143 lines
3.1 KiB
V
143 lines
3.1 KiB
V
// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module builtin
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// IError holds information about an error instance
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pub interface IError {
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// >> Hack to allow old style custom error implementations
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// TODO: remove once deprecation period for `IError` methods has ended
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msg string
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code int // <<
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msg() string
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code() int
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}
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// str returns the message of IError
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pub fn (err IError) str() string {
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return match err {
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None__ {
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'none'
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}
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Error {
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err.msg()
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}
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MessageError {
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err.msg()
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}
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else {
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// >> Hack to allow old style custom error implementations
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// TODO: remove once deprecation period for `IError` methods has ended
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// old_error_style := unsafe { voidptr(&err.msg) != voidptr(&err.code) } // if fields are not defined (new style) they don't have an offset between
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// <<
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'$err.type_name(): $err.msg()'
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}
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}
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}
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// Error is the empty default implementation of `IError`.
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pub struct Error {}
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pub fn (err Error) msg() string {
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return ''
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}
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pub fn (err Error) code() int {
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return 0
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}
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// MessageError is the default implementation of the `IError` interface that is returned by the `error()` function
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struct MessageError {
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pub:
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msg string
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code int
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}
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// msg returns the message of MessageError
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pub fn (err MessageError) msg() string {
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return err.msg
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}
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// code returns the code of MessageError
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pub fn (err MessageError) code() int {
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return err.code
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}
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[unsafe]
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pub fn (err &MessageError) free() {
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unsafe { err.msg.free() }
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}
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const none__ = IError(&None__{})
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struct None__ {
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Error
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}
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fn (_ None__) str() string {
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return 'none'
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}
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[if trace_error ?]
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fn trace_error(x string) {
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eprintln('> ${@FN} | $x')
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}
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// error returns a default error instance containing the error given in `message`.
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// Example: if ouch { return error('an error occurred') }
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[inline]
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pub fn error(message string) IError {
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trace_error(message)
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return &MessageError{
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msg: message
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}
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}
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// error_with_code returns a default error instance containing the given `message` and error `code`.
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// Example: if ouch { return error_with_code('an error occurred', 1) }
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[inline]
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pub fn error_with_code(message string, code int) IError {
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trace_error('$message | code: $code')
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return &MessageError{
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msg: message
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code: code
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}
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}
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// Option is the base of V's internal optional return system.
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struct Option {
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state u8
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err IError = none__
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// Data is trailing after err
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// and is not included in here but in the
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// derived Option_xxx types
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}
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fn opt_ok(data voidptr, mut option Option, size int) {
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unsafe {
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*option = Option{}
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// use err to get the end of OptionBase and then memcpy into it
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vmemcpy(&u8(&option.err) + sizeof(IError), data, size)
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}
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}
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struct result {
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is_error bool
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err IError = none__
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// Data is trailing after err
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// and is not included in here but in the
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// derived Result_xxx types
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}
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fn result_ok(data voidptr, mut res result, size int) {
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unsafe {
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*res = result{}
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// use err to get the end of ResultBase and then memcpy into it
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vmemcpy(&u8(&res.err) + sizeof(IError), data, size)
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}
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}
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pub fn (_ none) str() string {
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return 'none'
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}
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