Use predicates to check simple function types.

sdk/lib/_internal/compiler/implementation/js_backend/namer.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.
 
 part of js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 207 matching lines @@
         usedGlobalNames = new Set<String>(),
         usedInstanceNames = new Set<String>(),
         instanceNameMap = new Map<String, String>(),
         operatorNameMap = new Map<String, String>(),
         globalNameMap = new Map<String, String>(),
         suggestedGlobalNames = new Map<String, String>(),
         suggestedInstanceNames = new Map<String, String>(),
         popularNameCounters = new Map<String, int>(),
         constantNames = new Map<Constant, String>(),
         constantLongNames = new Map<Constant, String>(),
-        constantHasher = new ConstantCanonicalHasher(compiler);
+        constantHasher = new ConstantCanonicalHasher(compiler),
+        functionTypeNamer = new FunctionTypeNamer(compiler);
 
   String get isolateName => 'Isolate';
   String get isolatePropertiesName => r'$isolateProperties';
   /**
    * Some closures must contain their name. The name is stored in
    * [STATIC_CLOSURE_NAME_NAME].
    */
   String get STATIC_CLOSURE_NAME_NAME => r'$name';
   SourceString get closureInvocationSelectorName => Compiler.CALL_OPERATOR_NAME;
   bool get shouldMinify => false;
@@ skipping 554 matching lines @@
   String functionTypeReturnTypeTag() => r'ret';
 
   String functionTypeRequiredParametersTag() => r'args';
 
   String functionTypeOptionalParametersTag() => r'opt';
 
   String functionTypeNamedParametersTag() => r'named';
 
   Map<FunctionType,String> functionTypeNameMap =
       new Map<FunctionType,String>();
-  FunctionTypeNamer functionTypeNamer = new FunctionTypeNamer();
+  final FunctionTypeNamer functionTypeNamer;
 
   String getFunctionTypeName(FunctionType functionType) {
     return functionTypeNameMap.putIfAbsent(functionType, () {
       String proposedName = functionTypeNamer.computeName(functionType);
       String freshName = getFreshName(proposedName, usedInstanceNames,
                                       suggestedInstanceNames, ensureSafe: true);
       return freshName;
     });
   }
 
@@ skipping 402 matching lines @@
   }
 
   static int _finish(int hash) {
     hash = _MASK & (hash + (((_MASK >> 3) & hash) <<  3));
     hash = hash & (hash >> 11);
     return _MASK & (hash + (((_MASK >> 15) & hash) << 15));
   }
 }
 
 class FunctionTypeNamer extends DartTypeVisitor {
+  final Compiler compiler;
   StringBuffer sb;
 
+  FunctionTypeNamer(this.compiler);
+
+  JavaScriptBackend get backend => compiler.backend;
+
   String computeName(DartType type) {
     sb = new StringBuffer();
     visit(type);
     return sb.toString();
   }
 
   visit(DartType type) {
     type.accept(this, null);
   }
 
   visitType(DartType type, _) {
     sb.write(type.name.slowToString());
   }
 
   visitFunctionType(FunctionType type, _) {
+    if (backend.rti.isSimpleFunctionType(type)) {
+      sb.write('args${type.parameterTypes.slowLength()}');
+      return;
+    }
     visit(type.returnType);
     sb.write('_');
     for (Link<DartType> link = type.parameterTypes;
          !link.isEmpty;
          link = link.tail) {
       sb.write('_');
       visit(link.head);
     }
     bool first = false;
     for (Link<DartType> link = type.optionalParameterTypes;
@@ skipping 14 matching lines @@
         if (!first) {
           sb.write('_');
         }
         sb.write('_');
         visit(link.head);
         first = true;
       }
     }
   }
 }