/
hyphenator.go
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/
hyphenator.go
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/*
* hyphenator.go
* hyphenator
*
* Created by Jim Dovey on 19/07/2010.
*
* Copyright (c) 2010 Jim Dovey
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the project's author nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
The hyphenator package implements a TeX-style hyphenation algorithm based on
the paper by Franklin Mark Liang <http://www.tug.org/docs/liang/liang-thesis.pdf>.
*/
package hyphenator
import (
trie "github.com/AlanQuatermain/go-trie"
"strings"
"io"
"scanner"
"os"
"fmt"
"utf8"
"container/vector"
)
// The hyphenator struct itself. The nil value is a hyphenator which has not been
// initialized with any hyphenation patterns or language yet.
type Hyphenator struct {
patterns *trie.Trie
exceptions map[string]string
language string
}
// Import hyphenation patterns from the given input stream.
func (h *Hyphenator) LoadPatterns(language string, reader io.Reader) os.Error {
if h.language != language {
h.patterns = nil
h.exceptions = nil
h.language = language
}
if h.patterns != nil && h.patterns.Size() != 0 {
// looks like it's already been set up
return nil
}
if reader == nil {
return os.ErrorString("nil reader argument")
}
h.patterns = trie.NewTrie()
h.exceptions = make(map[string]string, 20)
return h.loadPatterns(reader)
}
func (h *Hyphenator) loadPatterns(reader io.Reader) os.Error {
var s scanner.Scanner
s.Init(reader)
s.Mode = scanner.ScanIdents | scanner.ScanRawStrings | scanner.SkipComments
var which string
tok := s.Scan()
for tok != scanner.EOF {
switch tok {
case scanner.Ident:
// we handle two identifiers: 'patterns' and 'exceptions'
switch ident := s.TokenText(); ident {
case `patterns`, `exceptions`:
which = ident
default:
return os.ErrorString(fmt.Sprintf("Unrecognized identifier '%s' at position %v",
ident, s.Pos()))
}
case scanner.String, scanner.RawString:
// trim the quotes from around the string
tokstr := s.TokenText()
str := tokstr[1 : len(tokstr)-1]
switch which {
case `patterns`:
h.patterns.AddPatternString(str)
case `exceptions`:
key := strings.Replace(str, `-`, ``, -1)
h.exceptions[key] = str
}
}
tok = s.Scan()
}
return nil
}
func (h *Hyphenator) hyphenateWord(s, hyphen string) string {
testStr := `.` + s + `.`
v := make([]int, utf8.RuneCountInString(testStr))
vIndex := 0
for pos, _ := range testStr {
t := testStr[pos:]
strs, values := h.patterns.AllSubstringsAndValues(t)
for i := 0; i < values.Len(); i++ {
str := strs.At(i)
val := values.At(i).(*vector.IntVector)
diff := val.Len() - len(str)
vs := v[vIndex-diff:]
for i := 0; i < val.Len(); i++ {
if val.At(i) > vs[i] {
vs[i] = val.At(i)
}
}
}
vIndex++
}
var outstr string
// trim the values for the beginning and ending dots
markers := v[1 : len(v)-1]
mIndex := 0
u := make([]byte, 4)
for _, ch := range s {
l := utf8.EncodeRune(ch, u)
outstr += string(u[0:l])
// don't hyphenate between (or after) the last two characters of a string
if mIndex < len(markers)-2 {
// hyphens are inserted on odd values, skipped on even ones
if markers[mIndex]%2 != 0 {
outstr += hyphen
}
}
mIndex++
}
return outstr
}
func (h *Hyphenator) Hyphenate(s, hyphen string) (string, bool) {
var sc scanner.Scanner
sc.Init(strings.NewReader(s))
sc.Mode = scanner.ScanIdents
sc.Whitespace = 0
var outstr string
tok := sc.Scan()
for tok != scanner.EOF {
switch tok {
case scanner.Ident:
// a word (or part thereof) to hyphenate
t := sc.TokenText()
// try the exceptions first
exc := h.exceptions[t]
if len(exc) != 0 {
if hyphen != `-` {
strings.Replace(exc, `-`, hyphen, -1)
}
return exc, true
}
// not an exception, hyphenate normally
outstr += h.hyphenateWord(sc.TokenText(), hyphen)
default:
// A Unicode rune to append to the output
p := make([]byte, utf8.UTFMax)
l := utf8.EncodeRune(tok, p)
outstr += string(p[0:l])
}
tok = sc.Scan()
}
return outstr, true
}