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Diffstat (limited to 'vendor/golang.org/x/exp/slices/slices.go')
-rw-r--r-- | vendor/golang.org/x/exp/slices/slices.go | 515 |
1 files changed, 0 insertions, 515 deletions
diff --git a/vendor/golang.org/x/exp/slices/slices.go b/vendor/golang.org/x/exp/slices/slices.go deleted file mode 100644 index 46ceac343..000000000 --- a/vendor/golang.org/x/exp/slices/slices.go +++ /dev/null @@ -1,515 +0,0 @@ -// Copyright 2021 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// Package slices defines various functions useful with slices of any type. -package slices - -import ( - "unsafe" - - "golang.org/x/exp/constraints" -) - -// Equal reports whether two slices are equal: the same length and all -// elements equal. If the lengths are different, Equal returns false. -// Otherwise, the elements are compared in increasing index order, and the -// comparison stops at the first unequal pair. -// Floating point NaNs are not considered equal. -func Equal[S ~[]E, E comparable](s1, s2 S) bool { - if len(s1) != len(s2) { - return false - } - for i := range s1 { - if s1[i] != s2[i] { - return false - } - } - return true -} - -// EqualFunc reports whether two slices are equal using an equality -// function on each pair of elements. If the lengths are different, -// EqualFunc returns false. Otherwise, the elements are compared in -// increasing index order, and the comparison stops at the first index -// for which eq returns false. -func EqualFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, eq func(E1, E2) bool) bool { - if len(s1) != len(s2) { - return false - } - for i, v1 := range s1 { - v2 := s2[i] - if !eq(v1, v2) { - return false - } - } - return true -} - -// Compare compares the elements of s1 and s2, using [cmp.Compare] on each pair -// of elements. The elements are compared sequentially, starting at index 0, -// until one element is not equal to the other. -// The result of comparing the first non-matching elements is returned. -// If both slices are equal until one of them ends, the shorter slice is -// considered less than the longer one. -// The result is 0 if s1 == s2, -1 if s1 < s2, and +1 if s1 > s2. -func Compare[S ~[]E, E constraints.Ordered](s1, s2 S) int { - for i, v1 := range s1 { - if i >= len(s2) { - return +1 - } - v2 := s2[i] - if c := cmpCompare(v1, v2); c != 0 { - return c - } - } - if len(s1) < len(s2) { - return -1 - } - return 0 -} - -// CompareFunc is like [Compare] but uses a custom comparison function on each -// pair of elements. -// The result is the first non-zero result of cmp; if cmp always -// returns 0 the result is 0 if len(s1) == len(s2), -1 if len(s1) < len(s2), -// and +1 if len(s1) > len(s2). -func CompareFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, cmp func(E1, E2) int) int { - for i, v1 := range s1 { - if i >= len(s2) { - return +1 - } - v2 := s2[i] - if c := cmp(v1, v2); c != 0 { - return c - } - } - if len(s1) < len(s2) { - return -1 - } - return 0 -} - -// Index returns the index of the first occurrence of v in s, -// or -1 if not present. -func Index[S ~[]E, E comparable](s S, v E) int { - for i := range s { - if v == s[i] { - return i - } - } - return -1 -} - -// IndexFunc returns the first index i satisfying f(s[i]), -// or -1 if none do. -func IndexFunc[S ~[]E, E any](s S, f func(E) bool) int { - for i := range s { - if f(s[i]) { - return i - } - } - return -1 -} - -// Contains reports whether v is present in s. -func Contains[S ~[]E, E comparable](s S, v E) bool { - return Index(s, v) >= 0 -} - -// ContainsFunc reports whether at least one -// element e of s