-
-
Notifications
You must be signed in to change notification settings - Fork 701
/
primitives.d
2380 lines (2127 loc) · 66.1 KB
/
primitives.d
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/**
This module is a submodule of $(MREF std, range).
It provides basic range functionality by defining several templates for testing
whether a given object is a _range, and what kind of _range it is:
$(SCRIPT inhibitQuickIndex = 1;)
$(BOOKTABLE ,
$(TR $(TD $(LREF isInputRange))
$(TD Tests if something is an $(I input _range), defined to be
something from which one can sequentially read data using the
primitives $(D front), $(D popFront), and $(D empty).
))
$(TR $(TD $(LREF isOutputRange))
$(TD Tests if something is an $(I output _range), defined to be
something to which one can sequentially write data using the
$(LREF put) primitive.
))
$(TR $(TD $(LREF isForwardRange))
$(TD Tests if something is a $(I forward _range), defined to be an
input _range with the additional capability that one can save one's
current position with the $(D save) primitive, thus allowing one to
iterate over the same _range multiple times.
))
$(TR $(TD $(LREF isBidirectionalRange))
$(TD Tests if something is a $(I bidirectional _range), that is, a
forward _range that allows reverse traversal using the primitives $(D
back) and $(D popBack).
))
$(TR $(TD $(LREF isRandomAccessRange))
$(TD Tests if something is a $(I random access _range), which is a
bidirectional _range that also supports the array subscripting
operation via the primitive $(D opIndex).
))
)
It also provides number of templates that test for various _range capabilities:
$(BOOKTABLE ,
$(TR $(TD $(LREF hasMobileElements))
$(TD Tests if a given _range's elements can be moved around using the
primitives $(D moveFront), $(D moveBack), or $(D moveAt).
))
$(TR $(TD $(LREF ElementType))
$(TD Returns the element type of a given _range.
))
$(TR $(TD $(LREF ElementEncodingType))
$(TD Returns the encoding element type of a given _range.
))
$(TR $(TD $(LREF hasSwappableElements))
$(TD Tests if a _range is a forward _range with swappable elements.
))
$(TR $(TD $(LREF hasAssignableElements))
$(TD Tests if a _range is a forward _range with mutable elements.
))
$(TR $(TD $(LREF hasLvalueElements))
$(TD Tests if a _range is a forward _range with elements that can be
passed by reference and have their address taken.
))
$(TR $(TD $(LREF hasLength))
$(TD Tests if a given _range has the $(D length) attribute.
))
$(TR $(TD $(LREF isInfinite))
$(TD Tests if a given _range is an $(I infinite _range).
))
$(TR $(TD $(LREF hasSlicing))
$(TD Tests if a given _range supports the array slicing operation $(D
R[x .. y]).
))
)
Finally, it includes some convenience functions for manipulating ranges:
$(BOOKTABLE ,
$(TR $(TD $(LREF popFrontN))
$(TD Advances a given _range by up to $(I n) elements.
))
$(TR $(TD $(LREF popBackN))
$(TD Advances a given bidirectional _range from the right by up to
$(I n) elements.
))
$(TR $(TD $(LREF popFrontExactly))
$(TD Advances a given _range by up exactly $(I n) elements.
))
$(TR $(TD $(LREF popBackExactly))
$(TD Advances a given bidirectional _range from the right by exactly
$(I n) elements.
))
$(TR $(TD $(LREF moveFront))
$(TD Removes the front element of a _range.
))
$(TR $(TD $(LREF moveBack))
$(TD Removes the back element of a bidirectional _range.
))
$(TR $(TD $(LREF moveAt))
$(TD Removes the $(I i)'th element of a random-access _range.
))
$(TR $(TD $(LREF walkLength))
$(TD Computes the length of any _range in O(n) time.
))
$(TR $(TD $(LREF put))
$(TD Outputs element $(D e) to a _range.
))
)
Source: $(PHOBOSSRC std/range/_primitives.d)
License: $(HTTP boost.org/LICENSE_1_0.txt, Boost License 1.0).
