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var Q = require('q');
var Immutable = require('immutable');
/**
Reduce an array to a promise
@param {Array|List} arr
@param {Function(value, element, index)}
@return {Promise<Mixed>}
*/
function reduce(arr, iter, base) {
arr = Immutable.List(arr);
return arr.reduce(function(prev, elem, i) {
return prev.then(function(val) {
return iter(val, elem, i);
});
}, Q(base));
}
/**
Iterate over an array using an async iter
@param {Array|List} arr
@param {Function(value, element, index)}
@return {Promise}
*/
function forEach(arr, iter) {
return reduce(arr, function(val, el) {
return iter(el);
});
}
/**
Transform an array
@param {Array|List} arr
@param {Function(value, element, index)}
@return {Promise}
*/
function serie(arr, iter, base) {
return reduce(arr, function(before, item, i) {
return Q(iter(item, i))
.then(function(r) {
before.push(r);
return before;
});
}, []);
}
/**
Iter over an array and return first result (not null)
@param {Array|List} arr
@param {Function(element, index)}
@return {Promise<Mixed>}
*/
function some(arr, iter) {
arr = Immutable.List(arr);
return arr.reduce(function(prev, elem, i) {
return prev.then(function(val) {
if (val) return val;
return iter(elem, i);
});
}, Q());
}
/**
Map an array using an async (promised) iterator
@param {Array|List} arr
@param {Function(element, index)}
@return {Promise<List>}
*/
function map(arr, iter) {
return reduce(arr, function(prev, entry, i) {
return Q(iter(entry, i))
.then(function(out) {
prev.push(out);
return prev;
});
}, []);
}
/**
Wrap a fucntion in a promise
@param {Function} func
@return {Funciton}
*/
function wrap(func) {
return function() {
var args = Array.prototype.slice.call(arguments, 0);
return Q()
.then(function() {
return func.apply(null, args);
});
};
}
module.exports = Q;
module.exports.forEach = forEach;
module.exports.reduce = reduce;
module.exports.map = map;
module.exports.serie = serie;
module.exports.some = some;
module.exports.wrapfn = wrap;
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