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1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 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. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 library polymer_expressions.eval; | 5 library polymer_expressions.eval; |
6 | 6 |
7 import 'dart:async'; | 7 import 'dart:async'; |
8 import 'dart:collection'; | 8 import 'dart:collection'; |
9 | 9 |
10 import 'package:observe/observe.dart'; | 10 import 'package:observe/observe.dart'; |
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73 } | 73 } |
74 | 74 |
75 /** | 75 /** |
76 * Assign [value] to the variable or field referenced by [expr] in the context | 76 * Assign [value] to the variable or field referenced by [expr] in the context |
77 * of [scope]. | 77 * of [scope]. |
78 * | 78 * |
79 * [expr] must be an /assignable/ expression, it must not contain | 79 * [expr] must be an /assignable/ expression, it must not contain |
80 * operators or function invocations, and any index operations must use a | 80 * operators or function invocations, and any index operations must use a |
81 * literal index. | 81 * literal index. |
82 */ | 82 */ |
83 void assign(Expression expr, Object value, Scope scope) { | 83 Object assign(Expression expr, Object value, Scope scope) { |
84 | 84 |
85 notAssignable() => | 85 notAssignable() => |
86 throw new EvalException("Expression is not assignable: $expr"); | 86 throw new EvalException("Expression is not assignable: $expr"); |
87 | 87 |
88 Expression expression; | 88 Expression expression; |
89 var property; | 89 var property; |
90 bool isIndex = false; | 90 bool isIndex = false; |
91 var filters = <Expression>[]; // reversed order for assignment | 91 var filters = <Expression>[]; // reversed order for assignment |
92 | 92 |
93 while (expr is BinaryOperator) { | 93 while (expr is BinaryOperator) { |
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133 value = filter.reverse(value); | 133 value = filter.reverse(value); |
134 } | 134 } |
135 // make the assignment | 135 // make the assignment |
136 var o = eval(expression, scope); | 136 var o = eval(expression, scope); |
137 if (o == null) throw new EvalException("Can't assign to null: $expression"); | 137 if (o == null) throw new EvalException("Can't assign to null: $expression"); |
138 if (isIndex) { | 138 if (isIndex) { |
139 o[property] = value; | 139 o[property] = value; |
140 } else { | 140 } else { |
141 smoke.write(o, smoke.nameToSymbol(property), value); | 141 smoke.write(o, smoke.nameToSymbol(property), value); |
142 } | 142 } |
| 143 return value; |
143 } | 144 } |
144 | 145 |
145 | 146 |
146 /** | 147 /** |
147 * A scope in polymer expressions that can map names to objects. Scopes contain | 148 * A scope in polymer expressions that can map names to objects. Scopes contain |
148 * a set of named variables and a unique model object. The scope structure | 149 * a set of named variables and a unique model object. The scope structure |
149 * is then used to lookup names using the `[]` operator. The lookup first | 150 * is then used to lookup names using the `[]` operator. The lookup first |
150 * searches for the name in local variables, then in global variables, | 151 * searches for the name in local variables, then in global variables, |
151 * and then finally looks up the name as a property in the model. | 152 * and then finally looks up the name as a property in the model. |
152 */ | 153 */ |
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744 | 745 |
745 Comprehension(this.identifier, Iterable iterable) | 746 Comprehension(this.identifier, Iterable iterable) |
746 : iterable = (iterable != null) ? iterable : const []; | 747 : iterable = (iterable != null) ? iterable : const []; |
747 } | 748 } |
748 | 749 |
749 class EvalException implements Exception { | 750 class EvalException implements Exception { |
750 final String message; | 751 final String message; |
751 EvalException(this.message); | 752 EvalException(this.message); |
752 String toString() => "EvalException: $message"; | 753 String toString() => "EvalException: $message"; |
753 } | 754 } |
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