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var Q = require('q');
var Immutable = require('immutable');
// Debugging for long stack traces
if (process.env.DEBUG || process.env.CI) {
Q.longStackSupport = true;
}
/**
* 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.Iterable.isIterable(arr)? arr : Immutable.List(arr);
return arr.reduce(function(prev, elem, key) {
return prev
.then(function(val) {
return iter(val, elem, key);
});
}, 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, key) {
return iter(el, key);
});
}
/**
* 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, key) {
return Q(iter(item, key))
.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 mapAsList(arr, iter) {
return reduce(arr, function(prev, entry, i) {
return Q(iter(entry, i))
.then(function(out) {
prev.push(out);
return prev;
});
}, []);
}
/**
* Map an array or map
*
* @param {Array|List|Map|OrderedMap} arr
* @param {Function(element, key)}
* @return {Promise<List|Map|OrderedMap>}
*/
function map(arr, iter) {
if (Immutable.Map.isMap(arr)) {
var type = 'Map';
if (Immutable.OrderedMap.isOrderedMap(arr)) {
type = 'OrderedMap';
}
return mapAsList(arr, function(value, key) {
return Q(iter(value, key))
.then(function(result) {
return [key, result];
});
})
.then(function(result) {
return Immutable[type](result);
});
} else {
return mapAsList(arr, iter)
.then(function(result) {
return Immutable.List(result);
});
}
}
/**
* Wrap a function 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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