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exp/regexp/syntax: case-folding in character classes

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Also fix \x{123} parsing.

R=r
CC=golang-dev
https://golang.org/cl/4632052
This commit is contained in:
Russ Cox 2011-06-27 23:23:51 -04:00
parent 6b648cafde
commit 52cd055f91
2 changed files with 207 additions and 39 deletions
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161
src/pkg/exp/regexp/syntax/parse.go
View File

@ -81,6 +81,7 @@ type parser struct {
stack []*Regexp // stack of parsed expressions
numCap int // number of capturing groups seen
wholeRegexp string
tmpClass []int // temporary char class work space
}
// Parse stack manipulation.
@ -371,7 +372,6 @@ func Parse(s string, flags Flags) (*Regexp, os.Error) {
if r != nil {
re.Rune = r
t = rest
// TODO: Handle FoldCase flag.
p.push(re)
break BigSwitch
}
@ -729,6 +729,7 @@ Switch:
if r > unicode.MaxRune {
break Switch
}
nhex++
}
if nhex == 0 {
break Switch
@ -801,12 +802,7 @@ func (p *parser) parsePerlClassEscape(s string, r []int) (out []int, rest string
if g.sign == 0 {
return
}
if g.sign < 0 {
r = appendNegatedClass(r, g.class)
} else {
r = appendClass(r, g.class)
}
return r, s[2:]
return p.appendGroup(r, g), s[2:]
}
// parseNamedClass parses a leading POSIX named character class like [:alnum:]
@ -827,23 +823,40 @@ func (p *parser) parseNamedClass(s string, r []int) (out []int, rest string, err
if g.sign == 0 {
return nil, "", &Error{ErrInvalidCharRange, name}
}
if g.sign < 0 {
r = appendNegatedClass(r, g.class)
} else {
r = appendClass(r, g.class)
}
return r, s, nil
return p.appendGroup(r, g), s, nil
}
// unicodeTable returns the unicode.RangeTable identified by name.
func unicodeTable(name string) *unicode.RangeTable {
func (p *parser) appendGroup(r []int, g charGroup) []int {
if p.flags&FoldCase == 0 {
if g.sign < 0 {
r = appendNegatedClass(r, g.class)
} else {
r = appendClass(r, g.class)
}
} else {
tmp := p.tmpClass[:0]
tmp = appendFoldedClass(tmp, g.class)
p.tmpClass = tmp
tmp = cleanClass(&p.tmpClass)
if g.sign < 0 {
r = appendNegatedClass(r, tmp)
} else {
r = appendClass(r, tmp)
}
}
return r
}
// unicodeTable returns the unicode.RangeTable identified by name
// and the table of additional fold-equivalent code points.
func unicodeTable(name string) (*unicode.RangeTable, *unicode.RangeTable) {
if t := unicode.Categories[name]; t != nil {
return t
return t, unicode.FoldCategory[name]
}
if t := unicode.Scripts[name]; t != nil {
return t
return t, unicode.FoldScript[name]
}
return nil
return nil, nil
}
// parseUnicodeClass parses a leading Unicode character class like \p{Han}
@ -891,14 +904,31 @@ func (p *parser) parseUnicodeClass(s string, r []int) (out []int, rest string, e
name = name[1:]
}
tab := unicodeTable(name)
tab, fold := unicodeTable(name)
if tab == nil {
return nil, "", &Error{ErrInvalidCharRange, seq}
}
if sign > 0 {
r = appendTable(r, tab)
if p.flags&FoldCase == 0 || fold == nil {
if sign > 0 {
r = appendTable(r, tab)
} else {
r = appendNegatedTable(r, tab)
}
} else {
r = appendNegatedTable(r, tab)
// Merge and clean tab and fold in a temporary buffer.
// This is necessary for the negative case and just tidy
// for the positive case.
tmp := p.tmpClass[:0]
tmp = appendTable(tmp, tab)
tmp = appendTable(tmp, fold)
p.tmpClass = tmp
tmp = cleanClass(&p.tmpClass)
if sign > 0 {
r = appendClass(r, tmp)
} else {
r = appendNegatedClass(r, tmp)
}
}
return r, t, nil
}
@ -979,7 +1009,11 @@ func (p *parser) parseClass(s string) (rest string, err os.Error) {
return "", &Error{Code: ErrInvalidCharRange, Expr: rng}
}
}
class = appendRange(class, lo, hi)
if p.flags&FoldCase == 0 {
class = appendRange(class, lo, hi)
} else {
class = appendFoldedRange(class, lo, hi)
}
}
t = t[1:] // chop ]
@ -999,10 +1033,15 @@ func (p *parser) parseClass(s string) (rest string, err os.Error) {
// cleanClass sorts the ranges (pairs of elements of r),
// merges them, and eliminates duplicates.
func cleanClass(rp *[]int) []int {
// 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 {
@ -1025,23 +1064,71 @@ func cleanClass(rp *[]int) []int {
// appendRange returns the result of appending the range lo-hi to the class r.
func appendRange(r []int, lo, hi int) []int {
// Expand last range if overlaps or abuts.
if n := len(r); n > 0 {
rlo, rhi := r[n-2], r[n-1]
if lo <= rhi+1 && rlo <= hi+1 {
if lo < rlo {
r[n-2] = lo
// 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
}
if hi > rhi {
r[n-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 []int, lo, hi int) []int {
// 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
}
// appendClass returns the result of appending the class x to the class r.
// It assume x is clean.
func appendClass(r []int, x []int) []int {
@ -1051,6 +1138,14 @@ func appendClass(r []int, x []int) []int {
return r
}
// appendFolded returns the result of appending the case folding of the class x to the class r.
func appendFoldedClass(r []int, x []int) []int {
for i := 0; i < len(x); i += 2 {
r = appendFoldedRange(r, x[i], x[i+1])
}
return r
}
// appendNegatedClass returns the result of appending the negation of the class x to the class r.
// It assumes x is clean.
func appendNegatedClass(r []int, x []int) []int {

