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Merge pull request #7 from p-x9/feature/support-wiiset-and-didset
support `wiiSet` and `didSet`
2 parents 5057cc7 + db15991 commit bb10116

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4 files changed

+269
-29
lines changed

4 files changed

+269
-29
lines changed

‎README.md

+43
Original file line numberDiff line numberDiff line change
@@ -34,6 +34,49 @@ class ViewController: UIViewController {
3434

3535
}
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```
37+
### willSet/didSet
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Properties defined using `@AssociatedObject` can implement willSet and didSet.
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In swift, it is not possible to implement `willSet` and `didSet` at the same time as setter, so they are expanded as follows.
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```swift
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@AssociatedObject(.OBJC_ASSOCIATION_COPY_NONATOMIC)
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public var hello: String = "こんにちは" {
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didSet {
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print("didSet")
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}
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willSet {
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print("willSet: \(newValue)")
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}
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}
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// ↓↓↓ expand to ... ↓↓↓
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public var hello: String = "こんにちは" {
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get {
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objc_getAssociatedObject(
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self,
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&Self.__associated_helloKey
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) as? String
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?? "こんにちは"
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}
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set {
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let willSet: (String) -> Void = { newValue in
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print("willSet: \(newValue)")
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}
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willSet(newValue)
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objc_setAssociatedObject(
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self,
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&Self.__associated_helloKey,
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newValue,
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.OBJC_ASSOCIATION_COPY_NONATOMIC
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)
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let didSet = {
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print("didSet")
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}
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didSet()
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}
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}
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```
3780

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## License
3982
AssociatedObject is released under the MIT License. See [LICENSE](./LICENSE)

‎Sources/AssociatedObjectPlugin/AssociatedObjectMacro.swift

+56-23
Original file line numberDiff line numberDiff line change
@@ -65,9 +65,15 @@ extension AssociatedObjectMacro: AccessorMacro {
6565
return []
6666
}
6767

68-
// Error if accessor already exists
69-
if let accessor = binding.accessor {
70-
context.diagnose(AssociatedObjectMacroDiagnostic.accessorShouldBeNil.diagnose(at: accessor))
68+
// Error if setter already exists
69+
if let setter = binding.setter {
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context.diagnose(AssociatedObjectMacroDiagnostic.getterAndSetterShouldBeNil.diagnose(at: setter))
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return []
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}
73+
74+
// Error if getter already exists
75+
if let getter = binding.getter {
76+
context.diagnose(AssociatedObjectMacroDiagnostic.getterAndSetterShouldBeNil.diagnose(at: getter))
7177
return []
7278
}
7379

@@ -83,28 +89,55 @@ extension AssociatedObjectMacro: AccessorMacro {
8389
return []
8490
}
8591

86-
return [
87-
"""
88-
get {
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objc_getAssociatedObject(
90-
self,
91-
&Self.__associated_\(identifier)Key
92-
) as? \(type)
93-
?? \(defaultValue)
94-
}
95-
""",
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if let willSet = binding.willSet,
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let parameter = willSet.parameter,
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parameter.name.trimmed.text != "newValue" {
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context.diagnose(AssociatedObjectMacroDiagnostic.accessorParameterNameMustBeNewValue.diagnose(at: parameter))
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return []
97+
}
9698

97-
"""
99+
return [
100+
AccessorDeclSyntax(
101+
accessorKind: .keyword(.get),
102+
body: CodeBlockSyntax {
103+
"""
104+
objc_getAssociatedObject(
105+
self,
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&Self.__associated_\(identifier)Key
107+
) as? \(type)
108+
?? \(defaultValue)
109+
"""
110+
}
111+
),
98112

99-
set {
100-
objc_setAssociatedObject(
101-
self,
102-
&Self.__associated_\(identifier)Key,
103-
newValue,
104-
\(policy)
105-
)
106-
}
107-
"""
113+
AccessorDeclSyntax(
114+
accessorKind: .keyword(.set),
115+
body: CodeBlockSyntax {
116+
if let willSet = binding.willSet?.body {
117+
"""
118+
let willSet: (\(type.trimmed)) -> Void = { newValue in
119+
\(willSet.statements.trimmed)
120+
}
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willSet(newValue)
122+
"""
123+
}
124+
"""
125+
objc_setAssociatedObject(
126+
self,
127+
&Self.__associated_\(identifier)Key,
128+
newValue,
129+
\(policy)
130+
)
131+
"""
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if let didSet = binding.didSet?.body {
133+
"""
134+
let didSet = {
135+
\(didSet.statements.trimmed)
136+
}
137+
didSet()
138+
"""
139+
}
140+
})
108141
]
109142
}
110143
}

‎Sources/AssociatedObjectPlugin/AssociatedObjectMacroDiagnostic.swift

+9-6
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,8 @@ import SwiftDiagnostics
1111

1212
public enum AssociatedObjectMacroDiagnostic {
1313
case requiresVariableDeclaration
14-
case accessorShouldBeNil
14+
case getterAndSetterShouldBeNil
15+
case accessorParameterNameMustBeNewValue
1516
case requiresInitialValue
1617
case specifyTypeExplicitly
1718
}
@@ -24,13 +25,15 @@ extension AssociatedObjectMacroDiagnostic: DiagnosticMessage {
2425
public var message: String {
2526
switch self {
2627
case .requiresVariableDeclaration:
27-
return "`@AssociatedObject` must be appended to the property declaration."
28-
case .accessorShouldBeNil:
29-
return "`accessor should not be specified."
28+
return "`@AssociatedObject` must be attached to the property declaration."
29+
case .getterAndSetterShouldBeNil:
30+
return "getter and setter must not be implemented when using `@AssociatedObject`."
31+
case .accessorParameterNameMustBeNewValue:
32+
return "accessor parameter name must be `newValue` when using `@AssociatedObject`."
3033
case .requiresInitialValue:
31-
return "Initial values must be specified."
34+
return "Initial values must be specified when using `@AssociatedObject`."
3235
case .specifyTypeExplicitly:
33-
return "Specify a type explicitly"
36+
return "Specify a type explicitly when using `@AssociatedObject`."
3437
}
3538
}
3639

