src/v8/test/mjsunit/es6/typedarray-slice.js

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --allow-natives-syntax

var typedArrayConstructors = [
  Uint8Array,
  Int8Array,
  Uint16Array,
  Int16Array,
  Uint32Array,
  Int32Array,
  Uint8ClampedArray,
  Float32Array,
  Float64Array
];

for (var constructor of typedArrayConstructors) {
  // Check various variants of empty array's slicing.
  var array = new constructor(0);
  for (var i = 0; i < 7; i++) {
    assertEquals(0, array.slice(0, 0).length);
    assertEquals(0, array.slice(1, 0).length);
    assertEquals(0, array.slice(0, 1).length);
    assertEquals(0, array.slice(-1, 0).length);
  }


  // Check various forms of arguments omission.
  array = new constructor(7);

  for (var i = 0; i < 7; i++) {
    assertEquals(array, array.slice());
    assertEquals(array, array.slice(0));
    assertEquals(array, array.slice(undefined));
    assertEquals(array, array.slice("foobar"));
    assertEquals(array, array.slice(undefined, undefined));
  }


  // Check variants of negatives and positive indices.
  array = new constructor(7);

  assertEquals(7, array.slice(-100).length);
  assertEquals(3, array.slice(-3).length);
  assertEquals(3, array.slice(4).length);
  assertEquals(1, array.slice(6).length);
  assertEquals(0, array.slice(7).length);
  assertEquals(0, array.slice(8).length);
  assertEquals(0, array.slice(100).length);

  assertEquals(0, array.slice(0, -100).length);
  assertEquals(4, array.slice(0, -3).length);
  assertEquals(4, array.slice(0, 4).length);
  assertEquals(6, array.slice(0, 6).length);
  assertEquals(7, array.slice(0, 7).length);
  assertEquals(7, array.slice(0, 8).length);
  assertEquals(7, array.slice(0, 100).length);

  // Does not permit being called on other types
  assertThrows(() => constructor.prototype.slice.call([], 0, 0), TypeError);

  // Check that elements are copied properly in slice
  array = new constructor([1, 2, 3, 4]);
  var slice = array.slice(1, 3);
  assertEquals(2, slice.length);
  assertEquals(2, slice[0]);
  assertEquals(3, slice[1]);
  assertTrue(slice instanceof constructor);

  // Detached Operation
  var tmp = {
    [Symbol.toPrimitive]() {
      assertUnreachable("Parameter should not be processed when " +
                        "array.[[ViewedArrayBuffer]] is detached.");
      return 0;
    }
  };
  var array = new constructor([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
  %ArrayBufferDetach(array.buffer);
  assertThrows(() => array.slice(tmp, tmp), TypeError);

  // Check that the species array must be a typed array
  class MyTypedArray extends constructor {
    static get[Symbol.species]() {
      return Array;
    }
  }
  var arr = new MyTypedArray([-1.0, 0, 1.1, 255, 256]);
  assertThrows(() => arr.slice(), TypeError);
}

// Check that the result array is properly created by checking species
for (var constructor1 of typedArrayConstructors) {
  for (var constructor2 of typedArrayConstructors) {
    testCustomSubclass(constructor1, constructor2);
    testSpeciesConstructor(constructor1, constructor2);
  }
}

function testSpeciesConstructor(cons1, cons2) {
  var ta = new cons1([1, 2, 3, 4, 5, 6]);
  ta.constructor = {
    [Symbol.species]: cons2
  };
  assertArrayEquals([4, 5, 6], ta.slice(3));
}

function testCustomSubclass(superClass, speciesClass) {
  // Simple subclass that has another TypedArray as species
  class CustomTypedArray extends superClass {
    static get[Symbol.species]() {
      return speciesClass;
    }
  }
  // 16 entries.
  let exampleArray = [-1.0, 0, 1.1, 255, 256, 0xFFFFFFFF, 2**50, NaN];
  let customArray = new CustomTypedArray(exampleArray);
  let basicArray = new superClass(exampleArray);
  assertEquals(new speciesClass(basicArray), customArray.slice(),
               superClass.name + ' -> ' + speciesClass.name);

  // Custom constructor with shared buffer.
  exampleArray =  new Array(64).fill(0).map((v,i) => i);
  let filledBuffer = new Uint8Array(exampleArray).buffer;
  // Create a view for the beginning of the buffer.
  let customArray2 = new superClass(filledBuffer, 0, 3);
  customArray2.constructor = {
    [Symbol.species]: function(length) {
      let bytes_per_element = speciesClass.BYTES_PER_ELEMENT;
      // Reuse the same buffer for the custom species constructor.
      // Skip the first BYTES_PER_ELEMENT bytes of the buffer.
      return new speciesClass(filledBuffer, bytes_per_element, length);
    }
  };
  // Since slice is defined iteratively, the species created new array uses the
  // same underlying buffer shifted by one element. Hence the first value is
  // copied over and over again.
  let convertedCopy = Array.from(customArray2);
  let firstValue = convertedCopy[0];
  assertEquals(firstValue, customArray2[0]);
  let sliceResult = customArray2.slice();
  if (superClass == speciesClass) {
    assertEquals(new Array(3).fill(firstValue), Array.from(customArray2));
    assertEquals(new Array(3).fill(firstValue), Array.from(sliceResult));
  }
  assertEquals(3, customArray2.length);
  assertEquals(3, sliceResult.length);
}