Handle more constants in Constantifier

pkg/compiler/lib/src/kernel/element_adapter.dart

 // Copyright (c) 2017, 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.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/names.dart';
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
 import '../common_elements.dart';
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../native/native.dart' as native;
+import '../resolution/operators.dart';

[Siggi Cherem (dart-lang), 2017/05/04 19:13:40]

minor: it would be good to move the operators file elsewhere if we intend to
continue using it in the future

[Johnni Winther, 2017/05/05 08:17:25]

Will do in a follow-up.

 import '../universe/call_structure.dart';
 import '../universe/selector.dart';
 import 'kernel_debug.dart';
 
 /// Interface that translates between Kernel IR nodes and entities.
 abstract class KernelElementAdapter {
   /// Access to the commonly used elements and types.
   CommonElements get commonElements;
 
   /// [ElementEnvironment] for library, class and member lookup.
@@ skipping 434 matching lines @@
 }
 
 /// Visitor that converts a kernel constant expression into a
 /// [ConstantExpression].
 class Constantifier extends ir.ExpressionVisitor<ConstantExpression> {
   final bool requireConstant;
   final KernelElementAdapter elementAdapter;
 
   Constantifier(this.elementAdapter, {this.requireConstant: true});
 
+  CommonElements get _commonElements => elementAdapter.commonElements;
+
   ConstantExpression visit(ir.Expression node) {
     ConstantExpression constant = node.accept(this);
     if (constant == null && requireConstant) {
       throw new UnsupportedError(
           "No constant computed for $node (${node.runtimeType})");
     }
     return constant;
   }
 
   ConstantExpression defaultExpression(ir.Expression node) {
@@ skipping 52 matching lines @@
         assert(function.namedParameters.contains(node.variable));
         return new NamedArgumentReference(node.variable.name);
       }
     }
     throw new UnimplementedError(
         'Unimplemented constant expression $node (${node.runtimeType})');
   }
 
   @override
   ConstantExpression visitStaticGet(ir.StaticGet node) {
-    return new FieldConstantExpression(elementAdapter.getField(node.target));
+    if (node.target is ir.Field) {
+      return new FieldConstantExpression(elementAdapter.getField(node.target));
+    } else if (node.target is ir.Procedure) {
+      FunctionEntity function = elementAdapter.getMethod(node.target);
+      DartType type /* = elementAdapter.getFunctionType(function)*/;

[Siggi Cherem (dart-lang), 2017/05/04 19:13:40]

uncomment?

[Johnni Winther, 2017/05/05 08:17:25]

Done.

+      return new FunctionConstantExpression(function, type);
+    }
+    throw new UnimplementedError(
+        'Unexpected constant expression $node (${node.runtimeType})');
   }
 
   @override
+  ConstantExpression visitNullLiteral(ir.NullLiteral node) {
+    return new NullConstantExpression();
+  }
+
+  @override
+  ConstantExpression visitBoolLiteral(ir.BoolLiteral node) {
+    return new BoolConstantExpression(node.value);
+  }
+
+  @override
+  ConstantExpression visitIntLiteral(ir.IntLiteral node) {
+    return new IntConstantExpression(node.value);
+  }
+
+  @override
+  ConstantExpression visitDoubleLiteral(ir.DoubleLiteral node) {
+    return new DoubleConstantExpression(node.value);
+  }
+
+  @override
   ConstantExpression visitStringLiteral(ir.StringLiteral node) {
     return new StringConstantExpression(node.value);
   }
 
   @override
+  ConstantExpression visitSymbolLiteral(ir.SymbolLiteral node) {
+    return new SymbolConstantExpression(node.value);
+  }
+
+  @override
   ConstantExpression visitStringConcatenation(ir.StringConcatenation node) {
     return new ConcatenateConstantExpression(_computeList(node.expressions));
   }
 
+  @override
+  ConstantExpression visitMapLiteral(ir.MapLiteral node) {
+    if (!node.isConst) {
+      throw new UnimplementedError(
+          'Unexpected constant expression $node (${node.runtimeType})');
+    }
+    DartType keyType = elementAdapter.getDartType(node.keyType);
+    DartType valueType = elementAdapter.getDartType(node.valueType);
+    List<ConstantExpression> keys = <ConstantExpression>[];
+    List<ConstantExpression> values = <ConstantExpression>[];
+    for (ir.MapEntry entry in node.entries) {
+      keys.add(visit(entry.key));
+      values.add(visit(entry.value));
+    }
+    return new MapConstantExpression(
+        _commonElements.mapType(keyType, valueType), keys, values);
+  }
+
+  @override
+  ConstantExpression visitListLiteral(ir.ListLiteral node) {
+    if (!node.isConst) {
+      throw new UnimplementedError(
+          'Unexpected constant expression $node (${node.runtimeType})');
+    }
+    DartType elementType = elementAdapter.getDartType(node.typeArgument);
+    List<ConstantExpression> values = <ConstantExpression>[];
+    for (ir.Expression value in node.expressions) {
+      values.add(visit(value));
+    }
+    return new ListConstantExpression(
+        _commonElements.listType(elementType), values);
+  }
+
+  @override
+  ConstantExpression visitConditionalExpression(ir.ConditionalExpression node) {
+    ConstantExpression condition = visit(node.condition);
+    ConstantExpression trueExp = visit(node.then);
+    ConstantExpression falseExp = visit(node.otherwise);
+    return new ConditionalConstantExpression(condition, trueExp, falseExp);
+  }
+
+  @override
+  ConstantExpression visitPropertyGet(ir.PropertyGet node) {
+    if (node.name.name != 'length') {
+      throw new UnimplementedError(
+          'Unexpected constant expression $node (${node.runtimeType})');
+    }
+    ConstantExpression receiver = visit(node.receiver);

[Siggi Cherem (dart-lang), 2017/05/04 19:13:39]

do we need to check that receiver is String?

