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import SwiftSyntax
import SwiftSyntaxBuilder
import SwiftSyntaxMacros
/// Implementation of the `#fontLiteral` macro, which is similar in spirit
/// to the built-in expressions `#colorLiteral`, `#imageLiteral`, etc., but in
/// a small macro.
public struct FontLiteralMacro: ExpressionMacro {
public static func expansion(
of macro: some FreestandingMacroExpansionSyntax,
in context: some MacroExpansionContext
) -> ExprSyntax {
let argList = replaceFirstLabel(
of: macro.argumentList,
with: "fontLiteralName"
)
let initSyntax: ExprSyntax = ".init(\(argList))"
if let leadingTrivia = macro.leadingTrivia {
return initSyntax.with(\.leadingTrivia, leadingTrivia)
}
return initSyntax
}
}
/// Replace the label of the first element in the tuple with the given
/// new label.
private func replaceFirstLabel(
of tuple: TupleExprElementListSyntax,
with newLabel: String
) -> TupleExprElementListSyntax {
guard let firstElement = tuple.first else {
return tuple
}
return tuple.replacing(
childAt: 0,
with: firstElement.with(\.label, .identifier(newLabel))
)
}
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