mirror of
https://github.com/kubernetes-sigs/prometheus-adapter.git
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a293b2bf94
Travis seems to be having issues pulling deps, so we'll have to check in the vendor directory and prevent the makefile from trying to regenerate it normally.
260 lines
6.6 KiB
Go
260 lines
6.6 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package rangetable
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import (
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"unicode"
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)
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// atEnd is used to mark a completed iteration.
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const atEnd = unicode.MaxRune + 1
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// Merge returns a new RangeTable that is the union of the given tables.
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// It can also be used to compact user-created RangeTables. The entries in
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// R16 and R32 for any given RangeTable should be sorted and non-overlapping.
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//
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// A lookup in the resulting table can be several times faster than using In
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// directly on the ranges. Merge is an expensive operation, however, and only
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// makes sense if one intends to use the result for more than a couple of
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// hundred lookups.
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func Merge(ranges ...*unicode.RangeTable) *unicode.RangeTable {
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rt := &unicode.RangeTable{}
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if len(ranges) == 0 {
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return rt
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}
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iter := tablesIter(make([]tableIndex, len(ranges)))
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for i, t := range ranges {
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iter[i] = tableIndex{t, 0, atEnd}
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if len(t.R16) > 0 {
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iter[i].next = rune(t.R16[0].Lo)
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}
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}
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if r0 := iter.next16(); r0.Stride != 0 {
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for {
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r1 := iter.next16()
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if r1.Stride == 0 {
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rt.R16 = append(rt.R16, r0)
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break
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}
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stride := r1.Lo - r0.Hi
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if (r1.Lo == r1.Hi || stride == r1.Stride) && (r0.Lo == r0.Hi || stride == r0.Stride) {
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// Fully merge the next range into the previous one.
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r0.Hi, r0.Stride = r1.Hi, stride
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continue
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} else if stride == r0.Stride {
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// Move the first element of r1 to r0. This may eliminate an
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// entry.
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r0.Hi = r1.Lo
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r0.Stride = stride
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r1.Lo = r1.Lo + r1.Stride
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if r1.Lo > r1.Hi {
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continue
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}
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}
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rt.R16 = append(rt.R16, r0)
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r0 = r1
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}
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}
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for i, t := range ranges {
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iter[i] = tableIndex{t, 0, atEnd}
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if len(t.R32) > 0 {
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iter[i].next = rune(t.R32[0].Lo)
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}
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}
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if r0 := iter.next32(); r0.Stride != 0 {
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for {
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r1 := iter.next32()
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if r1.Stride == 0 {
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rt.R32 = append(rt.R32, r0)
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break
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}
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stride := r1.Lo - r0.Hi
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if (r1.Lo == r1.Hi || stride == r1.Stride) && (r0.Lo == r0.Hi || stride == r0.Stride) {
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// Fully merge the next range into the previous one.
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r0.Hi, r0.Stride = r1.Hi, stride
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continue
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} else if stride == r0.Stride {
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// Move the first element of r1 to r0. This may eliminate an
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// entry.
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r0.Hi = r1.Lo
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r1.Lo = r1.Lo + r1.Stride
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if r1.Lo > r1.Hi {
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continue
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}
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}
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rt.R32 = append(rt.R32, r0)
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r0 = r1
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}
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}
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for i := 0; i < len(rt.R16) && rt.R16[i].Hi <= unicode.MaxLatin1; i++ {
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rt.LatinOffset = i + 1
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}
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return rt
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}
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type tableIndex struct {
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t *unicode.RangeTable
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p uint32
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next rune
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}
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type tablesIter []tableIndex
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// sortIter does an insertion sort using the next field of tableIndex. Insertion
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// sort is a good sorting algorithm for this case.
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func sortIter(t []tableIndex) {
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for i := range t {
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for j := i; j > 0 && t[j-1].next > t[j].next; j-- {
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t[j], t[j-1] = t[j-1], t[j]
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}
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}
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}
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// next16 finds the ranged to be added to the table. If ranges overlap between
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// multiple tables it clips the result to a non-overlapping range if the
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// elements are not fully subsumed. It returns a zero range if there are no more
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// ranges.
