subtypes.js - mozsearch

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// |jit-test| skip-if: !this.SharedArrayBuffer

// Test cases for subclasses of SharedArrayBuffer.

load(libdir + "asserts.js");

// Basic subclassing.

class MySharedArrayBuffer1 extends SharedArrayBuffer {

    constructor(n) { super(n) }

let mv1 = new MySharedArrayBuffer1(1024);

assertEq(mv1 instanceof SharedArrayBuffer, true);

assertEq(mv1 instanceof MySharedArrayBuffer1, true);

assertEq(mv1.byteLength, 1024);

// Can construct views on the subclasses and read/write elements.

let mva1 = new Int8Array(mv1);

assertEq(mva1.length, mv1.byteLength);

assertEq(mva1.buffer, mv1);

for ( let i=1 ; i < mva1.length ; i++ )

    mva1[i] = i;

for ( let i=1 ; i < mva1.length ; i++ )

    assertEq(mva1[i], (i << 24) >> 24);

// Passing modified arguments to superclass to get a different length.

class MySharedArrayBuffer2 extends SharedArrayBuffer {

    constructor(n) { super(n-1) }

let mv2 = new MySharedArrayBuffer2(10);

assertEq(mv2 instanceof SharedArrayBuffer, true);

assertEq(mv2 instanceof MySharedArrayBuffer2, true);

assertEq(mv2.byteLength, 9);

// Returning a different object altogether.

class MySharedArrayBuffer3 extends SharedArrayBuffer {

    constructor(n) {

	return new Array(n);

let mv3 = new MySharedArrayBuffer3(10);

assertEq(mv3 instanceof Array, true);

assertEq(mv3 instanceof MySharedArrayBuffer3, false);

assertEq(mv3.length, 10);