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https://github.com/nim-lang/Nim.git
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8942586fa6
* wrapnils: add option-like API with ??., isSome, get * fix test after rebase * cleanups * fix changelog * address comments regarding get vs unsafeGet
86 lines
1.8 KiB
Nim
86 lines
1.8 KiB
Nim
import std/wrapnils
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proc checkNotZero(x: float): float =
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doAssert x != 0
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x
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proc main() =
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var witness = 0
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type Bar = object
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b1: int
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b2: ptr string
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type Foo = ref object
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x1: float
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x2: Foo
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x3: string
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x4: Bar
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x5: seq[int]
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x6: ptr Bar
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x7: array[2, string]
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x8: seq[int]
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x9: ref Bar
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type Gook = ref object
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foo: Foo
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proc fun(a: Bar): auto = a.b2
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var a: Foo
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var x6: ptr Bar
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when nimvm: discard # pending https://github.com/timotheecour/Nim/issues/568
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else:
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x6 = create(Bar)
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x6.b1 = 42
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var a2 = Foo(x1: 1.0, x5: @[10, 11], x6: x6)
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var a3 = Foo(x1: 1.2, x3: "abc")
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a3.x2 = a3
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var gook = Gook(foo: a)
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proc initFoo(x1: float): auto =
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witness.inc
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result = Foo(x1: x1)
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doAssert ?.a.x2.x2.x1 == 0.0
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doAssert ?.a3.x2.x2.x1 == 1.2
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doAssert ?.a3.x2.x2.x3[1] == 'b'
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doAssert ?.a3.x2.x2.x5.len == 0
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doAssert a3.x2.x2.x3.len == 3
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doAssert ?.a.x2.x2.x3[1] == default(char)
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# here we only apply wrapnil around gook.foo, not gook (and assume gook is not nil)
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doAssert ?.(gook.foo).x2.x2.x1 == 0.0
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when nimvm: discard
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else:
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doAssert ?.a2.x6[] == Bar(b1: 42) # deref for ptr Bar
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doAssert ?.a2.x1.checkNotZero == 1.0
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doAssert a == nil
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# shows that checkNotZero won't be called if a nil is found earlier in chain
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doAssert ?.a.x1.checkNotZero == 0.0
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when nimvm: discard
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else:
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# checks that a chain without nil but with an empty seq still raises
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doAssertRaises(IndexDefect): discard ?.a2.x8[3]
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# make sure no double evaluation bug
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doAssert witness == 0
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doAssert ?.initFoo(1.3).x1 == 1.3
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doAssert witness == 1
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# here, it's used twice, to deref `ref Bar` and then `ptr string`
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doAssert ?.a.x9[].fun[] == ""
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block: # `??.`
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doAssert (??.a3.x2.x2.x3.len).get == 3
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doAssert (??.a2.x4).isSome
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doAssert not (??.a.x4).isSome
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main()
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static: main()
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