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| 1 // Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. |
| 4 |
| 5 import 'ast.dart'; |
| 6 import 'visitor.dart'; |
| 7 |
| 8 typedef bool _Semantics(String variable); |
| 9 |
| 10 /// A visitor for evaluating boolean selectors against a specific set of |
| 11 /// semantics. |
| 12 class Evaluator implements Visitor<bool> { |
| 13 /// The semantics to evaluate against. |
| 14 final _Semantics _semantics; |
| 15 |
| 16 Evaluator(semantics) |
| 17 : _semantics = semantics is Iterable |
| 18 ? semantics.toSet().contains |
| 19 : semantics; |
| 20 |
| 21 bool visitVariable(VariableNode node) => _semantics(node.name); |
| 22 |
| 23 bool visitNot(NotNode node) => !node.child.accept(this); |
| 24 |
| 25 bool visitOr(OrNode node) => |
| 26 node.left.accept(this) || node.right.accept(this); |
| 27 |
| 28 bool visitAnd(AndNode node) => |
| 29 node.left.accept(this) && node.right.accept(this); |
| 30 |
| 31 bool visitConditional(ConditionalNode node) => node.condition.accept(this) |
| 32 ? node.whenTrue.accept(this) |
| 33 : node.whenFalse.accept(this); |
| 34 } |
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