Revert "Emit constants using ASTs"

sdk/lib/_internal/compiler/implementation/js_backend/constant_emitter.dart

 // Copyright (c) 2012, 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;
 
-class ConstantEmitter  {
-  ConstantReferenceEmitter _referenceEmitter;
-  ConstantInitializerEmitter _initializerEmitter;
+class ConstantEmitter implements ConstantVisitor {
+  final Compiler compiler;
+  final Namer namer;
 
-  ConstantEmitter(Compiler compiler, Namer namer) {
-    _referenceEmitter = new ConstantReferenceEmitter(compiler, namer);
-    _initializerEmitter = new ConstantInitializerEmitter(
-        compiler, namer, _referenceEmitter);
+  CodeBuffer buffer;
+  bool shouldEmitCanonicalVersion;
+
+  ConstantEmitter(this.compiler, this.namer);
+
+  /**
+   * Unless the constant can be emitted multiple times (as for numbers and
+   * strings) use the canonical name.
+   */
+  void emitCanonicalVersionOfConstant(Constant constant, CodeBuffer newBuffer) {
+    shouldEmitCanonicalVersion = true;
+    buffer = newBuffer;
+    _visit(constant);
   }
 
   /**
-   * Constructs an expression that is a reference to the constant.  Uses a
-   * canonical name unless the constant can be emitted multiple times (as for
-   * numbers and strings).
+   * Emit the JavaScript code of the constant. If the constant must be
+   * canonicalized this method emits the initialization value.
    */
-  js.Expression reference(Constant constant) {
-    return _referenceEmitter.generate(constant);
+  void emitJavaScriptCodeForConstant(Constant constant, CodeBuffer newBuffer) {
+    shouldEmitCanonicalVersion = false;
+    buffer = newBuffer;
+    _visit(constant);
+  }
+
+  _visit(Constant constant) {
+    constant.accept(this);
+  }
+
+  void visitSentinel(SentinelConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      buffer.add(namer.CURRENT_ISOLATE);
+    } else {
+      compiler.internalError(
+          "The parameter sentinel constant does not need specific JS code");
+    }
+  }
+
+  void visitFunction(FunctionConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      buffer.add(namer.isolatePropertiesAccess(constant.element));
+    } else {
+      compiler.internalError(
+          "The function constant does not need specific JS code");
+    }
+  }
+
+  void visitNull(NullConstant constant) {
+    buffer.add("null");
+  }
+
+  void visitInt(IntConstant constant) {
+    buffer.add(constant.value.toString());
+  }
+
+  void visitDouble(DoubleConstant constant) {
+    double value = constant.value;
+    if (value.isNaN) {
+      buffer.add("(0/0)");
+    } else if (value == double.INFINITY) {
+      buffer.add("(1/0)");
+    } else if (value == -double.INFINITY) {
+      buffer.add("(-1/0)");
+    } else {
+      buffer.add("$value");
+    }
+  }
+
+  void visitTrue(TrueConstant constant) {
+    buffer.add("true");
+  }
+
+  void visitFalse(FalseConstant constant) {
+    buffer.add("false");
   }
 
