git ssb - make initial reduce() accumulator value optional

Kyle E. Mitchell committed on 10/22/2016, 2:31:15 AM
Parent: 9d9abd26492b94a6b650b38e7db4ef41257d64d7

sinks/reduce.js	changed
test/drain-if.js	changed

sinks/reduce.jsView
		@@ -1,12 +1,32 @@
1	1	'use strict'
2	2
3	3	var drain = require('./drain')
4	4
5		-module.exports = function reduce (reducer, acc, cb) {
6		- return drain(function (data) {
7		- acc = reducer(acc, data)
8		- }, function (err) {
9		- cb(err, acc)
10		- })
	5	+module.exports = function reduce (/* reducer, acc, cb */) {
	6	+ var reducer = arguments[0]
	7	+ var acc
	8	+ var cb
	9	+ if (arguments.length === 3) {
	10	+ acc = arguments[1]
	11	+ cb = arguments[2]
	12	+ return drain(function (data) {
	13	+ acc = reducer(acc, data)
	14	+ }, function (err) {
	15	+ cb(err, acc)
	16	+ })
	17	+ } else {
	18	+ cb = arguments[1]
	19	+ var first = true
	20	+ return drain(function (data) {
	21	+ if (first) {
	22	+ acc = data
	23	+ first = false
	24	+ } else {
	25	+ acc = reducer(acc, data)
	26	+ }
	27	+ }, function (err) {
	28	+ cb(err, acc)
	29	+ })
	30	+ }
11	31	}
12	32

test/drain-if.jsView
		@@ -11,9 +11,19 @@
11	11	})
12	12	)
13	13	})
14	14
	15	+test('reduce without initial value', function (t) {
	16	+ pull(
	17	+ pull.values([1,2,3]),
	18	+ pull.reduce(function (a, b) {return a + b}, function (err, val) {
	19	+ t.equal(val, 6)
	20	+ t.end()
	21	+ })
	22	+ )
	23	+})
15	24
	25	+
16	26	test('reduce becomes drain', function (t) {
17	27	pull(
18	28	pull.values([1,2,3]),
19	29	pull.reduce(

Dominic / pull-stream