Authors: $(HTTP erdani.com, Andrei Alexandrescu), David Simcha,
and Jonathan M Davis. Credit for some of the ideas in building this module goes
to $(HTTP fantascienza.net/leonardo/so/, Leonardo Maffi).
*/
module std.range.primitives;
import std.traits;
/**
Returns $(D true) if $(D R) is an input range. An input range must
define the primitives $(D empty), $(D popFront), and $(D front). The
following code should compile for any input range.
----
R r; // can define a range object
if (r.empty) {} // can test for empty
r.popFront(); // can invoke popFront()
auto h = r.front; // can get the front of the range of non-void type
----
The following are rules of input ranges are assumed to hold true in all
Phobos code. These rules are not checkable at compile-time, so not conforming
to these rules when writing ranges or range based code will result in
undefined behavior.
$(UL
$(LI `r.empty` returns `false` if and only if there is more data
available in the range.)
$(LI `r.empty` evaluated multiple times, without calling
`r.popFront`, or otherwise mutating the range object or the
underlying data, yields the same result for every evaluation.)
$(LI `r.front` returns the current element in the range.
It may return by value or by reference.)
$(LI `r.front` can be legally evaluated if and only if evaluating
`r.empty` has, or would have, equaled `false`.)
$(LI `r.front` evaluated multiple times, without calling
`r.popFront`, or otherwise mutating the range object or the
underlying data, yields the same result for every evaluation.)
$(LI `r.popFront` advances to the next element in the range.)
$(LI `r.popFront` can be called if and only if evaluating `r.empty`
has, or would have, equaled `false`.)
)
Also, note that Phobos code assumes that the primitives `r.front` and
`r.empty` are $(BIGOH 1) time complexity wise or "cheap" in terms of
running time. $(BIGOH) statements in the documentation of range functions
are made with this assumption.
Params:
R = type to be tested
Returns:
true if R is an InputRange, false if not
*/
template isInputRange(R)
{
enum bool isInputRange = is(typeof(
(inout int = 0)
{
R r = R.init; // can define a range object
if (r.empty) {} // can test for empty
r.popFront; // can invoke popFront()
auto h = r.front; // can get the front of the range
}));
}
///
@safe unittest
{
struct A {}
struct B
{
void popFront();
@property bool empty();
@property int front();
}
static assert(!isInputRange!A);
static assert( isInputRange!B);
static assert( isInputRange!(int[]));
static assert( isInputRange!(char[]));
static assert(!isInputRange!(char[4]));
static assert( isInputRange!(inout(int)[]));
}
/+
puts the whole raw element $(D e) into $(D r). doPut will not attempt to
iterate, slice or transcode $(D e) in any way shape or form. It will $(B only)
call the correct primitive ($(D r.put(e)), $(D r.front = e) or
$(D r(0)) once.
This can be important when $(D e) needs to be placed in $(D r) unchanged.
Furthermore, it can be useful when working with $(D InputRange)s, as doPut
guarantees that no more than a single element will be placed.
+/
private void doPut(R, E)(ref R r, auto ref E e)
{
static if (is(PointerTarget!R == struct))
enum usingPut = hasMember!(PointerTarget!R, "put");
else
enum usingPut = hasMember!(R, "put");
static if (usingPut)
{
static assert(is(typeof(r.put(e))),
"Cannot put a " ~ E.stringof ~ " into a " ~ R.stringof ~ ".");
r.put(e);
}
else static if (isInputRange!R)
{
static assert(is(typeof(r.front = e)),
"Cannot put a " ~ E.stringof ~ " into a " ~ R.stringof ~ ".");
r.front = e;
r.popFront();
}
else static if (is(typeof(r(e))))
{
r(e);
}
else
{
static assert(false,
"Cannot put a " ~ E.stringof ~ " into a " ~ R.stringof ~ ".");
}
}
@safe unittest
{
static assert(!isNativeOutputRange!(int, int));
static assert( isNativeOutputRange!(int[], int));
static assert(!isNativeOutputRange!(int[][], int));
static assert(!isNativeOutputRange!(int, int[]));
static assert(!isNativeOutputRange!(int[], int[]));
static assert( isNativeOutputRange!(int[][], int[]));
static assert(!isNativeOutputRange!(int, int[][]));
static assert(!isNativeOutputRange!(int[], int[][]));
static assert(!isNativeOutputRange!(int[][], int[][]));
static assert(!isNativeOutputRange!(int[4], int));
static assert( isNativeOutputRange!(int[4][], int)); //Scary!
