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elk/libraries/Native/List.js
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1Elm.Native.List = {};
2Elm.Native.List.make = function(elm) {
3 elm.Native = elm.Native || {};
4 elm.Native.List = elm.Native.List || {};
5 if (elm.Native.List.values) return elm.Native.List.values;
6 if ('values' in Elm.Native.List)
7 return elm.Native.List.values = Elm.Native.List.values;
9 var Utils = Elm.Native.Utils.make(elm);
11 // TODO: Improve Nil handling
12 // We can change places like: if (xs.ctor === '[]') ... to if (xs === Nil) ...
13 // but only if we're confident Nil can only be defined once.
14 // Currently (27Mar2013) each module can have different instantiations, so multiple Nil objects can exist
15 // (and if they're used interchangeably then direct object comparison fails where ctor doesn't).
16 // So, this can only be fixed when modules initialisation is also fixed.
17 // The performance overhead of the .ctor calls is 5-10% according to jsperf (depending on fn + list size)
18 // (on firefox 19)
20 var Nil = { ctor:'[]' };
22 // using freeze for every cons would be nice but is a huge (9x on firefox 19)
23 // performance penalty
24 function Cons(hd,tl) { return { ctor:"::", _0:hd, _1:tl }; }
26 function throwError(f) {
27 throw new Error("Function '" + f + "' expects a non-empty list!");
28 }
30 function toArray(xs) {
31 var out = [];
32 while (xs.ctor !== '[]') {
33 out.push(xs._0);
34 xs = xs._1;
35 }
36 return out;
37 }
39 function fromArray(arr) {
40 var out = Nil;
41 for (var i = arr.length; i--; ) {
42 out = Cons(arr[i], out);
43 }
44 return out;
45 }
47 function range(lo,hi) {
48 var lst = Nil;
49 if (lo <= hi) {
50 do { lst = Cons(hi,lst) } while (hi-->lo);
51 }
52 return lst
53 }
55 function append(xs,ys) {
56 if (xs.isText) return Utils.txt(xs.concat(ys));
57 if (typeof xs === "string") return xs.concat(ys);
58 if (xs.ctor === '[]') { return ys; }
59 var root = Cons(xs._0, Nil);
60 var curr = root;
61 xs = xs._1;
62 while (xs.ctor !== '[]') {
63 curr._1 = Cons(xs._0, Nil);
64 xs = xs._1;
65 curr = curr._1;
66 }
67 curr._1 = ys;
68 return root;
69 }
71 function head(v) { return v.ctor === '[]' ? throwError('head') : v._0; }
72 function tail(v) { return v.ctor === '[]' ? throwError('tail') : v._1; }
74 function last(xs) {
75 if (xs.ctor === '[]') { throwError('last'); }
76 var out = xs._0;
77 while (xs.ctor !== '[]') {
78 out = xs._0;
79 xs = xs._1;
80 }
81 return out;
82 }
84 function map(f, xs) {
85 var arr = [];
86 while (xs.ctor !== '[]') {
87 arr.push(f(xs._0));
88 xs = xs._1;
89 }
90 return fromArray(arr);
91 }
93 // f defined similarly for both foldl and foldr (NB: different from Haskell)
94 // ie, foldl : (a -> b -> b) -> b -> [a] -> b
95 function foldl(f, b, xs) {
96 var acc = b;
97 while (xs.ctor !== '[]') {
98 acc = A2(f, xs._0, acc);
99 xs = xs._1;
100 }
101 return acc;
102 }
104 function foldr(f, b, xs) {
105 var arr = toArray(xs);
106 var acc = b;
107 for (var i = arr.length; i--; ) {
108 acc = A2(f, arr[i], acc);
109 }
110 return acc;
111 }
113 function foldl1(f, xs) {
114 return xs.ctor === '[]' ? throwError('foldl1') : foldl(f, xs._0, xs._1);
115 }
117 function foldr1(f, xs) {
118 if (xs.ctor === '[]') { throwError('foldr1'); }
119 var arr = toArray(xs);
120 var acc = arr.pop();
121 for (var i = arr.length; i--; ) {
122 acc = A2(f, arr[i], acc);
123 }
124 return acc;
125 }
127 function scanl(f, b, xs) {
128 var arr = toArray(xs);
129 arr.unshift(b);
130 var len = arr.length;
131 for (var i = 1; i < len; ++i) {
132 arr[i] = A2(f, arr[i], arr[i-1]);
133 }
134 return fromArray(arr);
135 }
137 function scanl1(f, xs) {
