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109 lines
2.3 KiB
Go
109 lines
2.3 KiB
Go
package optional
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import (
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"sync"
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)
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// Optional is a type that may or may not contain a non-nil value.
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type Optional[T any] struct {
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value *T
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mu *sync.RWMutex
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}
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// Empty returns an empty Optional instance.
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func Empty[T any]() Optional[T] {
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return Optional[T]{mu: &sync.RWMutex{}}
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}
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// Of returns an Optional with a non-nil value.
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func Of[T any](value T) Optional[T] {
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return Optional[T]{value: &value, mu: &sync.RWMutex{}}
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}
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// OfNullable returns an Optional for a given value, which may be nil.
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func OfNullable[T any](value *T) Optional[T] {
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if value == nil {
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return Empty[T]()
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}
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return Optional[T]{value: value, mu: &sync.RWMutex{}}
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}
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// IsPresent checks if there is a value present.
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func (o Optional[T]) IsPresent() bool {
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o.mu.RLock()
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defer o.mu.RUnlock()
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return o.value != nil
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}
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// IsEmpty checks if the Optional is empty.
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func (o Optional[T]) IsEmpty() bool {
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return !o.IsPresent()
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}
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// IfPresent performs the given action with the value if a value is present.
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func (o Optional[T]) IfPresent(action func(value T)) {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value != nil {
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action(*o.value)
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}
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}
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// IfPresentOrElse performs the action with the value if present, otherwise performs the empty-based action.
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func (o Optional[T]) IfPresentOrElse(action func(value T), emptyAction func()) {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value != nil {
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action(*o.value)
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} else {
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emptyAction()
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}
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}
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// Get returns the value if present, otherwise panics.
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func (o Optional[T]) Get() T {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value == nil {
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panic("Optional.Get: no value present")
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}
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return *o.value
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}
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// OrElse returns the value if present, otherwise returns other.
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func (o Optional[T]) OrElse(other T) T {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value != nil {
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return *o.value
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}
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return other
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}
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// OrElseGet returns the value if present, otherwise invokes supplier and returns the result.
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func (o Optional[T]) OrElseGet(supplier func() T) T {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value != nil {
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return *o.value
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}
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return supplier()
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}
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// OrElseThrow returns the value if present, otherwise returns an error.
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func (o Optional[T]) OrElseThrow(errorSupplier func() error) (T, error) {
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o.mu.RLock()
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defer o.mu.RUnlock()
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if o.value == nil {
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return *new(T), errorSupplier()
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}
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return *o.value, nil
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}
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