FFMArraysTest.java

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2025 Apple Inc. and the Swift.org project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of Swift.org project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//

package com.example.swift;

import org.junit.jupiter.api.Test;
import org.swift.swiftkit.core.*;
import org.swift.swiftkit.ffm.*;

import static org.junit.jupiter.api.Assertions.*;

import java.lang.foreign.ValueLayout;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.IntStream;

public class FFMArraysTest {

    @Test
    void test_getArray() {
        // snippet.primitiveArraysUsage
        byte[] javaBytes = MySwiftLibrary.getArray(); // automatically converted [UInt8] to byte[]
        assertArrayEquals(new byte[]{1, 2, 3}, javaBytes);
        // snippet.end
    }

    @Test
    void test_sumAllByteArrayElements_arrayCopy() {
        byte[] bytes = new byte[124];
        Arrays.fill(bytes, (byte) 1);

        var swiftSideSum = MySwiftLibrary.sumAllByteArrayElements(bytes);

        int javaSideSum = IntStream.range(0, bytes.length).map(i -> bytes[i]).sum();
        assertEquals(javaSideSum, swiftSideSum);
    }

    @Test
    void test_sumAllByteArrayElements_throughMemorySegment() {
        byte[] bytes =  new byte[124];
        Arrays.fill(bytes, (byte) 1);

        try (var arena = AllocatingSwiftArena.ofConfined()) {
            // NOTE: We cannot use MemorySegment.ofArray because that creates a HEAP backed segment and therefore cannot pass into native:
            //         java.lang.IllegalArgumentException: Heap segment not allowed: MemorySegment{ kind: heap, heapBase: [B@5b6ec132, address: 0x0, byteSize: 124 }
            //            MemorySegment bytesSegment = MemorySegment.ofArray(bytes); // NO COPY (!)
            //            MySwiftLibrary.sumAllByteArrayElements(bytesSegment, bytes.length);

            var bytesCopy = arena.allocateFrom(ValueLayout.JAVA_BYTE, bytes);
            var swiftSideSum = MySwiftLibrary.sumAllByteArrayElements(bytesCopy, bytes.length);

            int javaSideSum = IntStream.range(0, bytes.length).map(i -> bytes[i]).sum();
            assertEquals(javaSideSum, swiftSideSum);
        }
    }
}