   /**
-   * Constructs an expression like [reference], but the expression is valid
-   * during isolate initialization.
-   */
-  js.Expression referenceInInitializationContext(Constant constant) {
-    return _referenceEmitter.generateInInitializationContext(constant);
-  }
-
-  /**
-   * Constructs an expression used to initialize a canonicalized constant.
-   */
-  js.Expression initializationExpression(Constant constant) {
-    return _initializerEmitter.generate(constant);
-  }
-}
-
-/**
- * Visitor for generating JavaScript expressions to refer to [Constant]s.
- * Do not use directly, use methods from [ConstantEmitter].
- */
-class ConstantReferenceEmitter implements ConstantVisitor<js.Expression> {
-  final Compiler compiler;
-  final Namer namer;
-  bool inIsolateInitializationContext = false;
-
-  ConstantReferenceEmitter(this.compiler, this.namer);
-
-  js.Expression generate(Constant constant) {
-    inIsolateInitializationContext = false;
-    return _visit(constant);
-  }
-
-  js.Expression generateInInitializationContext(Constant constant) {
-    inIsolateInitializationContext = true;
-    return _visit(constant);
-  }
-
-  js.Expression _visit(Constant constant) {
-    return constant.accept(this);
-  }
-
-  js.Expression visitSentinel(SentinelConstant constant) {
-    return new js.VariableUse(namer.CURRENT_ISOLATE);
-  }
-
-  js.Expression visitFunction(FunctionConstant constant) {
-    return inIsolateInitializationContext
-        ? new js.VariableUse(namer.isolatePropertiesAccess(constant.element))
-        : new js.VariableUse(namer.isolateAccess(constant.element));
-  }
-
-  js.Expression visitNull(NullConstant constant) {
-    return new js.LiteralNull();
-  }
-
-  js.Expression visitInt(IntConstant constant) {
-    return new js.LiteralNumber('${constant.value}');
-  }
-
-  js.Expression visitDouble(DoubleConstant constant) {
-    double value = constant.value;
-    if (value.isNaN) {
-      return new js.LiteralNumber("(0/0)");
-    } else if (value == double.INFINITY) {
-      return new js.LiteralNumber("(1/0)");
-    } else if (value == -double.INFINITY) {
-      return new js.LiteralNumber("(-1/0)");
-    } else {
-      return new js.LiteralNumber("$value");
-    }
-  }
-
-  js.Expression visitTrue(TrueConstant constant) {
-    if (compiler.enableMinification) {
-      // Use !0 for true.
-      return new js.Prefix("!", new js.LiteralNumber("0"));
-    } else {
-      return new js.LiteralBool(true);
-    }
-
-  }
-
-  js.Expression visitFalse(FalseConstant constant) {
-    if (compiler.enableMinification) {
-      // Use !1 for false.
-      return new js.Prefix("!", new js.LiteralNumber("1"));
-    } else {
-      return new js.LiteralBool(false);
-    }
-  }
-
-  /**
    * Write the contents of the quoted string to a [CodeBuffer] in
    * a form that is valid as JavaScript string literal content.
    * The string is assumed quoted by double quote characters.
    */
-  js.Expression visitString(StringConstant constant) {
-    // TODO(sra): If the string is long *and repeated* (and not on a hot path)
-    // then it should be assigned to a name.  We don't have reference counts (or
-    // profile information) here, so this is the wrong place.
-    StringBuffer sb = new StringBuffer();
-    writeJsonEscapedCharsOn(constant.value.slowToString(), sb);
-    return new js.LiteralString('"$sb"');
+  void visitString(StringConstant constant) {
+    buffer.add('"');
+    writeJsonEscapedCharsOn(constant.value.slowToString(), buffer);
+    buffer.add('"');
   }
 
-  js.Expression emitCanonicalVersion(Constant constant) {
+  void emitCanonicalVersion(Constant constant) {
     String name = namer.constantName(constant);
-    if (inIsolateInitializationContext) {
-      //  $ISOLATE.$ISOLATE_PROPERTIES.$name
-      return new js.PropertyAccess.field(
-          new js.PropertyAccess.field(
-              new js.VariableUse(namer.ISOLATE),
-              namer.ISOLATE_PROPERTIES),
-          name);
-    } else {
-      return new js.PropertyAccess.field(
-          new js.VariableUse(namer.CURRENT_ISOLATE),
-          name);
-    }
+    buffer.add(namer.isolatePropertiesAccessForConstant(name));
   }
 