satisfies f(e). -func ContainsFunc[S ~[]E, E any](s S, f func(E) bool) bool { - return IndexFunc(s, f) >= 0 -} - -// Insert inserts the values v... into s at index i, -// returning the modified slice. -// The elements at s[i:] are shifted up to make room. -// In the returned slice r, r[i] == v[0], -// and r[i+len(v)] == value originally at r[i]. -// Insert panics if i is out of range. -// This function is O(len(s) + len(v)). -func Insert[S ~[]E, E any](s S, i int, v ...E) S { - m := len(v) - if m == 0 { - return s - } - n := len(s) - if i == n { - return append(s, v...) - } - if n+m > cap(s) { - // Use append rather than make so that we bump the size of - // the slice up to the next storage class. - // This is what Grow does but we don't call Grow because - // that might copy the values twice. - s2 := append(s[:i], make(S, n+m-i)...) - copy(s2[i:], v) - copy(s2[i+m:], s[i:]) - return s2 - } - s = s[:n+m] - - // before: - // s: aaaaaaaabbbbccccccccdddd - // ^ ^ ^ ^ - // i i+m n n+m - // after: - // s: aaaaaaaavvvvbbbbcccccccc - // ^ ^ ^ ^ - // i i+m n n+m - // - // a are the values that don't move in s. - // v are the values copied in from v. - // b and c are the values from s that are shifted up in index. - // d are the values that get overwritten, never to be seen again. - - if !overlaps(v, s[i+m:]) { - // Easy case - v does not overlap either the c or d regions. - // (It might be in some of a or b, or elsewhere entirely.) - // The data we copy up doesn't write to v at all, so just do it. - - copy(s[i+m:], s[i:]) - - // Now we have - // s: aaaaaaaabbbbbbbbcccccccc - // ^ ^ ^ ^ - // i i+m n n+m - // Note the b values are duplicated. - - copy(s[i:], v) - - // Now we have - // s: aaaaaaaavvvvbbbbcccccccc - // ^ ^ ^ ^ - // i i+m n n+m - // That's the result we want. - return s - } - - // The hard case - v overlaps c or d. We can't just shift up - // the data because we'd move or clobber the values we're trying - // to insert. - // So instead, write v on top of d, then rotate. - copy(s[n:], v) - - // Now we have - // s: aaaaaaaabbbbccccccccvvvv - // ^ ^ ^ ^ - // i i+m n n+m - - rotateRight(s[i:], m) - - // Now we have - // s: aaaaaaaavvvvbbbbcccccccc - // ^ ^ ^ ^ - // i i+m n n+m - // That's the result we want. - return s -} - -// clearSlice sets all elements up to the length of s to the zero value of E. -// We may use the builtin clear func instead, and remove clearSlice, when upgrading -// to Go 1.21+. -func clearSlice[S ~[]E, E any](s S) { - var zero E - for i := range s { - s[i] = zero - } -} - -// Delete removes the elements s[i:j] from s, returning the modified slice. -// Delete panics if j > len(s) or s[i:j] is not a valid slice of s. -// Delete is O(len(s)-i), so if many items must be deleted, it is better to -// make a single call deleting them all together than to delete one at a time. -// Delete zeroes the elements s[len(s)-(j-i):len(s)]. -func Delete[S ~[]E, E any](s S, i, j int) S { - _ = s[i:j:len(s)] // bounds check - - if i == j { - return s - } - - oldlen := len(s) - s = append(s[:i], s[j:]...) - clearSlice(s[len(s):oldlen]) // zero/nil out the obsolete elements, for GC - return s -} - -// DeleteFunc removes any elements from s for which del returns true, -// returning the modified slice. -// DeleteFunc zeroes the elements between the new length and the original length. -func DeleteFunc[S ~[]E, E any](s S, del func(E) bool) S { - i := IndexFunc(s, del) - if i == -1 { - return s - } - // Don't start copying elements until we find one to delete. - for j := i + 1; j < len(s); j++ { - if v := s[j]; !del(v) { - s[i] = v - i++ - } - } - clearSlice(s[i:]) // zero/nil