forked from JuliaObjects/Accessors.jl
-
Notifications
You must be signed in to change notification settings - Fork 0
/
optics.jl
537 lines (433 loc) · 13.3 KB
/
optics.jl
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
export @optic
export set, modify
export ∘, opcompose, var"⨟"
export Elements, Recursive, Query, If, Properties
export setproperties
export constructorof
using ConstructionBase
using CompositionsBase
using Base: getproperty
using Base
const EXPERIMENTAL = """This function/method/type is experimental. It can be changed or deleted at any point without warning"""
"""
modify(f, obj, optic)
Replace a part `x` of `obj` by `f(x)`. The `optic` argument selects
which part to replace.
```jldoctest
julia> using Accessors
julia> obj = (a=1, b=2); optic=@optic _.a; f = x -> "hello \$x";
julia> modify(f, obj, optic)
(a = "hello 1", b = 2)
```
See also [`set`](@ref).
"""
function modify end
"""
set(obj, optic, val)
Replace a part according to `optic` of `obj` by `val`.
```jldoctest
julia> using Accessors
julia> obj = (a=1, b=2); lens=@optic _.a; val = 100;
julia> set(obj, lens, val)
(a = 100, b = 2)
```
See also [`modify`](@ref).
"""
function set end
"""
optic₁ ⨟ optic₂
Compose optics `optic₁`, `optic₂`, ..., `opticₙ` to access nested objects.
# Example
```jldoctest
julia> using Accessors
julia> obj = (a = (b = (c = 1,),),);
julia> la = @optic _.a
lb = @optic _.b
lc = @optic _.c
lens = la ⨟ lb ⨟ lc
(@optic _.c) ∘ (@optic _.b) ∘ (@optic _.a)
julia> lens(obj)
1
```
"""
opcompose
const BASE_COMPOSED_FUNCTION_HAS_SHOW = VERSION >= v"1.6.0-DEV.85"
const BASE_COMPOSED_FUNCTION_IS_PUBLIC = VERSION >= v"1.6.0-DEV.1037"
if !BASE_COMPOSED_FUNCTION_IS_PUBLIC
using Compat: ComposedFunction
end
if !BASE_COMPOSED_FUNCTION_HAS_SHOW
function show_composed_function(io::IO, c::ComposedFunction)
show(io, c.outer)
print(io, " ∘ ")
show(io, c.inner)
end
function Base.show(io::IO, c::ComposedFunction)
show_composed_function(io, c)
end
function Base.show(io::IO, ::MIME"text/plain", c::ComposedFunction)
show_composed_function(io, c)
end
end
const ComposedOptic{Outer, Inner} = ComposedFunction{Outer, Inner}
outertype(::Type{ComposedOptic{Outer, Inner}}) where {Outer, Inner} = Outer
innertype(::Type{ComposedOptic{Outer, Inner}}) where {Outer, Inner} = Inner
# TODO better name
# also better way to organize traits will
# probably only emerge over time
abstract type OpticStyle end
struct ModifyBased <: OpticStyle end
struct SetBased <: OpticStyle end
OpticStyle(obj) = OpticStyle(typeof(obj))
# defining lenses should be very lightweight
# e.g. only a single `set` implementation
# so we choose this as the default trait
OpticStyle(::Type{T}) where {T} = SetBased()
function OpticStyle(::Type{ComposedOptic{O,I}}) where {O,I}
composed_optic_style(OpticStyle(O), OpticStyle(I))
end
composed_optic_style(::SetBased, ::SetBased) = SetBased()
composed_optic_style(::ModifyBased, ::SetBased) = ModifyBased()
composed_optic_style(::SetBased, ::ModifyBased) = ModifyBased()
