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MatejkobMatejkob
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Move macro examples code to repo as-is
- Code was sourced from Doug's repo and moved without any alterations except for formatting changes. - Original target names have been updated to more descriptive ones. - References in macros to target names have been updated accordingly.
1 parent 1060677 commit 3c160b9

25 files changed

+2338
-1
lines changed

‎Examples/Package.swift

Lines changed: 33 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
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// swift-tools-version: 5.7
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// swift-tools-version: 5.9
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33
import PackageDescription
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import CompilerPluginSupport
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let package = Package(
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name: "Examples",
@@ -38,6 +39,37 @@ let package = Package(
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.product(name: "SwiftDiagnostics", package: "swift-syntax"),
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]
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),
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.macro(
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name: "MacroExamplesImplementation",
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dependencies: [
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.product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
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.product(name: "SwiftSyntax", package: "swift-syntax"),
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.product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
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.product(name: "SwiftDiagnostics", package: "swift-syntax"),
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],
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path: "Sources/MacroExamples/Implementation"
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),
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.target(
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name: "MacroExamplesInterface",
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dependencies: [
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"MacroExamplesImplementation"
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],
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path: "Sources/MacroExamples/Interface"
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),
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.executableTarget(
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name: "MacroExamplesPlayground",
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dependencies: [
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"MacroExamplesInterface"
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],
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path: "Sources/MacroExamples/Playground"
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),
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.testTarget(
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name: "MacroExamplesImplementationTests",
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dependencies: [
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"MacroExamplesImplementation"
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],
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path: "Tests/MacroExamples/Implementation"
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),
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]
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)
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‎Examples/Sources/MacroExamples/Implementation/AddAsyncMacro.swift

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,161 @@
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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftSyntax
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import SwiftSyntaxMacros
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extension SyntaxCollection {
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mutating func removeLast() {
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self.remove(at: self.index(before: self.endIndex))
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}
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}
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public struct AddAsyncMacro: PeerMacro {
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public static func expansion<
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Context: MacroExpansionContext,
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Declaration: DeclSyntaxProtocol
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>(
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of node: AttributeSyntax,
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providingPeersOf declaration: Declaration,
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in context: Context
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) throws -> [DeclSyntax] {
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// Only on functions at the moment.
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guard let funcDecl = declaration.as(FunctionDeclSyntax.self) else {
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throw CustomError.message("@addAsync only works on functions")
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}
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// This only makes sense for non async functions.
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if funcDecl.signature.effectSpecifiers?.asyncSpecifier != nil {
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throw CustomError.message(
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"@addAsync requires an non async function"
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)
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}
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// This only makes sense void functions
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if funcDecl.signature.returnClause?.type.with(\.leadingTrivia, []).with(\.trailingTrivia, []).description != "Void" {
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throw CustomError.message(
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"@addAsync requires an function that returns void"
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)
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}
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// Requires a completion handler block as last parameter
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guard let completionHandlerParameterAttribute = funcDecl.signature.parameterClause.parameters.last?.type.as(AttributedTypeSyntax.self),
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let completionHandlerParameter = completionHandlerParameterAttribute.baseType.as(FunctionTypeSyntax.self)
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else {
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throw CustomError.message(
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"@addAsync requires an function that has a completion handler as last parameter"
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)
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}
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// Completion handler needs to return Void
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if completionHandlerParameter.returnClause.type.with(\.leadingTrivia, []).with(\.trailingTrivia, []).description != "Void" {
62+
throw CustomError.message(
63+
"@addAsync requires an function that has a completion handler that returns Void"
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)
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}
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let returnType = completionHandlerParameter.parameters.first?.type
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let isResultReturn = returnType?.children(viewMode: .all).first?.description == "Result"
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let successReturnType = isResultReturn ? returnType!.as(IdentifierTypeSyntax.self)!.genericArgumentClause?.arguments.first!.argument : returnType
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// Remove completionHandler and comma from the previous parameter
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var newParameterList = funcDecl.signature.parameterClause.parameters
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newParameterList.removeLast()
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let newParameterListLastParameter = newParameterList.last!
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newParameterList.removeLast()
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newParameterList.append(newParameterListLastParameter.with(\.trailingTrivia, []).with(\.trailingComma, nil))
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// Drop the @addAsync attribute from the new declaration.
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let newAttributeList = AttributeListSyntax(
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funcDecl.attributes?.filter {
82+
guard case let .attribute(attribute) = $0,
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let attributeType = attribute.attributeName.as(IdentifierTypeSyntax.self),
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let nodeType = node.attributeName.as(IdentifierTypeSyntax.self)
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else {
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return true
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}
88+
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return attributeType.name.text != nodeType.name.text
90+
} ?? []
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)
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let callArguments: [String] = newParameterList.map { param in
94+
let argName = param.secondName ?? param.firstName
95+
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let paramName = param.firstName
97+
if paramName.text != "_" {
98+
return "\(paramName.text): \(argName.text)"
99+
}
100+
101+
return "\(argName.text)"
102+
}
103+
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let switchBody: ExprSyntax =
105+
"""
106+
switch returnValue {
107+
case .success(let value):
108+
continuation.resume(returning: value)
109+
case .failure(let error):
110+
continuation.resume(throwing: error)
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}
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"""
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let newBody: ExprSyntax =
115+
"""
116+
117+
\(isResultReturn ? "try await withCheckedThrowingContinuation { continuation in" : "await withCheckedContinuation { continuation in")
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\(funcDecl.name)(\(raw: callArguments.joined(separator: ", "))) { \(returnType != nil ? "returnValue in" : "")
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\(isResultReturn ? switchBody : "continuation.resume(returning: \(returnType != nil ? "returnValue" : "()"))")
121+
122+
}
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}
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"""
126+
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let newFunc =
128+
funcDecl
129+
.with(
130+
\.signature,
131+
funcDecl.signature
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.with(
133+
\.effectSpecifiers,
134+
FunctionEffectSpecifiersSyntax(leadingTrivia: .space, asyncSpecifier: "async", throwsSpecifier: isResultReturn ? " throws" : nil) // add async
135+
)
136+
.with(
137+
\.returnClause,
138+
successReturnType != nil ? ReturnClauseSyntax(leadingTrivia: .space, type: successReturnType!.with(\.leadingTrivia, .space)) : nil
139+
) // add result type
140+
.with(
141+
\.parameterClause,
142+
funcDecl.signature.parameterClause.with(\.parameters, newParameterList) // drop completion handler
143+
.with(\.trailingTrivia, [])
144+
)
145+
)
146+
.with(
147+
\.body,
148+
CodeBlockSyntax(
149+
leftBrace: .leftBraceToken(leadingTrivia: .space),
150+
statements: CodeBlockItemListSyntax(
151+
[CodeBlockItemSyntax(item: .expr(newBody))]
152+
),
153+
rightBrace: .rightBraceToken(leadingTrivia: .newline)
154+
)
155+
)
156+
.with(\.attributes, newAttributeList)
157+
.with(\.leadingTrivia, .newlines(2))
158+
159+
return [DeclSyntax(newFunc)]
160+
}
161+
}

