parse(indentMatch[1]);
+      description = description.substring(indentMatch.end);
+    }
+
+    if (description == "") {
+      description = "line ${i + 1}";
+    } else {
+      description = "line ${i + 1}: $description";
+    }
+    var startLine = i + 1;
+
+    var input = "";
+    while (!lines[i].startsWith("<<<")) {
+      input += lines[i++] + "\n";
+    }
+
+    var expectedOutput = "";
+    while (++i < lines.length && !lines[i].startsWith(">>>")) {
+      expectedOutput += lines[i] + "\n";
+    }
+
+    if (line != startLine) continue;
+
+    var isCompilationUnit = p.extension(path) == ".unit";
+
+    var inputCode =
+        _extractSelection(input, isCompilationUnit: isCompilationUnit);
+
+    var expected =
+        _extractSelection(expectedOutput, isCompilationUnit: isCompilationUnit);
+
+    var formatter =
+        new DartFormatter(pageWidth: pageWidth, indent: leadingIndent);
+
+    var actual = formatter.formatSource(inputCode);
+
+    // The test files always put a newline at the end of the expectation.
+    // Statements from the formatter (correctly) don't have that, so add
+    // one to line up with the expected result.
+    var actualText = actual.text;
+    if (!isCompilationUnit) actualText += "\n";
+
+    print("$path $description");
+    drawRuler("before", pageWidth);
+    print(input);
+    if (actualText == expected.text) {
+      drawRuler("result", pageWidth);
+      print(actualText);
+    } else {
+      print("FAIL");
+      drawRuler("expected", pageWidth);
+      print(expected.text);
+      drawRuler("actual", pageWidth);
+      print(actualText);
+    }
+  }
+}
+
+/// Given a source string that contains ‹ and › to indicate a selection, returns
+/// a [SourceCode] with the text (with the selection markers removed) and the
+/// correct selection range.
+SourceCode _extractSelection(String source, {bool isCompilationUnit: false}) {
+  var start = source.indexOf("‹");
+  source = source.replaceAll("‹", "");
+
+  var end = source.indexOf("›");
+  source = source.replaceAll("›", "");
+
+  return new SourceCode(source,
+      isCompilationUnit: isCompilationUnit,
+      selectionStart: start == -1 ? null : start,
+      selectionLength: end == -1 ? null : end - start);
+}