-  js.Expression visitList(ListConstant constant) {
-    return emitCanonicalVersion(constant);
-  }
-
-  js.Expression visitMap(MapConstant constant) {
-    return emitCanonicalVersion(constant);
-  }
-
-  js.Expression visitType(TypeConstant constant) {
-    return emitCanonicalVersion(constant);
-  }
-
-  js.Expression visitConstructed(ConstructedConstant constant) {
-    return emitCanonicalVersion(constant);
-  }
-}
-
-/**
- * Visitor for generating JavaScript expressions to initialize [Constant]s.
- * Do not use directly; use methods from [ConstantEmitter].
- */
-class ConstantInitializerEmitter implements ConstantVisitor<js.Expression> {
-  final Compiler compiler;
-  final Namer namer;
-  final ConstantReferenceEmitter referenceEmitter;
-
-  ConstantInitializerEmitter(this.compiler, this.namer, this.referenceEmitter);
-
-  js.Expression generate(Constant constant) {
-    return _visit(constant);
-  }
-
-  js.Expression _visit(Constant constant) {
-    return constant.accept(this);
-  }
-
-  js.Expression _reference(Constant constant) {
-    return referenceEmitter.generateInInitializationContext(constant);
-  }
-
-  js.Expression visitSentinel(SentinelConstant constant) {
-    compiler.internalError(
-        "The parameter sentinel constant does not need specific JS code");
-  }
-
-  js.Expression visitFunction(FunctionConstant constant) {
-    compiler.internalError(
-        "The function constant does not need specific JS code");
-  }
-
-  js.Expression visitNull(NullConstant constant) {
-    return _reference(constant);
-  }
-
-  js.Expression visitInt(IntConstant constant) {
-    return _reference(constant);
-  }
-
-  js.Expression visitDouble(DoubleConstant constant) {
-    return _reference(constant);
-  }
-
-  js.Expression visitTrue(TrueConstant constant) {
-    return _reference(constant);
-  }
-
-  js.Expression visitFalse(FalseConstant constant) {
-    return _reference(constant);
-  }
-
-  js.Expression visitString(StringConstant constant) {
-    // TODO(sra): Some larger strings are worth sharing.
-    return _reference(constant);
-  }
-
-  js.Expression visitList(ListConstant constant) {
-    return new js.Call(
-        new js.PropertyAccess.field(
-            new js.VariableUse(namer.ISOLATE),
-            'makeConstantList'),
-        [new js.ArrayInitializer.from(_array(constant.entries))]);
+  void visitList(ListConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      emitCanonicalVersion(constant);
+    } else {
+      shouldEmitCanonicalVersion = true;
+      buffer.add("${namer.ISOLATE}.makeConstantList");
+      buffer.add("([");
+      for (int i = 0; i < constant.entries.length; i++) {
+        if (i != 0) buffer.add(", ");
+        _visit(constant.entries[i]);
+      }
+      buffer.add("])");
+    }
   }
 
   String getJsConstructor(ClassElement element) {
     return namer.isolatePropertiesAccess(element);
   }
 
-  js.Expression visitMap(MapConstant constant) {
-    js.Expression jsMap() {
-      List<js.Property> properties = <js.Property>[];
-      int valueIndex = 0;
-      for (int i = 0; i < constant.keys.entries.length; i++) {
-        StringConstant key = constant.keys.entries[i];
-        if (key.value == MapConstant.PROTO_PROPERTY) continue;
+  void visitMap(MapConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      emitCanonicalVersion(constant);
+    } else {
+      void writeJsMap() {
+        buffer.add("{");
+        int valueIndex = 0;
+        for (int i = 0; i < constant.keys.entries.length; i++) {
+          StringConstant key = constant.keys.entries[i];
+          if (key.value == MapConstant.PROTO_PROPERTY) continue;
 
-        // Keys in literal maps must be emitted in place.
-        js.Literal keyExpression = _visit(key);
-        js.Expression valueExpression =
-            _reference(constant.values[valueIndex++]);
-        properties.add(new js.Property(keyExpression, valueExpression));
+          if (valueIndex != 0) buffer.add(", ");
+
+          // Keys in literal maps must be emitted in place.
+          emitJavaScriptCodeForConstant(key, buffer);
+
+          buffer.add(": ");
+          emitCanonicalVersionOfConstant(constant.values[valueIndex++], buffer);
+        }
+        buffer.add("}");
+        if (valueIndex != constant.values.length) {
+          compiler.internalError("Bad value count.");
+        }
       }
-      if (valueIndex != constant.values.length) {
-        compiler.internalError("Bad value count.");
+
+      void badFieldCountError() {
+        compiler.internalError(
+          "Compiler and ConstantMap disagree on number of fields.");
       }
-      return new js.ObjectInitializer(properties);
+
+      shouldEmitCanonicalVersion = true;
+
+      ClassElement classElement = constant.type.element;
+      buffer.add("new ");
+      buffer.add(getJsConstructor(classElement));
+      buffer.add("(");
+      // The arguments of the JavaScript constructor for any given Dart class
+      // are in the same order as the members of the class element.
+      int emittedArgumentCount = 0;
+      classElement.implementation.forEachInstanceField(
+          (ClassElement enclosing, Element field) {
+            if (emittedArgumentCount != 0) buffer.add(", ");
+            if (field.name == MapConstant.LENGTH_NAME) {
+              buffer.add(constant.keys.entries.length);
+            } else if (field.name == MapConstant.JS_OBJECT_NAME) {
+              writeJsMap();
+            } else if (field.name == MapConstant.KEYS_NAME) {
+              emitCanonicalVersionOfConstant(constant.keys, buffer);
+            } else if (field.name == MapConstant.PROTO_VALUE) {
+              assert(constant.protoValue != null);
+              emitCanonicalVersionOfConstant(constant.protoValue, buffer);
+            } else {
+              badFieldCountError();
+            }
+            emittedArgumentCount++;
+          },
+          includeBackendMembers: true,
+          includeSuperMembers: true);
+      if ((constant.protoValue == null && emittedArgumentCount != 3) ||
+          (constant.protoValue != null && emittedArgumentCount != 4)) {
+        badFieldCountError();
+      }
+      buffer.add(")");
     }
-
-    void badFieldCountError() {
-      compiler.internalError(
-          "Compiler and ConstantMap disagree on number of fields.");
-    }
-
-    ClassElement classElement = constant.type.element;
-
-    List<js.Expression> arguments = <js.Expression>[];
-
-    // The arguments of the JavaScript constructor for any given Dart class
-    // are in the same order as the members of the class element.
-    int emittedArgumentCount = 0;
-    classElement.implementation.forEachInstanceField(
-        (ClassElement enclosing, Element field) {
-          if (field.name == MapConstant.LENGTH_NAME) {
-            arguments.add(
-                new js.LiteralNumber('${constant.keys.entries.length}'));
-          } else if (field.name == MapConstant.JS_OBJECT_NAME) {
-            arguments.add(jsMap());
-          } else if (field.name == MapConstant.KEYS_NAME) {
-            arguments.add(_reference(constant.keys));
-          } else if (field.name == MapConstant.PROTO_VALUE) {
-            assert(constant.protoValue != null);
-            arguments.add(_reference(constant.protoValue));
-          } else {
-            badFieldCountError();
-          }
-          emittedArgumentCount++;
-        },
-        includeBackendMembers: true,
-        includeSuperMembers: true);
-
-    if ((constant.protoValue == null && emittedArgumentCount != 3) ||
-        (constant.protoValue != null && emittedArgumentCount != 4)) {
-      badFieldCountError();
-    }
-
-    return new js.New(
-        new js.VariableUse(getJsConstructor(classElement)),
-        arguments);
   }
 
