JS templates

sdk/lib/_internal/compiler/implementation/js/template.dart

+// Copyright (c) 2014, 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;
+
+class TemplateManager {
+  Map<String, Template> expressionTemplates = new Map<String, Template>();
+  Map<String, Template> statementTemplates = new Map<String, Template>();
+
+  TemplateManager();
+
+
+  Template lookupExpressionTemplate(String source) {
+    return expressionTemplates[source];
+  }
+
+  Template defineExpressionTemplate(String source, Node ast) {
+    Template template =
+        new Template(source, ast, isExpression: true, forceCopy: false);
+    expressionTemplates[source] = template;
+    return template;
+  }
+
+  Template lookupStatementTemplate(String source) {
+    return statementTemplates[source];
+  }
+
+  Template defineStatementTemplate(String source, Node ast) {
+    Template template =
+        new Template(source, ast, isExpression: false, forceCopy: false);
+    statementTemplates[source] = template;
+    return template;
+  }
+}
+
+/**
+ * A Template is created with JavaScript AST containing placeholders (interface
+ * InterpolatedNode).  The [instantiate] method creates an AST that looks like
+ * the original with the placeholders replaced by the arguments to
+ * [instantiate].
+ */
+class Template {
+  final String source;
+  final bool isExpression;
+  final bool forceCopy;
+  final Node ast;
+
+  Instantiator instantiator;
+  int positionalArgumentCount = -1;
+  // TODO(sra): Named arguments.
+
+  Template(this.source, this.ast,
+           {this.isExpression: true, this.forceCopy: false}) {
+    _compile();
+  }
+
+  Template.withExpressionResult(this.ast)
+      : source = null, isExpression = true, forceCopy = false {
+    assert(ast is Expression);
+    assert(_checkNoPlaceholders());
+    positionalArgumentCount = 0;
+    instantiator = (arguments) => ast;
+  }
+
+  Template.withStatementResult(this.ast)
+      : source = null, isExpression = false, forceCopy = false {
+    assert(ast is Statement);
+    assert(_checkNoPlaceholders());
+    positionalArgumentCount = 0;
+    instantiator = (arguments) => ast;
+  }
+
+  bool _checkNoPlaceholders() {
+    InstantiatorGeneratorVisitor generator =
+        new InstantiatorGeneratorVisitor(false);
+    generator.compile(ast);
+    return generator.analysis.count == 0;
+  }
+
+  void _compile() {
+    InstantiatorGeneratorVisitor generator =
+        new InstantiatorGeneratorVisitor(forceCopy);
+    instantiator = generator.compile(ast);
+    positionalArgumentCount = generator.analysis.count;
+  }
+
+  Node instantiate(List arguments) {
+    if (arguments is List) {
+      if (arguments.length != positionalArgumentCount) {
+        throw 'Wrong number of template arguments, given ${arguments.length}, '
+            'expected $positionalArgumentCount';
+      }
+      return instantiator(arguments);
+    }
+    // TODO(sra): Add named placeholders and a Map of arguments.
+    throw new UnimplementedError('Template arguments must be a list');
+  }
+}
+
+/**
+ * An Instantiator is a Function that generates a JS AST tree or List of
+ * trees. [arguments] is a List for positional templates, or (TODO) Map for
+ * named templates.
+ */
+typedef Node Instantiator(var arguments);
+
+
+/**
+ * InstantiatorGeneratorVisitor compiles a template.  This class compiles a tree
+ * containing [InterpolatedNode]s into a function that will create a copy of the
+ * tree with the interpolated nodes substituted with provided values.
+ */
+class InstantiatorGeneratorVisitor implements NodeVisitor<Instantiator> {
+
+  final bool forceCopy;
+
+  InterpolatedNodeAnalysis analysis = new InterpolatedNodeAnalysis();
+
+  /**
+   * The entire tree is cloned if [forceCopy] is true.
