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96 lines
2.3 KiB
Go
96 lines
2.3 KiB
Go
// GoToSocial
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// Copyright (C) GoToSocial Authors admin@gotosocial.org
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// SPDX-License-Identifier: AGPL-3.0-or-later
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package util
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// KeyBy creates a map of T->S, keyed by value returned from key func.
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func KeyBy[S any, T comparable](in []S, key func(S) T) map[T]S {
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if key == nil {
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panic("nil func")
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}
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m := make(map[T]S, len(in))
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for _, v := range in {
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m[key(v)] = v
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}
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return m
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}
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// Set represents a hashmap of only keys,
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// useful for deduplication / key checking.
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type Set[T comparable] map[T]struct{}
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// ToSet creates a Set[T] from given values.
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func ToSet[T comparable](in []T) Set[T] {
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set := make(Set[T], len(in))
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for _, v := range in {
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set[v] = struct{}{}
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}
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return set
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}
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// ToSetFunc creates a Set[T] from input slice, keys provided by func.
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func ToSetFunc[S any, T comparable](in []S, key func(S) T) Set[T] {
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if key == nil {
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panic("nil func")
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}
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set := make(Set[T], len(in))
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for _, v := range in {
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set[key(v)] = struct{}{}
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}
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return set
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}
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// FromSet extracts the values from set to slice.
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func FromSet[T comparable](in Set[T]) []T {
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out := make([]T, len(in))
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var i int
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for v := range in {
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out[i] = v
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i++
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}
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return out
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}
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// In returns input slice filtered to
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// only contain those in receiving set.
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func (s Set[T]) In(vs []T) []T {
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out := make([]T, 0, len(vs))
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for _, v := range vs {
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if _, ok := s[v]; ok {
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out = append(out, v)
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}
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}
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return out
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}
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// NotIn is the functional inverse of In().
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func (s Set[T]) NotIn(vs []T) []T {
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out := make([]T, 0, len(vs))
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for _, v := range vs {
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if _, ok := s[v]; !ok {
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out = append(out, v)
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}
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}
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return out
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}
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// Has returns if value is in Set.
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func (s Set[T]) Has(v T) bool {
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_, ok := s[v]
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return ok
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}
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