Support conditional expressions in analyzer2dart.

pkg/analyzer2dart/lib/src/cps_generator.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.
 
 library analyzer2dart.cps_generator;
 
 import 'package:analyzer/analyzer.dart';
 
 import 'package:compiler/implementation/elements/elements.dart' as dart2js;
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 12 matching lines @@
 
 class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
     with IrBuilderMixin {
   final analyzer.Element element;
   final ElementConverter converter;
 
   CpsGeneratingVisitor(this.converter, this.element);
 
   Source get currentSource => element.source;
 
+  ir.Node visit(AstNode node) => node != null ? node.accept(this) : null;

[sigurdm, 2014/10/20 10:48:32]

This is not what I expect "visit" to do - it should have another name.
Most times we want to fail immediately if node is null.

[Johnni Winther, 2014/10/20 12:25:13]

Done.

+
+  /// Returns a closure that takes an [IrBuilder] and visits [node] in its
+  /// context.
+  build(AstNode node) {

[sigurdm, 2014/10/20 10:48:32]

I don't really like the name - the function does not build anything.

[Johnni Winther, 2014/10/20 12:25:13]

Done.

+    return (IrBuilder builder) => withBuilder(builder, () => visit(node));
+  }
+
   @override
   ir.FunctionDefinition visitFunctionDeclaration(FunctionDeclaration node) {
     analyzer.FunctionElement function = node.element;
     dart2js.FunctionElement element = converter.convertElement(function);
     return withBuilder(
         new IrBuilder(DART_CONSTANT_SYSTEM,
                       element,
                       // TODO(johnniwinther): Supported closure variables.
                       const <dart2js.Local>[]),
         () {
       function.parameters.forEach((analyzer.ParameterElement parameter) {
         // TODO(johnniwinther): Support "closure variables", that is variables
         // accessed from an inner function.
         irBuilder.createParameter(converter.convertElement(parameter),
                                   isClosureVariable: false);
       });
       // Visit the body directly to avoid processing the signature as
       // expressions.
-      node.functionExpression.body.accept(this);
+      visit(node.functionExpression.body);
       return irBuilder.buildFunctionDefinition(element, const []);
     });
   }
 
   List<ir.Definition> visitArguments(ArgumentList argumentList) {
     List<ir.Definition> arguments = <ir.Definition>[];
     for (Expression argument in argumentList.arguments) {
-      ir.Definition value = argument.accept(this);
+      ir.Definition value = visit(argument);
       if (value == null) {
         giveUp(argument,
             'Unsupported argument: $argument (${argument.runtimeType}).');
       }
       arguments.add(value);
     }
     return arguments;
   }
 
   @override
   ir.Primitive visitDynamicInvocation(MethodInvocation node,
                                       AccessSemantics semantics) {
     // TODO(johnniwinther): Handle implicit `this`.
-    ir.Primitive receiver = semantics.target.accept(this);
+    ir.Primitive receiver = visit(semantics.target);
     List<ir.Definition> arguments = visitArguments(node.argumentList);
     return irBuilder.buildDynamicInvocation(
         receiver,
         createSelectorFromMethodInvocation(node, node.methodName.name),
         arguments);
   }
 
   @override
   ir.Primitive visitStaticMethodInvocation(MethodInvocation node,
                                            AccessSemantics semantics) {
@@ skipping 40 matching lines @@
     return irBuilder.buildStringLiteral(node.value);
   }
 
   @override
   visitStringInterpolation(StringInterpolation node) {
     giveUp(node, "String interpolation.");
   }
 
   @override
   visitReturnStatement(ReturnStatement node) {
-    if (node.expression != null) {
-      irBuilder.buildReturn(node.expression.accept(this));
-    } else {
-      irBuilder.buildReturn();
-    }
+    irBuilder.buildReturn(visit(node.expression));
   }
 
   @override
   ir.Node visitLocalVariableAccess(AstNode node, AccessSemantics semantics) {
     return handleLocalAccess(node, semantics);
   }
 
   @override
   ir.Node visitParameterAccess(AstNode node, AccessSemantics semantics) {
     return handleLocalAccess(node, semantics);
   }
 
