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29 lines
795 B
29 lines
795 B
package immutable
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// Immutable represents an immutable chain that, if passed to FastForward,
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// applies Fn() to every element of a chain, the first element of this chain is
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// represented by Base().
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type Immutable interface {
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// Prev is the previous element on a chain.
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Prev() Immutable
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// Fn a function that is able to modify the passed element.
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Fn(interface{}) error
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// Base is the first element on a chain, there's no previous element before
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// the Base element.
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Base() interface{}
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}
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// FastForward applies all Fn methods in order on the given new Base.
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func FastForward(curr Immutable) (interface{}, error) {
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prev := curr.Prev()
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if prev == nil {
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return curr.Base(), nil
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}
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in, err := FastForward(prev)
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if err != nil {
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return nil, err
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}
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err = curr.Fn(in)
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return in, err
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}
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