Optimize boolean asserts

frog/parser.dart

 // Copyright (c) 2011, 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.
 
 // TODO(jimhug): Error recovery needs major work!
 /**
  * A simple recursive descent parser for the dart language.
  *
  * This parser is designed to be more permissive than the official
  * Dart grammar.  It is expected that many grammar errors would be
@@ skipping 830 matching lines @@
           var isTrue = !_maybeEat(TokenKind.NOT);
           var typeRef = type();
           x = new IsExpression(isTrue, x, typeRef, _makeSpan(x.span.start));
           continue;
         }
         // Using prec + 1 ensures that a - b - c will group correctly.
         // Using prec for ASSIGN ops ensures that a = b = c groups correctly.
         var y = infixExpression(prec == 2 ? prec: prec+1);
         if (op.kind == TokenKind.CONDITIONAL) {
           _eat(TokenKind.COLON);
-          var z = infixExpression(prec+1);
+          // Using prec for so "a ? b : c ? d : e" groups correctly as
+          // "a ? b : (c ? d : e)"
+          var z = infixExpression(prec);
           x = new ConditionalExpression(x, y, z, _makeSpan(x.span.start));
         } else {
           x = new BinaryExpression(op, x, y, _makeSpan(x.span.start));
         }
       } else {
         break;
       }
     }
     return x;
   }
@@ skipping 92 matching lines @@
         }
     }
   }
 
   /** Checks if the given expression is a binary op of the given kind. */
   _isBin(expr, kind) {
     return expr is BinaryExpression && expr.op.kind == kind;
   }
 
   _boolTypeRef(SourceSpan span) {
-    return new TypeReference(span, world.boolType);
+    return new TypeReference(span, world.nonNullBool);
   }
 
   _intTypeRef(SourceSpan span) {
     return new TypeReference(span, world.intType);
   }
 
   _doubleTypeRef(SourceSpan span) {
     return new TypeReference(span, world.doubleType);
   }
 
@@ skipping 700 matching lines @@
 class IncompleteSourceException implements Exception {
   final Token token;
 
   IncompleteSourceException(this.token);
 
   String toString() {
     if (token.span == null) return 'Unexpected $token';
     return token.span.toMessageString('Unexpected $token');
   }
 }