composed_optic_style(::ModifyBased, ::ModifyBased) = ModifyBased()
@inline function set(obj, optic, val)
_set(obj, optic, val, OpticStyle(optic))
end
function _set(obj, optic, val, ::SetBased)
Optic = typeof(optic)
error("""
This should be unreachable. You probably need to overload
`Accessors.set(obj, ::$Optic, val)
"""
)
end
struct Changed end
struct Unchanged end
struct MaybeConstruct end
_constructor(::MaybeConstruct, ::Type{T}) where T = constructorof(T)
struct List end
_constructor(::List, ::Type) = tuple
struct Skip end
_constructor(::Skip, ::Type) = _splat_all
_splat_all(args...) = _splat_all(args)
@generated function _splat_all(args::A) where A<:Tuple
exp = Expr(:tuple)
for i in fieldnames(A)
push!(exp.args, Expr(:..., :(args[$i])))
end
exp
end
struct Constant{V}
value::V
end
(o::Constant)(x) = o.value
@inline function _set(obj, optic, val, ::ModifyBased)
modify(Constant(val), obj, optic)
end
@inline function _set(obj, optic::ComposedOptic, val, ::SetBased)
inner_obj = optic.inner(obj)
inner_val = set(inner_obj, optic.outer, val)
set(obj, optic.inner, inner_val)
end
@inline function modify(f, obj, optic)
_modify(f, obj, optic, OpticStyle(optic))
end
function _modify(f, obj, optic, ::ModifyBased)
Optic = typeof(optic)
error("""
This should be unreachable. You probably need to overload:
`Accessors.modify(f, obj, ::$Optic)`
""")
end
function _modify(f, obj, optic::ComposedOptic, ::ModifyBased)
otr = optic.outer
inr = optic.inner
modify(obj, inr) do o1
modify(f, o1, otr)
end
end
@inline function _modify(f, obj, optic, ::SetBased)
set(obj, optic, f(optic(obj)))
end
"""
Elements
Access all elements of a collection that implements `map`.
```jldoctest
julia> using Accessors
julia> obj = (1,2,3);
julia> set(obj, Elements(), 0)
(0, 0, 0)
julia> modify(x -> 2x, obj, Elements())
(2, 4, 6)
```
$EXPERIMENTAL
"""
struct Elements end
OpticStyle(::Type{<:Elements}) = ModifyBased()
modify(f, obj, ::Elements) = map(f, obj)
"""
If(modify_condition)
Restric access to locations for which `modify_condition` holds.
```jldoctest
julia> using Accessors
julia> obj = (1,2,3,4,5,6);
julia> @set obj |> Elements() |> If(iseven) *= 10
(1, 20, 3, 40, 5, 60)
```
$EXPERIMENTAL
"""
struct If{C}
modify_condition::C
end
OpticStyle(::Type{<:If}) = ModifyBased()
function modify(f, obj, w::If)
if w.modify_condition(obj)
f(obj)
else
obj
end
end
abstract type ObjectMap end
OpticStyle(::Type{<:ObjectMap}) = ModifyBased()
modify(f, o, optic::ObjectMap) = mapobject(f, o, optic, Construct, nothing)
"""
Properties()
Access all properties of an objects.
```jldoctest
julia> using Accessors
julia> obj = (a=1, b=2, c=3)
(a = 1, b = 2, c = 3)
julia> set(obj, Properties(), "hi")
(a = "hi", b = "hi", c = "hi")
julia> modify(x -> 2x, obj, Properties())
(a = 2, b = 4, c = 6)
```
Based on [`mapobject`](@ref).
$EXPERIMENTAL
"""
struct Properties <: ObjectMap end
"""
mapobject(f, obj)
Construct a copy of `obj`, with each property replaced by
the result of applying `f` to it.
