blob: 9102add652703809758b50a3a6d4aa382851639a [file] [log] [blame]
// Copyright (c) 2016, 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 'ast.dart';
import 'visitor.dart';
typedef bool _Semantics(String variable);
/// A visitor for evaluating boolean selectors against a specific set of
/// semantics.
class Evaluator implements Visitor<bool> {
/// The semantics to evaluate against.
final _Semantics _semantics;
: _semantics = semantics is Iterable
? semantics.toSet().contains
: semantics;
bool visitVariable(VariableNode node) => _semantics(;
bool visitNot(NotNode node) => !node.child.accept(this);
bool visitOr(OrNode node) =>
node.left.accept(this) || node.right.accept(this);
bool visitAnd(AndNode node) =>
node.left.accept(this) && node.right.accept(this);
bool visitConditional(ConditionalNode node) => node.condition.accept(this)
? node.whenTrue.accept(this)
: node.whenFalse.accept(this);