Fix interpretation of string contents after interpolation expressions.

pkg/analyzer/lib/src/generated/parser.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.parser;
 
 import "dart:math" as math;
@@ skipping 3436 matching lines @@
   /**
    * Return the content of a string with the given literal representation. The
    * [lexeme] is the literal representation of the string. The flag [isFirst] is
    * `true` if this is the first token in a string literal. The flag [isLast] is
    * `true` if this is the last token in a string literal.
    */
   String _computeStringValue(String lexeme, bool isFirst, bool isLast) {
     StringLexemeHelper helper = new StringLexemeHelper(lexeme, isFirst, isLast);
     int start = helper.start;
     int end = helper.end;
-    if (end - start + 1 < 0) {
+    bool stringEndsAfterStart = end >= start;
+    assert(stringEndsAfterStart);
+    if (!stringEndsAfterStart) {
       AnalysisEngine.instance.logger.logError(
           "Internal error: computeStringValue($lexeme, $isFirst, $isLast)");
       return "";
     }
     if (helper.isRaw) {
       return lexeme.substring(start, end);
     }
     StringBuffer buffer = new StringBuffer();
     int index = start;
     while (index < end) {
@@ skipping 753 matching lines @@
       bool wasInInitializer = _inInitializer;
       _inInitializer = false;
       try {
         Expression index = parseExpression2();
         Token rightBracket = _expect(TokenType.CLOSE_SQUARE_BRACKET);
         return new IndexExpression.forTarget(
             prefix, leftBracket, index, rightBracket);
       } finally {
         _inInitializer = wasInInitializer;
       }
-    } else if (_matches(TokenType.PERIOD) || _matches(TokenType.QUESTION_PERIOD)) {
+    } else if (_matches(TokenType.PERIOD) ||
+        _matches(TokenType.QUESTION_PERIOD)) {
       Token operator = getAndAdvance();
       return new PropertyAccess(prefix, operator, parseSimpleIdentifier());
     } else {
       if (!optional) {
         // Report the missing selector.
         _reportErrorForCurrentToken(
             ParserErrorCode.MISSING_ASSIGNABLE_SELECTOR);
       }
       return prefix;
     }
@@ skipping 3573 matching lines @@
     Token token = _skipSimpleIdentifier(startToken);
     if (token == null) {
       return null;
     } else if (!_tokenMatches(token, TokenType.PERIOD)) {
       return token;
     }
     token = token.next;
     Token nextToken = _skipSimpleIdentifier(token);
     if (nextToken != null) {
       return nextToken;
-    } else if (_tokenMatches(token, TokenType.CLOSE_PAREN)
-            || _tokenMatches(token, TokenType.COMMA)) {
+    } else if (_tokenMatches(token, TokenType.CLOSE_PAREN) ||
+        _tokenMatches(token, TokenType.COMMA)) {
       // If the `id.` is followed by something that cannot produce a valid
       // structure then assume this is a prefixed identifier but missing the
       // trailing identifier
       return token;
     }
     return null;
   }
 
   /**
    * Parse a return type, starting at the [startToken], without actually
@@ skipping 2706 matching lines @@
   }
 
   /**
    * Copy resolution data from the [fromNode] to the [toNode].
    */
   static void copyResolutionData(AstNode fromNode, AstNode toNode) {
     ResolutionCopier copier = new ResolutionCopier();
     copier._isEqualNodes(fromNode, toNode);
   }
 }