+   */
+  InstantiatorGeneratorVisitor(this.forceCopy);
+
+  Instantiator compile(Node node) {
+    analysis.visit(node);
+    Instantiator result = visit(node);
+    return result;
+  }
+
+  static error(String message) {
+    throw message;
+  }
+
+  static Instantiator same(Node node) => (arguments) => node;
+  static Node makeNull(arguments) => null;
+
+  Instantiator visit(Node node) {
+    if (forceCopy || analysis.containsInterpolatedNodes(node)) {
+      return node.accept(this);
+    }
+    return same(node);
+  }
+
+  Instantiator visitNullable(Node node) {
+    if (node == null) return makeNull;
+    return visit(node);
+  }
+
+  Instantiator visitSplayable(Node node) {
+    // TODO(sra): Process immediate [InterpolatedNode]s, permitting splaying.
+    return visit(node);
+  }
+
+  Instantiator visitNode(Node node) {
+    throw 'Unimplemented InstantiatorGeneratorVisitor for $node';
+  }
+
+  static RegExp identiferRE = new RegExp(r'^[A-Za-z_$][A-Za-z_$0-9]*$');
+
+  static Expression convertStringToVariableUse(String value) {
+    assert(identiferRE.hasMatch(value));
+    return new VariableUse(value);
+  }
+
+  Instantiator visitInterpolatedExpression(InterpolatedExpression node) {
+    int position = node.name;
+    return (arguments) {
+      var value = arguments[position];
+      if (value is Expression) return value;
+      if (value is String) return convertStringToVariableUse(value);;
+      error('Interpolated value #$position is not an Expression: $value');
+    };
+  }
+
+  Instantiator visitSplayableExpression(Node node) {
+    if (node is InterpolatedExpression) {
+      int position = node.name;
+      return (arguments) {
+        var value = arguments[position];
+        Expression toExpression(item) {
+          if (item is Expression) return item;
+          if (item is String) return convertStringToVariableUse(item);
+          error('Interpolated value #$position is not '
+              'an Expression or List of Expressions: $value');
+        }
+        if (value is Iterable) return value.map(toExpression);
+        return toExpression(value);
+      };
+    }
+    return visit(node);
+  }
+
+  Instantiator visitInterpolatedLiteral(InterpolatedLiteral node) {
+    int position = node.name;
+    return (arguments) {
+      var value = arguments[position];
+      if (value is Literal) return value;
+      error('Interpolated value #$position is not a Literal: '
+          '$value  (${value.runtimeType})');
+    };
+  }
+
+  Instantiator visitInterpolatedParameter(InterpolatedParameter node) {
+    int position = node.name;
+    return (arguments) {
+      var value = arguments[position];
+
+      Parameter toParameter(item) {
+        if (item is Parameter) return item;
+        if (item is String) return new Parameter(item);
+        error('Interpolated value #$position is not a Parameter or '
+            'List of Parameters: $value  (a ${value.runtimeType})');
+      }
+      if (value is Iterable) return value.map(toParameter);
+      return toParameter(value);
+    };
+  }
+
+  Instantiator visitInterpolatedSelector(InterpolatedSelector node) {
+    // A selector is an expression, as in `a[selector]`.
+    // A String argument converted into a LiteralString, so `a.#` with argument
+    // 'foo' generates `a["foo"]` which prints as `a.foo`.