```jldoctest
julia> using Accessors
julia> obj = (a=1, b=2);
julia> Accessors.mapobject(x -> x+1, obj)
(a = 2, b = 3)
```
$EXPERIMENTAL
"""
function mapobject(f, obj::O, ::Properties, handler, itr::Nothing) where O
# TODO move this helper elsewhere?
pnames = propertynames(obj)
if isempty(pnames)
return _maybeskip(handler, obj)
else
new_props = map(pnames) do p
f(getproperty(obj, p))
end
ctr = _constructor(handler, O)
return ctr(new_props...)
end
end
function mapobject(f, obj::O, ::Properties, handler, itr::Int) where O
pnames = propertynames(obj)
if isempty(pnames)
return obj, itr
else
# TODO: this is too slow
new_props, itr = reduce(pnames; init=((), itr)) do (vals, itr), p
val, itr = f(getproperty(obj, p), itr)
(vals..., val), itr
end
ctr = _constructor(handler, O)
return ctr(new_props...), itr
end
end
"""
Fields()
Access all fields of an objects.
```jldoctest
julia> using Accessors
julia> obj = (a=1, b=2, c=3)
(a = 1, b = 2, c = 3)
julia> set(obj, Fields(), "hi")
(a = "hi", b = "hi", c = "hi")
julia> modify(x -> 2x, obj, Fields())
(a = 2, b = 4, c = 6)
```
Based on [`mapfields`](@ref).
$EXPERIMENTAL
"""
struct Fields <: ObjectMap end
@generated function mapobject(f, obj::O, ::Fields, handler::H, itr::Nothing) where {O,H,I}
# TODO: This is how Flatten.jl works, but it's not really
# correct use of ConstructionBase as it assumers properties=fields
fnames = fieldnames(O)
ctr = _constructor(H(), O)
if isempty(fnames)
:(return _maybeskip(handler, obj))
else
prop_args = map(fn -> :(getfield(obj, $(QuoteNode(fn)))), fnames)
prop_exp = Expr(:tuple, prop_args...)
new_prop_exp = Expr(:tuple, map(pa -> :(f($pa)), prop_args)...)
quote
props = $prop_exp
new_props = $new_prop_exp
return $ctr(new_props...)
end
end
end
@generated function mapobject(f, obj::O, ::Fields, handler::H, itr::Int) where {O,H}
# TODO: This is how Flatten.jl works, but it's not really
# correct use of ConstructionBase as it assumers properties=fields
fnames = fieldnames(O)
ctr = _constructor(H(), O)
if isempty(fnames)
:(return (obj, itr) => Unchanged())
else
prop_args = map(fn -> :(getfield(obj, $(QuoteNode(fn)))), fnames)
prop_exp = Expr(:tuple, prop_args...)
### Unrolled iterating function appliation (it will compile away) ####
# Each function call also updates the iterator value in local scoope with
# the return value from the function. But it only actually inserts the
# value into the parent tuple.
val_exps = map(prop_args) do pa
:(((val, itr), change) = f($pa, itr); val => change)
end
new_prop_exp = Expr(:tuple, val_exps...)
quote
props = $prop_exp
new_props = $new_prop_exp
new_props, change = _splitchanged(new_props)
# Don't construct when we don't absolutely have to.
# `constructorof` may not be defined for an object.
if change isa Changed
return ($ctr(new_props...), itr) => change
else
return (obj, itr) => change
end
end
end
end
_splitchanged(props) = map(first, props), _findchanged(map(last, props))
_findchanged(::Tuple{Changed,Vararg}) = Changed()
_findchanged(cs::Tuple) = _findchanged(Base.tail(cs))
_findchanged(::Tuple{}) = Unchanged()
_maybeitr(x, ::Nothing) = x
_maybeitr(x, itr) = x, itr
_maybeskip(::Skip, v) = ()
_maybeskip(x, v) = v
"""
Recursive(descent_condition, optic)
Apply `optic` recursively as long as `descent_condition` holds.
