-
-
Notifications
You must be signed in to change notification settings - Fork 1.6k
/
object.cr
1425 lines (1352 loc) · 36.3 KB
/
object.cr
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
# `Object` is the base type of all Crystal objects.
class Object
# Returns `true` if this object is equal to *other*.
#
# Subclasses override this method to provide class-specific meaning.
abstract def ==(other)
# Returns `true` if this object is not equal to *other*.
#
# By default this method is implemented as `!(self == other)`
# so there's no need to override this unless there's a more efficient
# way to do it.
def !=(other)
!(self == other)
end
# Shortcut to `!(self =~ other)`.
def !~(other)
!(self =~ other)
end
# Case equality.
#
# The `===` method is used in a `case ... when ... end` expression.
#
# For example, this code:
#
# ```
# case value
# when x
# # something when x
# when y
# # something when y
# end
# ```
#
# Is equivalent to this code:
#
# ```
# if x === value
# # something when x
# elsif y === value
# # something when y
# end
# ```
#
# Object simply implements `===` by invoking `==`, but subclasses
# (notably `Regex`) can override it to provide meaningful case-equality semantics.
def ===(other)
self == other
end
# Pattern match.
#
# Overridden by descendants (notably `Regex` and `String`) to provide meaningful
# pattern-match semantics.
def =~(other)
nil
end
# Appends this object's value to *hasher*, and returns the modified *hasher*.
#
# Usually the macro `def_hash` can be used to generate this method.
# Otherwise, invoke `hash(hasher)` on each object's instance variables to
# accumulate the result:
#
# ```
# def hash(hasher)
# hasher = @some_ivar.hash(hasher)
# hasher = @some_other_ivar.hash(hasher)
# hasher
# end
# ```
abstract def hash(hasher)
