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// Copyright 2024 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package predicate
// P is a predicate function that tests whether a value of type T satisfies some condition.
type P[T any] func(T) bool
// And returns a predicate that is a short-circuiting logical AND of this and the given predicates.
func (p P[T]) And(ps ...P[T]) P[T] {
return func(v T) bool {
for _, pp := range ps {
if !pp(v) {
return false
}
}
return p(v)
}
}
// Or returns a predicate that is a short-circuiting logical OR of this and the given predicates.
func (p P[T]) Or(ps ...P[T]) P[T] {
return func(v T) bool {
for _, pp := range ps {
if pp(v) {
return true
}
}
return p(v)
}
}
// Negate returns a predicate that is a logical negation of this predicate.
func (p P[T]) Negate() P[T] {
return func(v T) bool {
return !p(v)
}
}
// Filter returns a new slice holding only the elements of s that satisfy p.
// Filter modifies the contents of the slice s and returns the modified slice, which may have a smaller length.
func (p P[T]) Filter(s []T) []T {
var n int
for _, v := range s {
if p(v) {
s[n] = v
n++
}
}
return s[:n]
}
// FilterCopy returns a new slice holding only the elements of s that satisfy p.
func (p P[T]) FilterCopy(s []T) []T {
var result []T
for _, v := range s {
if p(v) {
result = append(result, v)
}
}
return result
}
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