static assert( isNativeOutputRange!(int[4][], int[4]));
static assert(!isNativeOutputRange!( char[], char));
static assert(!isNativeOutputRange!( char[], dchar));
static assert( isNativeOutputRange!(dchar[], char));
static assert( isNativeOutputRange!(dchar[], dchar));
}
/++
Outputs $(D e) to $(D r). The exact effect is dependent upon the two
types. Several cases are accepted, as described below. The code snippets
are attempted in order, and the first to compile "wins" and gets
evaluated.
In this table "doPut" is a method that places $(D e) into $(D r), using the
correct primitive: $(D r.put(e)) if $(D R) defines $(D put), $(D r.front = e)
if $(D r) is an input range (followed by $(D r.popFront())), or $(D r(e))
otherwise.
$(BOOKTABLE ,
$(TR
$(TH Code Snippet)
$(TH Scenario)
)
$(TR
$(TD $(D r.doPut(e);))
$(TD $(D R) specifically accepts an $(D E).)
)
$(TR
$(TD $(D r.doPut([ e ]);))
$(TD $(D R) specifically accepts an $(D E[]).)
)
$(TR
$(TD $(D r.putChar(e);))
$(TD $(D R) accepts some form of string or character. put will
transcode the character $(D e) accordingly.)
)
$(TR
$(TD $(D for (; !e.empty; e.popFront()) put(r, e.front);))
$(TD Copying range $(D E) into $(D R).)
)
)
Tip: $(D put) should $(I not) be used "UFCS-style", e.g. $(D r.put(e)).
Doing this may call $(D R.put) directly, by-passing any transformation
feature provided by $(D Range.put). $(D put(r, e)) is prefered.
+/
void put(R, E)(ref R r, E e)
{
//First level: simply straight up put.
static if (is(typeof(doPut(r, e))))
{
doPut(r, e);
}
//Optional optimization block for straight up array to array copy.
else static if (isDynamicArray!R && !isNarrowString!R && isDynamicArray!E && is(typeof(r[] = e[])))
{
immutable len = e.length;
r[0 .. len] = e[];
r = r[len .. $];
}
//Accepts E[] ?
else static if (is(typeof(doPut(r, [e]))) && !isDynamicArray!R)
{
if (__ctfe)
{
E[1] arr = [e];
doPut(r, arr[]);
}
else
doPut(r, (ref e) @trusted { return (&e)[0 .. 1]; }(e));
}
//special case for char to string.
else static if (isSomeChar!E && is(typeof(putChar(r, e))))
{
putChar(r, e);
}
//Extract each element from the range
//We can use "put" here, so we can recursively test a RoR of E.
else static if (isInputRange!E && is(typeof(put(r, e.front))))
{
//Special optimization: If E is a narrow string, and r accepts characters no-wider than the string's
//Then simply feed the characters 1 by 1.