# Generates an `UInt64` hash value for this object.
#
# This method must have the property that `a == b` implies `a.hash == b.hash`.
#
# The hash value is used along with `==` by the `Hash` class to determine if two objects
# reference the same hash key.
#
# Subclasses must not override this method. Instead, they must define `hash(hasher)`,
# though usually the macro `def_hash` can be used to generate this method.
def hash
hash(Crystal::Hasher.new).result
end
# Returns a string representation of this object.
#
# Descendants must usually **not** override this method. Instead,
# they must override `to_s(io)`, which must append to the given
# IO object.
def to_s : String
String.build do |io|
to_s io
end
end
# Appends a `String` representation of this object
# to the given `IO` object.
#
# An object must never append itself to the io argument,
# as this will in turn call `to_s(io)` on it.
abstract def to_s(io : IO) : Nil
# Returns a `String` representation of this object suitable
# to be embedded inside other expressions, sometimes providing
# more information about this object.
#
# `#inspect` (and `#inspect(io)`) are the methods used when
# you invoke `#to_s` or `#inspect` on an object that holds
# other objects and wants to show them. For example when you
# invoke `Array#to_s`, `#inspect` will be invoked on each element:
#
# ```
# ary = ["one", "two", "three, etc."]
# ary.inspect # => ["one", "two", "three, etc."]
# ```
#
# Note that if Array invoked `#to_s` on each of the elements
# above, the output would have been this:
#
# ```
# ary = ["one", "two", "three, etc."]
# # If inspect invoked to_s on each element...
# ary.inspect # => [one, two, three, etc.]
# ```
#
# Note that it's not clear how many elements the array has,
# or which are they, because `#to_s` doesn't guarantee that
# the string representation is clearly delimited (in the case
# of `String` the quotes are not shown).
#
# Also note that sometimes the output of `#inspect` will look
# like a Crystal expression that will compile, but this isn't
# always the case, nor is it necessary. Notably, `Reference#inspect`
# and `Struct#inspect` return values that don't compile.
#
# Classes must usually **not** override this method. Instead,
# they must override `inspect(io)`, which must append to the
# given `IO` object.
def inspect : String
String.build do |io|
inspect io
end
end
# Appends a string representation of this object
# to the given `IO` object.
#
# Similar to `to_s(io)`, but usually appends more information
# about this object.
# See `#inspect`.
def inspect(io : IO) : Nil
to_s io
end
# Pretty prints `self` into the given printer.
#
# By default appends a text that is the result of invoking
# `#inspect` on `self`. Subclasses should override
# for custom pretty printing.
def pretty_print(pp : PrettyPrint) : Nil
pp.text(inspect)
end
# Returns a pretty printed version of `self`.
def pretty_inspect(width = 79, newline = "\n", indent = 0) : String
String.build do |io|
PrettyPrint.format(self, io, width, newline, indent)
end
end
# Yields `self` to the block, and then returns `self`.
#
# The primary purpose of this method is to "tap into" a method chain,
# in order to perform operations on intermediate results within the chain.
#
# ```
# (1..10).tap { |x| puts "original: #{x.inspect}" }
# .to_a.tap { |x| puts "array: #{x.inspect}" }
# .select { |x| x % 2 == 0 }.tap { |x| puts "evens: #{x.inspect}" }
# .map { |x| x*x }.tap { |x| puts "squares: #{x.inspect}" }
# ```
def tap
yield self
self
end
# Yields `self`. `Nil` overrides this method and doesn't yield.
#
# This method is useful for dealing with nilable types, to safely
# perform operations only when the value is not `nil`.
#
# ```
# # First program argument in downcase, or nil
# ARGV[0]?.try &.downcase
# ```
def try
yield self
end
# Returns `true` if `self` is included in the *collection* argument.
#
# ```
# 10.in?(0..100) # => true
# 10.in?({0, 1, 10}) # => true
# 10.in?(0, 1, 10) # => true
# 10.in?(:foo, :bar) # => false
# ```
def in?(collection) : Bool
collection.includes?(self)
end
# :ditto:
def in?(*values : Object) : Bool
in?(values)
end
# Returns `self`.
# `Nil` overrides this method and raises `NilAssertionError`, see `Nil#not_nil!`.
def not_nil!