‎Sources/AssociatedObjectPlugin/Extension/PatternBindingSyntax+.swift

+161
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,161 @@
1+
//
2+
// PatternBindingSyntax+.swift
3+
//
4+
//
5+
// Created by p-x9 on 2023/06/17.
6+
//
7+
//
8+
9+
import Foundation
10+
import SwiftSyntax
11+
12+
extension PatternBindingSyntax {
13+
var setter: AccessorDeclSyntax? {
14+
get {
15+
if case let .accessors(list) = accessor {
16+
return list.accessors.first(where: {
17+
$0.accessorKind.tokenKind == .keyword(.set)
18+
})
19+
}
20+
return nil
21+
}
22+
23+
set {
24+
// NOTE: Be careful that setter cannot be implemented without a getter.
25+
setNewAccessor(kind: .keyword(.set), newValue: newValue)
26+
}
27+
}
28+
29+
var getter: AccessorDeclSyntax? {
30+
get {
31+
switch accessor {
32+
case let .accessors(list):
33+
return list.accessors.first(where: {
34+
$0.accessorKind.tokenKind == .keyword(.get)
35+
})
36+
case let .getter(body):
37+
return AccessorDeclSyntax(accessorKind: .keyword(.get), body: body)
38+
case .none:
39+
return nil
40+
}
41+
}
42+
43+
set {
44+
switch accessor {
45+
case .getter, .none:
46+
if let newValue {
47+
if let body = newValue.body {
48+
accessor = .getter(body)
49+
} else {
50+
let accessors = AccessorListSyntax {
51+
newValue
52+
}
53+
accessor = .accessors(.init(accessors: accessors))
54+
}
55+
} else {
56+
accessor = .none
57+
}
58+
59+
case let .accessors(block):
60+
var accessors = block.accessors
61+
for (i, accessor) in block.accessors.enumerated() {
62+
guard accessor.accessorKind.tokenKind == .keyword(.get) else {
63+
continue
64+
}
65+
if let newValue {
66+
accessors = accessors.replacing(childAt: i, with: newValue)
67+
} else {
68+
accessors = accessors.removing(childAt: i)
69+
}
70+
break
71+
}
72+
let newBlock = block.with(\.accessors, accessors)
73+
accessor = .accessors(newBlock)
74+
}
75+
}
76+
}
77+
78+
var isGetOnly: Bool {
79+
if initializer != nil {
80+
return false
81+
}
82+
if case let .accessors(list) = accessor,
83+
list.accessors.contains(where: { $0.accessorKind.tokenKind == .keyword(.set) }) {
84+
return false
85+
}
86+
if accessor == nil && initializer == nil {
87+
return false
88+
}
89+
return true
90+
}
91+
}
92+
93+
extension PatternBindingSyntax {
94+
var willSet: AccessorDeclSyntax? {
95+
get {
96+
if case let .accessors(list) = accessor {
97+
return list.accessors.first(where: {
98+
$0.accessorKind.tokenKind == .keyword(.willSet)
99+
})
100+
}
101+
return nil
102+
}
103+
set {
104+
// NOTE: Be careful that willSet cannot be implemented without a setter.
105+
setNewAccessor(kind: .keyword(.willSet), newValue: newValue)
106+
}
107+
}
108+
109+
var didSet: AccessorDeclSyntax? {
110+
get {
111+
if case let .accessors(list) = accessor {
112+
return list.accessors.first(where: {
113+
$0.accessorKind.tokenKind == .keyword(.didSet)
114+
})
115+
}
116+
return nil
117+
}
118+
set {
119+
// NOTE: Be careful that willSet cannot be implemented without a setter.
120+
setNewAccessor(kind: .keyword(.willSet), newValue: newValue)
121+
}
122+
}
123+
}
124+
125+
extension PatternBindingSyntax {
126+
// NOTE: - getter requires extra steps and should not be used.
127+
private mutating func setNewAccessor(kind: TokenKind, newValue: AccessorDeclSyntax?) {
128+
var newAccessor: Accessor?
129+
130+
switch accessor {
131+
case let .getter(body):
132+
guard let newValue else { return }
133+
newAccessor = .accessors(.init(accessors: AccessorListSyntax {
134+
AccessorDeclSyntax(accessorKind: .keyword(.get), body: body)
135+
newValue
136+
}))
137+
case let .accessors(block):
138+
var accessors = block.accessors
139+
for (i, accessor) in block.accessors.enumerated() {
140+
guard accessor.accessorKind.tokenKind == kind else {
141+
continue
142+
}
143+
if let newValue {
144+
accessors = accessors.replacing(childAt: i, with: newValue)
145+
} else {
146+
accessors = accessors.removing(childAt: i)
147+
}
148+
break
149+
}
150+
let newBlock = block.with(\.accessors, accessors)
151+
newAccessor = .accessors(newBlock)
152+
case .none:
153+
guard let newValue else { return }
154+
newAccessor = .accessors(.init(accessors: AccessorListSyntax {
155+
newValue
156+
}))
157+
}
158+
159+
self.accessor = newAccessor
160+
}
161+
}

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