1 ! Copyright (C) 2004, 2008 Chris Double, Matthew Willis, James Cash.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors arrays combinators io kernel lists math
4 promises quotations sequences ;
7 M: promise car force car ;
9 M: promise cdr force cdr ;
11 M: promise nil? force nil? ;
13 TUPLE: lazy-cons-state { car promise } { cdr promise } ;
15 C: <lazy-cons-state> lazy-cons-state
17 : lazy-cons ( car cdr -- promise )
18 [ <promise> ] bi@ <lazy-cons-state>
19 [ f t ] dip promise boa ;
21 M: lazy-cons-state car car>> force ;
23 M: lazy-cons-state cdr cdr>> force ;
25 M: lazy-cons-state nil? car nil? ;
27 : 1lazy-list ( a -- lazy-cons )
30 : 2lazy-list ( a b -- lazy-cons )
31 1lazy-list 1quotation lazy-cons ;
33 : 3lazy-list ( a b c -- lazy-cons )
34 2lazy-list 1quotation lazy-cons ;
36 TUPLE: memoized-cons original car cdr nil? ;
38 SYMBOL: +not-memoized+
40 : <memoized-cons> ( cons -- memoized-cons )
41 +not-memoized+ +not-memoized+ +not-memoized+
45 dup car>> +not-memoized+ eq? [
46 dup original>> car [ >>car drop ] keep
52 dup cdr>> +not-memoized+ eq? [
53 dup original>> cdr [ >>cdr drop ] keep
59 dup nil?>> +not-memoized+ eq? [
60 dup original>> nil? [ >>nil? drop ] keep
65 TUPLE: lazy-map cons quot ;
67 C: <lazy-map> lazy-map
69 : lmap-lazy ( list quot -- result )
70 over nil? [ 2drop nil ] [ <lazy-map> <memoized-cons> ] if ;
73 [ cons>> car ] [ quot>> call( old -- new ) ] bi ;
76 [ cons>> cdr ] [ quot>> lmap-lazy ] bi ;
81 TUPLE: lazy-take n cons ;
83 C: <lazy-take> lazy-take
85 : ltake ( n list -- result )
86 over zero? [ 2drop nil ] [ <lazy-take> ] if ;
92 [ n>> 1 - ] [ cons>> cdr ltake ] bi ;
95 dup n>> zero? [ drop t ] [ cons>> nil? ] if ;
97 TUPLE: lazy-until cons quot ;
99 C: <lazy-until> lazy-until
101 : luntil ( list quot: ( elt -- ? ) -- result )
102 over nil? [ drop ] [ <lazy-until> ] if ;
108 [ [ cons>> cdr ] [ quot>> ] bi ]
109 [ [ cons>> car ] [ quot>> ] bi call( elt -- ? ) ] bi
110 [ 2drop nil ] [ luntil ] if ;
115 TUPLE: lazy-while cons quot ;
117 C: <lazy-while> lazy-while
119 : lwhile ( list quot: ( elt -- ? ) -- result )
120 over nil? [ drop ] [ <lazy-while> ] if ;
126 [ cons>> cdr ] keep quot>> lwhile ;
129 [ car ] keep quot>> call( elt -- ? ) not ;
131 TUPLE: lazy-filter cons quot ;
133 C: <lazy-filter> lazy-filter
135 : lfilter ( list quot: ( elt -- ? ) -- result )
136 over nil? [ 2drop nil ] [ <lazy-filter> <memoized-cons> ] if ;
140 : car-filtered? ( lazy-filter -- ? )
141 [ cons>> car ] [ quot>> ] bi call( elt -- ? ) ;
143 : skip ( lazy-filter -- lazy-filter )
144 [ cdr ] change-cons ;
149 dup car-filtered? [ cons>> ] [ skip ] if car ;
153 [ cons>> cdr ] [ quot>> ] bi lfilter
160 { [ dup cons>> nil? ] [ drop t ] }
161 { [ dup car-filtered? ] [ drop f ] }
165 TUPLE: lazy-append list1 list2 ;
167 C: <lazy-append> lazy-append
169 : lappend-lazy ( list1 list2 -- result )
170 over nil? [ nip ] [ <lazy-append> ] if ;
176 [ list1>> cdr ] [ list2>> ] bi lappend-lazy ;
181 TUPLE: lazy-from-by n quot ;
183 : lfrom-by ( n quot: ( n -- o ) -- result ) lazy-from-by boa ; inline
185 : lfrom ( n -- result )
192 [ n>> ] [ quot>> ] bi [ call( old -- new ) ] keep lfrom-by ;
197 TUPLE: lazy-zip list1 list2 ;
199 C: <lazy-zip> lazy-zip
201 : lzip ( list1 list2 -- result )
202 2dup [ nil? ] either?