-  js.Expression visitType(TypeConstant constant) {
-    SourceString helperSourceName = const SourceString('createRuntimeType');
-    Element helper = compiler.findHelper(helperSourceName);
-    JavaScriptBackend backend = compiler.backend;
-    String helperName = backend.namer.getName(helper);
-    DartType type = constant.representedType;
-    Element element = type.element;
-    String typeName;
-    if (type.kind == TypeKind.INTERFACE) {
-      typeName =
-          backend.rti.getStringRepresentation(type, expandRawType: true);
+  void visitType(TypeConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      emitCanonicalVersion(constant);
     } else {
-      assert(type.kind == TypeKind.TYPEDEF);
-      typeName = element.name.slowToString();
+      SourceString helperSourceName =
+          const SourceString('createRuntimeType');
+      Element helper = compiler.findHelper(helperSourceName);
+      JavaScriptBackend backend = compiler.backend;
+      String helperName = backend.namer.getName(helper);
+      DartType type = constant.representedType;
+      Element element = type.element;
+      String typeName;
+      if (type.kind == TypeKind.INTERFACE) {
+        typeName =
+            backend.rti.getStringRepresentation(type, expandRawType: true);
+      } else {
+        assert(type.kind == TypeKind.TYPEDEF);
+        typeName = element.name.slowToString();
+      }
+      buffer.add("${namer.CURRENT_ISOLATE}.$helperName('$typeName')");
     }
-    return new js.Call(
-        new js.PropertyAccess.field(
-            new js.VariableUse(namer.CURRENT_ISOLATE),
-            helperName),
-        [new js.LiteralString("'$typeName'")]);
   }
 
-  js.Expression visitConstructed(ConstructedConstant constant) {
-    return new js.New(
-        new js.VariableUse(getJsConstructor(constant.type.element)),
-        _array(constant.fields));
-  }
+  void visitConstructed(ConstructedConstant constant) {
+    if (shouldEmitCanonicalVersion) {
+      emitCanonicalVersion(constant);
+    } else {
+      shouldEmitCanonicalVersion = true;
 
-  List<js.Expression> _array(List<Constant> values) {
-    List<js.Expression> valueList = <js.Expression>[];
-    for (int i = 0; i < values.length; i++) {
-      valueList.add(_reference(values[i]));
+      buffer.add("new ");
+      buffer.add(getJsConstructor(constant.type.element));
+      buffer.add("(");
+      for (int i = 0; i < constant.fields.length; i++) {
+        if (i != 0) buffer.add(", ");
+        _visit(constant.fields[i]);
+      }
+      buffer.add(")");
     }
-    return valueList;
   }
 }