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111 lines
2.1 KiB
111 lines
2.1 KiB
5 years ago
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var ArrayIndex = require('./')
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var inherits = require('util').inherits
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var assert = require('assert')
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/**
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* Create a "subclass".
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*/
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function Arrayish (length) {
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ArrayIndex.call(this, length)
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this.sets = Object.create(null)
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}
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// inherit from `ArrayIndex`
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inherits(Arrayish, ArrayIndex)
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// create an instance and run some tests
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var a = new Arrayish(11)
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assert.equal(a.length, 11);
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assert.throws(function () {
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a[0]
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}, /you must implement the `ArrayIndex.get` Symbol/)
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assert.throws(function () {
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a[0] = 0
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}, /you must implement the `ArrayIndex.set` Symbol/)
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/**
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* This "getter" function checks if the index has previosly been "set", and if so
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* returns the index * the value previously set. If the index hasn't been set,
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* return the index as-is.
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*/
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Arrayish.prototype[ArrayIndex.get] = function get (index) {
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if (index in this.sets) {
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return +this.sets[index] * index
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} else {
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return index
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}
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}
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/**
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* Store the last value set for this index.
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*/
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Arrayish.prototype[ArrayIndex.set] = function set (index, value) {
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this.sets[index] = value
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}
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// test getters without being "set"
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assert.equal(0, a[0])
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assert.equal(1, a[1])
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assert.equal(2, a[2])
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assert.equal(3, a[3])
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assert.equal(4, a[4])
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// test setters, followed by getters
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a[10] = 1
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assert.equal(10, a[10])
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a[10] = 2
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assert.equal(20, a[10])
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a[10] = 3
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assert.equal(30, a[10])
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// test "length"
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assert.equal(11, a.length)
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a[4] = 20
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a[6] = 5.55432
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var b = [0, 1, 2, 3, 80, 5, 33.325919999999996, 7, 8, 9, 30]
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assert.equal(JSON.stringify(b), JSON.stringify(a))
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/**
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* It should work when invoking as a Mixin.
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*/
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function Foo () {
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ArrayIndex.call(this, 5);
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}
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var f = new Foo();
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// these throw because there's no __get__ and __set__ function defined
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assert.throws(function () {
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f[0];
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});
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assert.throws(function () {
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f[0] = 0
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});
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f[ArrayIndex.get] = function (index) {
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return index * 2;
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};
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assert.equal(f[0], 0);
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assert.equal(f[1], 2);
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assert.equal(f[2], 4);
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assert.equal(f[3], 6);
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f[ArrayIndex.set] = function (index, value) {
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this['foo' + index] = value;
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};
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f[1] = 'bar';
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assert.equal(f.foo1, 'bar');
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