‎Examples/Sources/MacroExamples/Implementation/AddBlocker.swift

Lines changed: 106 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,106 @@
1+
//===----------------------------------------------------------------------===//
2+
//
3+
// This source file is part of the Swift.org open source project
4+
//
5+
// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
6+
// Licensed under Apache License v2.0 with Runtime Library Exception
7+
//
8+
// See https://swift.org/LICENSE.txt for license information
9+
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
10+
//
11+
//===----------------------------------------------------------------------===//
12+
13+
import SwiftSyntaxMacros
14+
import SwiftSyntax
15+
import SwiftOperators
16+
import SwiftDiagnostics
17+
18+
/// Implementation of the `addBlocker` macro, which demonstrates how to
19+
/// produce detailed diagnostics from a macro implementation for an utterly
20+
/// silly task: warning about every "add" (binary +) in the argument, with a
21+
/// Fix-It that changes it to a "-".
22+
public struct AddBlocker: ExpressionMacro {
23+
class AddVisitor: SyntaxRewriter {
24+
var diagnostics: [Diagnostic] = []
25+
26+
override func visit(
27+
_ node: InfixOperatorExprSyntax
28+
) -> ExprSyntax {
29+
// Identify any infix operator + in the tree.
30+
if let binOp = node.operator.as(BinaryOperatorExprSyntax.self) {
31+
if binOp.operator.text == "+" {
32+
// Form the warning
33+
let messageID = MessageID(domain: "silly", id: "addblock")
34+
diagnostics.append(
35+
Diagnostic(
36+
// Where the warning should go (on the "+").
37+
node: Syntax(node.operator),
38+
// The warning message and severity.
39+
message: SimpleDiagnosticMessage(
40+
message: "blocked an add; did you mean to subtract?",
41+
diagnosticID: messageID,
42+
severity: .warning
43+
),
44+
// Highlight the left and right sides of the `+`.
45+
highlights: [
46+
Syntax(node.leftOperand),
47+
Syntax(node.rightOperand),
48+
],
49+
fixIts: [
50+
// Fix-It to replace the '+' with a '-'.
51+
FixIt(
52+
message: SimpleDiagnosticMessage(
53+
message: "use '-'",
54+
diagnosticID: messageID,
55+
severity: .error
56+
),
57+
changes: [
58+
FixIt.Change.replace(
59+
oldNode: Syntax(binOp.operator),
60+
newNode: Syntax(
61+
TokenSyntax(
62+
.binaryOperator("-"),
63+
leadingTrivia: binOp.operator.leadingTrivia,
64+
trailingTrivia: binOp.operator.trailingTrivia,
65+
presence: .present
66+
)
67+
)
68+
)
69+
]
70+
)
71+
]
72+
)
73+
)
74+
75+
return ExprSyntax(
76+
node.with(
77+
\.operator,
78+
ExprSyntax(
79+
binOp.with(
80+
\.operator,
81+
binOp.operator.with(\.tokenKind, .binaryOperator("-"))
82+
)
83+
)
84+
)
85+
)
86+
}
87+
}
88+
89+
return ExprSyntax(node)
90+
}
91+
}
92+
93+
public static func expansion(
94+
of node: some FreestandingMacroExpansionSyntax,
95+
in context: some MacroExpansionContext
96+
) throws -> ExprSyntax {
97+
let visitor = AddVisitor()
98+
let result = visitor.rewrite(Syntax(node))
99+
100+
for diag in visitor.diagnostics {
101+
context.diagnose(diag)
102+
}
103+
104+
return result.asProtocol(FreestandingMacroExpansionSyntax.self)!.argumentList.first!.expression
105+
}
106+
}

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