1 files changed, 37 insertions, 0 deletions
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/StringHelper.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/StringHelper.swift
new file mode 100644
index 0000000000..b7d3466bdd
--- /dev/null
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/StringHelper.swift
@@ -0,0 +1,37 @@
+fileprivate struct FfiConverterString: FfiConverter {
+    typealias SwiftType = String
+    typealias FfiType = RustBuffer
+
+    public static func lift(_ value: RustBuffer) throws -> String {
+        defer {
+            value.deallocate()
+        }
+        if value.data == nil {
+            return String()
+        }
+        let bytes = UnsafeBufferPointer<UInt8>(start: value.data!, count: Int(value.len))
+        return String(bytes: bytes, encoding: String.Encoding.utf8)!
+    }
+
+    public static func lower(_ value: String) -> RustBuffer {
+        return value.utf8CString.withUnsafeBufferPointer { ptr in
+            // The swift string gives us int8_t, we want uint8_t.
+            ptr.withMemoryRebound(to: UInt8.self) { ptr in
+                // The swift string gives us a trailing null byte, we don't want it.
+                let buf = UnsafeBufferPointer(rebasing: ptr.prefix(upTo: ptr.count - 1))
+                return RustBuffer.from(buf)
+            }
+        }
+    }
+
+    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> String {
+        let len: Int32 = try readInt(&buf)
+        return String(bytes: try readBytes(&buf, count: Int(len)), encoding: String.Encoding.utf8)!
+    }
+
+    public static func write(_ value: String, into buf: inout [UInt8]) {
+        let len = Int32(value.utf8.count)
+        writeInt(&buf, len)
+        writeBytes(&buf, value.utf8)
+    }
+}