File yui3/src/collection/js/array-extras.js
/**
Adds additional utility methods to the `Y.Array` class.
@module collection
@submodule array-extras
**/
var A = Y.Array,
L = Y.Lang,
ArrayProto = Array.prototype;
/**
Returns the index of the last item in the array that contains the specified
value, or `-1` if the value isn't found.
@method lastIndexOf
@param {Array} a Array to search in.
@param {Any} val Value to search for.
@param {Number} [fromIndex] Index at which to start searching backwards.
Defaults to the array's length - 1. If negative, it will be taken as an offset
from the end of the array. If the calculated index is less than 0, the array
will not be searched and `-1` will be returned.
@return {Number} Index of the item that contains the value, or `-1` if not
found.
@static
@for Array
**/
A.lastIndexOf = L._isNative(ArrayProto.lastIndexOf) ?
function(a, val, fromIndex) {
// An undefined fromIndex is still considered a value by some (all?)
// native implementations, so we can't pass it unless it's actually
// specified.
return fromIndex || fromIndex === 0 ? a.lastIndexOf(val, fromIndex) :
a.lastIndexOf(val);
} :
function(a, val, fromIndex) {
var len = a.length,
i = len - 1;
if (fromIndex || fromIndex === 0) {
i = Math.min(fromIndex < 0 ? len + fromIndex : fromIndex, len);
}
if (i > -1 && len > 0) {
for (; i > -1; --i) {
if (i in a && a[i] === val) {
return i;
}
}
}
return -1;
};
/**
Returns a copy of the input array with duplicate items removed.
Note: If the input array only contains strings, the `Y.Array.dedupe()` method is
a much faster alternative.
@method unique
@param {Array} array Array to dedupe.
@param {Function} [testFn] Custom function to use to test the equality of two
values. A truthy return value indicates that the values are equal. A falsy
return value indicates that the values are not equal.
@param {Any} testFn.a First value to compare.
@param {Any} testFn.b Second value to compare.
@param {Number} testFn.index Index of the current item in the original
array.
@param {Array} testFn.array The original array.
@return {Boolean} _true_ if the items are equal, _false_ otherwise.
@return {Array} Copy of the input array with duplicate items removed.
@static
**/
A.unique = function (array, testFn) {
var i = 0,
len = array.length,
results = [],
j, result, resultLen, value;
// Note the label here. It's used to jump out of the inner loop when a value
// is not unique.
outerLoop: for (; i < len; i++) {
value = array[i];
// For each value in the input array, iterate through the result array
// and check for uniqueness against each result value.
for (j = 0, resultLen = results.length; j < resultLen; j++) {
result = results[j];
// If the test function returns true or there's no test function and
// the value equals the current result item, stop iterating over the
// results and continue to the next value in the input array.
if (testFn) {
if (testFn.call(array, value, result, i, array)) {
continue outerLoop;
}
} else if (value === result) {
continue outerLoop;
}
}
// If we get this far, that means the current value is not already in
// the result array, so add it.
results.push(value);
}
return results;
};
/**
Executes the supplied function on each item in the array. Returns a new array
containing the items for which the supplied function returned a truthy value.
@method filter
@param {Array} a Array to filter.
@param {Function} f Function to execute on each item.
@param {Object} [o] Optional context object.
@return {Array} Array of items for which the supplied function returned a
truthy value (empty if it never returned a truthy value).
@static
*/
A.filter = L._isNative(ArrayProto.filter) ?
function(a, f, o) {
return ArrayProto.filter.call(a, f, o);
} :
function(a, f, o) {
var i = 0,
len = a.length,
results = [],
item;
for (; i < len; ++i) {
if (i in a) {
item = a[i];
if (f.call(o, item, i, a)) {
results.push(item);
}
}
}
return results;
};
/**
The inverse of `Array.filter()`. Executes the supplied function on each item.
Returns a new array containing the items for which the supplied function
returned `false`.
@method reject
@param {Array} a the array to iterate.
@param {Function} f the function to execute on each item.
@param {object} [o] Optional context object.
@return {Array} The items for which the supplied function returned `false`.
@static
*/
A.reject = function(a, f, o) {
return A.filter(a, function(item, i, a) {
return !f.call(o, item, i, a);
});
};
/**
Executes the supplied function on each item in the array. Iteration stops if the
supplied function does not return a truthy value.
@method every
@param {Array} a the array to iterate.
@param {Function} f the function to execute on each item.
@param {Object} [o] Optional context object.
@return {Boolean} `true` if every item in the array returns `true` from the
supplied function, `false` otherwise.
@static
*/
A.every = L._isNative(ArrayProto.every) ?
function(a, f, o) {
return ArrayProto.every.call(a, f, o);
} :
function(a, f, o) {
for (var i = 0, l = a.length; i < l; ++i) {
if (i in a && !f.call(o, a[i], i, a)) {
return false;
}
}
return true;
};
/**
Executes the supplied function on each item in the array and returns a new array
containing all the values returned by the supplied function.