static if (isNarrowString!E && (
(is(E : const char[]) && is(typeof(doPut(r, char.max))) && !is(typeof(doPut(r, dchar.max))) &&
!is(typeof(doPut(r, wchar.max)))) ||
(is(E : const wchar[]) && is(typeof(doPut(r, wchar.max))) && !is(typeof(doPut(r, dchar.max)))) ) )
{
foreach (c; e)
doPut(r, c);
}
else
{
for (; !e.empty; e.popFront())
put(r, e.front);
}
}
else
{
static assert(false, "Cannot put a " ~ E.stringof ~ " into a " ~ R.stringof ~ ".");
}
}
@safe pure nothrow @nogc unittest
{
static struct R() { void put(in char[]) {} }
R!() r;
put(r, 'a');
}
//Helper function to handle chars as quickly and as elegantly as possible
//Assumes r.put(e)/r(e) has already been tested
private void putChar(R, E)(ref R r, E e)
if (isSomeChar!E)
{
////@@@9186@@@: Can't use (E[]).init
ref const( char)[] cstringInit();
ref const(wchar)[] wstringInit();
ref const(dchar)[] dstringInit();
enum csCond = !isDynamicArray!R && is(typeof(doPut(r, cstringInit())));
enum wsCond = !isDynamicArray!R && is(typeof(doPut(r, wstringInit())));
enum dsCond = !isDynamicArray!R && is(typeof(doPut(r, dstringInit())));
//Use "max" to avoid static type demotion
enum ccCond = is(typeof(doPut(r, char.max)));
enum wcCond = is(typeof(doPut(r, wchar.max)));
//enum dcCond = is(typeof(doPut(r, dchar.max)));
//Fast transform a narrow char into a wider string
static if ((wsCond && E.sizeof < wchar.sizeof) || (dsCond && E.sizeof < dchar.sizeof))
{
enum w = wsCond && E.sizeof < wchar.sizeof;
Select!(w, wchar, dchar) c = e;
typeof(c)[1] arr = [c];
doPut(r, arr[]);
}
//Encode a wide char into a narrower string
else static if (wsCond || csCond)
{
import std.utf : encode;
/+static+/ Select!(wsCond, wchar[2], char[4]) buf; //static prevents purity.
doPut(r, buf[0 .. encode(buf, e)]);
}
//Slowly encode a wide char into a series of narrower chars
else static if (wcCond || ccCond)
{
import std.encoding : encode;
alias C = Select!(wcCond, wchar, char);
encode!(C, R)(e, r);
}
else
{
static assert(false, "Cannot put a " ~ E.stringof ~ " into a " ~ R.stringof ~ ".");
}
}
pure @safe unittest
{
auto f = delegate (const(char)[]) {};
putChar(f, cast(dchar)'a');
}
@safe pure unittest
{
static struct R() { void put(in char[]) {} }
R!() r;
putChar(r, 'a');
}
@safe unittest
{
struct A {}
static assert(!isInputRange!(A));
struct B
{
void put(int) {}
}
B b;
put(b, 5);
}
@safe unittest
{
int[] a = [1, 2, 3], b = [10, 20];
auto c = a;
put(a, b);
assert(c == [10, 20, 3]);
assert(a == [3]);
}
@safe unittest
{
int[] a = new int[10];
int b;
static assert(isInputRange!(typeof(a)));
put(a, b);
}
@safe unittest
{
void myprint(in char[] s) { }
auto r = &myprint;
put(r, 'a');
}
@safe unittest
{
int[] a = new int[10];
static assert(!__traits(compiles, put(a, 1.0L)));
put(a, 1);
assert(a.length == 9);
/*
* a[0] = 65; // OK
* a[0] = 'A'; // OK
* a[0] = "ABC"[0]; // OK
* put(a, "ABC"); // OK
*/
put(a, "ABC");
assert(a.length == 6);
}
@safe unittest
{
char[] a = new char[10];
static assert(!__traits(compiles, put(a, 1.0L)));
static assert(!__traits(compiles, put(a, 1)));
// char[] is NOT output range.
static assert(!__traits(compiles, put(a, 'a')));
static assert(!__traits(compiles, put(a, "ABC")));
}
@safe unittest
{
int[][] a = new int[][10];
int[] b = new int[10];
int c;
put(b, c);
assert(b.length == 9);
put(a, b);
assert(a.length == 9);
static assert(!__traits(compiles, put(a, c)));
}
@safe unittest
{
int[][] a = new int[][](3);
int[] b = [1];
auto aa = a;
put(aa, b);
assert(aa == [[], []]);
assert(a == [[1], [], []]);
int[][3] c = [2];
aa = a;
put(aa, c[]);
assert(aa.empty);
assert(a == [[2], [2], [2]]);
}
@safe unittest
{
// Test fix for bug 7476.
