com.lowagie.text.pdf.hyphenation
Class HyphenationTree

java.lang.Object
  extended by com.lowagie.text.pdf.hyphenation.TernaryTree
      extended by com.lowagie.text.pdf.hyphenation.HyphenationTree
All Implemented Interfaces:
PatternConsumer, java.io.Serializable, java.lang.Cloneable

public class HyphenationTree
extends TernaryTree
implements PatternConsumer

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
See Also:
Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from class com.lowagie.text.pdf.hyphenation.TernaryTree
TernaryTree.Iterator
 
Field Summary
protected  TernaryTree classmap
          This map stores the character classes
protected  java.util.HashMap stoplist
          This map stores hyphenation exceptions
protected  ByteVector vspace
          value space: stores the interletter values
 
Fields inherited from class com.lowagie.text.pdf.hyphenation.TernaryTree
BLOCK_SIZE, eq, freenode, hi, kv, length, lo, root, sc
 
Constructor Summary
HyphenationTree()
           
 
Method Summary
 void addClass(java.lang.String chargroup)
          Add a character class to the tree.
 void addException(java.lang.String word, java.util.ArrayList hyphenatedword)
          Add an exception to the tree.
 void addPattern(java.lang.String pattern, java.lang.String ivalue)
          Add a pattern to the tree.
 java.lang.String findPattern(java.lang.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(char[] w, int offset, int len, int remainCharCount, int pushCharCount)
          Hyphenate word and return an array of hyphenation points.
 Hyphenation hyphenate(java.lang.String word, int remainCharCount, int pushCharCount)
          Hyphenate word and return a Hyphenation object.
 void loadSimplePatterns(java.io.InputStream stream)
           
protected  int packValues(java.lang.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  java.lang.String unpackValues(int k)
           
 
Methods inherited from class com.lowagie.text.pdf.hyphenation.TernaryTree
balance, clone, find, find, init, insert, insert, insertBalanced, keys, knows, size, strcmp, strcmp, strcpy, strlen, strlen, trimToSize
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

vspace

protected ByteVector vspace
value space: stores the interletter values


stoplist

protected java.util.HashMap stoplist
This map stores hyphenation exceptions


classmap

protected TernaryTree classmap
This map stores the character classes

Constructor Detail

HyphenationTree

public HyphenationTree()
Method Detail

packValues

protected int packValues(java.lang.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 java.lang.String unpackValues(int k)

loadSimplePatterns

public void loadSimplePatterns(java.io.InputStream stream)

findPattern

public java.lang.String findPattern(java.lang.String pat)

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


getValues

protected byte[] getValues(int k)

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(java.lang.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(java.lang.String chargroup)
Add a character class to the tree. It is used by 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.

Specified by:
addClass in interface PatternConsumer
Parameters:
chargroup - character group

addException

public void addException(java.lang.String word,
                         java.util.ArrayList hyphenatedword)
Add an exception to the tree. It is used by SimplePatternParser 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(java.lang.String pattern,
                       java.lang.String ivalue)
Add a pattern to the tree. Mainly, to be used by SimplePatternParser 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').

printStats

public void printStats()
Overrides:
printStats in class TernaryTree


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