43 lines
1.3 KiB
Go
43 lines
1.3 KiB
Go
package stl
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// ImplicitSortable are types that can be compared with
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// the less operator <, among others.
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//
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// As with C++, two keys are considered equal if neither
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// x < y nor y < x, so these interfaces have nothing to
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// do with Go's 'comparable' whatsoever.
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//
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// This behavior can be overridden by defining another
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// type and then add a Compare method to the original key.
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type ImplicitSortable interface {
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~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | ~string | ~float32 | ~float64
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}
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// Sorter is a interface used in the construction of
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// many collection types, to compare two keys with
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// the '<' operator by default.
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type Sorter[T any] interface {
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Compare(x, y T) bool
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}
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// Less implements Sorter for ImplicitSortables using the '<' operator.
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type Less[T ImplicitSortable] struct{}
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func (Less[T]) Compare(x, y T) bool {
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return x < y
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}
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// Greater implements Sorter for ImplicitSortables using the '>' operator.
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type Greater[T ImplicitSortable] struct{}
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func (Greater[T]) Compare(x, y T) bool {
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return x > y
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}
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// Equal determines if the two keys are considered equal,
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// i.e., neither x < y nor y < x, per C++ traditions.
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func Equal[C Sorter[T], T any](x, y T) bool {
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var c C
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return !c.Compare(x, y) && !c.Compare(y, x)
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}
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