[Johnni Winther, 2017/05/05 08:17:25]

We can't tell. Only when you evaluate can you determine the type. For instance

const value = (const bool.fromEnvironment('foo') ? 'foo' : 0).length;

+    return new StringLengthConstantExpression(receiver);
+  }
+
+  @override
+  ConstantExpression visitMethodInvocation(ir.MethodInvocation node) {

[Siggi Cherem (dart-lang), 2017/05/04 19:13:39]

minor: it might be worth adding a 1-line comment here explaining that method
invocations are not constants, but some unary and binary operators are (which
kernel encodes as method invocations)

+    if (node.arguments.named.isNotEmpty) {
+      throw new UnimplementedError(
+          'Unexpected constant expression $node (${node.runtimeType})');
+    }
+    if (node.arguments.positional.length == 0) {
+      UnaryOperator operator;
+      if (node.name.name == UnaryOperator.NEGATE.selectorName) {
+        operator = UnaryOperator.NEGATE;
+      } else {
+        operator = UnaryOperator.parse(node.name.name);
+      }
+      if (operator != null) {
+        ConstantExpression expression = visit(node.receiver);
+        return new UnaryConstantExpression(operator, expression);
+      }
+    }
+    if (node.arguments.positional.length == 1) {
+      BinaryOperator operator = BinaryOperator.parse(node.name.name);
+      if (operator != null) {
+        ConstantExpression left = visit(node.receiver);
+        ConstantExpression right = visit(node.arguments.positional.single);
+        return new BinaryConstantExpression(left, operator, right);
+      }
+    }
+    throw new UnimplementedError(
+        'Unexpected constant expression $node (${node.runtimeType})');
+  }
+
+  @override
+  ConstantExpression visitStaticInvocation(ir.StaticInvocation node) {
+    MemberEntity member = elementAdapter.getMember(node.target);
+    if (member == _commonElements.identicalFunction) {
+      if (node.arguments.positional.length == 2 &&
+          node.arguments.named.isEmpty) {
+        ConstantExpression left = visit(node.arguments.positional[0]);
+        ConstantExpression right = visit(node.arguments.positional[1]);
+        return new IdenticalConstantExpression(left, right);
+      }
+    } else if (member.name == 'fromEnvironment' &&
+        node.arguments.positional.length == 1) {
+      ConstantExpression name = visit(node.arguments.positional.single);
+      ConstantExpression defaultValue;
+      if (node.arguments.named.length == 1) {
+        if (node.arguments.named.single.name != 'defaultValue') {
+          throw new UnimplementedError(
+              'Unexpected constant expression $node (${node.runtimeType})');
+        }
+        defaultValue = visit(node.arguments.named.single.value);
+      }
+      if (member.enclosingClass == _commonElements.boolClass) {
+        return new BoolFromEnvironmentConstantExpression(name, defaultValue);
+      } else if (member.enclosingClass == _commonElements.intClass) {
+        return new IntFromEnvironmentConstantExpression(name, defaultValue);
+      } else if (member.enclosingClass == _commonElements.stringClass) {
+        return new StringFromEnvironmentConstantExpression(name, defaultValue);
+      }
+    }
+    throw new UnimplementedError(
+        'Unexpected constant expression $node (${node.runtimeType})');
+  }
+
+  @override
+  ConstantExpression visitLogicalExpression(ir.LogicalExpression node) {
+    BinaryOperator operator = BinaryOperator.parse(node.operator);
+    if (operator != null) {
+      ConstantExpression left = visit(node.left);
+      ConstantExpression right = visit(node.right);
+      return new BinaryConstantExpression(left, operator, right);
+    }
+    throw new UnimplementedError(
+        'Unexpected constant expression $node (${node.runtimeType})');
+  }
+
   /// Compute the [ConstantConstructor] corresponding to the const constructor
   /// [node].
   ConstantConstructor computeConstantConstructor(ir.Constructor node) {
     assert(node.isConst);
     ir.Class cls = node.enclosingClass;
     InterfaceType type = elementAdapter.elementEnvironment
         .getThisType(elementAdapter.getClass(cls));
 
     Map<dynamic, ConstantExpression> defaultValues =
         <dynamic, ConstantExpression>{};
@@ skipping 48 matching lines @@
     }
     if (isRedirecting) {
       return new RedirectingGenerativeConstantConstructor(
           defaultValues, superConstructorInvocation);
     } else {
       return new GenerativeConstantConstructor(
           type, defaultValues, fieldMap, superConstructorInvocation);
     }
   }
 }