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import std/wrapnils
const wrapnilExtendedExports = declared(wrapnil)
# for now, wrapnil, isValid, unwrap are not exported
proc checkNotZero(x: float): float =
doAssert x != 0
x
var witness = 0
proc main() =
type Bar = object
b1: int
b2: ptr string
type Foo = ref object
x1: float
x2: Foo
x3: string
x4: Bar
x5: seq[int]
x6: ptr Bar
x7: array[2, string]
x8: seq[int]
x9: ref Bar
type Gook = ref object
foo: Foo
proc fun(a: Bar): auto = a.b2
var a: Foo
var x6 = create(Bar)
x6.b1 = 42
var a2 = Foo(x1: 1.0, x5: @[10, 11], x6: x6)
var a3 = Foo(x1: 1.2, x3: "abc")
a3.x2 = a3
var gook = Gook(foo: a)
proc initFoo(x1: float): auto =
witness.inc
result = Foo(x1: x1)
doAssert ?.a.x2.x2.x1 == 0.0
doAssert ?.a3.x2.x2.x1 == 1.2
doAssert ?.a3.x2.x2.x3[1] == 'b'
doAssert ?.a3.x2.x2.x5.len == 0
doAssert a3.x2.x2.x3.len == 3
when wrapnilExtendedExports:
# example calling wrapnil directly, with and without unwrap
doAssert a3.wrapnil.x2.x2.x3.len == wrapnil(3)
doAssert a3.wrapnil.x2.x2.x3.len.unwrap == 3
doAssert a2.wrapnil.x4.isValid
doAssert not a.wrapnil.x4.isValid
doAssert ?.a.x2.x2.x3[1] == default(char)
# here we only apply wrapnil around gook.foo, not gook (and assume gook is not nil)
doAssert ?.(gook.foo).x2.x2.x1 == 0.0
doAssert ?.a2.x6[] == Bar(b1: 42) # deref for ptr Bar
doAssert ?.a2.x1.checkNotZero == 1.0
doAssert a == nil
# shows that checkNotZero won't be called if a nil is found earlier in chain
doAssert ?.a.x1.checkNotZero == 0.0
# checks that a chain without nil but with an empty seq still throws IndexDefect
doAssertRaises(IndexDefect): discard ?.a2.x8[3]
# make sure no double evaluation bug
doAssert witness == 0
doAssert ?.initFoo(1.3).x1 == 1.3
doAssert witness == 1
# here, it's used twice, to deref `ref Bar` and then `ptr string`
doAssert ?.a.x9[].fun[] == ""
main()
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