```jldoctest
julia> using Accessors
julia> obj = (a=missing, b=1, c=(d=missing, e=(f=missing, g=2)))
(a = missing, b = 1, c = (d = missing, e = (f = missing, g = 2)))
julia> set(obj, Recursive(!ismissing, Properties()), 100)
(a = 100, b = 1, c = (d = 100, e = (f = 100, g = 2)))
julia> obj = (1,2,(3,(4,5),6))
(1, 2, (3, (4, 5), 6))
julia> modify(x -> 100x, obj, Recursive(x -> (x isa Tuple), Elements()))
(100, 200, (300, (400, 500), 600))
```
"""
struct Recursive{Descent, Optic}
descent_condition::Descent
optic::Optic
end
OpticStyle(::Type{Recursive{D,O}}) where {D,O} = ModifyBased() # Is this a good idea?
function _modify(f, obj, r::Recursive, ::ModifyBased)
modify(obj, r.optic) do o
if r.descent_condition(o)
modify(f, o, r)
else
f(o)
end
end
end
################################################################################
##### Lenses
################################################################################
struct PropertyLens{fieldname} end
function (l::PropertyLens{field})(obj) where {field}
getproperty(obj, field)
end
@inline function set(obj, l::PropertyLens{field}, val) where {field}
patch = (;field => val)
setproperties(obj, patch)
end
struct IndexLens{I <: Tuple}
indices::I
end
Base.@propagate_inbounds function (lens::IndexLens)(obj)
getindex(obj, lens.indices...)
end
Base.@propagate_inbounds function set(obj, lens::IndexLens, val)
setindex(obj, val, lens.indices...)
end
struct DynamicIndexLens{F}
f::F
end
Base.@propagate_inbounds function (lens::DynamicIndexLens)(obj)
return obj[lens.f(obj)...]
end
Base.@propagate_inbounds function set(obj, lens::DynamicIndexLens, val)
return setindex(obj, val, lens.f(obj)...)
end
"""
Query(select, descend)
Query an object recursively, choosing fields when `select`
returns `true`, and descending when `descend`.
```jldoctest
julia> using Accessors
julia> obj = (a=missing, b=1, c=(d=missing, e=(f=missing, g=2)))
(a = missing, b = 1, c = (d = missing, e = (f = missing, g = 2)))
julia> set(obj, Query(ismissing), (1.0, 2.0, 3.0))
(a = 1.0, b = 1, c = (d = 2.0, e = (f = 3.jjjjjjtk,rg, g = 2)))
julia> obj = (1,2,(3,(4,5),6))
(1, 2, (3, (4, 5), 6))
julia> modify(x -> 100x, obj, Recursive(x -> (x isa Tuple), Elements()))
(100, 200, (300, (400, 500), 600))
```
$EXPERIMENTAL
"""
struct Query{Select,Descend,Optic<:Union{ComposedOptic,Fields,Properties}}
select_condition::Select
descent_condition::Descend
optic::Optic
end
Query(select, descend = x -> true) = Query(select, descend, Fields())
Query(; select=Any, descend=x -> true, optic=Fields()) = Query(select, descend, optic)
function (q::Query)(obj)
mapobject(obj, _inner(q.optic), Skip(), nothing) do o
if q.select_condition(o)
(_getouter(o, q.optic),)
elseif q.descent_condition(o)
q(o) # also a tuple
else
()
end
end
end
set(obj, q::Query, vals) = _set(obj, q::Query, (vals, 1))[1][1]
function _set(obj, q::Query, (vals, itr))
mapobject(obj, _inner(q.optic), MaybeConstruct(), itr) do o, itr
if q.select_condition(o)
(_setouter(o, q.optic, vals[itr]), itr + 1) => Changed()
elseif q.descent_condition(o)
_set(o, q, (vals, itr))
else
(o, itr) => Unchanged()
end
end
end
modify(f, obj, q::Query) = set(obj, q, map(f, q(obj)))
_inner(optic::ComposedOptic) = optic.inner
_inner(optic) = optic
_getouter(o, optic::ComposedOptic) = optic.outer(o)
_getouter(o, optic) = o
_setouter(o, optic::ComposedOptic, v) = set(o, optic.outer, v)
_setouter(o, optic, v) = v