out the obsolete elements, for GC - return s[:i] -} - -// Replace replaces the elements s[i:j] by the given v, and returns the -// modified slice. Replace panics if s[i:j] is not a valid slice of s. -// When len(v) < (j-i), Replace zeroes the elements between the new length and the original length. -func Replace[S ~[]E, E any](s S, i, j int, v ...E) S { - _ = s[i:j] // verify that i:j is a valid subslice - - if i == j { - return Insert(s, i, v...) - } - if j == len(s) { - return append(s[:i], v...) - } - - tot := len(s[:i]) + len(v) + len(s[j:]) - if tot > cap(s) { - // Too big to fit, allocate and copy over. - s2 := append(s[:i], make(S, tot-i)...) // See Insert - copy(s2[i:], v) - copy(s2[i+len(v):], s[j:]) - return s2 - } - - r := s[:tot] - - if i+len(v) <= j { - // Easy, as v fits in the deleted portion. - copy(r[i:], v) - if i+len(v) != j { - copy(r[i+len(v):], s[j:]) - } - clearSlice(s[tot:]) // zero/nil out the obsolete elements, for GC - return r - } - - // We are expanding (v is bigger than j-i). - // The situation is something like this: - // (example has i=4,j=8,len(s)=16,len(v)=6) - // s: aaaaxxxxbbbbbbbbyy - // ^ ^ ^ ^ - // i j len(s) tot - // a: prefix of s - // x: deleted range - // b: more of s - // y: area to expand into - - if !overlaps(r[i+len(v):], v) { - // Easy, as v is not clobbered by the first copy. - copy(r[i+len(v):], s[j:]) - copy(r[i:], v) - return r - } - - // This is a situation where we don't have a single place to which - // we can copy v. Parts of it need to go to two different places. - // We want to copy the prefix of v into y and the suffix into x, then - // rotate |y| spots to the right. - // - // v[2:] v[:2] - // | | - // s: aaaavvvvbbbbbbbbvv - // ^ ^ ^ ^ - // i j len(s) tot - // - // If either of those two destinations don't alias v, then we're good. - y := len(v) - (j - i) // length of y portion - - if !overlaps(r[i:j], v) { - copy(r[i:j], v[y:]) - copy(r[len(s):], v[:y]) - rotateRight(r[i:], y) - return r - } - if !overlaps(r[len(s):], v) { - copy(r[len(s):], v[:y]) - copy(r[i:j], v[y:]) - rotateRight(r[i:], y) - return r - } - - // Now we know that v overlaps both x and y. - // That means that the entirety of b is *inside* v. - // So we don't need to preserve b at all; instead we - // can copy v first, then copy the b part of v out of - // v to the right destination. - k := startIdx(v, s[j:]) - copy(r[i:], v) - copy(r[i+len(v):], r[i+k:]) - return r -} - -// Clone returns a copy of the slice. -// The elements are copied using assignment, so this is a shallow clone. -func Clone[S ~[]E, E any](s S) S { - // Preserve nil in case it matters. - if s == nil { - return nil - } - return append(S([]E{}), s...) -} - -// Compact replaces consecutive runs of equal elements with a single copy. -// This is like the uniq command found on Unix. -// Compact modifies the contents of the slice s and returns the modified slice, -// which may have a smaller length. -// Compact zeroes the elements between the new length and the original length. -func Compact[S ~[]E, E comparable](s S) S { - if len(s) < 2 { - return s - } - i := 1 - for k := 1; k < len(s); k++ { - if s[k] != s[k-1] { - if i != k { - s[i] = s[k] - } - i++ - } - } - clearSlice(s[i:]) // zero/nil out the obsolete elements, for GC - return s[:i] -} - -// CompactFunc is like [Compact] but uses an equality function to compare elements. -// For runs of elements that compare equal, CompactFunc keeps the first one. -// CompactFunc zeroes the elements between the new length and the original length. -func CompactFunc[S ~[]E, E any](s S, eq func(E, E) bool) S { - if len(s) < 2 { - return