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Merged
merged 4 commits into from
Sep 3, 2025
Merged

Add support for Void-returning database functions #155

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1c0f0c4
Allow for void returning database functions.
mbrandonw Sep 3, 2025
088e3dc
wip
stephencelis Sep 3, 2025
a6e0175
wip
stephencelis Sep 3, 2025
0eada18
fix
stephencelis Sep 3, 2025
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19 changes: 19 additions & 0 deletions Sources/StructuredQueriesSQLite/Macros.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -35,3 +35,22 @@ public macro DatabaseFunction<each T: QueryBindable, R: QueryBindable>(
module: "StructuredQueriesSQLiteMacros",
type: "DatabaseFunctionMacro"
)

/// Defines and implements a conformance to the ``/StructuredQueriesSQLiteCore/DatabaseFunction``
/// protocol.
///
/// - Parameters
/// - name: The function's name. Defaults to the name of the function the macro is applied to.
/// - representableFunctionType: The function as represented in a query.
/// - isDeterministic: Whether or not the function is deterministic (or "pure" or "referentially
/// transparent"), _i.e._ given an input it will always return the same output.
@attached(peer, names: overloaded, prefixed(`$`))
public macro DatabaseFunction<each T: QueryBindable>(
_ name: String = "",
as representableFunctionType: ((repeat each T) -> Void).Type,
isDeterministic: Bool = false
) =
#externalMacro(
module: "StructuredQueriesSQLiteMacros",
type: "DatabaseFunctionMacro"
)
68 changes: 25 additions & 43 deletions Sources/StructuredQueriesSQLiteMacros/DatabaseFunctionMacro.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -25,31 +25,11 @@ extension DatabaseFunctionMacro: PeerMacro {
return []
}

guard declaration.signature.returnClause != nil else {
context.diagnose(
Diagnostic(
node: declaration.signature,
position: declaration.signature.endPositionBeforeTrailingTrivia,
message: MacroExpansionErrorMessage(
"Missing required return type"
),
fixIt: .replace(
message: MacroExpansionFixItMessage("Insert '-> <#QueryBindable#>'"),
oldNode: declaration.signature,
newNode: declaration.signature.with(
\.returnClause,
ReturnClauseSyntax(
type: IdentifierTypeSyntax(name: "<#QueryBindable#>")
.with(\.leadingTrivia, .space)
.with(\.trailingTrivia, .space)
)
)
)
)
let returnClause =
declaration.signature.returnClause
?? ReturnClauseSyntax(
type: "Swift.Void" as TypeSyntax
)
return []
}

let declarationName = declaration.name.trimmedDescription.trimmingBackticks()
var functionName = declarationName
var functionRepresentation: FunctionTypeSyntax?
Expand Down Expand Up @@ -158,43 +138,45 @@ extension DatabaseFunctionMacro: PeerMacro {
argumentBindings.append((parameterName, "\(type)(queryBinding: arguments[\(offset)])"))
}
var inputType = bodyArguments.joined(separator: ", ")
let bodyReturnClause: String
let outputType: TypeSyntax
if let returnClause = signature.returnClause {
outputType = returnClause.type.trimmed
signature.returnClause?.type = (functionRepresentation?.returnClause ?? returnClause).type
.asQueryExpression()
bodyReturnClause = " \(returnClause.trimmedDescription)"
} else {
outputType = "Void"
bodyReturnClause = " -> Void"
}
let isVoidReturning = signature.returnClause == nil
let outputType = returnClause.type.trimmed
signature.returnClause = returnClause
signature.returnClause?.type = (functionRepresentation?.returnClause ?? returnClause).type
.asQueryExpression()
let bodyReturnClause = " \(returnClause.trimmedDescription)"
let bodyType = """
(\(inputType))\
\(declaration.signature.effectSpecifiers?.trimmedDescription ?? "")\
\(bodyReturnClause)
"""
let bodyInvocation = """
\(declaration.signature.effectSpecifiers?.throwsClause != nil ? "try " : "")self.body(\
\(argumentBindings.map { name, _ in "\(name).queryOutput" }.joined(separator: ", "))\
)
"""
// TODO: Diagnose 'asyncClause'?
signature.effectSpecifiers?.throwsClause = nil