self
end
# Returns `self`.
#
# ```
# str = "hello"
# str.itself.object_id == str.object_id # => true
# ```
def itself
self
end
# Returns a shallow copy (“duplicate”) of this object.
#
# In order to create a new object with the same value as an existing one, there
# are two possible routes:
#
# * create a *shallow copy* (`#dup`): Constructs a new object with all its
# properties' values identical to the original object's properties. They
# are shared references. That means for mutable values that changes to
# either object's values will be present in both's.
# * create a *deep copy* (`#clone`): Constructs a new object with all its
# properties' values being recursive deep copies of the original object's
# properties.
# There is no shared state and the new object is a completely independent
# copy, including everything inside it. This may not be available for every
# type.
#
# A shallow copy is only one level deep whereas a deep copy copies everything
# below.
#
# This distinction is only relevant for compound values. Primitive types
# do not have any properties that could be shared or cloned.
# In that case, `dup` and `clone` are exactly the same.
#
# The `#clone` method can't be defined on `Object`. It's not
# generically available for every type because cycles could be involved, and
# the clone logic might not need to clone everything.
#
# Many types in the standard library, like `Array`, `Hash`, `Set` and
# `Deque`, and all primitive types, define `dup` and `clone`.
#
# Example:
#
# ```
# original = {"foo" => [1, 2, 3]}
# shallow_copy = original.dup
# deep_copy = original.clone
#
# # "foo" references the same array object for both original and shallow copy,
# # but not for a deep copy:
# original["foo"] << 4
# shallow_copy["foo"] # => [1, 2, 3, 4]
# deep_copy["foo"] # => [1, 2, 3]
#
# # Assigning new value does not share it to either copy:
# original["foo"] = [1]
# shallow_copy["foo"] # => [1, 2, 3, 4]
# deep_copy["foo"] # => [1, 2, 3]
# ```
abstract def dup
# Unsafely reinterprets the bytes of an object as being of another `type`.
#
# This method is useful to treat a type that is represented as a chunk of
# bytes as another type where those bytes convey useful information. As an
# example, you can check the individual bytes of an `Int32`:
#
# ```
# 0x01020304.unsafe_as(StaticArray(UInt8, 4)) # => StaticArray[4, 3, 2, 1]
# ```
#
# Or treat the bytes of a `Float64` as an `Int64`:
#
# ```
# 1.234_f64.unsafe_as(Int64) # => 4608236261112822104
# ```
#
# This method is **unsafe** because it behaves unpredictably when the given
# `type` doesn't have the same bytesize as the receiver, or when the given
# `type` representation doesn't semantically match the underlying bytes.
#
# Also note that because `unsafe_as` is a regular method, unlike the pseudo-method
# `as`, you can't specify some types in the type grammar using a short notation, so
# specifying a static array must always be done as `StaticArray(T, N)`, a tuple
# as `Tuple(...)` and so on, never as `UInt8[4]` or `{Int32, Int32}`.
def unsafe_as(type : T.class) forall T
x = self
pointerof(x).as(T*).value
end
{% for prefixes in { {"", "", "@", "#"}, {"class_", "self.", "@@", "."} } %}
{%
macro_prefix = prefixes[0].id
method_prefix = prefixes[1].id
var_prefix = prefixes[2].id
doc_prefix = prefixes[3].id
%}
# Defines getter methods for each of the given arguments.
#
# Writing:
#
# ```
# class Person
# {{macro_prefix}}getter name
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}name
# {{var_prefix}}name
# end
# end
# ```
#
# The arguments can be string literals, symbol literals or plain names:
#
# ```
# class Person
# {{macro_prefix}}getter :name, "age"
# end
# ```
#
# If a type declaration is given, a variable with that name
# is declared with that type.
#
# ```
# class Person
# {{macro_prefix}}getter name : String
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String
#
# def {{method_prefix}}name : String
# {{var_prefix}}name
# end
# end
# ```
#
# The type declaration can also include an initial value:
#
# ```
# class Person
# {{macro_prefix}}getter name : String = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String = "John Doe"
#
# def {{method_prefix}}name : String
# {{var_prefix}}name
# end
# end
# ```
#
# An assignment can be passed too, but in this case the type of the
# variable must be easily inferable from the initial value:
#
# ```
# class Person
# {{macro_prefix}}getter name = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name = "John Doe"
#
# def {{method_prefix}}name : String
# {{var_prefix}}name
# end
# end
# ```
#
# If a block is given to the macro, a getter is generated
# with a variable that is lazily initialized with
# the block's contents:
#
# ```
# class Person
# {{macro_prefix}}getter(birth_date) { Time.local }
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}birth_date
# if (value = {{var_prefix}}birth_date).nil?
# {{var_prefix}}birth_date = Time.local
# else
# value
# end
# end
# end
# ```
macro {{macro_prefix}}getter(*names, &block)
\{% if block %}
\{% if names.size != 1 %}
\{{ raise "Only one argument can be passed to `getter` with a block" }}
\{% end %}
\{% name = names[0] %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name.var.id}} : \{{name.type}}?
def {{method_prefix}}\{{name.var.id}} : \{{name.type}}
if (value = {{var_prefix}}\{{name.var.id}}).nil?
{{var_prefix}}\{{name.var.id}} = \{{yield}}
else
value
end
end
\{% else %}
def {{method_prefix}}\{{name.id}}
if (value = {{var_prefix}}\{{name.id}}).nil?
{{var_prefix}}\{{name.id}} = \{{yield}}
else
value
end
end
\{% end %}
\{% else %}
\{% for name in names %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.var.id}} : \{{name.type}}
{{var_prefix}}\{{name.var.id}}
end
\{% elsif name.is_a?(Assign) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.target.id}}
{{var_prefix}}\{{name.target.id}}
end
\{% else %}
def {{method_prefix}}\{{name.id}}
{{var_prefix}}\{{name.id}}
end
\{% end %}
\{% end %}
\{% end %}
end
# Defines raise-on-nil and nilable getter methods for each of the given arguments.
#
# Writing:
#
# ```
# class Person
# {{macro_prefix}}getter! name
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}name?
# {{var_prefix}}name
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name.not_nil!
# end
# end
# ```
#
# The arguments can be string literals, symbol literals or plain names:
#
# ```
# class Person
# {{macro_prefix}}getter! :name, "age"
# end
# ```
#
# If a type declaration is given, a variable with that name
# is declared with that type, as nilable.
#
# ```
# class Person
# {{macro_prefix}}getter! name : String
# end
# ```
#
# is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String?
#
# def {{method_prefix}}name?
# {{var_prefix}}name
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name.not_nil!