struct LockingTextWriter
{
void put(dchar c){}
}
struct RetroResult
{
bool end = false;
@property bool empty() const { return end; }
@property dchar front(){ return 'a'; }
void popFront(){ end = true; }
}
LockingTextWriter w;
RetroResult r;
put(w, r);
}
@system unittest
{
import std.conv : to;
import std.meta : AliasSeq;
import std.typecons : tuple;
static struct PutC(C)
{
string result;
void put(const(C) c) { result ~= to!string((&c)[0 .. 1]); }
}
static struct PutS(C)
{
string result;
void put(const(C)[] s) { result ~= to!string(s); }
}
static struct PutSS(C)
{
string result;
void put(const(C)[][] ss)
{
foreach (s; ss)
result ~= to!string(s);
}
}
PutS!char p;
putChar(p, cast(dchar)'a');
//Source Char
foreach (SC; AliasSeq!(char, wchar, dchar))
{
SC ch = 'I';
dchar dh = '♥';
immutable(SC)[] s = "日本語!";
immutable(SC)[][] ss = ["日本語", "が", "好き", "ですか", "?"];
//Target Char
foreach (TC; AliasSeq!(char, wchar, dchar))
{
//Testing PutC and PutS
foreach (Type; AliasSeq!(PutC!TC, PutS!TC))
(){ // avoid slow optimizations for large functions @@@BUG@@@ 2396
Type type;
auto sink = new Type();
//Testing put and sink
foreach (value ; tuple(type, sink))
{
put(value, ch);
assert(value.result == "I");
put(value, dh);
assert(value.result == "I♥");
put(value, s);
assert(value.result == "I♥日本語!");
put(value, ss);
assert(value.result == "I♥日本語!日本語が好きですか?");
}
}();
}
}
}
@safe unittest
{
static struct CharRange
{
char c;
enum empty = false;
void popFront(){}
ref char front() return @property
{
return c;
}
}
CharRange c;
put(c, cast(dchar)'H');
put(c, "hello"d);
}
@system unittest
{
// issue 9823
const(char)[] r;
void delegate(const(char)[]) dg = (s) { r = s; };
put(dg, ["ABC"]);
assert(r == "ABC");
}
@safe unittest
{
// issue 10571
import std.format;
string buf;
formattedWrite((in char[] s) { buf ~= s; }, "%s", "hello");
assert(buf == "hello");
}
@safe unittest
{
import std.format;
import std.meta : AliasSeq;
struct PutC(C)
{
void put(C){}
}
struct PutS(C)
{
void put(const(C)[]){}
}
struct CallC(C)
{
void opCall(C){}
}
struct CallS(C)
{
void opCall(const(C)[]){}
}
struct FrontC(C)
{
enum empty = false;
auto front()@property{return C.init;}
void front(C)@property{}
void popFront(){}
}
struct FrontS(C)
{
enum empty = false;
auto front()@property{return C[].init;}
void front(const(C)[])@property{}
void popFront(){}
}
void foo()
{
foreach (C; AliasSeq!(char, wchar, dchar))
{
formattedWrite((C c){}, "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite((const(C)[]){}, "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite(PutC!C(), "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite(PutS!C(), "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
CallC!C callC;
CallS!C callS;
formattedWrite(callC, "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite(callS, "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite(FrontC!C(), "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
formattedWrite(FrontS!C(), "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
}
formattedWrite((dchar[]).init, "", 1, 'a', cast(wchar)'a', cast(dchar)'a', "a"c, "a"w, "a"d);
}
}
/+
Returns $(D true) if $(D R) is a native output range for elements of type
$(D E). An output range is defined functionally as a range that
supports the operation $(D doPut(r, e)) as defined above. if $(D doPut(r, e))
is valid, then $(D put(r,e)) will have the same behavior.
The two guarantees isNativeOutputRange gives over the larger $(D isOutputRange)
are:
1: $(D e) is $(B exactly) what will be placed (not $(D [e]), for example).
2: if $(D E) is a non $(empty) $(D InputRange), then placing $(D e) is
guaranteed to not overflow the range.
