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v/vlib/builtin/option.v

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// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
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module builtin
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/*
struct Option2<T> {
data T
error string
ecode int
ok bool
is_none bool
}
*/
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struct Option {
data [400]byte
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error string
ecode int
ok bool
is_none bool
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}
pub fn (o Option) str() string {
if o.ok && !o.is_none {
return 'Option{ data: ' + o.data[0..32].hex() + ' }'
}
if o.is_none {
return 'Option{ none }'
}
return 'Option{ error: "${o.error}" }'
}
// `fn foo() ?Foo { return foo }` => `fn foo() ?Foo { return opt_ok(foo); }`
fn opt_ok(data voidptr, size int) Option {
if size >= 400 {
panic('option size too big: $size (max is 400), this is a temporary limit')
}
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res := Option{
ok: true
}
C.memcpy(res.data, data, size)
return res
}
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// used internally when returning `none`
fn opt_none() Option {
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return Option{
is_none: true
}
}
pub fn error(s string) Option {
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return Option{
error: s
}
}
pub fn error_with_code(s string, code int) Option {
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return Option{
error: s
ecode: code
}
}