var invocationBody = """
\(functionRepresentation?.returnClause.type ?? outputType)(
queryOutput: self.body(\
\(argumentBindings.map { name, _ in "\(name).queryOutput" }.joined(separator: ", "))\
)
var invocationBody =
isVoidReturning
? """
\(bodyInvocation)
return .null
"""
: """
return \(functionRepresentation?.returnClause.type ?? outputType)(
queryOutput: \(bodyInvocation)
)
.queryBinding
"""
if declaration.signature.effectSpecifiers?.throwsClause != nil {
invocationBody = """
do {
return try \(invocationBody)
\(invocationBody)
} catch {
return .invalid(error)
}
"""
} else {
invocationBody = "return \(invocationBody)"
}

var attributes = declaration.attributes
Expand Down
81 changes: 56 additions & 25 deletions Tests/StructuredQueriesMacrosTests/DatabaseFunctionMacroTests.swift
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Expand Up @@ -572,8 +572,8 @@ extension SnapshotTests {
return .invalid(InvalidInvocation())
}
do {
return try Date(
queryOutput: self.body()
return Date(
queryOutput: try self.body()
)
.queryBinding
} catch {
Expand Down Expand Up @@ -627,8 +627,8 @@ extension SnapshotTests {
return .invalid(InvalidInvocation())
}
do {
return try Date(
queryOutput: self.body()
return Date(
queryOutput: try self.body()
)
.queryBinding
} catch {
Expand Down Expand Up @@ -869,35 +869,64 @@ extension SnapshotTests {
}
}

@Test func returnTypeDiagnostic() {
@Test func voidReturnType() {
assertMacro {
"""
@DatabaseFunction
public func void() {
print("...")
}
"""
} diagnostics: {
"""
@DatabaseFunction
} expansion: {
#"""
public func void() {
──┬
╰─ 🛑 Missing required return type
✏️ Insert '-> <#QueryBindable#>'
print("...")
}
"""
} fixes: {

public var $void: __macro_local_4voidfMu_ {
__macro_local_4voidfMu_(void)
}

public struct __macro_local_4voidfMu_: StructuredQueriesSQLiteCore.ScalarDatabaseFunction {
public typealias Input = ()
public typealias Output = Swift.Void
public let name = "void"
public let argumentCount: Int? = 0
public let isDeterministic = false
public let body: () -> Swift.Void
public init(_ body: @escaping () -> Swift.Void) {
self.body = body
}
public func callAsFunction() -> some StructuredQueriesCore.QueryExpression<Swift.Void> {
StructuredQueriesCore.SQLQueryExpression(
"\(quote: self.name)()"
)
}
public func invoke(
_ arguments: [StructuredQueriesCore.QueryBinding]
) -> StructuredQueriesCore.QueryBinding {
guard self.argumentCount == nil || self.argumentCount == arguments.count else {
return .invalid(InvalidInvocation())
}
self.body()
return .null
}
private struct InvalidInvocation: Error {
}
}
"""#
}
assertMacro {
"""
@DatabaseFunction
public func void() -> <#QueryBindable#> {
print("...")
public func void() throws {
throw Failure()
}
"""
} expansion: {
#"""
public func void() -> <#QueryBindable#> {
print("...")
public func void() throws {
throw Failure()
}

public var $void: __macro_local_4voidfMu_ {
Expand All @@ -906,15 +935,15 @@ extension SnapshotTests {

