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| 1 | +// Copyright 2018 Google Inc. Use of this source code is governed by an |
| 2 | +// MIT-style license that can be found in the LICENSE file or at |
| 3 | +// https://opensource.org/licenses/MIT. |
| 4 | + |
| 5 | +import 'package:meta/meta.dart'; |
| 6 | + |
| 7 | +import '../ast/sass.dart'; |
| 8 | +import 'interface/statement.dart'; |
| 9 | + |
| 10 | +/// A visitor that recursively traverses each statement in a Sass AST. |
| 11 | +/// |
| 12 | +/// In addition to the methods from [StatementVisitor], this has more general |
| 13 | +/// protected methods that can be overriden to add behavior for a wide variety |
| 14 | +/// of AST nodes: |
| 15 | +/// |
| 16 | +/// * [visitCallableDeclaration] |
| 17 | +/// * [visitSupportsCondition] |
| 18 | +/// * [visitChildren] |
| 19 | +/// * [visitInterpolation] |
| 20 | +/// * [visitExpression] |
| 21 | +/// |
| 22 | +/// The default implementation of the visit methods all return `null`. |
| 23 | +abstract class RecursiveStatementVisitor<T> implements StatementVisitor<T> { |
| 24 | + T visitAtRootRule(AtRootRule node) { |
| 25 | + visitInterpolation(node.query); |
| 26 | + return visitChildren(node); |
| 27 | + } |
| 28 | + |
| 29 | + T visitAtRule(AtRule node) { |
| 30 | + visitInterpolation(node.value); |
| 31 | + return visitChildren(node); |
| 32 | + } |
| 33 | + |
| 34 | + T visitContentRule(ContentRule node) => null; |
| 35 | + |
| 36 | + T visitDebugRule(DebugRule node) { |
| 37 | + visitExpression(node.expression); |
| 38 | + return null; |
| 39 | + } |
| 40 | + |
| 41 | + T visitDeclaration(Declaration node) { |
| 42 | + visitInterpolation(node.name); |
| 43 | + visitExpression(node.value); |
| 44 | + return visitChildren(node); |
| 45 | + } |
| 46 | + |
| 47 | + T visitEachRule(EachRule node) { |
| 48 | + visitExpression(node.list); |
| 49 | + return visitChildren(node); |
| 50 | + } |
| 51 | + |
| 52 | + T visitErrorRule(ErrorRule node) { |
| 53 | + visitExpression(node.expression); |
| 54 | + return null; |
| 55 | + } |
| 56 | + |
| 57 | + T visitExtendRule(ExtendRule node) { |
| 58 | + visitInterpolation(node.selector); |
| 59 | + return null; |
| 60 | + } |
| 61 | + |
| 62 | + T visitForRule(ForRule node) { |
| 63 | + visitExpression(node.from); |
| 64 | + visitExpression(node.to); |
| 65 | + return visitChildren(node); |
| 66 | + } |
| 67 | + |
| 68 | + T visitFunctionRule(FunctionRule node) => visitCallableDeclaration(node); |
| 69 | + |
| 70 | + T visitIfRule(IfRule node) { |
| 71 | + for (var clause in node.clauses) { |
| 72 | + _visitIfClause(clause); |
| 73 | + } |
| 74 | + if (node.lastClause != null) _visitIfClause(node.lastClause); |
| 75 | + return null; |
| 76 | + } |
| 77 | + |
| 78 | + /// Visits [clause]'s expression and children. |
| 79 | + void _visitIfClause(IfClause clause) { |
| 80 | + if (clause.expression != null) visitExpression(clause.expression); |
| 81 | + for (var child in clause.children) { |
| 82 | + child.accept(this); |
| 83 | + } |
| 84 | + } |
| 85 | + |
| 86 | + T visitImportRule(ImportRule node) { |
| 87 | + for (var import in node.imports) { |
| 88 | + if (import is StaticImport) { |
| 89 | + visitInterpolation(import.url); |
| 90 | + if (import.supports != null) visitSupportsCondition(import.supports); |
| 91 | + if (import.media != null) visitInterpolation(import.media); |
| 92 | + } |
| 93 | + } |
| 94 | + return null; |
| 95 | + } |
| 96 | + |
| 97 | + T visitIncludeRule(IncludeRule node) { |
| 98 | + for (var expression in node.arguments.positional) { |
| 99 | + visitExpression(expression); |
| 100 | + } |
| 101 | + for (var expression in node.arguments.named.values) { |
| 102 | + visitExpression(expression); |
| 103 | + } |
| 104 | + if (node.arguments.rest != null) { |
| 105 | + visitExpression(node.arguments.rest); |
| 106 | + } |
| 107 | + if (node.arguments.keywordRest != null) { |
| 108 | + visitExpression(node.arguments.keywordRest); |
| 109 | + } |
| 110 | + |
| 111 | + return node.children == null ? null : visitChildren(node); |
| 112 | + } |
| 113 | + |
