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gitea/modules/optional/option.go

69 lines
1.5 KiB
Go

// Copyright 2024 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package optional
import "strconv"
// Option is a generic type that can hold a value of type T or be empty (None).
//
// It must use the slice type to work with "chi" form values binding:
// * non-existing value are represented as an empty slice (None)
// * existing value is represented as a slice with one element (Some)
// * multiple values are represented as a slice with multiple elements (Some), the Value is the first element (not well-defined in this case)
type Option[T any] []T
func None[T any]() Option[T] {
return nil
}
func Some[T any](v T) Option[T] {
return Option[T]{v}
}
func FromPtr[T any](v *T) Option[T] {
if v == nil {
return None[T]()
}
return Some(*v)
}
func FromNonDefaultFunc[T comparable](f T, isZero func(T) bool) Option[T] {
if isZero(f) {
return None[T]()
}
return Some(f)
}
func FromNonDefault[T comparable](v T) Option[T] {
return FromNonDefaultFunc(v, func(v T) bool {
var zero T
return v == zero
})
}
func (o Option[T]) Has() bool {
return o != nil
}
func (o Option[T]) Value() T {
var zero T
return o.ValueOrDefault(zero)
}
func (o Option[T]) ValueOrDefault(v T) T {
if o.Has() {
return o[0]
}
return v
}
// ParseBool get the corresponding optional.Option[bool] of a string using strconv.ParseBool
func ParseBool(s string) Option[bool] {
v, e := strconv.ParseBool(s)
if e != nil {
return None[bool]()
}
return Some(v)
}