org.apache.fop.hyphenation

Class HyphenationTree

Implemented Interfaces:
Cloneable, PatternConsumer, Serializable

public class HyphenationTree
extends TernaryTree
implements PatternConsumer, Serializable

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

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.fop.hyphenation.TernaryTree

TernaryTree.Iterator

Field Summary

protected TernaryTree
classmap
This map stores the character classes
protected HashMap
stoplist
This map stores hyphenation exceptions
protected ByteVector
vspace
value space: stores the interletter values

Fields inherited from class org.apache.fop.hyphenation.TernaryTree

BLOCK_SIZE, eq, freenode, hi, kv, length, lo, root, sc

Constructor Summary

HyphenationTree()

Method Summary

void
addClass(String chargroup)
Add a character class to the tree.
void
addException(String word, ArrayList hyphenatedword)
Add an exception to the tree.
void
addPattern(String pattern, String ivalue)
Add a pattern to the tree.
String
findPattern(String pat)
protected byte[]
getValues(int k)
protected int
hstrcmp(char[] s, int si, char[] t, int ti)
String compare, returns 0 if equal or t is a substring of s
Hyphenation
hyphenate(String word, int remainCharCount, int pushCharCount)
Hyphenate word and return a Hyphenation object.
Hyphenation
hyphenate(char[] w, int offset, int len, int remainCharCount, int pushCharCount)
Hyphenate word and return an array of hyphenation points.
void
loadPatterns(InputSource source)
Read hyphenation patterns from an XML file.
void
loadPatterns(String filename)
Read hyphenation patterns from an XML file.
static void
main(String[] argv)
protected int
packValues(String values)
Packs the values by storing them in 4 bits, two values into a byte Values range is from 0 to 9.
void
printStats()
protected void
searchPatterns(char[] word, int index, byte[] il)
Search for all possible partial matches of word starting at index an update interletter values.
protected String
unpackValues(int k)

Methods inherited from class org.apache.fop.hyphenation.TernaryTree

balance, clone, find, find, init, insert, insert, insertBalanced, keys, knows, main, printStats, size, strcmp, strcmp, strcpy, strlen, strlen, trimToSize

Field Details

classmap

protected TernaryTree classmap
This map stores the character classes

stoplist

protected HashMap stoplist
This map stores hyphenation exceptions

vspace

protected ByteVector vspace
value space: stores the interletter values

Constructor Details

HyphenationTree

public HyphenationTree()

Method Details

addClass

public void addClass(String chargroup)
Add a character class to the tree. It is used by PatternParser 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.
Specified by:
addClass in interface PatternConsumer

addException

public void addException(String word,
                         ArrayList hyphenatedword)
Add an exception to the tree. It is used by PatternParser class as callback to store the hyphenation exceptions.
Specified by:
addException in interface PatternConsumer
Parameters:
word - normalized word
hyphenatedword - a vector of alternating strings and hyphen objects.

addPattern

public void addPattern(String pattern,
                       String ivalue)
Add a pattern to the tree. Mainly, to be used by PatternParser class as callback to add a pattern to the tree.
Specified by:
addPattern in interface PatternConsumer
Parameters:
pattern - the hyphenation pattern
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').

findPattern

public String findPattern(String pat)

getValues

protected byte[] getValues(int k)

hstrcmp

protected int hstrcmp(char[] s,
                      int si,
                      char[] t,
                      int ti)
String compare, returns 0 if equal or t is a substring of s

hyphenate

public Hyphenation hyphenate(String word,
                             int remainCharCount,
                             int pushCharCount)
Hyphenate word and return a Hyphenation object.
Parameters:
word - the word to be hyphenated
remainCharCount - Minimum number of characters allowed before the hyphenation point.
pushCharCount - Minimum number of characters allowed after the hyphenation point.
Returns:
a Hyphenation object representing the hyphenated word or null if word is not hyphenated.

hyphenate

public Hyphenation hyphenate(char[] w,
                             int offset,
                             int len,
                             int remainCharCount,
                             int pushCharCount)
Hyphenate word and return an array of hyphenation points.
Parameters:
w - char array that contains the word
offset - Offset to first character in word
len - Length of word
remainCharCount - Minimum number of characters allowed before the hyphenation point.
pushCharCount - Minimum number of characters allowed after the hyphenation point.
Returns:
a Hyphenation object representing the hyphenated word or null if word is not hyphenated.

loadPatterns

public void loadPatterns(InputSource source)
            throws HyphenationException
Read hyphenation patterns from an XML file.
Parameters:
source - the InputSource for the file
Throws:
HyphenationException - In case the parsing fails

loadPatterns

public void loadPatterns(String filename)
            throws HyphenationException
Read hyphenation patterns from an XML file.
Parameters:
filename - the filename
Throws:
HyphenationException - In case the parsing fails

main

public static void main(String[] argv)
            throws Exception
Overrides:
main in interface TernaryTree

packValues

protected int packValues(String values)
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.
Parameters:
values - a string of digits from '0' to '9' representing the interletter values.
Returns:
the index into the vspace array where the packed values are stored.

printStats

public void printStats()
Overrides:
printStats in interface TernaryTree

searchPatterns

protected void searchPatterns(char[] word,
                              int index,
                              byte[] il)
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

Parameters:
word - null terminated word to match
index - start index from word
il - interletter values array to update

unpackValues

protected String unpackValues(int k)

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