   @override
   visitVariableDeclaration(VariableDeclaration node) {
     // TODO(johnniwinther): Handle constant local variables.
-    ir.Node initialValue;
-    if (node.initializer != null) {
-      initialValue = node.initializer.accept(this);
-    }
+    ir.Node initialValue = visit(node.initializer);
     irBuilder.declareLocalVariable(
         converter.convertElement(node.element),
         initialValue: initialValue);
   }
 
   ir.Primitive handleLocalAccess(AstNode node, AccessSemantics semantics) {
     analyzer.Element element = semantics.element;
     dart2js.Element target = converter.convertElement(element);
     assert(invariant(node, target.isLocal, '$target expected to be local.'));
     return irBuilder.buildLocalGet(target);
   }
 
   @override
   ir.Node visitDynamicAccess(AstNode node, AccessSemantics semantics) {
     // TODO(johnniwinther): Handle implicit `this`.
-    ir.Primitive receiver = semantics.target.accept(this);
+    ir.Primitive receiver = visit(semantics.target);
     return irBuilder.buildDynamicGet(receiver,
         new Selector.getter(semantics.identifier.name,
                             converter.convertElement(element.library)));
   }
 
   @override
   ir.Node visitStaticFieldAccess(AstNode node, AccessSemantics semantics) {
     analyzer.Element element = semantics.element;
     dart2js.Element target = converter.convertElement(element);
     // TODO(johnniwinther): Selector information should be computed in the
     // [TreeShaker] and shared with the [CpsGeneratingVisitor].
     assert(invariant(node, target.isTopLevel || target.isStatic,
                      '$target expected to be top-level or static.'));
     return irBuilder.buildStaticGet(target,
         new Selector.getter(target.name, target.library));
   }
 
   ir.Primitive handleBinaryExpression(BinaryExpression node,
                                       String op) {
-    ir.Primitive left = node.leftOperand.accept(this);
-    ir.Primitive right = node.rightOperand.accept(this);
+    ir.Primitive left = visit(node.leftOperand);
+    ir.Primitive right = visit(node.rightOperand);
     Selector selector = new Selector.binaryOperator(op);
     return irBuilder.buildDynamicInvocation(
         left, selector, <ir.Definition>[right]);
   }
 
   ir.Node handleLazyOperator(BinaryExpression node, {bool isLazyOr: false}) {
-    ir.Primitive left = node.leftOperand.accept(this);
-    ir.Primitive buildRightValue(IrBuilder builder) {
-      return withBuilder(builder, () => node.rightOperand.accept(this));
-    }
     return irBuilder.buildLogicalOperator(
-        left, buildRightValue, isLazyOr: isLazyOr);
+        visit(node.leftOperand),
+        build(node.rightOperand),
+        isLazyOr: isLazyOr);
   }
 
   @override
   ir.Node visitBinaryExpression(BinaryExpression node) {
     // TODO(johnniwinther,paulberry,brianwilkerson): The operator should be
     // available through an enum.
     String op = node.operator.lexeme;
     switch (op) {
     case '||':
     case '&&':
       return handleLazyOperator(node, isLazyOr: op == '||');
     case '!=':
       return irBuilder.buildNegation(handleBinaryExpression(node, '=='));
     default:
       return handleBinaryExpression(node, op);
     }
   }
 
   @override
+  ir.Node visitConditionalExpression(ConditionalExpression node) {
+    return irBuilder.buildConditional(
+        visit(node.condition),
+        build(node.thenExpression),
+        build(node.elseExpression));
+  }
+
+  @override
   visitIfStatement(IfStatement node) {
-    ir.Primitive condition = node.condition.accept(this);
-
-    void buildThenPart(IrBuilder thenBuilder) {
-      withBuilder(thenBuilder, () => node.thenStatement.accept(this));
-    }
-
-    void buildElsePart(IrBuilder elseBuilder) {
-      if (node.elseStatement != null) {
-        withBuilder(elseBuilder, () => node.elseStatement.accept(this));
-      }
-    }
-
-    irBuilder.buildIf(condition, buildThenPart, buildElsePart);
+    irBuilder.buildIf(
+        visit(node.condition),
+        build(node.thenStatement),
+        build(node.elseStatement));
   }
 }