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func (ti tablesIter) next16() unicode.Range16 {
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sortIter(ti)
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t0 := ti[0]
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if t0.next == atEnd {
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return unicode.Range16{}
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}
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r0 := t0.t.R16[t0.p]
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r0.Lo = uint16(t0.next)
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// We restrict the Hi of the current range if it overlaps with another range.
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for i := range ti {
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tn := ti[i]
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// Since our tableIndices are sorted by next, we can break if the there
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// is no overlap. The first value of a next range can always be merged
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// into the current one, so we can break in case of equality as well.
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if rune(r0.Hi) <= tn.next {
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break
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}
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rn := tn.t.R16[tn.p]
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rn.Lo = uint16(tn.next)
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// Limit r0.Hi based on next ranges in list, but allow it to overlap
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// with ranges as long as it subsumes it.
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m := (rn.Lo - r0.Lo) % r0.Stride
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if m == 0 && (rn.Stride == r0.Stride || rn.Lo == rn.Hi) {
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// Overlap, take the min of the two Hi values: for simplicity's sake
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// we only process one range at a time.
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if r0.Hi > rn.Hi {
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r0.Hi = rn.Hi
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}
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} else {
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// Not a compatible stride. Set to the last possible value before
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// rn.Lo, but ensure there is at least one value.
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if x := rn.Lo - m; r0.Lo <= x {
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r0.Hi = x
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}
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break
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}
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}
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// Update the next values for each table.
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for i := range ti {
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tn := &ti[i]
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if rune(r0.Hi) < tn.next {
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break
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}
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rn := tn.t.R16[tn.p]
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stride := rune(rn.Stride)
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tn.next += stride * (1 + ((rune(r0.Hi) - tn.next) / stride))
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if rune(rn.Hi) < tn.next {
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if tn.p++; int(tn.p) == len(tn.t.R16) {
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tn.next = atEnd
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} else {
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tn.next = rune(tn.t.R16[tn.p].Lo)
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}
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}
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}
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if r0.Lo == r0.Hi {
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r0.Stride = 1
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}
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return r0
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}
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// next32 finds the ranged to be added to the table. If ranges overlap between
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// multiple tables it clips the result to a non-overlapping range if the
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// elements are not fully subsumed. It returns a zero range if there are no more
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// ranges.
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func (ti tablesIter) next32() unicode.Range32 {
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sortIter(ti)
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t0 := ti[0]
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if t0.next == atEnd {
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return unicode.Range32{}
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}
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r0 := t0.t.R32[t0.p]
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r0.Lo = uint32(t0.next)
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// We restrict the Hi of the current range if it overlaps with another range.
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for i := range ti {
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tn := ti[i]
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// Since our tableIndices are sorted by next, we can break if the there
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// is no overlap. The first value of a next range can always be merged
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// into the current one, so we can break in case of equality as well.
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if rune(r0.Hi) <= tn.next {
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break
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}
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rn := tn.t.R32[tn.p]
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rn.Lo = uint32(tn.next)
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// Limit r0.Hi based on next ranges in list, but allow it to overlap
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// with ranges as long as it subsumes it.
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m := (rn.Lo - r0.Lo) % r0.Stride
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if m == 0 && (rn.Stride == r0.Stride || rn.Lo == rn.Hi) {
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// Overlap, take the min of the two Hi values: for simplicity's sake
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// we only process one range at a time.
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if r0.Hi > rn.Hi {
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r0.Hi = rn.Hi
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}
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} else {
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// Not a compatible stride. Set to the last possible value before
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// rn.Lo, but ensure there is at least one value.
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if x := rn.Lo - m; r0.Lo <= x {
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r0.Hi = x
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}
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break
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}
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}
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// Update the next values for each table.
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for i := range ti {
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tn := &ti[i]
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if rune(r0.Hi) < tn.next {
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break
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}
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rn := tn.t.R32[tn.p]
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stride := rune(rn.Stride)
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tn.next += stride * (1 + ((rune(r0.Hi) - tn.next) / stride))
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if rune(rn.Hi) < tn.next {
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if tn.p++; int(tn.p) == len(tn.t.R32) {
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tn.next = atEnd
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} else {
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tn.next = rune(tn.t.R32[tn.p].Lo)
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}
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}
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}
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if r0.Lo == r0.Hi {
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r0.Stride = 1
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}
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return r0
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}
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