249 lines
10 KiB
Swift
249 lines
10 KiB
Swift
// A public import: `addFunction(_:name:)` and `pushFunction(_:)` expose the
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// `CFunction` alias of `lua_CFunction` in their public signatures.
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internal import CPlaydate
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/// The cached `playdate->lua` C API table.
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var luaAPI: UnsafePointer<playdate_lua> { Playdate.luaAPI.unsafelyUnwrapped }
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/// The Lua bridge: registering C functions and classes, and exchanging
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/// values with Lua code.
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///
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/// Lua callbacks are C function pointers without userdata, so functions
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/// registered here must be `@convention(c)` (the `CFunction` typealias),
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/// not capturing closures.
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public enum Lua {}
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extension Lua {
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/// Buffers passed to `registerClass`/`addFunction`; the OS may keep
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/// referencing them, so they are retained for the life of the game.
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nonisolated(unsafe) private static var retainedBuffers: [UnsafeMutableRawPointer] = []
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private static func retainedCString(_ string: String) -> UnsafePointer<CChar> {
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let copy = string.copiedPlaydateCString()
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retainedBuffers.append(UnsafeMutableRawPointer(copy))
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return UnsafePointer(copy)
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}
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// MARK: - Registration
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/// Makes `function` callable from Lua as `name` (which may contain dots
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/// for namespacing, e.g. "mylib.myfunc").
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public static func addFunction(_ function: CFunction, name: String) throws(PlaydateError) {
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var error: UnsafePointer<CChar>?
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let ok = name.withPlaydateCString {
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luaAPI.pointee.addFunction.unsafelyUnwrapped(function, $0, &error) != 0
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}
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if !ok { throw PlaydateError(cString: error) }
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}
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/// Registers a Lua class named `name` with the given methods and
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/// constants. When `isStatic` is `true` a plain table of functions is
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/// created instead of a class.
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public static func registerClass(name: String,
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functions: [(name: String, function: CFunction)],
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values: [ClassValue] = [],
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isStatic: Bool = false) throws(PlaydateError) {
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// The registration tables are kept alive permanently: the OS
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// documents no copying guarantees for them.
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var registrations: [lua_reg] = functions.map { entry in
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lua_reg(name: retainedCString(entry.name), func: entry.function)
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}
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registrations.append(lua_reg(name: nil, func: nil))
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var constants: [lua_val] = values.map { value in
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switch value {
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case .int(let name, let intValue):
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return lua_val(name: retainedCString(name), type: kInt, v: .init(intval: intValue))
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case .float(let name, let floatValue):
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return lua_val(name: retainedCString(name), type: kFloat, v: .init(floatval: floatValue))
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case .string(let name, let stringValue):
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return lua_val(name: retainedCString(name), type: kStr,
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v: .init(strval: retainedCString(stringValue)))
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}
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}
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constants.append(lua_val(name: nil, type: kInt, v: .init(intval: 0)))
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let registrationsBuffer = UnsafeMutablePointer<lua_reg>.allocate(capacity: registrations.count)
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registrationsBuffer.initialize(from: registrations, count: registrations.count)
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retainedBuffers.append(UnsafeMutableRawPointer(registrationsBuffer))
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let constantsBuffer = UnsafeMutablePointer<lua_val>.allocate(capacity: constants.count)
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constantsBuffer.initialize(from: constants, count: constants.count)
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retainedBuffers.append(UnsafeMutableRawPointer(constantsBuffer))
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var error: UnsafePointer<CChar>?
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let ok = name.withPlaydateCString {
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luaAPI.pointee.registerClass.unsafelyUnwrapped($0, registrationsBuffer,
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values.isEmpty ? nil : constantsBuffer,
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isStatic ? 1 : 0, &error) != 0
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}
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if !ok { throw PlaydateError(cString: error) }
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}
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/// Pushes a function onto the stack, e.g. for `setUserValue`.
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public static func pushFunction(_ function: CFunction) {
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luaAPI.pointee.pushFunction.unsafelyUnwrapped(function)
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}
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/// From a class's `__index` callback: looks up the key in the instance
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/// metatable first. Returns 1 if a value was found.
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public static func indexMetatable() -> Bool {
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luaAPI.pointee.indexMetatable.unsafelyUnwrapped() != 0
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}
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/// Pauses the Lua runtime.
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public static func stop() {
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luaAPI.pointee.stop.unsafelyUnwrapped()
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}
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/// Resumes the Lua runtime.
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public static func start() {
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luaAPI.pointee.start.unsafelyUnwrapped()
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}
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// MARK: - Arguments
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/// The number of arguments the Lua caller passed. Positions are 1-based.
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public static var argumentCount: Int {
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Int(luaAPI.pointee.getArgCount.unsafelyUnwrapped())
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}
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/// The type of the argument at 1-based `position`; for objects, also the
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/// class name.
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public static func argumentType(at position: Int) -> (kind: Kind, className: String?) {
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var className: UnsafePointer<CChar>?