+    int position = node.name;
+    return (arguments) {
+      var value = arguments[position];
+      if (value is Expression) return value;
+      if (value is String) return new LiteralString('"$value"');
+      error('Interpolated value #$position is not a selector: $value');
+    };
+  }
+
+  Instantiator visitInterpolatedStatement(InterpolatedStatement node) {
+    int position = node.name;
+    return (arguments) {
+      var value = arguments[position];
+      if (value is Node) return value.toStatement();
+      error('Interpolated value #$position is not a Statement: $value');
+    };
+  }
+
+  Instantiator visitSplayableStatement(Node node) {
+    if (node is InterpolatedStatement) {
+      int position = node.name;
+      return (arguments) {
+        var value = arguments[position];
+        Statement toStatement(item) {
+          if (item is Statement) return item;
+          if (item is Expression) return item.toStatement();;
+          error('Interpolated value #$position is not '
+              'a Statement or List of Statements: $value');
+        }
+        if (value is Iterable) return value.map(toStatement);
+        return toStatement(value);
+      };
+    }
+    return visit(node);
+  }
+
+  Instantiator visitProgram(Program node) {
+    List instantiators = node.body.map(visitSplayableStatement).toList();
+    return (arguments) {
+      List<Statement> statements = <Statement>[];
+      void add(node) {
+        if (node is EmptyStatement) return;
+        if (node is Iterable) {
+          statements.addAll(node);
+        } else {
+          statements.add(node.toStatement());
+        }
+      }
+      for (Instantiator instantiator in instantiators) {
+        add(instantiator(arguments));
+      }
+      return new Program(statements);
+    };
+  }
+
+  Instantiator visitBlock(Block node) {
+    List instantiators = node.statements.map(visitSplayableStatement).toList();
+    return (arguments) {
+      List<Statement> statements = <Statement>[];
+      void add(node) {
+        if (node is EmptyStatement) return;
+        if (node is Iterable) {
+          statements.addAll(node);
+        } else if (node is Block) {
+          statements.addAll(node.statements);
+        } else {
+          statements.add(node.toStatement());
+        }
+      }
+      for (Instantiator instantiator in instantiators) {
+        add(instantiator(arguments));
+      }
+      return new Block(statements);
+    };
+  }
+
+  Instantiator visitExpressionStatement(ExpressionStatement node) {
+    Instantiator buildExpression = visit(node.expression);
+    return (arguments) {
+      return buildExpression(arguments).toStatement();
+    };
+  }
+
+  Instantiator visitEmptyStatement(EmptyStatement node) =>
+      (arguments) => new EmptyStatement();
+
+  Instantiator visitIf(If node) {
+    if (node.condition is InterpolatedExpression) {
+      return visitIfConditionalCompilation(node);
+    } else {
+      return visitIfNormal(node);
+    }
+  }
+
+  Instantiator visitIfConditionalCompilation(If node) {
+    // Special version of visitInterpolatedExpression that permits bools.
+    compileCondition(InterpolatedExpression node) {
+      int position = node.name;
+      return (arguments) {
+        var value = arguments[position];
+        if (value is bool) return value;
+        if (value is Expression) return value;
+        if (value is String) return convertStringToVariableUse(value);;
+        error('Interpolated value #$position is not an Expression: $value');
+      };
+    }
+    var makeCondition = compileCondition(node.condition);
+    Instantiator makeThen = visit(node.then);
+    Instantiator makeOtherwise = visit(node.otherwise);
+    return (arguments) {
+      var condition = makeCondition(arguments);
+      if (condition is bool) {
+        if (condition == true) {
+          return makeThen(arguments);
+        } else {
+          return makeOtherwise(arguments);
+        }
+      }
+      return new If(
