add stream folder with scan and scan-merge

2016-10-29 00:24:18 -05:00 · 2016-10-29 00:24:18 -05:00 · db445a899d
commit db445a899d
parent db956d7194
4 changed files with 147 additions and 0 deletions
--- a/stream/scan-merge.js
+++ b/stream/scan-merge.js
@ -0,0 +1,26 @@
+//! adapted for mithril from flyd https://github.com/paldepind/flyd
+'use strict'
+
+var combine = require('../stream').combine
+
+module.exports = function (tuples, seed) {
+  var streams = tuples.map(function (tuple) {
+		var stream = tuple[0]
+		if (stream._state.state === 0) stream(undefined)
+    return stream
+  })
+
+  var newStream = combine(function () {
+    var changed = arguments[arguments.length - 1]
+
+    streams.forEach(function (stream, idx) {
+      if (changed.indexOf(stream) > -1) {
+        seed = tuples[idx][1](seed, stream._state.value)
+      }
+    })
+
+    return seed
+  }, streams)
+
+  return newStream
+}
--- a/stream/scan.js
+++ b/stream/scan.js
@ -0,0 +1,14 @@
+//! adapted for mithril from flyd https://github.com/paldepind/flyd
+'use strict'
+
+var combine = require('../stream').combine
+
+module.exports = function (reducer, seed, stream) {
+   var newStream = combine(function (s) {
+    return seed = reducer(seed, s._state.value)
+  }, [stream])
+
+  if (newStream._state.state === 0) newStream(seed)
+
+  return newStream
+}
--- a/stream/tests/index.html
+++ b/stream/tests/index.html
@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+  </head>
+  <body>
+    <script src="../../module/module.js"></script>
+    <script src="../../ospec/ospec.js"></script>
+    <script src="../../util/stream.js"></script>
+    <script src="../../stream.js"></script>
+    <script src="../scan.js"></script>
+    <script src="../scan-merge.js"></script>
+    <script src="test-stream.js"></script>
+
+    <script>require("../../ospec/ospec").run()</script>
+  </body>
+</html>
--- a/stream/tests/test-stream.js
+++ b/stream/tests/test-stream.js
@ -0,0 +1,90 @@
+'use strict'
+
+var o = require('../../ospec/ospec')
+
+o.spec('stream', function () {
+  var prop
+
+  o.beforeEach(function () {
+    prop = require('../../stream')
+  })
+
+  o.spec('scan', function () {
+    var scan
+
+    o.beforeEach(function () {
+      scan = require('../scan')
+    })
+
+    o('defaults to seed', function () {
+      var parent = prop()
+      var child = scan(function (out, p) {
+        return out - p
+      }, 123, parent)
+      o(child()).equals(123)
+    })
+
+    o('accumulates values as expected', function () {
+      var parent = prop()
+      var child = scan(function (arr, p) {
+        return arr.concat(p)
+      }, [], parent)
+
+      parent(7)
+      parent('11')
+      parent(undefined)
+      parent({ a: 1 })
+      var result = child()
+
+      // deepEquals fails on arrays?
+      o(result[0]).equals(7)
+      o(result[1]).equals('11')
+      o(result[2]).equals(undefined)
+      o(result[3]).deepEquals({ a: 1 })
+    })
+  })
+
+  o.spec('scanMerge', function () {
+    var scanMerge
+
+    o.beforeEach(function () {
+      scanMerge = require('../scan-merge')
+    })
+
+    o('defaults to seed', function () {
+      var parent1 = prop()
+      var parent2 = prop()
+
+      var child = scanMerge([
+        [parent1, function (out, p1) {
+          return out + p1
+        }],
+        [parent2, function (out, p2) {
+          return out + p2
+        }]
+      ], -10)
+
+      o(child()).equals(-10)
+    })
+
+    o('accumulates as expected', function () {
+      var parent1 = prop()
+      var parent2 = prop()
+
+      var child = scanMerge([
+        [parent1, function (out, p1) {
+          return out + p1
+        }],
+        [parent2, function (out, p2) {
+          return out + p2 + p2
+        }]
+      ], 'a')
+
+      parent1('b')
+      parent2('c')
+      parent1('b')
+
+      o(child()).equals('abccb')
+    })
+  })
+})