sync.OnceValue and slices.Compact were both added in Go 1.21. cmp.Or was added in Go 1.22. Updates #8632 Updates #11058 Change-Id: I89ba4c404f40188e1f8a9566c8aaa049be377754 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>main
Brad Fitzpatrick
1 year ago
committed by
Brad Fitzpatrick
parent
5fdb4f83ad
commit
69b90742fe
@ -1,62 +0,0 @@ |
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package uniq provides removal of adjacent duplicate elements in slices.
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// It is similar to the unix command uniq.
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package uniq |
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// ModifySlice removes adjacent duplicate elements from the given slice. It
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// adjusts the length of the slice appropriately and zeros the tail.
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//
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// ModifySlice does O(len(*slice)) operations.
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func ModifySlice[E comparable](slice *[]E) { |
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// Remove duplicates
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dst := 0 |
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for i := 1; i < len(*slice); i++ { |
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if (*slice)[i] == (*slice)[dst] { |
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continue |
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} |
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dst++ |
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(*slice)[dst] = (*slice)[i] |
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} |
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// Zero out the elements we removed at the end of the slice
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end := dst + 1 |
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var zero E |
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for i := end; i < len(*slice); i++ { |
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(*slice)[i] = zero |
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} |
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// Truncate the slice
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if end < len(*slice) { |
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*slice = (*slice)[:end] |
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} |
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} |
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// ModifySliceFunc is the same as ModifySlice except that it allows using a
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// custom comparison function.
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//
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// eq should report whether the two provided elements are equal.
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func ModifySliceFunc[E any](slice *[]E, eq func(i, j E) bool) { |
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// Remove duplicates
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dst := 0 |
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for i := 1; i < len(*slice); i++ { |
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if eq((*slice)[dst], (*slice)[i]) { |
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continue |
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} |
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dst++ |
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(*slice)[dst] = (*slice)[i] |
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} |
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// Zero out the elements we removed at the end of the slice
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end := dst + 1 |
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var zero E |
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for i := end; i < len(*slice); i++ { |
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(*slice)[i] = zero |
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} |
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// Truncate the slice
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if end < len(*slice) { |
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*slice = (*slice)[:end] |
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} |
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} |
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@ -1,102 +0,0 @@ |
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package uniq_test |
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import ( |
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"reflect" |
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"strconv" |
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"testing" |
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"tailscale.com/util/uniq" |
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) |
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func runTests(t *testing.T, cb func(*[]uint32)) { |
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tests := []struct { |
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// Use uint32 to be different from an int-typed slice index
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in []uint32 |
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want []uint32 |
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}{ |
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{in: []uint32{0, 1, 2}, want: []uint32{0, 1, 2}}, |
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{in: []uint32{0, 1, 2, 2}, want: []uint32{0, 1, 2}}, |
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{in: []uint32{0, 0, 1, 2}, want: []uint32{0, 1, 2}}, |
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{in: []uint32{0, 1, 0, 2}, want: []uint32{0, 1, 0, 2}}, |
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{in: []uint32{0}, want: []uint32{0}}, |
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{in: []uint32{0, 0}, want: []uint32{0}}, |
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{in: []uint32{}, want: []uint32{}}, |
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} |
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for _, test := range tests { |
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in := make([]uint32, len(test.in)) |
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copy(in, test.in) |
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cb(&test.in) |
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if !reflect.DeepEqual(test.in, test.want) { |
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t.Errorf("uniq.Slice(%v) = %v, want %v", in, test.in, test.want) |
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} |
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start := len(test.in) |
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test.in = test.in[:cap(test.in)] |
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for i := start; i < len(in); i++ { |
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if test.in[i] != 0 { |
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t.Errorf("uniq.Slice(%v): non-0 in tail of %v at index %v", in, test.in, i) |
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} |
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} |
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} |
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} |
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func TestModifySlice(t *testing.T) { |
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runTests(t, func(slice *[]uint32) { |
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uniq.ModifySlice(slice) |
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}) |
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} |
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func TestModifySliceFunc(t *testing.T) { |
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runTests(t, func(slice *[]uint32) { |
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uniq.ModifySliceFunc(slice, func(i, j uint32) bool { |
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return i == j |
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}) |
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}) |
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} |
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func Benchmark(b *testing.B) { |
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benches := []struct { |
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name string |
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reset func(s []byte) |
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}{ |
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{name: "AllDups", |
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reset: func(s []byte) { |
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for i := range s { |
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s[i] = '*' |
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} |
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}, |
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}, |
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{name: "NoDups", |
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reset: func(s []byte) { |
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for i := range s { |
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s[i] = byte(i) |
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} |
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}, |
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}, |
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} |
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for _, bb := range benches { |
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b.Run(bb.name, func(b *testing.B) { |
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for size := 1; size <= 4096; size *= 16 { |
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b.Run(strconv.Itoa(size), func(b *testing.B) { |
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benchmark(b, 64, bb.reset) |
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}) |
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} |
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}) |
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} |
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} |
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func benchmark(b *testing.B, size int64, reset func(s []byte)) { |
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b.ReportAllocs() |
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b.SetBytes(size) |
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s := make([]byte, size) |
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b.ResetTimer() |
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for range b.N { |
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s = s[:size] |
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reset(s) |
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uniq.ModifySlice(&s) |
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} |
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} |
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