203 [ 2drop nil ] [ <lazy-zip> ] if ;
206 [ list1>> car ] keep list2>> car 2array ;
209 [ list1>> cdr ] keep list2>> cdr lzip ;
214 TUPLE: sequence-cons index seq ;
216 C: <sequence-cons> sequence-cons
218 : sequence-tail>list ( index seq -- list )
226 [ index>> ] [ seq>> nth ] bi ;
229 [ index>> 1 + ] [ seq>> sequence-tail>list ] bi ;
231 M: sequence-cons nil?
234 M: sequence >list 0 swap sequence-tail>list ;
236 TUPLE: lazy-concat car cdr ;
238 C: <lazy-concat> lazy-concat
244 : (lconcat) ( car cdr -- list )
245 over nil? [ nip lconcat ] [ <lazy-concat> ] if ;
249 : lconcat ( list -- result )
250 dup nil? [ drop nil ] [ uncons (lconcat) ] if ;
256 [ car>> cdr ] keep cdr>> (lconcat) ;
259 dup car>> nil? [ cdr>> nil? ] [ drop f ] if ;
261 : lcartesian-product ( list1 list2 -- result )
262 swap [ swap [ 2array ] with lmap-lazy ] with lmap-lazy lconcat ;
264 : lcartesian-product* ( lists -- result )
269 [ car lcartesian-product ] [ cdr ] bi
271 swap [ swap [ suffix ] with lmap-lazy ] with lmap-lazy lconcat
275 : lcartesian-map ( list quot: ( elt1 elt2 -- newelt ) -- result )
276 [ lcartesian-product* ] dip [ first2 ] prepose lmap-lazy ;
278 : lcartesian-map* ( list guards quot: ( elt1 elt2 -- newelt ) -- result )
279 [ [ [ first2 ] prepose ] map ] [ [ first2 ] prepose ] bi*
280 [ [ lcartesian-product* ] dip [ lfilter ] each ] dip lmap-lazy ;
286 :: (lmerge) ( list1 list2 -- result )
290 [ list1 cdr list2 cdr lmerge ]
296 : lmerge ( list1 list2 -- result )
298 { [ over nil? ] [ nip ] }
299 { [ dup nil? ] [ drop ] }
303 TUPLE: lazy-io stream car cdr quot ;
307 : lcontents ( stream -- result )
308 f f [ stream-read1 ] <lazy-io> ;
310 : llines ( stream -- result )
311 f f [ stream-readln ] <lazy-io> ;
317 dup [ stream>> ] [ quot>> ] bi
318 call( stream -- value ) [ >>car ] [ drop nil ] if*
325 drop dup [ stream>> ] [ quot>> ] [ car ] tri
327 [ f f ] dip <lazy-io> [ >>cdr drop ] keep
336 INSTANCE: sequence-cons list
337 INSTANCE: memoized-cons list
338 INSTANCE: promise list
339 INSTANCE: lazy-io list
340 INSTANCE: lazy-concat list
341 INSTANCE: lazy-cons-state list
342 INSTANCE: lazy-map list
343 INSTANCE: lazy-take list
344 INSTANCE: lazy-append list
345 INSTANCE: lazy-from-by list
346 INSTANCE: lazy-zip list
347 INSTANCE: lazy-while list
348 INSTANCE: lazy-until list
349 INSTANCE: lazy-filter list