50 lines
1.8 KiB
Swift
50 lines
1.8 KiB
Swift
 
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//
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// Support.swift
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// Internal helpers shared by the wrappers.
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//
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// C-string conversions are implemented manually (rather than with
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// `String(cString:)` / `withCString`) so the module stays within the
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// Embedded Swift subset used for device builds.
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//
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internal import CPlaydate
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extension String {
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/// Creates a string by copying a null-terminated UTF-8 C string.
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init(playdateCString pointer: UnsafePointer<CChar>) {
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var count = 0
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while pointer[count] != 0 { count += 1 }
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let bytes = UnsafeRawBufferPointer(start: pointer, count: count)
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self = String(decoding: bytes, as: UTF8.self)
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}
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/// Creates a string from a nullable C string, or `nil` if the pointer is null.
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init?(playdateCString pointer: UnsafePointer<CChar>?) {
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guard let pointer else { return nil }
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self.init(playdateCString: pointer)
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}
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/// Calls `body` with a temporary null-terminated UTF-8 copy of the string.
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func withPlaydateCString<Result>(_ body: (UnsafePointer<CChar>) -> Result) -> Result {
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var utf8 = ContiguousArray(self.utf8)
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utf8.append(0)
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return utf8.withUnsafeBufferPointer { buffer in
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buffer.withMemoryRebound(to: CChar.self) { rebound in
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body(rebound.baseAddress.unsafelyUnwrapped)
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}
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}
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}
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/// Copies the string into a newly allocated null-terminated C string.
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/// The caller owns the memory and must free it with `deallocate()`.
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func copiedPlaydateCString() -> UnsafeMutablePointer<CChar> {
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let utf8 = ContiguousArray(self.utf8)
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let buffer = UnsafeMutablePointer<CChar>.allocate(capacity: utf8.count + 1)
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for (index, byte) in utf8.enumerated() {
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buffer[index] = CChar(bitPattern: byte)
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}
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buffer[utf8.count] = 0
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return buffer
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}
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}
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