+/
package(std) template isNativeOutputRange(R, E)
{
enum bool isNativeOutputRange = is(typeof(
(inout int = 0)
{
R r = void;
E e;
doPut(r, e);
}));
}
@safe unittest
{
int[] r = new int[](4);
static assert(isInputRange!(int[]));
static assert( isNativeOutputRange!(int[], int));
static assert(!isNativeOutputRange!(int[], int[]));
static assert( isOutputRange!(int[], int[]));
if (!r.empty)
put(r, 1); //guaranteed to succeed
if (!r.empty)
put(r, [1, 2]); //May actually error out.
}
/++
Returns $(D true) if $(D R) is an output range for elements of type
$(D E). An output range is defined functionally as a range that
supports the operation $(D put(r, e)) as defined above.
+/
template isOutputRange(R, E)
{
enum bool isOutputRange = is(typeof(
(inout int = 0)
{
R r = R.init;
E e = E.init;
put(r, e);
}));
}
///
@safe unittest
{
void myprint(in char[] s) { }
static assert(isOutputRange!(typeof(&myprint), char));
static assert(!isOutputRange!(char[], char));
static assert( isOutputRange!(dchar[], wchar));
static assert( isOutputRange!(dchar[], dchar));
}
@safe unittest
{
import std.array;
import std.stdio : writeln;
auto app = appender!string();
string s;
static assert( isOutputRange!(Appender!string, string));
static assert( isOutputRange!(Appender!string*, string));
static assert(!isOutputRange!(Appender!string, int));
static assert(!isOutputRange!(wchar[], wchar));
static assert( isOutputRange!(dchar[], char));
static assert( isOutputRange!(dchar[], string));
static assert( isOutputRange!(dchar[], wstring));
static assert( isOutputRange!(dchar[], dstring));
static assert(!isOutputRange!(const(int)[], int));
static assert(!isOutputRange!(inout(int)[], int));
}
/**
Returns $(D true) if $(D R) is a forward range. A forward range is an
input range $(D r) that can save "checkpoints" by saving $(D r.save)
to another value of type $(D R). Notable examples of input ranges that
are $(I not) forward ranges are file/socket ranges; copying such a
range will not save the position in the stream, and they most likely
reuse an internal buffer as the entire stream does not sit in
memory. Subsequently, advancing either the original or the copy will
advance the stream, so the copies are not independent.
The following code should compile for any forward range.
----
static assert(isInputRange!R);
R r1;
auto s1 = r1.save;
static assert(is(typeof(s1) == R));
----
Saving a range is not duplicating it; in the example above, $(D r1)
and $(D r2) still refer to the same underlying data. They just
navigate that data independently.
The semantics of a forward range (not checkable during compilation)
are the same as for an input range, with the additional requirement
that backtracking must be possible by saving a copy of the range
object with $(D save) and using it later.
*/
template isForwardRange(R)
{
enum bool isForwardRange = isInputRange!R && is(typeof(
(inout int = 0)
{
R r1 = R.init;
// NOTE: we cannot check typeof(r1.save) directly
// because typeof may not check the right type there, and
// because we want to ensure the range can be copied.
auto s1 = r1.save;
static assert(is(typeof(s1) == R));
}));
}
///
@safe unittest
{
static assert(!isForwardRange!(int));
static assert( isForwardRange!(int[]));
static assert( isForwardRange!(inout(int)[]));
}
@safe unittest
{
// BUG 14544
struct R14544
{
int front() { return 0;}
void popFront() {}
bool empty() { return false; }
R14544 save() {return this;}
}
static assert( isForwardRange!R14544 );
}
/**
Returns $(D true) if $(D R) is a bidirectional range. A bidirectional
range is a forward range that also offers the primitives $(D back) and
$(D popBack). The following code should compile for any bidirectional
range.
The semantics of a bidirectional range (not checkable during
compilation) are assumed to be the following ($(D r) is an object of
type $(D R)):
$(UL $(LI $(D r.back) returns (possibly a reference to) the last
element in the range. Calling $(D r.back) is allowed only if calling
$(D r.empty) has, or would have, returned $(D false).))
