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iText, a free Java-PDF library
/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id: HyphenationTree.java 3117 2008-01-31 05:53:22Z xlv $ */
package com.lowagie.text.pdf.hyphenation;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
/**
* This tree structure stores the hyphenation patterns in an efficient
* way for fast lookup. It provides the provides the method to
* hyphenate a word.
*
* @author Carlos Villegas
*/
public class HyphenationTree extends TernaryTree
implements PatternConsumer {
private static final long serialVersionUID = -7763254239309429432L;
/**
* value space: stores the interletter values
*/
protected ByteVector vspace;
/**
* This map stores hyphenation exceptions
*/
protected HashMap stoplist;
/**
* This map stores the character classes
*/
protected TernaryTree classmap;
/**
* Temporary map to store interletter values on pattern loading.
*/
private transient TernaryTree ivalues;
public HyphenationTree() {
stoplist = new HashMap(23); // usually a small table
classmap = new TernaryTree();
vspace = new ByteVector();
vspace.alloc(1); // this reserves index 0, which we don't use
}
/**
* Packs the values by storing them in 4 bits, two values into a byte
* Values range is from 0 to 9. We use zero as terminator,
* so we'll add 1 to the value.
* @param values a string of digits from '0' to '9' representing the
* interletter values.
* @return the index into the vspace array where the packed values
* are stored.
*/
protected int packValues(String values) {
int i, n = values.length();
int m = (n & 1) == 1 ? (n >> 1) + 2 : (n >> 1) + 1;
int offset = vspace.alloc(m);
byte[] va = vspace.getArray();
for (i = 0; i < n; i++) {
int j = i >> 1;
byte v = (byte)((values.charAt(i) - '0' + 1) & 0x0f);
if ((i & 1) == 1) {
va[j + offset] = (byte)(va[j + offset] | v);
} else {
va[j + offset] = (byte)(v << 4); // big endian
}
}
va[m - 1 + offset] = 0; // terminator
return offset;
}
protected String unpackValues(int k) {
StringBuffer buf = new StringBuffer();
byte v = vspace.get(k++);
while (v != 0) {
char c = (char)((v >>> 4) - 1 + '0');
buf.append(c);
c = (char)(v & 0x0f);
if (c == 0) {
break;
}
c = (char)(c - 1 + '0');
buf.append(c);
v = vspace.get(k++);
}
return buf.toString();
}
public void loadSimplePatterns(InputStream stream) {
SimplePatternParser pp = new SimplePatternParser();
ivalues = new TernaryTree();
pp.parse(stream, this);
// patterns/values should be now in the tree
// let's optimize a bit
trimToSize();
vspace.trimToSize();
classmap.trimToSize();
// get rid of the auxiliary map
ivalues = null;
}
public String findPattern(String pat) {
int k = super.find(pat);
if (k >= 0) {
return unpackValues(k);
}
return "";
}
/**
* String compare, returns 0 if equal or
* t is a substring of s
*/
protected int hstrcmp(char[] s, int si, char[] t, int ti) {
for (; s[si] == t[ti]; si++, ti++) {
if (s[si] == 0) {
return 0;
}
}
if (t[ti] == 0) {
return 0;
}
return s[si] - t[ti];
}
protected byte[] getValues(int k) {
StringBuffer buf = new StringBuffer();
byte v = vspace.get(k++);
while (v != 0) {
char c = (char)((v >>> 4) - 1);
buf.append(c);
c = (char)(v & 0x0f);
if (c == 0) {
break;
}
c = (char)(c - 1);
buf.append(c);
v = vspace.get(k++);
}
byte[] res = new byte[buf.length()];
for (int i = 0; i < res.length; i++) {
res[i] = (byte)buf.charAt(i);
}
return res;
}
/**
* Search for all possible partial matches of word starting
* at index an update interletter values. In other words, it
* does something like:
*
* for(i=0; i
* But it is done in an efficient way since the patterns are
