feat: add swift from go

swift-from-go/Package.swift

@@ -0,0 +1,29 @@
+// swift-tools-version:4.2
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "go-swift",
+    products: [
+        // Products define the executables and libraries produced by a package, and make them visible to other packages.
+        .library(
+            name: "go_swift",
+            type: .dynamic,
+            targets: ["go-swift"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
+        .target(
+            name: "go-swift",
+            dependencies: []),
+        .testTarget(
+            name: "go-swiftTests",
+            dependencies: ["go-swift"]),
+    ]
+)

swift-from-go/README.md

@@ -0,0 +1,15 @@
+# go-swift
+
+> Clone from: https://github.com/onderweg/swift-from-go
+
+Example code, complementing the blog post: ["Calling Swift from Go"](https://dev.to/gerwert/calling-swift-from-go-5dbk)
+
+_Note: this repo is more than 3 years old. Feel free to use it as reference, but don't expect it to work with current versions of Go and Swift._
+
+## Building & Running
+
+```
+$ swift build
+$ go build -o hello
+$ ./hello
+```

swift-from-go/Sources/go-swift/go_swift.swift

@@ -0,0 +1,7 @@
+@_cdecl("sayHello") // export to C as `sayHello``
+public func sayHello(namePtr: UnsafePointer<CChar>?) {    
+    // Creates a new string by copying the null-terminated UTF-8 data (C String) 
+    // referenced by the given pointer.
+    let name = String(cString: namePtr!)
+    print("Welcome, \(name)!")
+}

swift-from-go/Tests/LinuxMain.swift

@@ -0,0 +1,7 @@
+import XCTest
+
+import go_swiftTests
+
+var tests = [XCTestCaseEntry]()
+tests += go_swiftTests.allTests()
+XCTMain(tests)

swift-from-go/Tests/go-swiftTests/XCTestManifests.swift

@@ -0,0 +1,9 @@
+import XCTest
+
+#if !os(macOS)
+public func allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(go_swiftTests.allTests),
+    ]
+}
+#endif

swift-from-go/Tests/go-swiftTests/go_swiftTests.swift

@@ -0,0 +1,15 @@
+import XCTest
+@testable import go_swift
+
+final class go_swiftTests: XCTestCase {
+    func testExample() {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct
+        // results.
+        XCTAssertEqual(go_swift().text, "Hello, World!")
+    }
+
+    static var allTests = [
+        ("testExample", testExample),
+    ]
+}

swift-from-go/include/go_swift.h

@@ -0,0 +1,2 @@
+// Manually crafted header file for C Library
+void sayHello(char* name);

swift-from-go/main.go

@@ -0,0 +1,22 @@
+package main
+
+/*
+#cgo CFLAGS: -I./include
+#cgo LDFLAGS: -L.build/debug/ -lgo_swift
+#include <stdlib.h>
+#include "include/go_swift.h"
+*/
+import "C"
+import "unsafe"
+
+func main() {
+	// Convert Go string to C string
+	cstr := C.CString("Bob")
+
+	// Call Swift function `sayHello``
+	C.sayHello(cstr)
+
+	// The C string is allocated in the C heap using malloc.
+	// Therefore memory must be freed when we're done
+	C.free(unsafe.Pointer(cstr))
+}