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// Copyright 2011 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.
// Copied from code.google.com/p/codesearch/regexp/copy.go.
// Copied from Go's regexp/syntax.
// Formatters edited to handle instByteRange.
package main
import (
"bytes"
"fmt"
"regexp/syntax"
"sort"
"strconv"
"unicode"
)
// cleanClass sorts the ranges (pairs of elements of r),
// merges them, and eliminates duplicates.
func cleanClass(rp *[]rune) []rune {
// Sort by lo increasing, hi decreasing to break ties.
sort.Sort(ranges{rp})
r := *rp
if len(r) < 2 {
return r
}
// Merge abutting, overlapping.
w := 2 // write index
for i := 2; i < len(r); i += 2 {
lo, hi := r[i], r[i+1]
if lo <= r[w-1]+1 {
// merge with previous range
if hi > r[w-1] {
r[w-1] = hi
}
continue
}
// new disjoint range
r[w] = lo
r[w+1] = hi
w += 2
}
return r[:w]
}
// appendRange returns the result of appending the range lo-hi to the class r.
func appendRange(r []rune, lo, hi rune) []rune {
// Expand last range or next to last range if it overlaps or abuts.
// Checking two ranges helps when appending case-folded
// alphabets, so that one range can be expanding A-Z and the
// other expanding a-z.
n := len(r)
for i := 2; i <= 4; i += 2 { // twice, using i=2, i=4
if n >= i {
rlo, rhi := r[n-i], r[n-i+1]
if lo <= rhi+1 && rlo <= hi+1 {
if lo < rlo {
r[n-i] = lo
}
if hi > rhi {
r[n-i+1] = hi
}
return r
}
}
}
return append(r, lo, hi)
}
const (
// minimum and maximum runes involved in folding.
// checked during test.
minFold = 0x0041
maxFold = 0x1044f
)
// appendFoldedRange returns the result of appending the range lo-hi
// and its case folding-equivalent runes to the class r.
func appendFoldedRange(r []rune, lo, hi rune) []rune {
// Optimizations.
if lo <= minFold && hi >= maxFold {
// Range is full: folding can't add more.
return appendRange(r, lo, hi)
}
if hi < minFold || lo > maxFold {
// Range is outside folding possibilities.
return appendRange(r, lo, hi)
}
if lo < minFold {
// [lo, minFold-1] needs no folding.
r = appendRange(r, lo, minFold-1)
lo = minFold
}
if hi > maxFold {
// [maxFold+1, hi] needs no folding.
r = appendRange(r, maxFold+1, hi)
hi = maxFold
}
// Brute force. Depend on appendRange to coalesce ranges on the fly.
for c := lo; c <= hi; c++ {
r = appendRange(r, c, c)
f := unicode.SimpleFold(c)
for f != c {
r = appendRange(r, f, f)
f = unicode.SimpleFold(f)
}
}
return r
}
// ranges implements sort.Interface on a []rune.
// The choice of receiver type definition is strange
// but avoids an allocation since we already have
// a *[]rune.
type ranges struct {
p *[]rune
}
func (ra ranges) Less(i, j int) bool {
p := *ra.p
i *= 2
j *= 2
return p[i] < p[j] || p[i] == p[j] && p[i+1] > p[j+1]
}
func (ra ranges) Len() int {
return len(*ra.p) / 2
}
func (ra ranges) Swap(i, j int) {
p := *ra.p
i *= 2
j *= 2
p[i], p[i+1], p[j], p[j+1] = p[j], p[j+1], p[i], p[i+1]
}
func progString(p *syntax.Prog) string {
var b bytes.Buffer
dumpProg(&b, p)
return b.String()
}
func instString(i *syntax.Inst) string {
var b bytes.Buffer
dumpInst(&b, i)
return b.String()
}
func bw(b *bytes.Buffer, args ...string) {
for _, s := range args {
b.WriteString(s)
}
}
func dumpProg(b *bytes.Buffer, p *syntax.Prog) {
for j := range p.Inst {
i := &p.Inst[j]
pc := strconv.Itoa(j)
if len(pc) < 3 {
b.WriteString(" "[len(pc):])
}
if j == p.Start {
pc += "*"
}
bw(b, pc, "\t")
dumpInst(b, i)
bw(b, "\n")
}
}
func u32(i uint32) string {
return strconv.FormatUint(uint64(i), 10)
}
func dumpInst(b *bytes.Buffer, i *syntax.Inst) {
switch i.Op {
case syntax.InstAlt:
bw(b, "alt -> ", u32(i.Out), ", ", u32(i.Arg))
case syntax.InstAltMatch:
bw(b, "altmatch -> ", u32(i.Out), ", ", u32(i.Arg))
case syntax.InstCapture:
bw(b, "cap ", u32(i.Arg), " -> ", u32(i.Out))
case syntax.InstEmptyWidth:
bw(b, "empty ", u32(i.Arg), " -> ", u32(i.Out))
case syntax.InstMatch:
bw(b, "match")
case syntax.InstFail:
bw(b, "fail")
case syntax.InstNop:
bw(b, "nop -> ", u32(i.Out))
case instByteRange:
fmt.Fprintf(b, "byte %02x-%02x", (i.Arg>>8)&0xFF, i.Arg&0xFF)
if i.Arg&argFold != 0 {
bw(b, "/i")
}
bw(b, " -> ", u32(i.Out))
// Should not happen
case syntax.InstRune:
if i.Rune == nil {
// shouldn't happen
bw(b, "rune <nil>")
}
bw(b, "rune ", strconv.QuoteToASCII(string(i.Rune)))
if syntax.Flags(i.Arg)&syntax.FoldCase != 0 {
bw(b, "/i")
}
bw(b, " -> ", u32(i.Out))
case syntax.InstRune1:
bw(b, "rune1 ", strconv.QuoteToASCII(string(i.Rune)), " -> ", u32(i.Out))
case syntax.InstRuneAny:
bw(b, "any -> ", u32(i.Out))
case syntax.InstRuneAnyNotNL:
bw(b, "anynotnl -> ", u32(i.Out))
}
}
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