| 114 | + T visitLoudComment(LoudComment node) { |
| 115 | + visitInterpolation(node.text); |
| 116 | + return null; |
| 117 | + } |
| 118 | + |
| 119 | + T visitMediaRule(MediaRule node) { |
| 120 | + visitInterpolation(node.query); |
| 121 | + return visitChildren(node); |
| 122 | + } |
| 123 | + |
| 124 | + T visitMixinRule(MixinRule node) => visitCallableDeclaration(node); |
| 125 | + |
| 126 | + T visitReturnRule(ReturnRule node) { |
| 127 | + visitExpression(node.expression); |
| 128 | + return null; |
| 129 | + } |
| 130 | + |
| 131 | + T visitSilentComment(SilentComment node) => null; |
| 132 | + |
| 133 | + T visitStyleRule(StyleRule node) { |
| 134 | + visitInterpolation(node.selector); |
| 135 | + return visitChildren(node); |
| 136 | + } |
| 137 | + |
| 138 | + T visitStylesheet(Stylesheet node) => visitChildren(node); |
| 139 | + |
| 140 | + T visitSupportsRule(SupportsRule node) { |
| 141 | + visitSupportsCondition(node.condition); |
| 142 | + return visitChildren(node); |
| 143 | + } |
| 144 | + |
| 145 | + T visitVariableDeclaration(VariableDeclaration node) { |
| 146 | + visitExpression(node.expression); |
| 147 | + return null; |
| 148 | + } |
| 149 | + |
| 150 | + T visitWarnRule(WarnRule node) { |
| 151 | + visitExpression(node.expression); |
| 152 | + return null; |
| 153 | + } |
| 154 | + |
| 155 | + T visitWhileRule(WhileRule node) { |
| 156 | + visitExpression(node.condition); |
| 157 | + return visitChildren(node); |
| 158 | + } |
| 159 | + |
| 160 | + /// Visits each of [node]'s expressions and children. |
| 161 | + /// |
| 162 | + /// The default implementations of [visitFunctionRule] and [visitMixinRule] |
| 163 | + /// call this. |
| 164 | + @protected |
| 165 | + T visitCallableDeclaration(CallableDeclaration node) { |
| 166 | + for (var argument in node.arguments.arguments) { |
| 167 | + if (argument.defaultValue != null) visitExpression(argument.defaultValue); |
| 168 | + } |
| 169 | + return visitChildren(node); |
| 170 | + } |
| 171 | + |
| 172 | + /// Visits each expression in [condition]. |
| 173 | + /// |
| 174 | + /// The default implementation of the visit methods call this to visit any |
| 175 | + /// [SupportsCondition] they encounter. |
| 176 | + @protected |
| 177 | + void visitSupportsCondition(SupportsCondition condition) { |
| 178 | + if (condition is SupportsOperation) { |
| 179 | + visitSupportsCondition(condition.left); |
| 180 | + visitSupportsCondition(condition.right); |
| 181 | + } else if (condition is SupportsNegation) { |
| 182 | + visitSupportsCondition(condition.condition); |
| 183 | + } else if (condition is SupportsInterpolation) { |
| 184 | + visitExpression(condition.expression); |
| 185 | + } else if (condition is SupportsDeclaration) { |
| 186 | + visitExpression(condition.name); |
| 187 | + visitExpression(condition.value); |
| 188 | + } |
| 189 | + } |
| 190 | + |
| 191 | + /// Visits each of [node]'s children. |
| 192 | + /// |
| 193 | + /// The default implementation of the visit methods for all [ParentStatement]s |
| 194 | + /// call this and return its result. |
| 195 | + @protected |
| 196 | + T visitChildren(ParentStatement node) { |
| 197 | + for (var child in node.children) { |
| 198 | + child.accept(this); |
| 199 | + } |
| 200 | + return null; |
| 201 | + } |
| 202 | + |
| 203 | + /// Visits each expression in an [interpolation]. |
| 204 | + /// |
| 205 | + /// The default implementation of the visit methods call this to visit any |
| 206 | + /// interpolation in a statement. |
| 207 | + @protected |
| 208 | + void visitInterpolation(Interpolation interpolation) { |
| 209 | + for (var node in interpolation.contents) { |
| 210 | + if (node is Expression) visitExpression(node); |
| 211 | + } |
| 212 | + } |
| 213 | + |
| 214 | + /// Visits [expression]. |
| 215 | + /// |
| 216 | + /// The default implementation of the visit methods call this to visit any |
| 217 | + /// expression in a statement. |
| 218 | + @protected |
| 219 | + void visitExpression(Expression expression) {} |
| 220 | +} |
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