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let type = luaAPI.pointee.getArgType.unsafelyUnwrapped(Int32(position), &className)
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return (Kind(type), String(playdateCString: className))
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}
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public static func argumentIsNil(at position: Int) -> Bool {
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luaAPI.pointee.argIsNil.unsafelyUnwrapped(Int32(position)) != 0
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}
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public static func boolArgument(at position: Int) -> Bool {
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luaAPI.pointee.getArgBool.unsafelyUnwrapped(Int32(position)) != 0
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}
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public static func intArgument(at position: Int) -> Int {
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Int(luaAPI.pointee.getArgInt.unsafelyUnwrapped(Int32(position)))
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}
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public static func floatArgument(at position: Int) -> Float {
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luaAPI.pointee.getArgFloat.unsafelyUnwrapped(Int32(position))
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}
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public static func stringArgument(at position: Int) -> String? {
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String(playdateCString: luaAPI.pointee.getArgString.unsafelyUnwrapped(Int32(position)))
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}
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/// The argument as raw bytes (which may contain embedded zeros).
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public static func bytesArgument(at position: Int) -> [UInt8]? {
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var length = 0
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guard let bytes = luaAPI.pointee.getArgBytes.unsafelyUnwrapped(Int32(position), &length) else {
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return nil
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}
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let buffer = UnsafeRawBufferPointer(start: bytes, count: length)
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return [UInt8](buffer)
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}
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/// The argument as an object instance of class `type`, with the
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/// `UDObject` handle for retaining it.
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public static func objectArgument(at position: Int, type: String)
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-> (object: UnsafeMutableRawPointer?, userdataObject: UDObject?) {
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var userdataObject: OpaquePointer?
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// The C API takes a non-const class name but only reads it, so the
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// stack copy can be passed with a mutating cast.
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let object = type.withPlaydateCString { cType in
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luaAPI.pointee.getArgObject.unsafelyUnwrapped(
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Int32(position), UnsafeMutablePointer(mutating: cType), &userdataObject)
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}
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return (object, userdataObject.map { UDObject(pointer: $0) })
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}
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/// The argument as a bitmap. References an object owned by Lua; retain
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/// the Lua value while using it.
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public static func bitmapArgument(at position: Int) -> Graphics.Bitmap? {
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guard let bitmap = luaAPI.pointee.getBitmap.unsafelyUnwrapped(Int32(position)) else { return nil }
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return Graphics.Bitmap(pointer: bitmap, isOwned: false)
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}
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/// The argument as a sprite.
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public static func spriteArgument(at position: Int) -> Sprite? {
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guard let sprite = luaAPI.pointee.getSprite.unsafelyUnwrapped(Int32(position)) else { return nil }
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return Sprite.wrapper(for: sprite)
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}
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// MARK: - Return values
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/// Pushes nil onto the stack.
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public static func pushNil() {
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luaAPI.pointee.pushNil.unsafelyUnwrapped()
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}
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/// Pushes a boolean onto the stack.
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public static func push(_ value: Bool) {
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luaAPI.pointee.pushBool.unsafelyUnwrapped(value ? 1 : 0)
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}
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/// Pushes an integer onto the stack.
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public static func push(_ value: Int) {
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luaAPI.pointee.pushInt.unsafelyUnwrapped(Int32(value))
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}
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/// Pushes a float onto the stack.
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public static func push(_ value: Float) {
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luaAPI.pointee.pushFloat.unsafelyUnwrapped(value)
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}
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/// Pushes a string onto the stack.
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public static func push(_ value: String) {
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value.withPlaydateCString { luaAPI.pointee.pushString.unsafelyUnwrapped($0) }
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}
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/// Pushes raw bytes (which may contain embedded zeros) onto the stack
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/// as a Lua string.
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public static func push(bytes: [UInt8]) {
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bytes.withUnsafeBytes { buffer in
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luaAPI.pointee.pushBytes.unsafelyUnwrapped(
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buffer.baseAddress?.assumingMemoryBound(to: CChar.self), buffer.count)
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}
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}
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/// Pushes a bitmap onto the stack.
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public static func push(_ bitmap: Graphics.Bitmap) {
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luaAPI.pointee.pushBitmap.unsafelyUnwrapped(bitmap.pointer)
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}
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/// Pushes a sprite onto the stack.
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public static func push(_ sprite: Sprite) {
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luaAPI.pointee.pushSprite.unsafelyUnwrapped(sprite.pointer)
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}
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/// Wraps `object` in a Lua instance of class `type` and pushes it, with
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/// `valueCount` extra user-value slots.
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@discardableResult
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public static func pushObject(_ object: UnsafeMutableRawPointer, type: String,
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valueCount: Int = 0) -> UDObject? {
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// The C API takes a non-const class name but only reads it, so the
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// stack copy can be passed with a mutating cast.
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let pointer = type.withPlaydateCString { cType in
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luaAPI.pointee.pushObject.unsafelyUnwrapped(
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object, UnsafeMutablePointer(mutating: cType), Int32(valueCount))
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}
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guard let pointer else { return nil }
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return UDObject(pointer: pointer)
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}
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// MARK: - Calling Lua
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/// Calls the Lua function `name`. Push the arguments onto the stack
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/// first. Calling Lua from Swift has overhead; use sparingly.
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public static func callFunction(_ name: String, argumentCount: Int = 0) throws(PlaydateError) {
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var error: UnsafePointer<CChar>?
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let ok = name.withPlaydateCString {
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luaAPI.pointee.callFunction.unsafelyUnwrapped($0, Int32(argumentCount), &error) != 0
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}
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if !ok { throw PlaydateError(cString: error) }
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}
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}
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