* stored in a ternary tree. In fact, this is the whole purpose
* of having the tree: doing this search without having to test
* every single pattern. The number of patterns for languages
* such as English range from 4000 to 10000. Thus, doing thousands
* of string comparisons for each word to hyphenate would be
* really slow without the tree. The tradeoff is memory, but
* using a ternary tree instead of a trie, almost halves the
* the memory used by Lout or TeX. It's also faster than using
* a hash table
* @param word null terminated word to match
* @param index start index from word
* @param il interletter values array to update
*/
protected void searchPatterns(char[] word, int index, byte[] il) {
byte[] values;
int i = index;
char p, q;
char sp = word[i];
p = root;
while (p > 0 && p < sc.length) {
if (sc[p] == 0xFFFF) {
if (hstrcmp(word, i, kv.getArray(), lo[p]) == 0) {
values = getValues(eq[p]); // data pointer is in eq[]
int j = index;
for (int k = 0; k < values.length; k++) {
if (j < il.length && values[k] > il[j]) {
il[j] = values[k];
}
j++;
}
}
return;
}
int d = sp - sc[p];
if (d == 0) {
if (sp == 0) {
break;
}
sp = word[++i];
p = eq[p];
q = p;
// look for a pattern ending at this position by searching for
// the null char ( splitchar == 0 )
while (q > 0 && q < sc.length) {
if (sc[q] == 0xFFFF) { // stop at compressed branch
break;
}
if (sc[q] == 0) {
values = getValues(eq[q]);
int j = index;
for (int k = 0; k < values.length; k++) {
if (j < il.length && values[k] > il[j]) {
il[j] = values[k];
}
j++;
}
break;
} else {
q = lo[q];
/**
* actually the code should be:
* q = sc[q] < 0 ? hi[q] : lo[q];
* but java chars are unsigned
*/
}
}
} else {
p = d < 0 ? lo[p] : hi[p];
}
}
}
/**
* Hyphenate word and return a Hyphenation object.
* @param word the word to be hyphenated
* @param remainCharCount Minimum number of characters allowed
* before the hyphenation point.
* @param pushCharCount Minimum number of characters allowed after
* the hyphenation point.
* @return a {@link Hyphenation Hyphenation} object representing
* the hyphenated word or null if word is not hyphenated.
*/
public Hyphenation hyphenate(String word, int remainCharCount,
int pushCharCount) {
char[] w = word.toCharArray();
return hyphenate(w, 0, w.length, remainCharCount, pushCharCount);
}
/**
* w = "****nnllllllnnn*****",
* where n is a non-letter, l is a letter,
* all n may be absent, the first n is at offset,
* the first l is at offset + iIgnoreAtBeginning;
* word = ".llllll.'\0'***",
* where all l in w are copied into word.
* In the first part of the routine len = w.length,
* in the second part of the routine len = word.length.
* Three indices are used:
* index(w), the index in w,
* index(word), the index in word,
* letterindex(word), the index in the letter part of word.
* The following relations exist:
* index(w) = offset + i - 1
* index(word) = i - iIgnoreAtBeginning
* letterindex(word) = index(word) - 1
* (see first loop).
* It follows that:
* index(w) - index(word) = offset - 1 + iIgnoreAtBeginning
* index(w) = letterindex(word) + offset + iIgnoreAtBeginning
*/
/**
* Hyphenate word and return an array of hyphenation points.
* @param w char array that contains the word
* @param offset Offset to first character in word
* @param len Length of word
* @param remainCharCount Minimum number of characters allowed
* before the hyphenation point.
* @param pushCharCount Minimum number of characters allowed after
* the hyphenation point.
* @return a {@link Hyphenation Hyphenation} object representing
* the hyphenated word or null if word is not hyphenated.
