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Diffstat (limited to 'third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift')
-rw-r--r-- | third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift new file mode 100644 index 0000000000..2f737b6635 --- /dev/null +++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift @@ -0,0 +1,183 @@ +fileprivate extension RustBuffer { + // Allocate a new buffer, copying the contents of a `UInt8` array. + init(bytes: [UInt8]) { + let rbuf = bytes.withUnsafeBufferPointer { ptr in + RustBuffer.from(ptr) + } + self.init(capacity: rbuf.capacity, len: rbuf.len, data: rbuf.data) + } + + static func from(_ ptr: UnsafeBufferPointer<UInt8>) -> RustBuffer { + try! rustCall { {{ ci.ffi_rustbuffer_from_bytes().name() }}(ForeignBytes(bufferPointer: ptr), $0) } + } + + // Frees the buffer in place. + // The buffer must not be used after this is called. + func deallocate() { + try! rustCall { {{ ci.ffi_rustbuffer_free().name() }}(self, $0) } + } +} + +fileprivate extension ForeignBytes { + init(bufferPointer: UnsafeBufferPointer<UInt8>) { + self.init(len: Int32(bufferPointer.count), data: bufferPointer.baseAddress) + } +} + +// For every type used in the interface, we provide helper methods for conveniently +// lifting and lowering that type from C-compatible data, and for reading and writing +// values of that type in a buffer. + +// Helper classes/extensions that don't change. +// Someday, this will be in a library of its own. + +fileprivate extension Data { + init(rustBuffer: RustBuffer) { + // TODO: This copies the buffer. Can we read directly from a + // Rust buffer? + self.init(bytes: rustBuffer.data!, count: Int(rustBuffer.len)) + } +} + +// Define reader functionality. Normally this would be defined in a class or +// struct, but we use standalone functions instead in order to make external +// types work. +// +// With external types, one swift source file needs to be able to call the read +// method on another source file's FfiConverter, but then what visibility +// should Reader have? +// - If Reader is fileprivate, then this means the read() must also +// be fileprivate, which doesn't work with external types. +// - If Reader is internal/public, we'll get compile errors since both source +// files will try define the same type. +// +// Instead, the read() method and these helper functions input a tuple of data + +fileprivate func createReader(data: Data) -> (data: Data, offset: Data.Index) { + (data: data, offset: 0) +} + +// Reads an integer at the current offset, in big-endian order, and advances +// the offset on success. Throws if reading the integer would move the +// offset past the end of the buffer. +fileprivate func readInt<T: FixedWidthInteger>(_ reader: inout (data: Data, offset: Data.Index)) throws -> T { + let range = reader.offset..<reader.offset + MemoryLayout<T>.size + guard reader.data.count >= range.upperBound else { + throw UniffiInternalError.bufferOverflow + } + if T.self == UInt8.self { + let value = reader.data[reader.offset] + reader.offset += 1 + return value as! T + } + var value: T = 0 + let _ = withUnsafeMutableBytes(of: &value, { reader.data.copyBytes(to: $0, from: range)}) + reader.offset = range.upperBound + return value.bigEndian +} + +// Reads an arbitrary number of bytes, to be used to read +// raw bytes, this is useful when lifting strings +fileprivate func readBytes(_ reader: inout (data: Data, offset: Data.Index), count: Int) throws -> Array<UInt8> { + let range = reader.offset..<(reader.offset+count) + guard reader.data.count >= range.upperBound else { + throw UniffiInternalError.bufferOverflow + } + var value = [UInt8](repeating: 0, count: count) + value.withUnsafeMutableBufferPointer({ buffer in + reader.data.copyBytes(to: buffer, from: range) + }) + reader.offset = range.upperBound + return value +} + +// Reads a float at the current offset. +fileprivate func readFloat(_ reader: inout (data: Data, offset: Data.Index)) throws -> Float { + return Float(bitPattern: try readInt(&reader)) +} + +// Reads a float at the current offset. +fileprivate func readDouble(_ reader: inout (data: Data, offset: Data.Index)) throws -> Double { + return Double(bitPattern: try readInt(&reader)) +} + +// Indicates if the offset has reached the end of the buffer. +fileprivate func hasRemaining(_ reader: (data: Data, offset: Data.Index)) -> Bool { + return reader.offset < reader.data.count +} + +// Define writer functionality. Normally this would be defined in a class or +// struct, but we use standalone functions instead in order to make external +// types work. See the above discussion on Readers for details. + +fileprivate func createWriter() -> [UInt8] { + return [] +} + +fileprivate func writeBytes<S>(_ writer: inout [UInt8], _ byteArr: S) where S: Sequence, S.Element == UInt8 { + writer.append(contentsOf: byteArr) +} + +// Writes an integer in big-endian order. +// +// Warning: make sure what you are trying to write +// is in the correct type! +fileprivate func writeInt<T: FixedWidthInteger>(_ writer: inout [UInt8], _ value: T) { + var value = value.bigEndian + withUnsafeBytes(of: &value) { writer.append(contentsOf: $0) } +} + +fileprivate func writeFloat(_ writer: inout [UInt8], _ value: Float) { + writeInt(&writer, value.bitPattern) +} + +fileprivate func writeDouble(_ writer: inout [UInt8], _ value: Double) { + writeInt(&writer, value.bitPattern) +} + +// Protocol for types that transfer other types across the FFI. This is +// analogous go the Rust trait of the same name. +fileprivate protocol FfiConverter { + associatedtype FfiType + associatedtype SwiftType + + static func lift(_ value: FfiType) throws -> SwiftType + static func lower(_ value: SwiftType) -> FfiType + static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> SwiftType + static func write(_ value: SwiftType, into buf: inout [UInt8]) +} + +// Types conforming to `Primitive` pass themselves directly over the FFI. +fileprivate protocol FfiConverterPrimitive: FfiConverter where FfiType == SwiftType { } + +extension FfiConverterPrimitive { + public static func lift(_ value: FfiType) throws -> SwiftType { + return value + } + + public static func lower(_ value: SwiftType) -> FfiType { + return value + } +} + +// Types conforming to `FfiConverterRustBuffer` lift and lower into a `RustBuffer`. +// Used for complex types where it's hard to write a custom lift/lower. +fileprivate protocol FfiConverterRustBuffer: FfiConverter where FfiType == RustBuffer {} + +extension FfiConverterRustBuffer { + public static func lift(_ buf: RustBuffer) throws -> SwiftType { + var reader = createReader(data: Data(rustBuffer: buf)) + let value = try read(from: &reader) + if hasRemaining(reader) { + throw UniffiInternalError.incompleteData + } + buf.deallocate() + return value + } + + public static func lower(_ value: SwiftType) -> RustBuffer { + var writer = createWriter() + write(value, into: &writer) + return RustBuffer(bytes: writer) + } +} |