1 files changed, 199 insertions, 0 deletions
diff --git a/vendor/github.com/mattermost/rsc/regexp/regmerge/sort.go b/vendor/github.com/mattermost/rsc/regexp/regmerge/sort.go
new file mode 100644
index 000000000..e40f87714
--- /dev/null
+++ b/vendor/github.com/mattermost/rsc/regexp/regmerge/sort.go
@@ -0,0 +1,199 @@
+// Copyright 2012 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.
+
+// Copy of go/src/pkg/sort/sort.go, specialized for []int
+// and to remove some array indexing.
+
+package main
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// Insertion sort
+func insertionSort(data []int, a, b int) {
+	for i := a + 1; i < b; i++ {
+		for j := i; j > a && data[j] < data[j-1]; j-- {
+			data[j], data[j-1] = data[j-1], data[j]
+		}
+	}
+}
+
+// siftDown implements the heap property on data[lo, hi).
+// first is an offset into the array where the root of the heap lies.
+func siftDown(data []int, lo, hi, first int) {
+	root := lo
+	for {
+		child := 2*root + 1
+		if child >= hi {
+			break
+		}
+		if child+1 < hi && data[first+child] < data[first+child+1] {
+			child++
+		}
+		if !(data[first+root] < data[first+child]) {
+			return
+		}
+		data[first+root], data[first+child] = data[first+child], data[first+root]
+		root = child
+	}
+}
+
+func heapSort(data []int, a, b int) {
+	first := a
+	lo := 0
+	hi := b - a
+
+	// Build heap with greatest element at top.
+	for i := (hi - 1) / 2; i >= 0; i-- {
+		siftDown(data, i, hi, first)
+	}
+
+	// Pop elements, largest first, into end of data.
+	for i := hi - 1; i >= 0; i-- {
+		data[first], data[first+i] = data[first+i], data[first]
+		siftDown(data, lo, i, first)
+	}
+}
+
+// Quicksort, following Bentley and McIlroy,
+// ``Engineering a Sort Function,'' SP&E November 1993.
+
+// medianOfThree moves the median of the three values data[a], data[b], data[c] into data[a].
+func medianOfThree(data []int, a, b, c int) {
+	m0 := b
+	m1 := a
+	m2 := c
+	// bubble sort on 3 elements
+	if data[m1] < data[m0] {
+		data[m1], data[m0] = data[m0], data[m1]
+	}
+	if data[m2] < data[m1] {
+		data[m2], data[m1] = data[m1], data[m2]
+	}
+	if data[m1] < data[m0] {
+		data[m1], data[m0] = data[m0], data[m1]
+	}
+	// now data[m0] <= data[m1] <= data[m2]
+}
+
+func swapRange(data []int, a, b, n int) {
+	for i := 0; i < n; i++ {
+		data[a+i], data[b+i] = data[b+i], data[a+i]
+	}
+}
+
+func doPivot(data []int, 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 slice.
+	pivot := lo
+	a, b, c, d := lo+1, lo+1, hi, hi
+	dpivot := data[pivot]
+	db, dc1 := data[b], data[c-1]
+	for b < c {
+		if db < dpivot { // data[b] < pivot
+			b++
+			if b < c {
+				db = data[b]
+			}
+			continue
+		}
+		if !(dpivot < db) { // data[b] = pivot
+			data[a], data[b] = db, data[a]
+			a++
+			b++
+			if b < c {
+				db = data[b]
+			}
+			continue
+		}
+		if dpivot < dc1 { // data[c-1] > pivot
+			c--
+			if c > 0 {
+				dc1 = data[c-1]
+			}
+			continue
+		}
+		if !(dc1 < dpivot) { // data[c-1] = pivot
+			data[c-1], data[d-1] = data[d-1], dc1
+			c--
+			d--
+			if c > 0 {
+				dc1 = data[c-1]
+			}
+			continue
+		}
+		// data[b] > pivot; data[c-1] < pivot
+		data[b], data[c-1] = dc1, db
+		b++
+		c--
+		if b < c {
+			db = data[b]
+			dc1 = data[c-1]
+		}
+	}
+
+	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 []int, a, b, maxDepth int) {
+	for b-a > 7 {
+		if maxDepth == 0 {
+			heapSort(data, a, b)
+			return
+		}
+		maxDepth--
+		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, maxDepth)
+			a = mhi // i.e., quickSort(data, mhi, b)
+		} else {
+			quickSort(data, mhi, b, maxDepth)
+			b = mlo // i.e., quickSort(data, a, mlo)
+		}
+	}
+	if b-a > 1 {
+		insertionSort(data, a, b)
+	}
+}
+
+func sortInts(data []int) {
+	// Switch to heapsort if depth of 2*ceil(lg(n)) is reached.
+	n := len(data)
+	maxDepth := 0
+	for 1<<uint(maxDepth) < n {
+		maxDepth++
+	}
+	maxDepth *= 2
+	quickSort(data, 0, n, maxDepth)
+}