From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- libgo/go/sort/sort.go | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) create mode 100644 libgo/go/sort/sort.go (limited to 'libgo/go/sort/sort.go') diff --git a/libgo/go/sort/sort.go b/libgo/go/sort/sort.go new file mode 100644 index 000000000..c7945d21b --- /dev/null +++ b/libgo/go/sort/sort.go @@ -0,0 +1,206 @@ +// Copyright 2009 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. + +// The sort package provides primitives for sorting arrays +// and user-defined collections. +package sort + +// A type, typically a collection, that satisfies sort.Interface can be +// sorted by the routines in this package. The methods require that the +// elements of the collection be enumerated by an integer index. +type Interface interface { + // Len is the number of elements in the collection. + Len() int + // Less returns whether the element with index i should sort + // before the element with index j. + Less(i, j int) bool + // Swap swaps the elements with indexes i and j. + Swap(i, j int) +} + +func min(a, b int) int { + if a < b { + return a + } + return b +} + +// Insertion sort +func insertionSort(data Interface, a, b int) { + for i := a + 1; i < b; i++ { + for j := i; j > a && data.Less(j, j-1); j-- { + data.Swap(j, j-1) + } + } +} + +// Quicksort, following Bentley and McIlroy, +// ``Engineering a Sort Function,'' SP&E November 1993. + +// Move the median of the three values data[a], data[b], data[c] into data[a]. +func medianOfThree(data Interface, a, b, c int) { + m0 := b + m1 := a + m2 := c + // bubble sort on 3 elements + if data.Less(m1, m0) { + data.Swap(m1, m0) + } + if data.Less(m2, m1) { + data.Swap(m2, m1) + } + if data.Less(m1, m0) { + data.Swap(m1, m0) + } + // now data[m0] <= data[m1] <= data[m2] +} + +func swapRange(data Interface, a, b, n int) { + for i := 0; i < n; i++ { + data.Swap(a+i, b+i) + } +} + +func doPivot(data Interface, lo, hi int) (midlo, midhi int) { + m := lo + (hi-lo)/2 // Written like this to avoid integer overflow. + if hi-lo > 40 { + // Tukey's ``Ninther,'' median of three medians of three. + s := (hi - lo) / 8 + medianOfThree(data, lo, lo+s, lo+2*s) + medianOfThree(data, m, m-s, m+s) + medianOfThree(data, hi-1, hi-1-s, hi-1-2*s) + } + medianOfThree(data, lo, m, hi-1) + + // Invariants are: + // data[lo] = pivot (set up by ChoosePivot) + // data[lo <= i < a] = pivot + // data[a <= i < b] < pivot + // data[b <= i < c] is unexamined + // data[c <= i < d] > pivot + // data[d <= i < hi] = pivot + // + // Once b meets c, can swap the "= pivot" sections + // into the middle of the array. + pivot := lo + a, b, c, d := lo+1, lo+1, hi, hi + for b < c { + if data.Less(b, pivot) { // data[b] < pivot + b++ + continue + } + if !data.Less(pivot, b) { // data[b] = pivot + data.Swap(a, b) + a++ + b++ + continue + } + if data.Less(pivot, c-1) { // data[c-1] > pivot + c-- + continue + } + if !data.Less(c-1, pivot) { // data[c-1] = pivot + data.Swap(c-1, d-1) + c-- + d-- + continue + } + // data[b] > pivot; data[c-1] < pivot + data.Swap(b, c-1) + b++ + c-- + } + + n := min(b-a, a-lo) + swapRange(data, lo, b-n, n) + + n = min(hi-d, d-c) + swapRange(data, c, hi-n, n) + + return lo + b - a, hi - (d - c) +} + +func quickSort(data Interface, a, b int) { + for b-a > 7 { + mlo, mhi := doPivot(data, a, b) + // Avoiding recursion on the larger subproblem guarantees + // a stack depth of at most lg(b-a). + if mlo-a < b-mhi { + quickSort(data, a, mlo) + a = mhi // i.e., quickSort(data, mhi, b) + } else { + quickSort(data, mhi, b) + b = mlo // i.e., quickSort(data, a, mlo) + } + } + if b-a > 1 { + insertionSort(data, a, b) + } +} + +func Sort(data Interface) { quickSort(data, 0, data.Len()) } + + +func IsSorted(data Interface) bool { + n := data.Len() + for i := n - 1; i > 0; i-- { + if data.Less(i, i-1) { + return false + } + } + return true +} + + +// Convenience types for common cases + +// IntArray attaches the methods of Interface to []int, sorting in increasing order. +type IntArray []int + +func (p IntArray) Len() int { return len(p) } +func (p IntArray) Less(i, j int) bool { return p[i] < p[j] } +func (p IntArray) Swap(i, j int) { p[i], p[j] = p[j], p[i] } + +// Sort is a convenience method. +func (p IntArray) Sort() { Sort(p) } + + +// Float64Array attaches the methods of Interface to []float64, sorting in increasing order. +type Float64Array []float64 + +func (p Float64Array) Len() int { return len(p) } +func (p Float64Array) Less(i, j int) bool { return p[i] < p[j] } +func (p Float64Array) Swap(i, j int) { p[i], p[j] = p[j], p[i] } + +// Sort is a convenience method. +func (p Float64Array) Sort() { Sort(p) } + + +// StringArray attaches the methods of Interface to []string, sorting in increasing order. +type StringArray []string + +func (p StringArray) Len() int { return len(p) } +func (p StringArray) Less(i, j int) bool { return p[i] < p[j] } +func (p StringArray) Swap(i, j int) { p[i], p[j] = p[j], p[i] } + +// Sort is a convenience method. +func (p StringArray) Sort() { Sort(p) } + + +// Convenience wrappers for common cases + +// SortInts sorts an array of ints in increasing order. +func SortInts(a []int) { Sort(IntArray(a)) } +// SortFloat64s sorts an array of float64s in increasing order. +func SortFloat64s(a []float64) { Sort(Float64Array(a)) } +// SortStrings sorts an array of strings in increasing order. +func SortStrings(a []string) { Sort(StringArray(a)) } + + +// IntsAreSorted tests whether an array of ints is sorted in increasing order. +func IntsAreSorted(a []int) bool { return IsSorted(IntArray(a)) } +// Float64sAreSorted tests whether an array of float64s is sorted in increasing order. +func Float64sAreSorted(a []float64) bool { return IsSorted(Float64Array(a)) } +// StringsAreSorted tests whether an array of strings is sorted in increasing order. +func StringsAreSorted(a []string) bool { return IsSorted(StringArray(a)) } -- cgit v1.2.3