//
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// SnapKit
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//
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// Copyright (c) 2011-Present SnapKit Team - https://github.com/SnapKit
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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#if canImport(UIKit)
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import UIKit
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#else
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import AppKit
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#endif
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public final class Constraint {
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internal let sourceLocation: (String, UInt)
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internal let label: String?
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private let from: ConstraintItem
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private let to: ConstraintItem
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private let relation: ConstraintRelation
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private let multiplier: ConstraintMultiplierTarget
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private var constant: ConstraintConstantTarget {
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didSet {
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self.updateConstantAndPriorityIfNeeded()
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}
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}
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private var priority: ConstraintPriorityTarget {
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didSet {
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self.updateConstantAndPriorityIfNeeded()
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}
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}
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public var layoutConstraints: [LayoutConstraint]
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public var isActive: Bool {
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set {
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if newValue {
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activate()
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}
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else {
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deactivate()
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}
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}
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get {
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for layoutConstraint in self.layoutConstraints {
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if layoutConstraint.isActive {
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return true
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}
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}
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return false
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}
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}
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// MARK: Initialization
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internal init(from: ConstraintItem,
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to: ConstraintItem,
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relation: ConstraintRelation,
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sourceLocation: (String, UInt),
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label: String?,
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multiplier: ConstraintMultiplierTarget,
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constant: ConstraintConstantTarget,
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priority: ConstraintPriorityTarget) {
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self.from = from
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self.to = to
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self.relation = relation
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self.sourceLocation = sourceLocation
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self.label = label
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self.multiplier = multiplier
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self.constant = constant
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self.priority = priority
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self.layoutConstraints = []
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// get attributes
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let layoutFromAttributes = self.from.attributes.layoutAttributes
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let layoutToAttributes = self.to.attributes.layoutAttributes
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// get layout from
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let layoutFrom = self.from.layoutConstraintItem!
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// get relation
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let layoutRelation = self.relation.layoutRelation
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for layoutFromAttribute in layoutFromAttributes {
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// get layout to attribute
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let layoutToAttribute: LayoutAttribute
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#if canImport(UIKit)
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if layoutToAttributes.count > 0 {
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if self.from.attributes == .edges && self.to.attributes == .margins {
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switch layoutFromAttribute {
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case .left:
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layoutToAttribute = .leftMargin
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case .right:
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layoutToAttribute = .rightMargin
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case .top:
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layoutToAttribute = .topMargin
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case .bottom:
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layoutToAttribute = .bottomMargin
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default:
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fatalError()
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}
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} else if self.from.attributes == .margins && self.to.attributes == .edges {
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switch layoutFromAttribute {
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case .leftMargin:
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layoutToAttribute = .left
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case .rightMargin:
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layoutToAttribute = .right
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case .topMargin:
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layoutToAttribute = .top
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case .bottomMargin:
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layoutToAttribute = .bottom
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default:
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fatalError()
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}
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} else if self.from.attributes == .directionalEdges && self.to.attributes == .directionalMargins {
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switch layoutFromAttribute {
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case .leading:
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layoutToAttribute = .leadingMargin
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case .trailing:
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layoutToAttribute = .trailingMargin
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case .top:
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layoutToAttribute = .topMargin
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case .bottom:
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layoutToAttribute = .bottomMargin
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default:
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fatalError()
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}
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} else if self.from.attributes == .directionalMargins && self.to.attributes == .directionalEdges {
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switch layoutFromAttribute {
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case .leadingMargin:
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layoutToAttribute = .leading
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case .trailingMargin:
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layoutToAttribute = .trailing
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case .topMargin:
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layoutToAttribute = .top
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case .bottomMargin:
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layoutToAttribute = .bottom
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default:
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fatalError()
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}
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} else if self.from.attributes == self.to.attributes {
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layoutToAttribute = layoutFromAttribute
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} else {
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layoutToAttribute = layoutToAttributes[0]
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}
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} else {
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if self.to.target == nil && (layoutFromAttribute == .centerX || layoutFromAttribute == .centerY) {
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layoutToAttribute = layoutFromAttribute == .centerX ? .left : .top
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} else {
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layoutToAttribute = layoutFromAttribute
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}
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}
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#else
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if self.from.attributes == self.to.attributes {
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layoutToAttribute = layoutFromAttribute
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} else if layoutToAttributes.count > 0 {
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layoutToAttribute = layoutToAttributes[0]
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} else {
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layoutToAttribute = layoutFromAttribute
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}
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#endif
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// get layout constant
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let layoutConstant: CGFloat = self.constant.constraintConstantTargetValueFor(layoutAttribute: layoutToAttribute)
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// get layout to