+          condition,
+          makeThen(arguments),
+          makeOtherwise(arguments));
+    };
+  }
+
+  Instantiator visitIfNormal(If node) {
+    Instantiator makeCondition = visit(node.condition);
+    Instantiator makeThen = visit(node.then);
+    Instantiator makeOtherwise = visit(node.otherwise);
+    return (arguments) {
+      return new If(
+          makeCondition(arguments),
+          makeThen(arguments),
+          makeOtherwise(arguments));
+    };
+  }
+
+  Instantiator visitFor(For node) {
+    Instantiator makeInit = visitNullable(node.init);
+    Instantiator makeCondition = visitNullable(node.condition);
+    Instantiator makeUpdate = visitNullable(node.update);
+    Instantiator makeBody = visit(node.body);
+    return (arguments) {
+      return new For(
+          makeInit(arguments), makeCondition(arguments), makeUpdate(arguments),
+          makeBody(arguments));
+    };
+  }
+
+  Instantiator visitForIn(ForIn node) {
+    Instantiator makeLeftHandSide = visit(node.leftHandSide);
+    Instantiator makeObject = visit(node.object);
+    Instantiator makeBody = visit(node.body);
+    return (arguments) {
+      return new ForIn(
+          makeLeftHandSide(arguments),
+          makeObject(arguments),
+          makeBody(arguments));
+    };
+  }
+
+  TODO(String name) {
+    throw new UnimplementedError('${this.runtimeType}.$name');
+  }
+
+  Instantiator visitWhile(While node) => TODO('visitWhile');
+  Instantiator visitDo(Do node) => TODO('visitDo');
+
+  Instantiator visitContinue(Continue node) =>
+      (arguments) => new Continue(node.targetLabel);
+
+  Instantiator visitBreak(Break node) =>
+      (arguments) => new Break(node.targetLabel);
+
+  Instantiator visitReturn(Return node) {
+    Instantiator makeExpression = visitNullable(node.value);
+    return (arguments) => new Return(makeExpression(arguments));
+  }
+
+  Instantiator visitThrow(Throw node) {
+    Instantiator makeExpression = visit(node.expression);
+    return (arguments) => new Throw(makeExpression(arguments));
+  }
+
+
+  Instantiator visitTry(Try node) {
+    Instantiator makeBody = visit(node.body);
+    Instantiator makeCatch = visitNullable(node.catchPart);
+    Instantiator makeFinally = visitNullable(node.finallyPart);
+    return (arguments) => new Try(
+        makeBody(arguments), makeCatch(arguments), makeFinally(arguments));
+  }
+
+  Instantiator visitCatch(Catch node) {
+    Instantiator makeDeclaration = visit(node.declaration);
+    Instantiator makeBody = visit(node.body);
+    return (arguments) => new Catch(
+        makeDeclaration(arguments), makeBody(arguments));
+  }
+
+  Instantiator visitSwitch(Switch node) => TODO('visitSwitch');
+  Instantiator visitCase(Case node) => TODO('visitCase');
+  Instantiator visitDefault(Default node) => TODO('visitDefault');
+
+  Instantiator visitFunctionDeclaration(FunctionDeclaration node) {
+    Instantiator makeName = visit(node.name);
+    Instantiator makeFunction = visit(node.function);
+    return (arguments) =>
+        new FunctionDeclaration(makeName(arguments), makeFunction(arguments));
+  }
+
+  Instantiator visitLabeledStatement(LabeledStatement node) =>
+      TODO('visitLabeledStatement');
+  Instantiator visitLiteralStatement(LiteralStatement node) =>
+      TODO('visitLiteralStatement');
+  Instantiator visitBlob(Blob node) =>
+      TODO('visitBlob');
+  Instantiator visitLiteralExpression(LiteralExpression node) =>
+      TODO('visitLiteralExpression');
+
+  Instantiator visitVariableDeclarationList(VariableDeclarationList node) {
+    List<Instantiator> declarationMakers =
+        node.declarations.map(visit).toList();
+    return (arguments) {
+      List<VariableInitialization> declarations = <VariableInitialization>[];
+      for (Instantiator instantiator in declarationMakers) {
+        var result = instantiator(arguments);
+        declarations.add(result);
+      }
+      return new VariableDeclarationList(declarations);
+    };
+  }
+
