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|
package split
import (
"strings"
"unicode"
"unicode/utf8"
)
const (
RuneUnicode32 = iota
RuneWhitespaceNotUnicode32
RuneLetter
RuneNumber
RuneOther
StateInitial
StateU32
StateWhitespaceNotUnicode32
StateLetter
StateNumber
StateOther
StateWhitespaceLookAhead
)
type FSA struct {
state int
static []string
}
func NewFSA() *FSA {
return &FSA{
state: StateInitial,
static: []string{"'s", "'t", "'re", "'m", "'ll", "'d"},
}
}
func (f *FSA) Reset() {
f.state = StateInitial
}
func (f *FSA) Read(next rune) bool {
var r int
if next == 32 {
r = RuneUnicode32
} else if unicode.IsSpace(next) {
r = RuneWhitespaceNotUnicode32
} else if unicode.IsLetter(next) {
r = RuneLetter
} else if unicode.IsNumber(next) {
r = RuneNumber
} else {
r = RuneOther
}
if f.state == StateInitial {
switch r {
case RuneUnicode32:
f.state = StateU32
break
case RuneWhitespaceNotUnicode32:
f.state = StateWhitespaceNotUnicode32
break
case RuneLetter:
f.state = StateLetter
break
case RuneNumber:
f.state = StateNumber
break
default:
f.state = StateOther
}
} else if f.state == StateU32 {
switch r {
case RuneUnicode32:
f.state = StateWhitespaceLookAhead
break
case RuneWhitespaceNotUnicode32:
f.state = StateWhitespaceLookAhead
break
case RuneLetter:
f.state = StateLetter
break
case RuneNumber:
f.state = StateNumber
break
default:
f.state = StateOther
}
} else if f.state == StateWhitespaceNotUnicode32 {
switch r {
case RuneUnicode32:
f.state = StateWhitespaceLookAhead
break
case RuneWhitespaceNotUnicode32:
f.state = StateWhitespaceLookAhead
break
default:
return false
}
} else if f.state == StateNumber {
switch r {
case RuneNumber:
f.state = StateNumber
break
default:
return false
}
} else if f.state == StateLetter {
switch r {
case RuneLetter:
f.state = StateLetter
break
default:
return false
}
} else if f.state == StateOther {
switch r {
case RuneOther:
f.state = StateOther
break
default:
return false
}
} else if f.state == StateWhitespaceLookAhead {
switch r {
case RuneUnicode32:
f.state = StateWhitespaceLookAhead
break
case RuneWhitespaceNotUnicode32:
f.state = StateWhitespaceLookAhead
break
default:
return false
}
} else {
panic("invalid state")
}
return true
}
func (f *FSA) FindAll(s string) []string {
if !utf8.ValidString(s) {
// s = strings.ToValidUTF8(s, string(utf8.RuneError)) replaces with a single utf8.RuneError
// s = strings.Map(func(r rune) rune { return r }, s) should be identical to s = string([]rune(s))
s = string([]rune(s)) // replaces each invalid byte with utf8.RuneError during decoding
}
var findAll func(start int, matches []string) []string
findAll = func(start int, matches []string) []string {
if start >= len(s) {
return matches
}
for _, v := range f.static {
if strings.HasPrefix(s[start:], v) {
matches = append(matches, v)
next := start + len(v)
if next >= len(s) {
return matches
}
return findAll(next, matches)
}
}
prev, stop := start, start
for stop < len(s) {
r, size := utf8.DecodeRuneInString(s[stop:])
ok := f.Read(r)
if ok {
prev = stop
stop += size
} else {
if f.state == StateInitial {
return matches
}
if f.state == StateWhitespaceLookAhead {
matches = append(matches, s[start:prev])
f.Reset()
return findAll(prev, matches)
}
matches = append(matches, s[start:stop])
f.Reset()
return findAll(stop, matches)
}
}
if start < len(s) {
matches = append(matches, s[start:])
}
return matches
}
defer f.Reset()
return findAll(0, make([]string, 0))
}
|