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var layoutTo: AnyObject? = self.to.target
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// use superview if possible
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if layoutTo == nil && layoutToAttribute != .width && layoutToAttribute != .height {
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layoutTo = layoutFrom.superview
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}
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// create layout constraint
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let layoutConstraint = LayoutConstraint(
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item: layoutFrom,
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attribute: layoutFromAttribute,
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relatedBy: layoutRelation,
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toItem: layoutTo,
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attribute: layoutToAttribute,
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multiplier: self.multiplier.constraintMultiplierTargetValue,
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constant: layoutConstant
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)
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// set label
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layoutConstraint.label = self.label
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// set priority
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layoutConstraint.priority = LayoutPriority(rawValue: self.priority.constraintPriorityTargetValue)
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// set constraint
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layoutConstraint.constraint = self
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// append
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self.layoutConstraints.append(layoutConstraint)
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}
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}
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// MARK: Public
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@available(*, deprecated, renamed:"activate()")
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public func install() {
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self.activate()
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}
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@available(*, deprecated, renamed:"deactivate()")
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public func uninstall() {
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self.deactivate()
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}
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public func activate() {
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self.activateIfNeeded()
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}
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public func deactivate() {
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self.deactivateIfNeeded()
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}
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@discardableResult
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public func update(offset: ConstraintOffsetTarget) -> Constraint {
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self.constant = offset.constraintOffsetTargetValue
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return self
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}
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@discardableResult
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public func update(inset: ConstraintInsetTarget) -> Constraint {
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self.constant = inset.constraintInsetTargetValue
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return self
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}
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#if canImport(UIKit)
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@discardableResult
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@available(iOS 11.0, tvOS 11.0, *)
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public func update(inset: ConstraintDirectionalInsetTarget) -> Constraint {
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self.constant = inset.constraintDirectionalInsetTargetValue
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return self
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}
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#endif
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@discardableResult
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public func update(priority: ConstraintPriorityTarget) -> Constraint {
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self.priority = priority.constraintPriorityTargetValue
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return self
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}
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@discardableResult
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public func update(priority: ConstraintPriority) -> Constraint {
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self.priority = priority.value
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return self
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}
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@available(*, deprecated, renamed:"update(offset:)")
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public func updateOffset(amount: ConstraintOffsetTarget) -> Void { self.update(offset: amount) }
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@available(*, deprecated, renamed:"update(inset:)")
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public func updateInsets(amount: ConstraintInsetTarget) -> Void { self.update(inset: amount) }
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@available(*, deprecated, renamed:"update(priority:)")
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public func updatePriority(amount: ConstraintPriorityTarget) -> Void { self.update(priority: amount) }
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@available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
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public func updatePriorityRequired() -> Void {}
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@available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
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public func updatePriorityHigh() -> Void { fatalError("Must be implemented by Concrete subclass.") }
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@available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
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public func updatePriorityMedium() -> Void { fatalError("Must be implemented by Concrete subclass.") }
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@available(*, deprecated, message:"Use update(priority: ConstraintPriorityTarget) instead.")
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public func updatePriorityLow() -> Void { fatalError("Must be implemented by Concrete subclass.") }
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// MARK: Internal
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internal func updateConstantAndPriorityIfNeeded() {
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for layoutConstraint in self.layoutConstraints {
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let attribute = (layoutConstraint.secondAttribute == .notAnAttribute) ? layoutConstraint.firstAttribute : layoutConstraint.secondAttribute
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layoutConstraint.constant = self.constant.constraintConstantTargetValueFor(layoutAttribute: attribute)
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let requiredPriority = ConstraintPriority.required.value
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if (layoutConstraint.priority.rawValue < requiredPriority), (self.priority.constraintPriorityTargetValue != requiredPriority) {
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layoutConstraint.priority = LayoutPriority(rawValue: self.priority.constraintPriorityTargetValue)
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}
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}
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}
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internal func activateIfNeeded(updatingExisting: Bool = false) {
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guard let item = self.from.layoutConstraintItem else {
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print("WARNING: SnapKit failed to get from item from constraint. Activate will be a no-op.")
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return
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}
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let layoutConstraints = self.layoutConstraints
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if updatingExisting {
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var existingLayoutConstraints: [LayoutConstraint] = []
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for constraint in item.constraints {
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existingLayoutConstraints += constraint.layoutConstraints
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}
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for layoutConstraint in layoutConstraints {
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let existingLayoutConstraint = existingLayoutConstraints.first { $0 == layoutConstraint }
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guard let updateLayoutConstraint = existingLayoutConstraint else {
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fatalError("Updated constraint could not find existing matching constraint to update: \(layoutConstraint)")
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}
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let updateLayoutAttribute = (updateLayoutConstraint.secondAttribute == .notAnAttribute) ? updateLayoutConstraint.firstAttribute : updateLayoutConstraint.secondAttribute
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updateLayoutConstraint.constant = self.constant.constraintConstantTargetValueFor(layoutAttribute: updateLayoutAttribute)
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}
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} else {
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NSLayoutConstraint.activate(layoutConstraints)
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item.add(constraints: [self])
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}
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}
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internal func deactivateIfNeeded() {
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guard let item = self.from.layoutConstraintItem else {
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print("WARNING: SnapKit failed to get from item from constraint. Deactivate will be a no-op.")
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return
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}
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let layoutConstraints = self.layoutConstraints
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NSLayoutConstraint.deactivate(layoutConstraints)
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item.remove(constraints: [self])
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}
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}
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