Release v0.4.0

README.md

@@ -1,4 +1,4 @@
-# IteratorStream [![Build Status](https://secure.travis-ci.org/brianloveswords/iterator-stream.png)](http://travis-ci.org/brianloveswords/iterator-stream)
+# IteratorStream v0.4.0 [![Build Status](https://secure.travis-ci.org/brianloveswords/iterator-stream.png)](http://travis-ci.org/brianloveswords/iterator-stream)
 
 An adapter for turning an iterator into a streaming iterator.
 
@@ -31,7 +31,7 @@ Note that it doesn't have to call `next()`! See `method` below.
 
 ### Options
 - `separator`: A string added to the end of each computation before
-  emitting. Defaults to `\n'`. Pass `null` to disable.
+  emitting. 
 - `format`: Can be a method or a format string that will be passed to
   `util.format`. Defaults to `'%s'`. If given a function, it will be
   called like `formatFn(value)` where value is the raw output of the
@@ -40,15 +40,23 @@ Note that it doesn't have to call `next()`! See `method` below.
   computed. If the resulting computations are small, this could be
   inefficient. If you pass a `bufferSize`, it will buffer **at least**
   that many bytes before emitting a data event.
-- `condition`: An optional condition function to run against the output
+- `takeWhile`: An optional condition function to run against the output
   of every computation. If this check fails, no more data will be send
   and an `end` event will be emitted. Useful for infinite iterators.
 - `iterations`: Maximum number of iterations to go through before
-  `end`ing. Defaults to Infinity.
+  `end`ing.
+- `take`: How many items to take before calling it quits. This is
+  different from `iterations` only when a `filter` is passed – `take` is
+  counted post-filter, iterations is pre-filter.
 - `method`: Name of the method to call over and over again. Defaults to
   `"next"`
 - `transform`: A method to run on every (non-null) value coming from the
-  iterator. Defaults to `function (x) { return x; }`
+  iterator. Defaults to `function (x) { return x }`
+
+#### Application Order
+```
+transform → takeWhile → filter → format
+```
 
 ### Example
 

index.js

@@ -2,18 +2,28 @@ var util = require('util');
 var Stream = require('stream');
 
 function identity(x) { return x };
+
 function alwaysTrue() { return true };
+
+function isDefined(s) {
+  return (typeof s !== undefined && s !== null && s !== '');
+}
+
 function IterStream(iter, options) {
   this.buffer = '';
   this.iterations = options.iterations || Infinity;
-  this.bufferSize = options.bufferSize || 0;
-  this.condition = options.condition || alwaysTrue;
-  this.format = options.format || '%s';
+  this.take = options.take || Infinity;
+
   this.method = options.method || 'next';
+  this.bufferSize = options.bufferSize || 0;
+
+  this.takeWhile = options.takeWhile || options.condition || alwaysTrue;
   this.transform = options.transform || identity;
-  this.separator = typeof options.separator === 'undefined'
-    ? '\n'
-    : (options.separator || '');
+  this.filter = options.filter || alwaysTrue;
+
+  this.format = options.format || '%s';
+  this.separator = options.separator || '';
+
   if (typeof this.format === 'function')
     this.formatOutput = this.format;
   this.iter = iter;
@@ -31,24 +41,43 @@ IterStream.prototype.pause = function pause() {
 
 IterStream.prototype.resume = function resume() {
   this.paused = false;
-  var formatted;
   var data = this.next();
+  var first = true;
+  var separator = this.separator;
+  var formatted;
   while (!this.paused && this.continuable(data)) {
+    this.iterations--;
+
+    if (!this.filter(data)) {
+      data = this.next();
+      continue;
+    }
+
     formatted = this.formatOutput(data);
-    formatted += this.separator;
+    if (!first && isDefined(separator))
+      this.emitDataEvent(this.separator);
     this.emitDataEvent(formatted);
+
     data = this.next();
+    first = false;
+    this.take--;
   }
+
   if (data === null || !this.continuable(data))
     this.emitEndEvent();
 };
 
 IterStream.prototype.continuable = function continuable(data) {
-  return data !== null && this.condition(data) && --this.iterations >= 0;
+  return (
+    data !== null &&
+      this.takeWhile(data) &&
+      this.iterations > 0 &&
+      this.take > 0
+  );
 };
 
