com.itextpdf.layout.hyphenation

Class HyphenationTree

java.lang.Object

com.itextpdf.layout.hyphenation.TernaryTree

com.itextpdf.layout.hyphenation.HyphenationTree

All Implemented Interfaces:

IPatternConsumer, Serializable

public class HyphenationTree
extends TernaryTree
implements IPatternConsumer

This tree structure stores the hyphenation patterns in an efficient way for fast lookup. It provides the provides the method to hyphenate a word.

This work was authored by Carlos Villegas (cav@uniscope.co.jp).

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected TernaryTree	classmap This map stores the character classes
protected Map<String,List>	stoplist This map stores hyphenation exceptions
protected ByteVector	vspace value space: stores the interletter values

Fields inherited from class com.itextpdf.layout.hyphenation.TernaryTree

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

Constructor Summary

Constructors

Constructor and Description
HyphenationTree() Default constructor.

Method Summary

Modifier and Type	Method and Description
void	addClass(String chargroup) Add a character class to the tree.
void	addException(String word, List hyphenatedword) Add an exception to the tree.
void	addPattern(String pattern, String ivalue) Add a pattern to the tree.
String	findPattern(String pat) Find pattern.
protected byte[]	getValues(int k) Get values.
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(char[] w, int offset, int len, int remainCharCount, int pushCharCount) Hyphenate word and return an array of hyphenation points.
Hyphenation	hyphenate(String word, int remainCharCount, int pushCharCount) Hyphenate word and return a Hyphenation object.
void	loadPatterns(InputStream stream, String name) Read hyphenation patterns from an XML file.
void	loadPatterns(String filename) Read hyphenation patterns from an XML file.
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.
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) Unpack values.

Methods inherited from class com.itextpdf.layout.hyphenation.TernaryTree

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

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

vspace

protected ByteVector vspace

value space: stores the interletter values

stoplist

protected Map<String,List> stoplist

This map stores hyphenation exceptions

classmap

protected TernaryTree classmap

This map stores the character classes

Constructor Detail

HyphenationTree

public HyphenationTree()

Default constructor.

Method Detail

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.

unpackValues

protected String unpackValues(int k)

Unpack values.

Parameters:

k - an integer

Returns:

a string

loadPatterns

public void loadPatterns(String filename)
                  throws HyphenationException,
                         FileNotFoundException

Read hyphenation patterns from an XML file.

Parameters:

filename - the filename

Throws:

HyphenationException - In case the parsing fails

FileNotFoundException - When the specified file is not found

loadPatterns

public void loadPatterns(InputStream stream,
                         String name)
                  throws HyphenationException

Read hyphenation patterns from an XML file.

Parameters:

stream - the InputSource for the file

name - unique key representing country-language combination

Throws:

HyphenationException - In case the parsing fails

findPattern

public String findPattern(String pat)

Find pattern.

Parameters:

pat - a pattern

Returns:

a string

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.

Parameters:

s - first character array

si - starting index into first array

t - second character array

ti - starting index into second array

Returns:

an integer

getValues

protected byte[] getValues(int k)

Get values.

Parameters:

k - an integer

Returns:

a byte array

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

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.

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 IPatternConsumer

Parameters:

chargroup - a character class (group)

addException

public void addException(String word,
                         List 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 IPatternConsumer

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 IPatternConsumer

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').