├── .gitignore
├── LICENSE
├── README.md
├── demo.html
└── index.js
/.gitignore:
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1 | # Logs
2 | logs
3 | *.log
4 | npm-debug.log*
5 |
6 | # Runtime data
7 | pids
8 | *.pid
9 | *.seed
10 |
11 | # Directory for instrumented libs generated by jscoverage/JSCover
12 | lib-cov
13 |
14 | # Coverage directory used by tools like istanbul
15 | coverage
16 |
17 | # nyc test coverage
18 | .nyc_output
19 |
20 | # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
21 | .grunt
22 |
23 | # node-waf configuration
24 | .lock-wscript
25 |
26 | # Compiled binary addons (http://nodejs.org/api/addons.html)
27 | build/Release
28 |
29 | # Dependency directories
30 | node_modules
31 | jspm_packages
32 |
33 | # Optional npm cache directory
34 | .npm
35 |
36 | # Optional REPL history
37 | .node_repl_history
38 |
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/LICENSE:
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1 | MIT License
2 |
3 | Copyright (c) 2016 luobotang
4 |
5 | Permission is hereby granted, free of charge, to any person obtaining a copy
6 | of this software and associated documentation files (the "Software"), to deal
7 | in the Software without restriction, including without limitation the rights
8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 |
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 |
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 |
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/README.md:
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1 | # simply-lazy
2 |
3 | A simple [Lazy.js](http://danieltao.com/lazy.js) implementation, to show the core of lazy evaluation.
4 |
5 | ## demo
6 |
7 | See: [demo](http://www.luobotang.cn/simply-lazy/demo.html).
8 |
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/demo.html:
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1 |
2 |
3 |
4 |
5 | simply-lazy
6 |
67 |
68 |
69 |
70 |
71 |
72 |
73 |
74 |
75 |
163 |
164 |
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/index.js:
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1 | (function(root, factory) {
2 | if (typeof define === 'function' && define.amd) {
3 | define(factory);
4 | } else if (typeof exports === 'object') {
5 | module.exports = factory();
6 | } else {
7 | root.Lazy = factory();
8 | }
9 | })(this, function() {
10 |
11 | function Lazy(source) {
12 | if (source instanceof Array) {
13 | return ArrayWrapper(source);
14 | }
15 | throw new Error('Sorry, only array is supported in simply-lazy.')
16 | }
17 |
18 | /* Sequence */
19 |
20 | function Sequence() { }
21 |
22 | Sequence.prototype.get = function get(i) {
23 | var element;
24 | this.each(function(e, index) {
25 | if (index === i) {
26 | element = e;
27 | return false;
28 | }
29 | });
30 | return element;
31 | }
32 |
33 | Sequence.prototype.each = function each(fn) {
34 | var iterator = this.getIterator()
35 | var i = -1
36 |
37 | while (iterator.moveNext()) {
38 | if (fn(iterator.current(), ++i) === false) {
39 | return false;
40 | }
41 | }
42 |
43 | return true;
44 | }
45 |
46 | Sequence.prototype.map = function (mapFn) {
47 | return MappedSequence(this, mapFn)
48 | }
49 |
50 | Sequence.prototype.take = function (count) {
51 | return TakeSequence(this, count || 1)
52 | }
53 |
54 | /* MappedSequence */
55 |
56 | function MappedSequence(parent, mapFn) {
57 | var seq = new Sequence()
58 | seq.getIterator = () => {
59 | var iterator = parent.getIterator()
60 | var index = -1
61 | return {
62 | current() { return mapFn(iterator.current(), index) },
63 | moveNext() {
64 | if (iterator.moveNext()) {
65 | ++index
66 | return true
67 | }
68 | return false
69 | }
70 | }
71 | }
72 | seq.each = fn => parent.each((e, i) => fn(mapFn(e, i), i))
73 | return seq
74 | }
75 |
76 | /* FilteredSequence */
77 |
78 | function FilteredSequence(parent, filterFn) {
79 | var seq = new Sequence()
80 | seq.getIterator = () => {
81 | var iterator = parent.getIterator()
