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98 lines
4.6 KiB
Go
98 lines
4.6 KiB
Go
package option
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import (
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F "github.com/IBM/fp-go/v2/function"
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"github.com/IBM/fp-go/v2/optics/lens"
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O "github.com/IBM/fp-go/v2/option"
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)
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// fromPredicate returns a `Lens` for a property accessibly as a getter and setter that can be optional
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// if the optional value is set then the nil value will be set instead
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func fromPredicate[GET ~func(S) Option[A], SET ~func(Option[A]) Endomorphism[S], S, A any](creator func(get GET, set SET) LensO[S, A], pred func(A) bool, nilValue A) func(sa Lens[S, A]) LensO[S, A] {
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fromPred := O.FromPredicate(pred)
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return func(sa Lens[S, A]) LensO[S, A] {
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return creator(F.Flow2(sa.Get, fromPred), O.Fold(F.Bind1of1(sa.Set)(nilValue), sa.Set))
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}
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}
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// FromPredicate returns a `Lens` for a property accessibly as a getter and setter that can be optional
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// if the optional value is set then the nil value will be set instead
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func FromPredicate[S, A any](pred func(A) bool, nilValue A) func(sa Lens[S, A]) LensO[S, A] {
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return fromPredicate(lens.MakeLensCurried[func(S) Option[A], func(Option[A]) Endomorphism[S]], pred, nilValue)
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}
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// FromPredicateRef returns a `Lens` for a property accessibly as a getter and setter that can be optional
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// if the optional value is set then the nil value will be set instead
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func FromPredicateRef[S, A any](pred func(A) bool, nilValue A) func(sa Lens[*S, A]) Lens[*S, Option[A]] {
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return fromPredicate(lens.MakeLensRefCurried[S, Option[A]], pred, nilValue)
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}
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// FromPredicate returns a `Lens` for a property accessibly as a getter and setter that can be optional
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// if the optional value is set then the `nil` value will be set instead
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func FromNillable[S, A any](sa Lens[S, *A]) Lens[S, Option[*A]] {
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return FromPredicate[S](F.IsNonNil[A], nil)(sa)
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}
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// FromNillableRef returns a `Lens` for a property accessibly as a getter and setter that can be optional
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// if the optional value is set then the `nil` value will be set instead
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func FromNillableRef[S, A any](sa Lens[*S, *A]) Lens[*S, Option[*A]] {
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return FromPredicateRef[S](F.IsNonNil[A], nil)(sa)
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}
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// fromNullableProp returns a `Lens` from a property that may be optional. The getter returns a default value for these items
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func fromNullableProp[GET ~func(S) A, SET ~func(A) Endomorphism[S], S, A any](creator func(get GET, set SET) Lens[S, A], isNullable func(A) Option[A], defaultValue A) func(sa Lens[S, A]) Lens[S, A] {
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orElse := O.GetOrElse(F.Constant(defaultValue))
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return func(sa Lens[S, A]) Lens[S, A] {
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return creator(F.Flow3(
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sa.Get,
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isNullable,
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orElse,
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), sa.Set)
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}
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}
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// FromNullableProp returns a `Lens` from a property that may be optional. The getter returns a default value for these items
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func FromNullableProp[S, A any](isNullable func(A) Option[A], defaultValue A) func(sa Lens[S, A]) Lens[S, A] {
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return fromNullableProp(lens.MakeLensCurried[func(S) A, func(A) Endomorphism[S]], isNullable, defaultValue)
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}
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// FromNullablePropRef returns a `Lens` from a property that may be optional. The getter returns a default value for these items
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func FromNullablePropRef[S, A any](isNullable func(A) Option[A], defaultValue A) func(sa Lens[*S, A]) Lens[*S, A] {
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return fromNullableProp(lens.MakeLensRefCurried[S, A], isNullable, defaultValue)
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}
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// fromOption returns a `Lens` from an option property. The getter returns a default value the setter will always set the some option
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func fromOption[GET ~func(S) A, SET ~func(A) Endomorphism[S], S, A any](creator func(get GET, set SET) Lens[S, A], defaultValue A) func(sa LensO[S, A]) Lens[S, A] {
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orElse := O.GetOrElse(F.Constant(defaultValue))
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return func(sa LensO[S, A]) Lens[S, A] {
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return creator(F.Flow2(
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sa.Get,
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orElse,
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), F.Flow2(O.Of[A], sa.Set))
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}
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}
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// FromOption returns a `Lens` from an option property. The getter returns a default value the setter will always set the some option
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func FromOption[S, A any](defaultValue A) func(sa LensO[S, A]) Lens[S, A] {
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return fromOption(lens.MakeLensCurried[func(S) A, func(A) Endomorphism[S]], defaultValue)
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}
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// FromOptionRef creates a lens from an Option property with a default value for pointer structures.
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//
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// This is the pointer version of [FromOption], with automatic copying to ensure immutability.
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// The getter returns the value inside Some[A], or the defaultValue if it's None[A].
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// The setter always wraps the value in Some[A].
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//
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// Type Parameters:
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// - S: Structure type (will be used as *S)
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// - A: Focus type
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//
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// Parameters:
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// - defaultValue: Value to return when the Option is None
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//
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// Returns:
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// - A function that takes a Lens[*S, Option[A]] and returns a Lens[*S, A]
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func FromOptionRef[S, A any](defaultValue A) func(sa Lens[*S, Option[A]]) Lens[*S, A] {
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return fromOption(lens.MakeLensRefCurried[S, A], defaultValue)
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}
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