s - } - i := 1 - for k := 1; k < len(s); k++ { - if !eq(s[k], s[k-1]) { - if i != k { - s[i] = s[k] - } - i++ - } - } - clearSlice(s[i:]) // zero/nil out the obsolete elements, for GC - return s[:i] -} - -// Grow increases the slice's capacity, if necessary, to guarantee space for -// another n elements. After Grow(n), at least n elements can be appended -// to the slice without another allocation. If n is negative or too large to -// allocate the memory, Grow panics. -func Grow[S ~[]E, E any](s S, n int) S { - if n < 0 { - panic("cannot be negative") - } - if n -= cap(s) - len(s); n > 0 { - // TODO(https://go.dev/issue/53888): Make using []E instead of S - // to workaround a compiler bug where the runtime.growslice optimization - // does not take effect. Revert when the compiler is fixed. - s = append([]E(s)[:cap(s)], make([]E, n)...)[:len(s)] - } - return s -} - -// Clip removes unused capacity from the slice, returning s[:len(s):len(s)]. -func Clip[S ~[]E, E any](s S) S { - return s[:len(s):len(s)] -} - -// Rotation algorithm explanation: -// -// rotate left by 2 -// start with -// 0123456789 -// split up like this -// 01 234567 89 -// swap first 2 and last 2 -// 89 234567 01 -// join first parts -// 89234567 01 -// recursively rotate first left part by 2 -// 23456789 01 -// join at the end -// 2345678901 -// -// rotate left by 8 -// start with -// 0123456789 -// split up like this -// 01 234567 89 -// swap first 2 and last 2 -// 89 234567 01 -// join last parts -// 89 23456701 -// recursively rotate second part left by 6 -// 89 01234567 -// join at the end -// 8901234567 - -// TODO: There are other rotate algorithms. -// This algorithm has the desirable property that it moves each element exactly twice. -// The triple-reverse algorithm is simpler and more cache friendly, but takes more writes. -// The follow-cycles algorithm can be 1-write but it is not very cache friendly. - -// rotateLeft rotates b left by n spaces. -// s_final[i] = s_orig[i+r], wrapping around. -func rotateLeft[E any](s []E, r int) { - for r != 0 && r != len(s) { - if r*2 <= len(s) { - swap(s[:r], s[len(s)-r:]) - s = s[:len(s)-r] - } else { - swap(s[:len(s)-r], s[r:]) - s, r = s[len(s)-r:], r*2-len(s) - } - } -} -func rotateRight[E any](s []E, r int) { - rotateLeft(s, len(s)-r) -} - -// swap swaps the contents of x and y. x and y must be equal length and disjoint. -func swap[E any](x, y []E) { - for i := 0; i < len(x); i++ { - x[i], y[i] = y[i], x[i] - } -} - -// overlaps reports whether the memory ranges a[0:len(a)] and b[0:len(b)] overlap. -func overlaps[E any](a, b []E) bool { - if len(a) == 0 || len(b) == 0 { - return false - } - elemSize := unsafe.Sizeof(a[0]) - if elemSize == 0 { - return false - } - // TODO: use a runtime/unsafe facility once one becomes available. See issue 12445. - // Also see crypto/internal/alias/alias.go:AnyOverlap - return uintptr(unsafe.Pointer(&a[0])) <= uintptr(unsafe.Pointer(&b[len(b)-1]))+(elemSize-1) && - uintptr(unsafe.Pointer(&b[0])) <= uintptr(unsafe.Pointer(&a[len(a)-1]))+(elemSize-1) -} - -// startIdx returns the index in haystack where the needle starts. -// prerequisite: the needle must be aliased entirely inside the haystack. -func startIdx[E any](haystack, needle []E) int { - p := &needle[0] - for i := range haystack { - if p == &haystack[i] { - return i - } - } - // TODO: what if the overlap is by a non-integral number of Es? - panic("needle not found") -} - -// Reverse reverses the elements of the slice in place. -func Reverse[S ~[]E, E any](s S) { - for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 { - s[i], s[j] = s[j], s[i] - } -} |