mirror of
https://github.com/IBM/fp-go.git
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63 lines
1.7 KiB
Go
63 lines
1.7 KiB
Go
// Copyright (c) 2023 - 2025 IBM Corp.
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// All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package generic
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import (
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F "github.com/IBM/fp-go/v2/function"
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O "github.com/IBM/fp-go/v2/option"
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P "github.com/IBM/fp-go/v2/pair"
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)
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// addToMap makes a deep copy of a map and adds a value
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func addToMap[A comparable](a A, m map[A]bool) map[A]bool {
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cpy := make(map[A]bool, len(m)+1)
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for k, v := range m {
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cpy[k] = v
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}
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cpy[a] = true
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return cpy
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}
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func Uniq[AS ~func() Option[Pair[AS, A]], K comparable, A any](f func(A) K) func(as AS) AS {
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var recurse func(as AS, mp map[K]bool) AS
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recurse = func(as AS, mp map[K]bool) AS {
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return F.Nullary2(
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as,
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O.Chain(func(a Pair[AS, A]) Option[Pair[AS, A]] {
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return F.Pipe3(
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P.Tail(a),
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f,
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O.FromPredicate(func(k K) bool {
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_, ok := mp[k]
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return !ok
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}),
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O.Fold(recurse(P.Head(a), mp), func(k K) Option[Pair[AS, A]] {
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return O.Of(P.MakePair(recurse(P.Head(a), addToMap(k, mp)), P.Tail(a)))
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}),
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)
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}),
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)
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}
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return F.Bind2nd(recurse, make(map[K]bool, 0))
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}
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func StrictUniq[AS ~func() Option[Pair[AS, A]], A comparable](as AS) AS {
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return Uniq[AS](F.Identity[A])(as)
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}
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