Support runtime check of 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 691 matching lines @@
   }
 
   String isolateLazyInitializerAccess(Element element) {
     return "$CURRENT_ISOLATE.${getLazyInitializerName(element)}";
   }
 
   String operatorIsPrefix() => r'$is';
 
   String operatorAsPrefix() => r'$as';
 
+  String operatorSignature() => r'$signature';
+
+  Map<FunctionType,String> functionTypeNameMap = new Map<FunctionType,String>();
+  FunctionTypeNamer functionTypeNamer = new FunctionTypeNamer();
+
+  String getFunctionTypeName(FunctionType functionType) {
+    return functionTypeNameMap.putIfAbsent(functionType, () {
+      String proposedName = functionTypeNamer.computeName(functionType);
+      String freshName = getFreshName(proposedName, usedInstanceNames,
+                                      suggestedInstanceNames, ensureSafe: true);
+      return freshName;
+    });
+  }
+
+  String operatorIsFunctionType(FunctionType type) {
+    // TODO(erikcorry): Reduce from $isx to ix when we are minifying.
+    return '${operatorIsPrefix()}${getFunctionTypeName(type)}';
+  }
+
   String operatorIs(Element element) {
     // TODO(erikcorry): Reduce from $isx to ix when we are minifying.
     return '${operatorIsPrefix()}${getName(element)}';
   }
 
   /*
    * Returns a name that does not clash with reserved JS keywords,
    * and also ensures it won't clash with other identifiers.
    */
   String _safeName(String name, Set<String> reserved) {
     if (reserved.contains(name) || name.startsWith(r'$')) {
       name = '\$$name';
     }
     assert(!reserved.contains(name));
     return name;
   }
 
   String substitutionName(Element element) {
     return '${operatorAsPrefix()}${getName(element)}';
   }
 
+  String signatureName(FunctionType type) {
+    ClassElement classElement = Types.getClassContext(type);
+    String signature = '${operatorSignature()}_${getFunctionTypeName(type)}';
+    if (classElement != null) {
+      return '${isolateAccess(classElement)}.$signature';
+    } else {
+      return '${CURRENT_ISOLATE}.$signature';
+    }
+  }
+
   String safeName(String name) => _safeName(name, jsReserved);
   String safeVariableName(String name) => _safeName(name, jsVariableReserved);
 
   SourceString operatorNameToIdentifier(SourceString name) {
     if (name == null) return null;
     String value = name.stringValue;
     if (value == null) {
       return name;
     } else if (value == '==') {
       return const SourceString(r'$eq');
@@ skipping 33 matching lines @@
       return const SourceString(r'$or');
     } else if (value == '-') {
       return const SourceString(r'$sub');
     } else if (value == 'unary-') {
       return const SourceString(r'$negate');
     } else {
       return name;
     }
   }
 }
+
+class FunctionTypeNamer extends DartTypeVisitor {
+  StringBuffer sb;
+
+  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, _) {
+    visit(type.returnType);
+    sb.write('_');
+    for (Link<DartType> link = type.parameterTypes;
+         !link.isEmpty;
+         link = link.tail) {
+      sb.write('_');
+      visit(link.head);
+    }
+    for (Link<DartType> link = type.optionalParameterTypes;
+         !link.isEmpty;
+         link = link.tail) {
+      sb.write('_');
+      visit(link.head);
+    }
+    if (!type.namedParameterTypes.isEmpty) {
+      for (Link<DartType> link = type.namedParameterTypes;
+          !link.isEmpty;
+          link = link.tail) {
+        sb.write('_');
+        visit(link.head);
+      }
+    }
+  }
+
+}