+  Instantiator visitSequence(Sequence node) => TODO('visitSequence');
+
+  Instantiator visitAssignment(Assignment node) {
+    Instantiator makeLeftHandSide = visit(node.leftHandSide);
+    Instantiator makeCompoundTarget = visitNullable(node.compoundTarget);
+    Instantiator makeValue = visitNullable(node.value);
+    return (arguments) {
+      return new Assignment._internal(
+          makeLeftHandSide(arguments),
+          makeCompoundTarget(arguments),
+          makeValue(arguments));
+    };
+  }
+
+  Instantiator visitVariableInitialization(VariableInitialization node) {
+    Instantiator makeDeclaration = visit(node.declaration);
+    Instantiator makeValue = visitNullable(node.value);
+    return (arguments) {
+      return new VariableInitialization(
+          makeDeclaration(arguments), makeValue(arguments));
+    };
+  }
+
+  Instantiator visitConditional(Conditional cond) {
+    Instantiator makeCondition = visit(cond.condition);
+    Instantiator makeThen = visit(cond.then);
+    Instantiator makeOtherwise = visit(cond.otherwise);
+    return (arguments) => new Conditional(
+        makeCondition(arguments),
+        makeThen(arguments),
+        makeOtherwise(arguments));
+  }
+
+  Instantiator visitNew(New node) =>
+      handleCallOrNew(node, (target, arguments) => new New(target, arguments));
+
+  Instantiator visitCall(Call node) =>
+      handleCallOrNew(node, (target, arguments) => new Call(target, arguments));
+
+  Instantiator handleCallOrNew(Call node, finish(target, arguments)) {
+    Instantiator makeTarget = visit(node.target);
+    Iterable<Instantiator> argumentMakers =
+        node.arguments.map(visitSplayableExpression).toList();
+
+    return (arguments) {
+      Node target = makeTarget(arguments);
+      List<Expression> callArguments = <Expression>[];
+      for (Instantiator instantiator in argumentMakers) {
+        var result = instantiator(arguments);
+        if (result is Iterable) {
+          callArguments.addAll(result);
+        } else {
+          callArguments.add(result);
+        }
+      }
+      return finish(target, callArguments);
+    };
+  }
+
+  Instantiator visitBinary(Binary node) {
+    Instantiator makeLeft = visit(node.left);
+    Instantiator makeRight = visit(node.right);
+    String op = node.op;
+    return (arguments) =>
+        new Binary(op, makeLeft(arguments), makeRight(arguments));
+  }
+
+  Instantiator visitPrefix(Prefix node) {
+    Instantiator makeOperand = visit(node.argument);
+    String op = node.op;
+    return (arguments) => new Prefix(op, makeOperand(arguments));
+  }
+
+  Instantiator visitPostfix(Postfix node) {
+    Instantiator makeOperand = visit(node.argument);
+    String op = node.op;
+    return (arguments) => new Postfix(op, makeOperand(arguments));
+  }
+
+  Instantiator visitVariableUse(VariableUse node) =>
+      (arguments) => new VariableUse(node.name);
+
+  Instantiator visitThis(This node) => (arguments) => new This();
+
+  Instantiator visitVariableDeclaration(VariableDeclaration node) =>
+      (arguments) => new VariableDeclaration(node.name);
+
+  Instantiator visitParameter(Parameter node) =>
+      (arguments) => new Parameter(node.name);
+
+  Instantiator visitAccess(PropertyAccess node) {
+    Instantiator makeReceiver = visit(node.receiver);
+    Instantiator makeSelector = visit(node.selector);
+    return (arguments) =>
+        new PropertyAccess(makeReceiver(arguments), makeSelector(arguments));
+  }
+
+  Instantiator visitNamedFunction(NamedFunction node) {
+    Instantiator makeDeclaration = visit(node.name);
+    Instantiator makeFunction = visit(node.function);
+    return (arguments) =>
+        new NamedFunction(makeDeclaration(arguments), makeFunction(arguments));
+  }
+
+  Instantiator visitFun(Fun node) {
+    List<Instantiator> paramMakers = node.params.map(visitSplayable).toList();
+    Instantiator makeBody = visit(node.body);
+    // TODO(sra): Avoid copying params if no interpolation or forced copying.
