Don't perform incremental resolution if curly brackets are not balanced.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 2088c516164db58fa2af547947c8d47e8b549b8b..710c0ef58d38496f76c23811c066e8fe1db3d7fa 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -1261,9 +1261,20 @@ class PoorMansIncrementalResolver {
   bool resolve(String newCode) {
     logger.enter('diff/resolve $_unitSource');
     try {
+      // prepare old unit
       CompilationUnit oldUnit = _units[_unitSource];
+      if (!_areCurlyBracketsBalanced(oldUnit.beginToken)) {
+        logger.log('Unbalanced number of curly brackets in the old unit.');
+        return false;
+      }
       _unitElement = oldUnit.element;
+      // prepare ne unit

[Brian Wilkerson, 2015/01/20 19:08:27]

'ne' --> 'new'

       CompilationUnit newUnit = _parseUnit(newCode);
+      if (!_areCurlyBracketsBalanced(newUnit.beginToken)) {
+        logger.log('Unbalanced number of curly brackets in the new unit.');
+        return false;
+      }
+      // find difference
       _TokenPair firstPair =
           _findFirstDifferentToken(oldUnit.beginToken, newUnit.beginToken);
       _TokenPair lastPair =
@@ -1485,6 +1496,17 @@ class PoorMansIncrementalResolver {
     _entry.setValue(DartEntry.PARSE_ERRORS, _newParseErrors);
   }
 
+  /**
+   * Checks if [token] has a balanced number of open and closed curly brackets.
+   */
+  static bool _areCurlyBracketsBalanced(Token token) {

[Brian Wilkerson, 2015/01/20 19:08:27]

Not for this CL, but... The scanner already computes these flags (as part of
bracket matching). As a future optimization we might want to store this
information in the CompilationUnit so that we don't have to traverse the token
stream two more times.

+    int numOpen = _getTokenCount(token, TokenType.OPEN_CURLY_BRACKET);
+    int numOpen2 =
+        _getTokenCount(token, TokenType.STRING_INTERPOLATION_EXPRESSION);
+    int numClosed = _getTokenCount(token, TokenType.CLOSE_CURLY_BRACKET);
+    return numOpen + numOpen2 == numClosed;
+  }
+
   static _TokenDifferenceKind _compareToken(Token oldToken, Token newToken,
       int delta) {
     if (oldToken == null && newToken == null) {
@@ -1580,7 +1602,6 @@ class PoorMansIncrementalResolver {
     return oldBeginToken;
   }
 
-
   static List<AstNode> _getParents(AstNode node) {
     List<AstNode> parents = <AstNode>[];
     while (node != null) {
@@ -1590,6 +1611,21 @@ class PoorMansIncrementalResolver {
     return parents;
   }
 
+
+  /**
+   * Returns number of tokens with the given [type].
+   */
+  static int _getTokenCount(Token token, TokenType type) {
+    int count = 0;
+    while (token.type != TokenType.EOF) {
+      if (token.type == type) {
+        count++;
+      }
+      token = token.next;
+    }
+    return count;
+  }
+
   /**
    * Set the given [comment] as a "precedingComments" for [parent].
    */