82 | var index = 0
83 | var value
84 | return {
85 | current() { return value },
86 | moveNext() {
87 | var _val
88 | while (iterator.moveNext()) {
89 | _val = iterator.current()
90 | if (filterFn(_val, index++)) {
91 | value = _val
92 | return true
93 | }
94 | }
95 | value = undefined
96 | return false
97 | }
98 | }
99 | }
100 | seq.each = fn => {
101 | var j = 0;
102 | return parent.each((e, i) => {
103 | if (filterFn(e, i)) {
104 | return fn(e, j++);
105 | }
106 | })
107 | }
108 | return seq
109 | }
110 |
111 | /* TakeSequence */
112 |
113 | function TakeSequence(parent, count) {
114 | var seq = new Sequence()
115 | seq.getIterator = () => {
116 | var iterator = parent.getIterator()
117 | var _count = count
118 | return {
119 | current() { return iterator.current() },
120 | moveNext() { return (--_count >= 0) && iterator.moveNext() }
121 | }
122 | }
123 | seq.each = (fn) => {
124 | var _count = count
125 | var i = 0
126 | var result
127 | parent.each(e => {
128 | if (i < count) { result = fn(e, i++); }
129 | if (i >= count) { return false; }
130 | return result
131 | })
132 | return i === count && result !== false
133 | }
134 | return seq
135 | }
136 |
137 | /* ArrayLikeSequence */
138 |
139 | function ArrayLikeSequence() {
140 | var seq = new Sequence()
141 | seq.length = () => seq.parent.length()
142 | seq.map = mapFn => IndexedMappedSequence(seq, mapFn)
143 | seq.filter = filterFn => IndexedFilteredSequence(seq, filterFn)
144 | return seq
145 | }
146 |
147 | /* IndexedMappedSequence */
148 |
149 | function IndexedMappedSequence(parent, mapFn) {
150 | var seq = ArrayLikeSequence()
151 | seq.parent = parent
152 | seq.get = (i) => {
153 | if (i < 0 || i >= parent.length()) {
154 | return undefined;
155 | }
156 | return mapFn(parent.get(i), i);
157 | }
158 | return seq
159 | }
160 |
161 | /* IndexedFilteredSequence */
162 |
163 | function IndexedFilteredSequence(parent, filterFn) {
164 | var seq = FilteredSequence(parent, filterFn)
165 | seq.parent = parent
166 | seq.each = (fn) => {
167 | var length = parent.length()
168 | var i = -1
169 | var j = 0
170 | var e
171 | while (++i < length) {
172 | e = parent.get(i)
173 | if (filterFn(e, i) && fn(e, j++) === false) {
174 | return false
175 | }
176 | }
177 | return true
178 | }
179 | return seq
180 | }
181 |
182 | /* ArrayWrapper */
183 |
184 | function ArrayWrapper(source) {
185 | var seq = ArrayLikeSequence()
186 | seq.source = source
187 | seq.get = i => source[i]
188 | seq.length = () => source.length
189 | seq.each = fn => {
190 | var i = -1
191 | var len = source.length
192 | while (++i < len) {
193 | if (fn(source[i], i) === false) {
194 | return false
195 | }
196 | }
197 | return true
198 | }
199 | seq.map = mapFn => MappedArrayWrapper(seq, mapFn)
200 | seq.filter = filterFn => FilteredArrayWrapper(seq, filterFn)
201 | return seq
202 | }
203 |
204 | /* MappedArrayWrapper */
205 |
206 | function MappedArrayWrapper(parent, mapFn) {
207 | var source = parent.source
208 | var length = source.length
209 | var seq = ArrayLikeSequence()
210 | seq.parent = parent
211 | seq.get = i => (i < 0 || i >= length) ? undefined : mapFn(source[i])
212 | seq.length = () => length
213 | seq.each = fn => {
214 | var i = -1;
215 | while (++i < length) {
216 | if (fn(mapFn(source[i], i), i) === false) {
217 | return false
218 | }
219 | }
220 | return true
221 | }
222 | return seq
223 | }
224 |
225 | /* FilteredArrayWrapper */
226 |
227 | function FilteredArrayWrapper(parent, filterFn) {
228 | var seq = FilteredSequence(parent, filterFn)
229 | seq.each = fn => {
230 | var source = parent.source
231 | var length = source.length
232 | var i = -1
233 | var j = 0
234 | var e
235 |
236 | while (++i < length) {
237 | e = source[i]
238 | if (filterFn(e, i) && fn(e, j++) === false) {
239 | return false
240 | }
241 | }
242 |
243 | return true
244 | }
245 | return seq
246 | }
247 |
248 | return Lazy
249 | })
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