85
src/pkg/exp/regexp/syntax/parse_test.go
View File

@ -74,18 +74,18 @@ var parseTests = []struct {
{"[a-z]", "cc{0x61-0x7a}"},
{"[^[:lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}"},
{"[[:^lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}"},
// { "(?i)[[:lower:]]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
// { "(?i)[a-z]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
// { "(?i)[^[:lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
// { "(?i)[[:^lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
{"(?i)[[:lower:]]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}"},
{"(?i)[a-z]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}"},
{"(?i)[^[:lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}"},
{"(?i)[[:^lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}"},
{"\\d", "cc{0x30-0x39}"},
{"\\D", "cc{0x0-0x2f 0x3a-0x10ffff}"},
{"\\s", "cc{0x9-0xa 0xc-0xd 0x20}"},
{"\\S", "cc{0x0-0x8 0xb 0xe-0x1f 0x21-0x10ffff}"},
{"\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a}"},
{"\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x10ffff}"},
// { "(?i)\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a 0x17f 0x212a}" },
// { "(?i)\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
{"(?i)\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a 0x17f 0x212a}"},
{"(?i)\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}"},
{"[^\\\\]", "cc{0x0-0x5b 0x5d-0x10ffff}"},
// { "\\C", "byte{}" },
@ -100,6 +100,13 @@ var parseTests = []struct {
{"[\\p{^Braille}]", "cc{0x0-0x27ff 0x2900-0x10ffff}"},
{"[\\P{^Braille}]", "cc{0x2800-0x28ff}"},
{"[\\pZ]", "cc{0x20 0xa0 0x1680 0x180e 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}"},
{"\\p{Lu}", mkCharClass(unicode.IsUpper)},
{"[\\p{Lu}]", mkCharClass(unicode.IsUpper)},
{"(?i)[\\p{Lu}]", mkCharClass(isUpperFold)},
// Hex, octal.
{"[\\012-\\234]\\141", "cat{cc{0xa-0x9c}lit{a}}"},
{"[\\x{41}-\\x7a]\\x61", "cat{cc{0x41-0x7a}lit{a}}"},
// More interesting regular expressions.
// { "a{,2}", "str{a{,2}}" },
@ -270,3 +277,69 @@ func dumpRegexp(b *bytes.Buffer, re *Regexp) {
}
b.WriteByte('}')
}
func mkCharClass(f func(int) bool) string {
re := &Regexp{Op: OpCharClass}
lo := -1
for i := 0; i <= unicode.MaxRune; i++ {
if f(i) {
if lo < 0 {
lo = i
}
} else {
if lo >= 0 {
re.Rune = append(re.Rune, lo, i-1)
lo = -1
}
}
}
if lo >= 0 {
re.Rune = append(re.Rune, lo, unicode.MaxRune)
}
return dump(re)
}
func isUpperFold(rune int) bool {
if unicode.IsUpper(rune) {
return true
}
c := unicode.SimpleFold(rune)
for c != rune {
if unicode.IsUpper(c) {
return true
}
c = unicode.SimpleFold(c)
}
return false
}
func TestFoldConstants(t *testing.T) {
last := -1
for i := 0; i <= unicode.MaxRune; i++ {
if unicode.SimpleFold(i) == i {
continue
}
if last == -1 && minFold != i {
t.Errorf("minFold=%#U should be %#U", minFold, i)
}
last = i
}
if maxFold != last {
t.Errorf("maxFold=%#U should be %#U", maxFold, last)
}
}
func TestAppendRangeCollapse(t *testing.T) {
// AppendRange should collapse each of the new ranges
// into the earlier ones (it looks back two ranges), so that
// the slice never grows very large.
// Note that we are not calling cleanClass.
var r []int
for i := 'A'; i <= 'Z'; i++ {
r = appendRange(r, i, i)
r = appendRange(r, i+'a'-'A', i+'a'-'A')
}
if string(r) != "AZaz" {
t.Errorf("appendRange interlaced A-Z a-z = %s, want AZaz", string(r))
}
}