# end
# end
# ```
macro {{macro_prefix}}getter!(*names)
\{% for name in names %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name}}?
def {{method_prefix}}\{{name.var.id}}? : \{{name.type}}?
{{var_prefix}}\{{name.var.id}}
end
def {{method_prefix}}\{{name.var.id}} : \{{name.type}}
if (value = {{var_prefix}}\{{name.var.id}}).nil?
::raise NilAssertionError.new("\{{@type}}\{{"{{doc_prefix}}".id}}\{{name.var.id}} cannot be nil")
else
value
end
end
\{% else %}
def {{method_prefix}}\{{name.id}}?
{{var_prefix}}\{{name.id}}
end
def {{method_prefix}}\{{name.id}}
if (value = {{var_prefix}}\{{name.id}}).nil?
::raise NilAssertionError.new("\{{@type}}\{{"{{doc_prefix}}".id}}\{{name.id}} cannot be nil")
else
value
end
end
\{% end %}
\{% end %}
end
# Defines query getter methods for each of the given arguments.
#
# Writing:
#
# ```
# class Person
# {{macro_prefix}}getter? happy
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}happy?
# {{var_prefix}}happy
# end
# end
# ```
#
# The arguments can be string literals, symbol literals or plain names:
#
# ```
# class Person
# {{macro_prefix}}getter? :happy, "famous"
# end
# ```
#
# If a type declaration is given, a variable with that name
# is declared with that type.
#
# ```
# class Person
# {{macro_prefix}}getter? happy : Bool
# end
# ```
#
# is the same as writing:
#
# ```
# class Person
# {{var_prefix}}happy : Bool
#
# def {{method_prefix}}happy? : Bool
# {{var_prefix}}happy
# end
# end
# ```
#
# The type declaration can also include an initial value:
#
# ```
# class Person
# {{macro_prefix}}getter? happy : Bool = true
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}happy : Bool = true
#
# def {{method_prefix}}happy? : Bool
# {{var_prefix}}happy
# end
# end
# ```
#
# An assignment can be passed too, but in this case the type of the
# variable must be easily inferable from the initial value:
#
# ```
# class Person
# {{macro_prefix}}getter? happy = true
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}happy = true
#
# def {{method_prefix}}happy?
# {{var_prefix}}happy
# end
# end
# ```
#
# If a block is given to the macro, a getter is generated
# with a variable that is lazily initialized with
# the block's contents, for examples see `#{{macro_prefix}}getter`.
macro {{macro_prefix}}getter?(*names, &block)
\{% if block %}
\{% if names.size != 1 %}
\{{ raise "Only one argument can be passed to `getter?` with a block" }}
\{% end %}
\{% name = names[0] %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name.var.id}} : \{{name.type}}?
def {{method_prefix}}\{{name.var.id}}? : \{{name.type}}
if (value = {{var_prefix}}\{{name.var.id}}).nil?
{{var_prefix}}\{{name.var.id}} = \{{yield}}
else
value
end
end
\{% else %}
def {{method_prefix}}\{{name.id}}?
if (value = {{var_prefix}}\{{name.id}}).nil?
{{var_prefix}}\{{name.id}} = \{{yield}}
else
value
end
end
\{% end %}
\{% else %}
\{% for name in names %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.var.id}}? : \{{name.type}}
{{var_prefix}}\{{name.var.id}}
end
\{% elsif name.is_a?(Assign) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.target.id}}?
{{var_prefix}}\{{name.target.id}}
end
\{% else %}
def {{method_prefix}}\{{name.id}}?
{{var_prefix}}\{{name.id}}
end
\{% end %}
\{% end %}
\{% end %}
end
# Defines setter methods for each of the given arguments.
#
# Writing:
#
# ```
# class Person
# {{macro_prefix}}setter name
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}name=({{var_prefix}}name)