*/
public Hyphenation hyphenate(char[] w, int offset, int len,
int remainCharCount, int pushCharCount) {
int i;
char[] word = new char[len + 3];
// normalize word
char[] c = new char[2];
int iIgnoreAtBeginning = 0;
int iLength = len;
boolean bEndOfLetters = false;
for (i = 1; i <= len; i++) {
c[0] = w[offset + i - 1];
int nc = classmap.find(c, 0);
if (nc < 0) { // found a non-letter character ...
if (i == (1 + iIgnoreAtBeginning)) {
// ... before any letter character
iIgnoreAtBeginning ++;
} else {
// ... after a letter character
bEndOfLetters = true;
}
iLength --;
} else {
if (!bEndOfLetters) {
word[i - iIgnoreAtBeginning] = (char)nc;
} else {
return null;
}
}
}
len = iLength;
if (len < (remainCharCount + pushCharCount)) {
// word is too short to be hyphenated
return null;
}
int[] result = new int[len + 1];
int k = 0;
// check exception list first
String sw = new String(word, 1, len);
if (stoplist.containsKey(sw)) {
// assume only simple hyphens (Hyphen.pre="-", Hyphen.post = Hyphen.no = null)
ArrayList hw = (ArrayList)stoplist.get(sw);
int j = 0;
for (i = 0; i < hw.size(); i++) {
Object o = hw.get(i);
// j = index(sw) = letterindex(word)?
// result[k] = corresponding index(w)
if (o instanceof String) {
j += ((String)o).length();
if (j >= remainCharCount && j < (len - pushCharCount)) {
result[k++] = j + iIgnoreAtBeginning;
}
}
}
} else {
// use algorithm to get hyphenation points
word[0] = '.'; // word start marker
word[len + 1] = '.'; // word end marker
word[len + 2] = 0; // null terminated
byte[] il = new byte[len + 3]; // initialized to zero
for (i = 0; i < len + 1; i++) {
searchPatterns(word, i, il);
}
// hyphenation points are located where interletter value is odd
// i is letterindex(word),
// i + 1 is index(word),
// result[k] = corresponding index(w)
for (i = 0; i < len; i++) {
if (((il[i + 1] & 1) == 1) && i >= remainCharCount
&& i <= (len - pushCharCount)) {
result[k++] = i + iIgnoreAtBeginning;
}
}
}
if (k > 0) {
// trim result array
int[] res = new int[k];
System.arraycopy(result, 0, res, 0, k);
return new Hyphenation(new String(w, offset, len), res);
} else {
return null;
}
}
/**
* Add a character class to the tree. It is used by
* {@link SimplePatternParser SimplePatternParser} as callback to
* add character classes. Character classes define the
* valid word characters for hyphenation. If a word contains
* a character not defined in any of the classes, it is not hyphenated.
* It also defines a way to normalize the characters in order
* to compare them with the stored patterns. Usually pattern
* files use only lower case characters, in this case a class
* for letter 'a', for example, should be defined as "aA", the first
* character being the normalization char.
*/
public void addClass(String chargroup) {
if (chargroup.length() > 0) {
char equivChar = chargroup.charAt(0);
char[] key = new char[2];
key[1] = 0;
for (int i = 0; i < chargroup.length(); i++) {
key[0] = chargroup.charAt(i);
classmap.insert(key, 0, equivChar);
}
}
}
/**
* Add an exception to the tree. It is used by
* {@link SimplePatternParser SimplePatternParser} class as callback to
* store the hyphenation exceptions.
* @param word normalized word
* @param hyphenatedword a vector of alternating strings and
* {@link Hyphen hyphen} objects.
*/
public void addException(String word, ArrayList hyphenatedword) {
stoplist.put(word, hyphenatedword);
}
/**
* Add a pattern to the tree. Mainly, to be used by
* {@link SimplePatternParser SimplePatternParser} class as callback to
* add a pattern to the tree.
* @param pattern the hyphenation pattern
* @param ivalue interletter weight values indicating the
* desirability and priority of hyphenating at a given point
* within the pattern. It should contain only digit characters.
* (i.e. '0' to '9').
*/
public void addPattern(String pattern, String ivalue) {
int k = ivalues.find(ivalue);
if (k <= 0) {
k = packValues(ivalue);
ivalues.insert(ivalue, (char)k);
}
insert(pattern, (char)k);
}
public void printStats() {
System.out.println("Value space size = "
+ Integer.toString(vspace.length()));
super.printStats();
}
}
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