138 return xs.ctor === '[]' ? throwError('scanl1') : scanl(f, xs._0, xs._1);
139 }
141 function filter(pred, xs) {
142 var arr = [];
143 while (xs.ctor !== '[]') {
144 if (pred(xs._0)) { arr.push(xs._0); }
145 xs = xs._1;
146 }
147 return fromArray(arr);
148 }
150 function length(xs) {
151 var out = 0;
152 while (xs.ctor !== '[]') {
153 out += 1;
154 xs = xs._1;
155 }
156 return out;
157 }
159 function member(x, xs) {
160 while (xs.ctor !== '[]') {
161 if (Utils.eq(x,xs._0)) return true;
162 xs = xs._1;
163 }
164 return false;
165 }
167 function reverse(xs) { return fromArray(toArray(xs).reverse()); }
169 function concat(xss) {
170 if (xss.ctor === '[]') return xss;
171 var arr = toArray(xss);
172 var xs = arr[arr.length-1];
173 for (var i = arr.length-1; i--; ) {
174 xs = append(arr[i], xs);
175 }
176 return xs;
177 }
179 function all(pred, xs) {
180 while (xs.ctor !== '[]') {
181 if (!pred(xs._0)) return false;
182 xs = xs._1;
183 }
184 return true;
185 }
187 function any(pred, xs) {
188 while (xs.ctor !== '[]') {
189 if (pred(xs._0)) return true;
190 xs = xs._1;
191 }
192 return false;
193 }
195 function zipWith(f, xs, ys) {
196 var arr = [];
197 while (xs.ctor !== '[]' && ys.ctor !== '[]') {
198 arr.push(A2(f, xs._0, ys._0));
199 xs = xs._1;
200 ys = ys._1;
201 }
202 return fromArray(arr);
203 }
205 function zip(xs, ys) {
206 var arr = [];
207 while (xs.ctor !== '[]' && ys.ctor !== '[]') {
208 arr.push(Utils.Tuple2(xs._0, ys._0));
209 xs = xs._1;
210 ys = ys._1;
211 }
212 return fromArray(arr);
213 }
215 function sort(xs) {
216 return fromArray(toArray(xs).sort(Utils.cmp));
217 }
219 function sortBy(f, xs) {
220 return fromArray(toArray(xs).sort(function(a,b){
221 return Utils.cmp(f(a), f(b));
222 }));
223 }
225 function sortWith(f, xs) {
226 return fromArray(toArray(xs).sort(function(a,b){
227 var ord = f(a)(b).ctor;
228 return ord === 'EQ' ? 0 : ord === 'LT' ? -1 : 1;
229 }));
230 }
232 function nth(xs, n) {
233 return toArray(xs)[n];
234 }
236 function take(n, xs) {
237 var arr = [];
238 while (xs.ctor !== '[]' && n > 0) {
239 arr.push(xs._0);
240 xs = xs._1;
241 --n;
242 }
243 return fromArray(arr);
244 }
246 function drop(n, xs) {
247 while (xs.ctor !== '[]' && n > 0) {
248 xs = xs._1;
249 --n;
250 }
251 return xs;
252 }
254 function repeat(n, x) {
255 var arr = [];
256 var pattern = [x];
257 while (n > 0) {
258 if (n & 1) arr = arr.concat(pattern);
259 n >>= 1, pattern = pattern.concat(pattern);
260 }
261 return fromArray(arr);
262 }
264 function join(sep, xss) {
265 if (sep.isText) return Utils.txt(toArray(xss).join(sep));
266 if (typeof sep === 'string') return toArray(xss).join(sep);
267 if (xss.ctor === '[]') return Nil;
268 var s = toArray(sep);
269 var out = toArray(xss._0);
270 xss = xss._1;
271 while (xss.ctor !== '[]') {
272 out = out.concat(s, toArray(xss._0));
273 xss = xss._1;
274 }
275 return fromArray(out);
276 }
278 Elm.Native.List.values = {
279 Nil:Nil,
280 Cons:Cons,
281 cons:F2(Cons),
282 toArray:toArray,
283 fromArray:fromArray,
284 range:range,
285 append:append,
287 head:head,
288 tail:tail,
289 last:last,
291 map:F2(map),
292 foldl:F3(foldl),
293 foldr:F3(foldr),
295 foldl1:F2(foldl1),
296 foldr1:F2(foldr1),
297 scanl:F3(scanl),
298 scanl1:F2(scanl1),
299 filter:F2(filter),
300 length:length,
301 member:F2(member),
302 reverse:reverse,
303 concat:concat,
305 all:F2(all),
306 any:F2(any),
307 zipWith:F3(zipWith),
308 zip:F2(zip),
309 sort:sort,
310 sortBy:F2(sortBy),
311 sortWith:F2(sortWith),
312 nth:F2(nth),
313 take:F2(take),
314 drop:F2(drop),
315 repeat:F2(repeat),
317 join:F2(join)
318 };
319 return elm.Native.List.values = Elm.Native.List.values;
321};