public struct __macro_local_4voidfMu_: StructuredQueriesSQLiteCore.ScalarDatabaseFunction {
public typealias Input = ()
public typealias Output = <#QueryBindable#>
public typealias Output = Swift.Void
public let name = "void"
public let argumentCount: Int? = 0
public let isDeterministic = false
public let body: () -> <#QueryBindable#>
public init(_ body: @escaping () -> <#QueryBindable#>) {
public let body: () throws -> Swift.Void
public init(_ body: @escaping () throws -> Swift.Void) {
self.body = body
}
public func callAsFunction() -> some StructuredQueriesCore.QueryExpression<<#QueryBindable#>> {
public func callAsFunction() -> some StructuredQueriesCore.QueryExpression<Swift.Void> {
StructuredQueriesCore.SQLQueryExpression(
"\(quote: self.name)()"
)
Expand All @@ -925,10 +954,12 @@ extension SnapshotTests {
guard self.argumentCount == nil || self.argumentCount == arguments.count else {
return .invalid(InvalidInvocation())
}
return <#QueryBindable#>(
queryOutput: self.body()
)
.queryBinding
do {
try self.body()
return .null
} catch {
return .invalid(error)
}
}
private struct InvalidInvocation: Error {
}
Expand Down
40 changes: 31 additions & 9 deletions Tests/StructuredQueriesTests/DatabaseFunctionTests.swift
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Expand Up @@ -10,12 +10,13 @@ import _StructuredQueriesSQLite

extension SnapshotTests {
@Suite struct DatabaseFunctionTests {
@Dependency(\.defaultDatabase) var database

@DatabaseFunction
func isEnabled() -> Bool {
true
}
@Test func customIsEnabled() {
@Dependency(\.defaultDatabase) var database
$isEnabled.install(database.handle)
assertQuery(
Values($isEnabled())
Expand All @@ -37,7 +38,6 @@ extension SnapshotTests {
Date(timeIntervalSince1970: 0)
}
@Test func customDateTime() {
@Dependency(\.defaultDatabase) var database
$dateTime.install(database.handle)
assertQuery(
Values($dateTime())
Expand All @@ -59,7 +59,6 @@ extension SnapshotTests {
first + second
}
@Test func customConcat() {
@Dependency(\.defaultDatabase) var database
$concat.install(database.handle)
assertQuery(
Values($concat(first: "foo", second: "bar"))
Expand All @@ -77,7 +76,6 @@ extension SnapshotTests {
}

@Test func erasedConcat() {
@Dependency(\.defaultDatabase) var database
$concat.install(database.handle)
assertQuery(
Values($concat("foo", "bar"))
Expand All @@ -104,7 +102,6 @@ extension SnapshotTests {
throw Failure()
}
@Test func customThrowing() {
@Dependency(\.defaultDatabase) var database
$throwing.install(database.handle)
assertQuery(
Values($throwing())
Expand Down Expand Up @@ -132,7 +129,6 @@ extension SnapshotTests {
completion == .incomplete ? .completing : .incomplete
}
@Test func customToggle() {
@Dependency(\.defaultDatabase) var database
$toggle.install(database.handle)
assertQuery(
Values($toggle(Completion.incomplete))
Expand All @@ -155,7 +151,6 @@ extension SnapshotTests {
}

@Test func customRepresentation() {
@Dependency(\.defaultDatabase) var database
$jsonCapitalize.install(database.handle)
assertQuery(
Values($jsonCapitalize(#bind(["hello", "world"])))
Expand Down Expand Up @@ -184,7 +179,6 @@ extension SnapshotTests {
}

@Test func customMixedRepresentation() {
@Dependency(\.defaultDatabase) var database
$jsonDropFirst.install(database.handle)
assertQuery(
Values($jsonDropFirst(#bind(["hello", "world", "goodnight", "moon"]), 2))
Expand Down Expand Up @@ -215,7 +209,6 @@ extension SnapshotTests {
}

@Test func customNilRepresentation() {
@Dependency(\.defaultDatabase) var database
$jsonCount.install(database.handle)
assertQuery(
Values($jsonCount(#bind(["hello", "world", "goodnight", "moon"])))
Expand Down Expand Up @@ -249,5 +242,34 @@ extension SnapshotTests {
"""
}
}

final class Logger {
var messages: [String] = []

@DatabaseFunction
func log(_ message: String) {
messages.append(message)
}
}

@Test func voidState() {
let logger = Logger()
logger.$log.install(database.handle)

assertQuery(
Values(logger.$log("Hello, world!"))
) {
"""
SELECT "log"('Hello, world!')
"""
} results: {
"""
┌──┐
└──┘
"""
}

#expect(logger.messages == ["Hello, world!"])
}
}
}