*/
template isBidirectionalRange(R)
{
enum bool isBidirectionalRange = isForwardRange!R && is(typeof(
(inout int = 0)
{
R r = R.init;
r.popBack;
auto t = r.back;
auto w = r.front;
static assert(is(typeof(t) == typeof(w)));
}));
}
///
@safe unittest
{
alias R = int[];
R r = [0,1];
static assert(isForwardRange!R); // is forward range
r.popBack(); // can invoke popBack
auto t = r.back; // can get the back of the range
auto w = r.front;
static assert(is(typeof(t) == typeof(w))); // same type for front and back
}
@safe unittest
{
struct A {}
struct B
{
void popFront();
@property bool empty();
@property int front();
}
struct C
{
@property bool empty();
@property C save();
void popFront();
@property int front();
void popBack();
@property int back();
}
static assert(!isBidirectionalRange!(A));
static assert(!isBidirectionalRange!(B));
static assert( isBidirectionalRange!(C));
static assert( isBidirectionalRange!(int[]));
static assert( isBidirectionalRange!(char[]));
static assert( isBidirectionalRange!(inout(int)[]));
}
/**
Returns $(D true) if $(D R) is a random-access range. A random-access
range is a bidirectional range that also offers the primitive $(D
opIndex), OR an infinite forward range that offers $(D opIndex). In
either case, the range must either offer $(D length) or be
infinite. The following code should compile for any random-access
range.
The semantics of a random-access range (not checkable during
compilation) are assumed to be the following ($(D r) is an object of
type $(D R)): $(UL $(LI $(D r.opIndex(n)) returns a reference to the
$(D n)th element in the range.))
Although $(D char[]) and $(D wchar[]) (as well as their qualified
versions including $(D string) and $(D wstring)) are arrays, $(D
isRandomAccessRange) yields $(D false) for them because they use
variable-length encodings (UTF-8 and UTF-16 respectively). These types
are bidirectional ranges only.
*/
template isRandomAccessRange(R)
{
enum bool isRandomAccessRange = is(typeof(
(inout int = 0)
{
static assert(isBidirectionalRange!R ||
isForwardRange!R && isInfinite!R);
R r = R.init;
auto e = r[1];
auto f = r.front;
static assert(is(typeof(e) == typeof(f)));
static assert(!isNarrowString!R);
static assert(hasLength!R || isInfinite!R);
static if (is(typeof(r[$])))
{
static assert(is(typeof(f) == typeof(r[$])));
static if (!isInfinite!R)
static assert(is(typeof(f) == typeof(r[$ - 1])));
}
}));
}
///
@safe unittest
{
import std.traits : isNarrowString;
alias R = int[];
// range is finite and bidirectional or infinite and forward.
static assert(isBidirectionalRange!R ||
isForwardRange!R && isInfinite!R);
R r = [0,1];
auto e = r[1]; // can index
auto f = r.front;
static assert(is(typeof(e) == typeof(f))); // same type for indexed and front
static assert(!isNarrowString!R); // narrow strings cannot be indexed as ranges
static assert(hasLength!R || isInfinite!R); // must have length or be infinite
// $ must work as it does with arrays if opIndex works with $
static if (is(typeof(r[$])))
{
static assert(is(typeof(f) == typeof(r[$])));
// $ - 1 doesn't make sense with infinite ranges but needs to work
// with finite ones.
static if (!isInfinite!R)
static assert(is(typeof(f) == typeof(r[$ - 1])));
}
}
@safe unittest
{
struct A {}
struct B
{
void popFront();
@property bool empty();
@property int front();
}
struct C
{
void popFront();
@property bool empty();
@property int front();
void popBack();
@property int back();
}
struct D
{
@property bool empty();
@property D save();
@property int front();
void popFront();
@property int back();
void popBack();
ref int opIndex(uint);
@property size_t length();
alias opDollar = length;
//int opSlice(uint, uint);
}
struct E
{
bool empty();