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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 'package:source_span/source_span.dart'; |
| 6 |
| 7 import 'visitor.dart'; |
| 8 |
| 9 /// The superclass of nodes in the boolean selector abstract syntax tree. |
| 10 abstract class Node { |
| 11 /// The span indicating where this node came from. |
| 12 /// |
| 13 /// This is a [FileSpan] because the nodes are parsed from a single continuous |
| 14 /// string, but the string itself isn't actually a file. It might come from a |
| 15 /// statically-parsed annotation or from a parameter. |
| 16 /// |
| 17 /// This may be `null` for nodes without source information. |
| 18 FileSpan get span; |
| 19 |
| 20 /// All the variables in this node, in the order they appear. |
| 21 Iterable<String> get variables; |
| 22 |
| 23 /// Calls the appropriate [Visitor] method on [this] and returns the result. |
| 24 accept(Visitor visitor); |
| 25 } |
| 26 |
| 27 /// A single variable. |
| 28 class VariableNode implements Node { |
| 29 final FileSpan span; |
| 30 |
| 31 /// The variable name. |
| 32 final String name; |
| 33 |
| 34 Iterable<String> get variables => [name]; |
| 35 |
| 36 VariableNode(this.name, [this.span]); |
| 37 |
| 38 accept(Visitor visitor) => visitor.visitVariable(this); |
| 39 |
| 40 String toString() => name; |
| 41 } |
| 42 |
| 43 /// A negation expression. |
| 44 class NotNode implements Node { |
| 45 final FileSpan span; |
| 46 |
| 47 /// The expression being negated. |
| 48 final Node child; |
| 49 |
| 50 Iterable<String> get variables => child.variables; |
| 51 |
| 52 NotNode(this.child, [this.span]); |
| 53 |
| 54 accept(Visitor visitor) => visitor.visitNot(this); |
| 55 |
| 56 String toString() => child is VariableNode || child is NotNode |
| 57 ? "!$child" |
| 58 : "!($child)"; |
| 59 } |
| 60 |
| 61 /// An or expression. |
| 62 class OrNode implements Node { |
| 63 FileSpan get span => _expandSafe(left.span, right.span); |
| 64 |
| 65 /// The left-hand branch of the expression. |
| 66 final Node left; |
| 67 |
| 68 /// The right-hand branch of the expression. |
| 69 final Node right; |
| 70 |
| 71 Iterable<String> get variables sync* { |
| 72 yield* left.variables; |
| 73 yield* right.variables; |
| 74 } |
| 75 |
| 76 OrNode(this.left, this.right); |
| 77 |
| 78 accept(Visitor visitor) => visitor.visitOr(this); |
| 79 |
| 80 String toString() { |
| 81 var string1 = left is AndNode || left is ConditionalNode |
| 82 ? "($left)" |
| 83 : left; |
| 84 var string2 = right is AndNode || right is ConditionalNode |
| 85 ? "($right)" |
| 86 : right; |
| 87 |
| 88 return "$string1 || $string2"; |
| 89 } |
| 90 } |
| 91 |
| 92 /// An and expression. |
| 93 class AndNode implements Node { |
| 94 FileSpan get span => _expandSafe(left.span, right.span); |
| 95 |
| 96 /// The left-hand branch of the expression. |
| 97 final Node left; |
| 98 |
| 99 /// The right-hand branch of the expression. |
| 100 final Node right; |
| 101 |
| 102 Iterable<String> get variables sync* { |
| 103 yield* left.variables; |
| 104 yield* right.variables; |
| 105 } |
| 106 |
| 107 AndNode(this.left, this.right); |
| 108 |
| 109 accept(Visitor visitor) => visitor.visitAnd(this); |
| 110 |
| 111 String toString() { |
| 112 var string1 = left is OrNode || left is ConditionalNode |
| 113 ? "($left)" |
| 114 : left; |
| 115 var string2 = right is OrNode || right is ConditionalNode |
| 116 ? "($right)" |
| 117 : right; |
| 118 |
| 119 return "$string1 && $string2"; |
| 120 } |
| 121 } |
| 122 |
| 123 /// A ternary conditional expression. |
| 124 class ConditionalNode implements Node { |
| 125 FileSpan get span => _expandSafe(condition.span, whenFalse.span); |
| 126 |
| 127 /// The condition expression to check. |
| 128 final Node condition; |
| 129 |
| 130 /// The branch to run if the condition is true. |
| 131 final Node whenTrue; |
| 132 |
| 133 /// The branch to run if the condition is false. |
| 134 final Node whenFalse; |
| 135 |
| 136 Iterable<String> get variables sync* { |
| 137 yield* condition.variables; |
| 138 yield* whenTrue.variables; |
| 139 yield* whenFalse.variables; |
| 140 } |
| 141 |
| 142 ConditionalNode(this.condition, this.whenTrue, this.whenFalse); |
| 143 |
| 144 accept(Visitor visitor) => visitor.visitConditional(this); |
| 145 |
| 146 String toString() { |
| 147 var conditionString = |
| 148 condition is ConditionalNode ? "($condition)" : condition; |
| 149 var trueString = whenTrue is ConditionalNode ? "($whenTrue)" : whenTrue; |
| 150 return "$conditionString ? $trueString : $whenFalse"; |
| 151 } |
| 152 } |
| 153 |
| 154 /// Like [FileSpan.expand], except if [start] and [end] are `null` or from |
| 155 /// different files it returns `null` rather than throwing an error. |
| 156 FileSpan _expandSafe(FileSpan start, FileSpan end) { |
| 157 if (start == null || end == null) return null; |
| 158 if (start.file != end.file) return null; |
| 159 return start.expand(end); |
| 160 } |
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