# end
# end
# ```
#
# The arguments can be string literals, symbol literals or plain names:
#
# ```
# class Person
# {{macro_prefix}}setter :name, "age"
# end
# ```
#
# If a type declaration is given, a variable with that name
# is declared with that type.
#
# ```
# class Person
# {{macro_prefix}}setter name : String
# end
# ```
#
# is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String
#
# def {{method_prefix}}name=({{var_prefix}}name : String)
# end
# end
# ```
#
# The type declaration can also include an initial value:
#
# ```
# class Person
# {{macro_prefix}}setter name : String = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String = "John Doe"
#
# def {{method_prefix}}name=({{var_prefix}}name : String)
# end
# end
# ```
#
# An assignment can be passed too, but in this case the type of the
# variable must be easily inferable from the initial value:
#
# ```
# class Person
# {{macro_prefix}}setter name = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name = "John Doe"
#
# def {{method_prefix}}name=({{var_prefix}}name)
# end
# end
# ```
macro {{macro_prefix}}setter(*names)
\{% for name in names %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.var.id}}=({{var_prefix}}\{{name.var.id}} : \{{name.type}})
end
\{% elsif name.is_a?(Assign) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.target.id}}=({{var_prefix}}\{{name.target.id}})
end
\{% else %}
def {{method_prefix}}\{{name.id}}=({{var_prefix}}\{{name.id}})
end
\{% end %}
\{% end %}
end
# Defines property methods for each of the given arguments.
#
# Writing:
#
# ```
# class Person
# {{macro_prefix}}property name
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}name=({{var_prefix}}name)
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name
# end
# end
# ```
#
# The arguments can be string literals, symbol literals or plain names:
#
# ```
# class Person
# {{macro_prefix}}property :name, "age"
# end
# ```
#
# If a type declaration is given, a variable with that name
# is declared with that type.
#
# ```
# class Person
# {{macro_prefix}}property name : String
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String
#
# def {{method_prefix}}name=({{var_prefix}}name)
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name
# end
# end
# ```
#
# The type declaration can also include an initial value:
#
# ```
# class Person
# {{macro_prefix}}property name : String = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name : String = "John Doe"
#
# def {{method_prefix}}name=({{var_prefix}}name : String)
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name
# end
# end
# ```
#
# An assignment can be passed too, but in this case the type of the
# variable must be easily inferable from the initial value:
#
# ```
# class Person
# {{macro_prefix}}property name = "John Doe"
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# {{var_prefix}}name = "John Doe"
#
# def {{method_prefix}}name=({{var_prefix}}name : String)
# end
#
# def {{method_prefix}}name
# {{var_prefix}}name
# end
# end
# ```
#
# If a block is given to the macro, a property is generated
# with a variable that is lazily initialized with
# the block's contents:
#
# ```
# class Person
# {{macro_prefix}}property(birth_date) { Time.local }
# end
# ```
#
# Is the same as writing:
#
# ```
# class Person
# def {{method_prefix}}birth_date
# if (value = {{var_prefix}}birth_date).nil?
# {{var_prefix}}birth_date = Time.local
# else
# value
# end
# end
#
# def {{method_prefix}}birth_date=({{var_prefix}}birth_date)
# end
# end
# ```
macro {{macro_prefix}}property(*names, &block)
\{% if block %}
\{% if names.size != 1 %}
\{{ raise "Only one argument can be passed to `property` with a block" }}
\{% end %}
\{% name = names[0] %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name.var.id}} : \{{name.type}}?
def {{method_prefix}}\{{name.var.id}} : \{{name.type}}
if (value = {{var_prefix}}\{{name.var.id}}).nil?
{{var_prefix}}\{{name.var.id}} = \{{yield}}
else
value
end
end
def {{method_prefix}}\{{name.var.id}}=({{var_prefix}}\{{name.var.id}} : \{{name.type}})
end
\{% else %}
def {{method_prefix}}\{{name.id}}
if (value = {{var_prefix}}\{{name.id}}).nil?
{{var_prefix}}\{{name.id}} = \{{yield}}
else
value
end
end
def {{method_prefix}}\{{name.id}}=({{var_prefix}}\{{name.id}})
end
\{% end %}
\{% else %}
\{% for name in names %}
\{% if name.is_a?(TypeDeclaration) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.var.id}} : \{{name.type}}
{{var_prefix}}\{{name.var.id}}
end
def {{method_prefix}}\{{name.var.id}}=({{var_prefix}}\{{name.var.id}} : \{{name.type}})
end
\{% elsif name.is_a?(Assign) %}
{{var_prefix}}\{{name}}
def {{method_prefix}}\{{name.target.id}}
{{var_prefix}}\{{name.target.id}}
end