40 lines
938 B
Go
40 lines
938 B
Go
package ucontainer
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// Memo holds a cached value.
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type Memo[T any] struct {
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cache T
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valid bool
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update func () T
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}
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// NewMemo creates a new Memo which will take its value from the specified
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// update callback.
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func NewMemo[T any] (update func () T) Memo[T] {
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return Memo[T] {
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update: update,
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}
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}
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// Value returns the Memo's value, updating it if the current cached value is
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// invalid.
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func (this *Memo[T]) Value () T {
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if !this.valid {
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this.cache = this.update()
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}
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return this.cache
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}
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// Invalidate marks the Memo's value as invalid, which will cause it to be
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// updated the next time Value is called.
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func (this *Memo[T]) Invalidate () {
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this.valid = false
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}
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// InvalidateTo invalidates the Memo and sets its value. The new value will be
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// entirely inaccessible. This is only intended to be used for setting a
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// reference to nil
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func (this *Memo[T]) InvalidateTo (value T) {
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this.Invalidate()
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this.cache = value
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}
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