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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package containers
import (
"golang.org/x/exp/constraints"
)
type _Ordered[T any] interface {
Compare(T) int
}
// An Ordered is a type that has a
//
// func (a T) Compare(b T) int
//
// method that returns a value <1 if a is "less than" b, >1 if a is
// "greater than" b, or 0 if a is "equal to" b.
//
// You can conceptualize as subtraction:
//
// func (a T) Compare(b T) int {
// return a - b
// }
//
// Be careful to avoid integer overflow if actually implementing it as
// subtraction.
type Ordered[T _Ordered[T]] _Ordered[T]
// NativeOrdered takes a type that is natively-ordered (integer types,
// float types, and string types), and wraps them such that they
// implement the Ordered interface.
type NativeOrdered[T constraints.Ordered] struct {
Val T
}
// NativeCompare implements the Ordered[T] Compare operation for
// natively-ordered (integer types, float types, and string types).
// While this operation be conceptualized as subtration, NativeCompare
// is careful to avoid integer overflow.
func NativeCompare[T constraints.Ordered](a, b T) int {
switch {
case a < b:
return -1
case a > b:
return 1
default:
return 0
}
}
// Compare implements Ordered[T].
func (a NativeOrdered[T]) Compare(b NativeOrdered[T]) int {
return NativeCompare(a.Val, b.Val)
}
var _ Ordered[NativeOrdered[int]] = NativeOrdered[int]{}
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