@example
// Convert an array of numbers into an array of strings.
Y.Array.map([1, 2, 3, 4], function (item) {
return '' + item;
});
// => ['1', '2', '3', '4']
@method map
@param {Array} a the array to iterate.
@param {Function} f the function to execute on each item.
@param {object} [o] Optional context object.
@return {Array} A new array containing the return value of the supplied function
for each item in the original array.
@static
*/
A.map = L._isNative(ArrayProto.map) ?
function(a, f, o) {
return ArrayProto.map.call(a, f, o);
} :
function(a, f, o) {
var i = 0,
len = a.length,
results = ArrayProto.concat.call(a);
for (; i < len; ++i) {
if (i in a) {
results[i] = f.call(o, a[i], i, a);
}
}
return results;
};
/**
Executes the supplied function on each item in the array, "folding" the array
into a single value.
@method reduce
@param {Array} a Array to iterate.
@param {Any} init Initial value to start with.
@param {Function} f Function to execute on each item. This function should
update and return the value of the computation. It will receive the following
arguments:
@param {Any} f.previousValue Value returned from the previous iteration,
or the initial value if this is the first iteration.
@param {Any} f.currentValue Value of the current item being iterated.
@param {Number} f.index Index of the current item.
@param {Array} f.array Array being iterated.
@param {Object} [o] Optional context object.
@return {Any} Final result from iteratively applying the given function to each
element in the array.
@static
*/
A.reduce = L._isNative(ArrayProto.reduce) ?
function(a, init, f, o) {
// ES5 Array.reduce doesn't support a thisObject, so we need to
// implement it manually.
return ArrayProto.reduce.call(a, function(init, item, i, a) {
return f.call(o, init, item, i, a);
}, init);
} :
function(a, init, f, o) {
var i = 0,
len = a.length,
result = init;
for (; i < len; ++i) {
if (i in a) {
result = f.call(o, result, a[i], i, a);
}
}
return result;
};
/**
Executes the supplied function on each item in the array, searching for the
first item that matches the supplied function.
@method find
@param {Array} a the array to search.
@param {Function} f the function to execute on each item. Iteration is stopped
as soon as this function returns `true`.
@param {Object} [o] Optional context object.
@return {Object} the first item that the supplied function returns `true` for,
or `null` if it never returns `true`.
@static
*/
A.find = function(a, f, o) {
for (var i = 0, l = a.length; i < l; i++) {
if (i in a && f.call(o, a[i], i, a)) {
return a[i];
}
}
return null;
};
/**
Iterates over an array, returning a new array of all the elements that match the
supplied regular expression.
@method grep
@param {Array} a Array to iterate over.
@param {RegExp} pattern Regular expression to test against each item.
@return {Array} All the items in the array that produce a match against the
supplied regular expression. If no items match, an empty array is returned.
@static
*/
A.grep = function(a, pattern) {
return A.filter(a, function(item, index) {
return pattern.test(item);
});
};
/**
Partitions an array into two new arrays, one with the items for which the
supplied function returns `true`, and one with the items for which the function
returns `false`.
@method partition
@param {Array} a Array to iterate over.
@param {Function} f Function to execute for each item in the array. It will
receive the following arguments:
@param {Any} f.item Current item.
@param {Number} f.index Index of the current item.
@param {Array} f.array The array being iterated.
@param {Object} [o] Optional execution context.
@return {Object} An object with two properties: `matches` and `rejects`. Each is
an array containing the items that were selected or rejected by the test
function (or an empty array if none).
@static
*/
A.partition = function(a, f, o) {
var results = {
matches: [],
rejects: []
};
A.each(a, function(item, index) {
var set = f.call(o, item, index, a) ? results.matches : results.rejects;
set.push(item);
});
return results;
};
/**
Creates an array of arrays by pairing the corresponding elements of two arrays
together into a new array.
@method zip
@param {Array} a Array to iterate over.
@param {Array} a2 Another array whose values will be paired with values of the
first array.
@return {Array} An array of arrays formed by pairing each element of the first
array with an item in the second array having the corresponding index.
@static
*/
A.zip = function(a, a2) {
var results = [];
A.each(a, function(item, index) {
results.push([item, a2[index]]);
});
return results;
};
/**
Flattens an array of nested arrays at any abitrary depth into a single, flat
array.
@method flatten
@param {Array} a Array with nested arrays to flatten.
@return {Array} An array whose nested arrays have been flattened.
@static
@since 3.7.0
**/
A.flatten = function(a) {
var result = [],
i, len, val;
// Always return an array.
if (!a) {
return result;
}
for (i = 0, len = a.length; i < len; ++i) {
val = a[i];
if (L.isArray(val)) {
// Recusively flattens any nested arrays.
result.push.apply(result, A.flatten(val));
} else {
result.push(val);
}
}
return result;
};