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v/vlib/builtin/option.v

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// Copyright (c) 2019-2021 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
// IError holds information about an error instance
pub interface IError {
msg string
code int
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}
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// Error is the default implementation of IError, that is returned by e.g. `error()`
pub struct Error {
pub:
msg string
code int
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}
const none__ = IError(&None__{})
struct None__ {
msg string
code int
}
fn (_ None__) str() string {
return 'none'
}
// error returns a default error instance containing the error given in `message`.
// Example: `if ouch { return error('an error occurred') }`
[inline]
pub fn error(message string) IError {
return &Error{
msg: message
}
}
// error_with_code returns a default error instance containing the given `message` and error `code`.
// `if ouch { return error_with_code('an error occurred', 1) }`
[inline]
pub fn error_with_code(message string, code int) IError {
return &Error{
msg: message
code: code
}
}
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// Option is the base of V's internal optional return system.
struct Option {
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state byte
err IError = none__
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// Data is trailing after err
// and is not included in here but in the
// derived Option_xxx types
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}
fn opt_ok(data voidptr, mut option Option, size int) {
unsafe {
*option = Option{}
// use err to get the end of OptionBase and then memcpy into it
C.memcpy(byteptr(&option.err) + sizeof(IError), data, size)
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}
}