53 lines
1.4 KiB
Dart
53 lines
1.4 KiB
Dart
// Copyright (c) 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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part of cassowary;
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enum Relation { equalTo, lessThanOrEqualTo, greaterThanOrEqualTo, }
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class Constraint {
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final Relation relation;
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final Expression expression;
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final bool required;
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static const double requiredPriority = 1000.0;
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double _priority = requiredPriority - 1.0;
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Constraint(this.expression, this.relation) : this.required = false;
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Constraint.Required(this.expression, this.relation) : this.required = true {
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this.priority = requiredPriority;
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}
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double get priority => required ? requiredPriority : _priority;
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set priority(double p) => _priority =
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required ? requiredPriority : p.clamp(0.0, requiredPriority - 1.0);
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Constraint operator |(double p) => this..priority = p;
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String toString() {
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StringBuffer buffer = new StringBuffer();
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buffer.write(expression.toString());
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switch (relation) {
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case Relation.equalTo:
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buffer.write(" <= 0 ");
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break;
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case Relation.greaterThanOrEqualTo:
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buffer.write(" >= 0 ");
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break;
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case Relation.lessThanOrEqualTo:
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buffer.write(" <= 0 ");
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break;
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}
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buffer.write(" | priority = ${priority}");
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if (required) {
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buffer.write(" (required)");
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}
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return buffer.toString();
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}
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}
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