https://github.com/Gozala/reducers
Tip revision: 4b5432a40fc01ed434431fbd874bcc259106e497 authored by Irakli Gozalishvili on 07 November 2012, 06:34:53 UTC
Version 1.0.1
Version 1.0.1
Tip revision: 4b5432a
take.js
"use strict";
var reducible = require("./reducible")
var accumulate = require("./accumulate")
var end = require("./end")
function take(source, n) {
/**
Returns sequence of first `n` items of the given `source`. If `source`
contains less items than `n` then that's how much items return sequence
will contain.
## Example
print(take([ 1, 2, 3, 4, 5 ], 2)) // => < 1 2 >
print(take([ 1, 2, 3 ], 5)) // => < 1 2 3 >
**/
// If take `0` then optimize by returning an empty if less then `0`
// then just return `source` back.
if (n === 0) return void(0)
if (n < 0) return source
return reducible(function accumulateTake(next, initial) {
// Capture `n` into count, since modifying `n` directly will have side
// effects on subsequent calls.
var count = n
accumulate(source, function accumulateTakeSource(value, result) {
count = count - 1
result = next(value, result)
// If we have not taken `n` items yet just pass result back. Otherwise
// pass `end` of stream to a consumer. Note `reducible` will return
// `reduced(result)` back signaling source it should stop.
return count > 0 ? result :
next(end)
}, initial)
})
}
module.exports = take