lib/src/backend/platform_selector/ast.dart - Issue 1717483002: Make PlatformSelector use boolean_selector.

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Issue 1717483002: Make PlatformSelector use boolean_selector. (Closed) Base URL: git@github.com:dart-lang/test@master

Patch Set: Created 4 years, 10 months ago

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1 // Copyright (c) 2015, 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 platform 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 /// Calls the appropriate [Visitor] method on [this] and returns the result.

21 accept(Visitor visitor);

22 }

23

24 /// A single variable.

25 class VariableNode implements Node {

26 final FileSpan span;

27

28 /// The variable name.

29 final String name;

30

31 VariableNode(this.name, [this.span]);

32

33 accept(Visitor visitor) => visitor.visitVariable(this);

34

35 String toString() => name;

36 }

37

38 /// A negation expression.

39 class NotNode implements Node {

40 final FileSpan span;

41

42 /// The expression being negated.

43 final Node child;

44

45 NotNode(this.child, [this.span]);

46

47 accept(Visitor visitor) => visitor.visitNot(this);

48

49 String toString() => child is VariableNode \|\| child is NotNode

50 ? "!$child"

51 : "!($child)";

52 }

53

54 /// An or expression.

55 class OrNode implements Node {

56 FileSpan get span => _expandSafe(left.span, right.span);

57

58 /// The left-hand branch of the expression.

59 final Node left;

60

61 /// The right-hand branch of the expression.

62 final Node right;

63

64 OrNode(this.left, this.right);

65

66 accept(Visitor visitor) => visitor.visitOr(this);

67

68 String toString() {

69 var string1 = left is AndNode \|\| left is ConditionalNode

70 ? "($left)"

71 : left;

72 var string2 = right is AndNode \|\| right is ConditionalNode

73 ? "($right)"

74 : right;

75

76 return "$string1 \|\| $string2";

77 }

78 }

79

80 /// An and expression.

81 class AndNode implements Node {

82 FileSpan get span => _expandSafe(left.span, right.span);

83

84 /// The left-hand branch of the expression.

85 final Node left;

86

87 /// The right-hand branch of the expression.

88 final Node right;

89

90 AndNode(this.left, this.right);

91

92 accept(Visitor visitor) => visitor.visitAnd(this);

93

94 String toString() {

95 var string1 = left is OrNode \|\| left is ConditionalNode

96 ? "($left)"

97 : left;

98 var string2 = right is OrNode \|\| right is ConditionalNode

99 ? "($right)"

100 : right;

101

102 return "$string1 && $string2";

103 }

104 }

105

106 /// A ternary conditional expression.

107 class ConditionalNode implements Node {

108 FileSpan get span => _expandSafe(condition.span, whenFalse.span);

109

110 /// The condition expression to check.

111 final Node condition;

112

113 /// The branch to run if the condition is true.

114 final Node whenTrue;

115

116 /// The branch to run if the condition is false.

117 final Node whenFalse;

118

119 ConditionalNode(this.condition, this.whenTrue, this.whenFalse);

120

121 accept(Visitor visitor) => visitor.visitConditional(this);

122

123 String toString() {

124 var conditionString =

125 condition is ConditionalNode ? "($condition)" : condition;

126 var trueString = whenTrue is ConditionalNode ? "($whenTrue)" : whenTrue;

127 return "$conditionString ? $trueString : $whenFalse";

128 }

129 }

130

131 /// Like [FileSpan.expand], except if [start] and [end] are `null` or from

132 /// different files it returns `null` rather than throwing an error.

133 FileSpan _expandSafe(FileSpan start, FileSpan end) {

134 if (start == null \|\| end == null) return null;

135 if (start.file != end.file) return null;

136 return start.expand(end);

137 }

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