Allow whitespace and \ before the first newline of multiline string.

sdk/lib/_internal/compiler/implementation/tree/nodes.dart

 // Copyright (c) 2012, 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.
 
 part of tree;
 
 abstract class Visitor<R> {
   const Visitor();
 
   R visitNode(Node node);
@@ skipping 808 matching lines @@
     if (identical(token.stringValue, 'false')) return false;
     (this.handler)(token, "not a bool ${token.value}");
     throw false;
   }
 
   accept(Visitor visitor) => visitor.visitLiteralBool(this);
 }
 
 
 class StringQuoting {
-  static const StringQuoting SINGLELINE_DQ =
-      const StringQuoting($DQ, raw: false, leftQuoteLength: 1);
-  static const StringQuoting RAW_SINGLELINE_DQ =
-      const StringQuoting($DQ, raw: true, leftQuoteLength: 1);
-  static const StringQuoting MULTILINE_DQ =
-      const StringQuoting($DQ, raw: false, leftQuoteLength: 3);
-  static const StringQuoting RAW_MULTILINE_DQ =
-      const StringQuoting($DQ, raw: true, leftQuoteLength: 3);
-  static const StringQuoting MULTILINE_NL_DQ =
-      const StringQuoting($DQ, raw: false, leftQuoteLength: 4);
-  static const StringQuoting RAW_MULTILINE_NL_DQ =
-      const StringQuoting($DQ, raw: true, leftQuoteLength: 4);
-  static const StringQuoting MULTILINE_NL2_DQ =
-      const StringQuoting($DQ, raw: false, leftQuoteLength: 5);
-  static const StringQuoting RAW_MULTILINE_NL2_DQ =
-      const StringQuoting($DQ, raw: true, leftQuoteLength: 5);
-  static const StringQuoting SINGLELINE_SQ =
-      const StringQuoting($SQ, raw: false, leftQuoteLength: 1);
-  static const StringQuoting RAW_SINGLELINE_SQ =
-      const StringQuoting($SQ, raw: true, leftQuoteLength: 1);
-  static const StringQuoting MULTILINE_SQ =
-      const StringQuoting($SQ, raw: false, leftQuoteLength: 3);
-  static const StringQuoting RAW_MULTILINE_SQ =
-      const StringQuoting($SQ, raw: true, leftQuoteLength: 3);
-  static const StringQuoting MULTILINE_NL_SQ =
-      const StringQuoting($SQ, raw: false, leftQuoteLength: 4);
-  static const StringQuoting RAW_MULTILINE_NL_SQ =
-      const StringQuoting($SQ, raw: true, leftQuoteLength: 4);
-  static const StringQuoting MULTILINE_NL2_SQ =
-      const StringQuoting($SQ, raw: false, leftQuoteLength: 5);
-  static const StringQuoting RAW_MULTILINE_NL2_SQ =
-      const StringQuoting($SQ, raw: true, leftQuoteLength: 5);
 
+  /// Cache of common quotings.
+  static const List<StringQuoting> _mapping = const <StringQuoting>[
+    const StringQuoting($SQ, raw: false, leftQuoteLength: 1),
+    const StringQuoting($SQ, raw: true, leftQuoteLength: 1),
+    const StringQuoting($DQ, raw: false, leftQuoteLength: 1),
+    const StringQuoting($DQ, raw: true, leftQuoteLength: 1),
+    // No string quotes with 2 characters.
+    null,
+    null,
+    null,
+    null,
+    // Multiline quotings.
+    const StringQuoting($SQ, raw: false, leftQuoteLength: 3),
+    const StringQuoting($SQ, raw: true, leftQuoteLength: 3),
+    const StringQuoting($DQ, raw: false, leftQuoteLength: 3),
+    const StringQuoting($DQ, raw: true, leftQuoteLength: 3),
+    // Leading single whitespace or espaped newline.
+    const StringQuoting($SQ, raw: false, leftQuoteLength: 4),
+    const StringQuoting($SQ, raw: true, leftQuoteLength: 4),
+    const StringQuoting($DQ, raw: false, leftQuoteLength: 4),
+    const StringQuoting($DQ, raw: true, leftQuoteLength: 4),
+    // Other combinations of leading whitespace and/or escaped newline.
+    const StringQuoting($SQ, raw: false, leftQuoteLength: 5),
+    const StringQuoting($SQ, raw: true, leftQuoteLength: 5),
+    const StringQuoting($DQ, raw: false, leftQuoteLength: 5),
+    const StringQuoting($DQ, raw: true, leftQuoteLength: 5),
+    const StringQuoting($SQ, raw: false, leftQuoteLength: 6),
+    const StringQuoting($SQ, raw: true, leftQuoteLength: 6),
+    const StringQuoting($DQ, raw: false, leftQuoteLength: 6),
+    const StringQuoting($DQ, raw: true, leftQuoteLength: 6)
+  ];
 
-  static const List<StringQuoting> mapping = const <StringQuoting>[
-    SINGLELINE_DQ,
-    RAW_SINGLELINE_DQ,
-    MULTILINE_DQ,
-    RAW_MULTILINE_DQ,
-    MULTILINE_NL_DQ,
-    RAW_MULTILINE_NL_DQ,
-    MULTILINE_NL2_DQ,
-    RAW_MULTILINE_NL2_DQ,
-    SINGLELINE_SQ,
-    RAW_SINGLELINE_SQ,
-    MULTILINE_SQ,
-    RAW_MULTILINE_SQ,
-    MULTILINE_NL_SQ,
-    RAW_MULTILINE_NL_SQ,
-    MULTILINE_NL2_SQ,
-    RAW_MULTILINE_NL2_SQ
-  ];
   final bool raw;
   final int leftQuoteCharCount;
   final int quote;
-  const StringQuoting(this.quote, {bool raw, int leftQuoteLength})
-      : this.raw = raw, this.leftQuoteCharCount = leftQuoteLength;
+  const StringQuoting(this.quote, { this.raw, int leftQuoteLength })
+      : this.leftQuoteCharCount = leftQuoteLength;
   String get quoteChar => identical(quote, $DQ) ? '"' : "'";
 
   int get leftQuoteLength => (raw ? 1 : 0) + leftQuoteCharCount;
   int get rightQuoteLength => (leftQuoteCharCount > 2) ? 3 : 1;
-  static StringQuoting getQuoting(int quote, bool raw, int quoteLength) {
-    int index = quoteLength - 1;
-    if (quoteLength > 2) index -= 1;
-    return mapping[(raw ? 1 : 0) + index * 2 + (identical(quote, $SQ) ? 8 : 0)];
+  static StringQuoting getQuoting(int quote, bool raw, int leftQuoteLength) {
+    int quoteKindOffset = (quote == $DQ) ? 2 : 0;
+    int rawOffset = raw ? 1 : 0;
+    int index = (leftQuoteLength - 1) * 4 + rawOffset + quoteKindOffset;
+    if (index < _mapping.length) return _mapping[index];
+    return new StringQuoting(quote, raw: raw, leftQuoteLength: leftQuoteLength);
   }
 }
 
 /**
   * Superclass for classes representing string literals.
   */
 abstract class StringNode extends Expression {
   DartString get dartString;
   bool get isInterpolation;
 
@@ skipping 1203 matching lines @@
 }
 
 class IsInterpolationVisitor extends Visitor<bool> {
   const IsInterpolationVisitor();
   bool visitNode(Node node) => false;
   bool visitStringInterpolation(StringInterpolation node) => true;
   bool visitStringJuxtaposition(StringJuxtaposition node)
       => node.isInterpolation;
 }