 IterStream.prototype.next = function next() {
-  var value;
+  var value, transformed;
   try {
     value = this.iter[this.method]();
   } catch(err) {
@@ -59,7 +88,11 @@ IterStream.prototype.next = function next() {
       this.emit('error', err);
     }
   }
-  return (value !== null ? this.transform(value) : null);
+  if (value === null)
+    return null;
+
+  transformed = this.transform(value);
+  return transformed;
 };
 
 IterStream.prototype.formatOutput = function formatOutput(data) {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "iterator-stream",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "An adapter for making any iterator streaming",
   "main": "index.js",
   "directories": {

test/iterstream.test.js

@@ -11,7 +11,7 @@ var random = iterators.random;
 
 test('testing regular ol ABCs', function (t) {
   var str = StreamString();
-  iterstream(letter(), { separator: null }).pipe(str).once('end', function () {
+  iterstream(letter()).pipe(str).once('end', function () {
     t.same(str.value, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ');
     t.end();
   });
@@ -21,7 +21,6 @@ test('formatting with a string', function (t) {
   var str = StreamString();
   iterstream(letter(), {
     format: '%s|',
-    separator: null
   }).pipe(str).once('end', function () {
     t.same(str.value, 'A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z|');
     t.end();
@@ -32,7 +31,6 @@ test('formatting with a method', function (t) {
   var str = StreamString();
   iterstream(letter(), {
     format: function (l) { return l.toLowerCase(); },
-    separator: null,
   }).pipe(str).once('end', function () {
     t.same(str.value, 'abcdefghijklmnopqrstuvwxyz');
     t.end();
@@ -45,17 +43,17 @@ test('record separator', function (t) {
     format: '%s',
     separator: '.'
   }).pipe(str).once('end', function () {
-    t.same(str.value, 'A.B.C.D.E.F.G.H.I.J.K.L.M.N.O.P.Q.R.S.T.U.V.W.X.Y.Z.');
+    t.same(str.value, 'A.B.C.D.E.F.G.H.I.J.K.L.M.N.O.P.Q.R.S.T.U.V.W.X.Y.Z');
     t.end();
   });
 });
 
-test('additional condition', function (t) {
+test('takeWhile', function (t) {
   var str = StreamString();
   iterstream(letter(), {
-    condition: function (value) { return value < 'D'; }
+    takeWhile: function (value) { return value < 'D'; }
   }).pipe(str).once('end', function () {
-    t.same(str.value, 'A\nB\nC\n');
+    t.same(str.value, 'ABC');
     t.end();
   });
 });
@@ -66,7 +64,7 @@ test('buffering stuff', function (t) {
     bufferSize: 8192
   }).pipe(str).once('end', function () {
     t.ok(str.events[0].size >= 8192, 'should have buffered the send');
-    t.same(str.value.indexOf('1.3069892237633987e+308\n'), 32907, 'should have the last event');
+    t.ok(str.value.indexOf('1.3069892237633987e+308') > -1, 'should have the last event');
     t.end();
   });
 });
@@ -94,13 +92,33 @@ test('method option', function (t) {
 
 test('transform option', function (t) {
   var str = StreamString();
-  iterstream(random(), {
-    transform: function(v) { return 'hi' },
+  iterstream(natural(), {
+    transform: function (v) { return 'hi' },
     iterations: 3,
-    method: 'random',
-    separator: '',
   }).pipe(str).once('end', function () {
     t.same(str.value, 'hihihi');
     t.end();
   });
 });
+
+
+test('filter option', function (t) {
+  var str = StreamString();
+  iterstream(natural(), {
+    filter: function (v) { return v % 2 == 0 },
+    takeWhile: function (v) { return v <= 10 },
+  }).pipe(str).once('end', function () {
+    t.same(str.value, '0246810');
+    t.end();
+  });
+});
+
+test('take option', function (t) {
+  var str = StreamString();
+  iterstream(natural(), {
+    take: 5,
+  }).pipe(str).once('end', function () {
+    t.same(str.value, '01234');
+    t.end();
+  });
+});