+    return (arguments) {
+      List<Parameter> params = <Parameter>[];
+      for (Instantiator instantiator in paramMakers) {
+        var result = instantiator(arguments);
+        if (result is Iterable) {
+          params.addAll(result);
+        } else {
+          params.add(result);
+        }
+      }
+      Statement body = makeBody(arguments);
+      return new Fun(params, body);
+    };
+  }
+
+  Instantiator visitLiteralBool(LiteralBool node) =>
+      (arguments) => new LiteralBool(node.value);
+
+  Instantiator visitLiteralString(LiteralString node) =>
+      (arguments) => new LiteralString(node.value);
+
+  Instantiator visitLiteralNumber(LiteralNumber node) =>
+      (arguments) => new LiteralNumber(node.value);
+
+  Instantiator visitLiteralNull(LiteralNull node) =>
+      (arguments) => new LiteralNull();
+
+  Instantiator visitArrayInitializer(ArrayInitializer node) {
+    // Assume array has no missing elements.
+    // TODO(sra): Splicing?
+    List<Instantiator> elementMakers = node.elements
+        .map((ArrayElement element) => visit(element.value))
+        .toList();
+    return (arguments) {
+      List<ArrayElement> elements = <ArrayElement>[];
+      void add(Expression value) {
+        elements.add(new ArrayElement(elements.length, value));
+      }
+      for (Instantiator instantiator in elementMakers) {
+        var result = instantiator(arguments);
+        add(result);
+      }
+      return new ArrayInitializer(elements.length, elements);
+    };
+  }
+
+  Instantiator visitArrayElement(ArrayElement node) {
+    throw 'Should not get here'; // Handled in visitArrayInitializer.
+  }
+
+  Instantiator visitObjectInitializer(ObjectInitializer node) {
+    List<Instantiator> propertyMakers =
+        node.properties.map(visitSplayable).toList();
+    bool isOneLiner = node.isOneLiner;
+    return (arguments) {
+      List<Property> properties = <Property>[];
+      for (Instantiator instantiator in propertyMakers) {
+        var result = instantiator(arguments);
+        if (result is Iterable) {
+          properties.addAll(result);
+        } else {
+          properties.add(result);
+        }
+      }
+      return new ObjectInitializer(properties, isOneLiner: isOneLiner);
+    };
+  }
+
+  Instantiator visitProperty(Property node) {
+    Instantiator makeName = visit(node.name);
+    Instantiator makeValue = visit(node.value);
+    return (arguments) {
+      return new Property(makeName(arguments), makeValue(arguments));
+    };
+  }
+
+  Instantiator visitRegExpLiteral(RegExpLiteral node) =>
+      (arguments) => new RegExpLiteral(node.pattern);
+
+  Instantiator visitComment(Comment node) => TODO('visitComment');
+}
+
+/**
+ * InterpolatedNodeAnalysis extract [InterpolatedNode]s from AST.
+ */
+class InterpolatedNodeAnalysis extends BaseVisitor {
+  final Set<Node> containsInterpolatedNode = new Set<Node>();
+  final List<InterpolatedNode> interpolatedNodes = <InterpolatedNode>[];
+  int count = 0;
+
+  InterpolatedNodeAnalysis();
+
+  bool containsInterpolatedNodes(Node node) =>
+      containsInterpolatedNode.contains(node);
+
+  void visit(Node node) {
+    node.accept(this);
+  }
+
+  void visitNode(Node node) {
+    int before = count;
+    node.visitChildren(this);
+    if (count != before) containsInterpolatedNode.add(node);
+    return null;
+  }
+
+  visitInterpolatedNode(InterpolatedNode node) {
+    interpolatedNodes.add(node);
+    containsInterpolatedNode.add(node);
+    ++count;
+  }
+}