LiangsHyphenationTable

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de.dante.extex.language.hyphenation.liang
Class LiangsHyphenationTable

java.lang.Object
  de.dante.extex.language.hyphenation.base.BaseHyphenationTable
      de.dante.extex.language.hyphenation.liang.LiangsHyphenationTable

All Implemented Interfaces:: Hyphenator, Language, LigatureBuilder, ModifiableLanguage, java.io.Serializable, WordTokenizer

Direct Known Subclasses:: CompressedLiangsHyphenationTable

public class LiangsHyphenationTable
extends BaseHyphenationTable

This class stores the values for hyphenations and hyphenates words. It uses Liang's algorithm as described in the TeXbook.

Liang's Algorithm

The hyphenation in TeX is based on Liang's thesis. This algorithm is based on patterns which consist of characters or a special marker for the beginning and the end of the word. For each pattern it is characterized how desirable or undesirable it would be to hyphenate before, between, or after it.

This weighted hyphenation codes cna be represented by integers. The even integers denote the undesirable positions and the odd numbers denote the optional hyphenation points.

Let us consider the pattern hyph} this pattern has associated to it the code 00300. The first number corresponds to the position before the letter h, the second number to the position before the letter p, and so on. Thus this pattern indicates that a hyphenation point can be inserted between y and p. This leads to hy\-ph if written explicitly in TeX.

The following table shows some more examples taken from the original hyphenation patterns of TeX for English. The character . denotes the beginning or the end of a word. In the TeX patterns the word pattern and the hyphenation codes are intermixed and the hyphenation codes 0 are left out.

Word pattern	Codes	TeX Pattern
ader.	005000	`ad5er.`
.ach	00004	`.ach4`
sub	0043	`su4b3`
ty	100	`1ty`
type	00003	`type3`
pe.	4000	`pe.`

To find all hyphenation points in a word all matching patterns have to be superimposed. During this superposition the higher hyphenation codes overrule the lower ones.

In the following figure the patterns for the word ``subtype'' are shown.

  subtype
  ₀s₀u₄b₃
     ₁t₀y₀
     ₀t₀y₀p₀e₃
       ₄p₀e₃.
  ---------------
  ₀s₀u₄b₃t₀y₄p₀e₃

The superposition of all patterns leads to the result sub\-type\-. Here two additional parameters come into play. \lefthyphenmin denotes the minimal number of characters before a hyphenation at the beginning of a word and \righthyphenmin the corresponding length at the end of a word. \lefthyphenmin is set to 2 and \righthyphenmin to 3 for English in TeX. Thus the final hyphen is not considered.

Version:: $Revision: 1.13 $
Author:: Gerd Neugebauer
See Also:: Serialized Form

Field Summary
`protected static long`	`serialVersionUID` The constant `serialVersionUID` contains the id for serialization.

Constructor Summary
`LiangsHyphenationTable()` Creates a new object.

Method Summary
`void`	`addPattern(Tokens pattern)` This methods allows the caller to add another pattern
`void`	`dump(java.util.logging.Logger logger)` Write the tree to a logger.
`protected de.dante.extex.language.hyphenation.liang.HyphenTree`	`getPatterns()` Getter for patterns.
`boolean`	`hyphenate(NodeList nodelist, TypesetterOptions context, UnicodeChar hyphen, int start, boolean forall, NodeFactory nodeFactory)` Insert the hyphenation marks for a horizontal list of nodes.
`boolean`	`hyphenateOne(NodeList nodelist, TypesetterOptions context, int start, UnicodeCharList word, CharNode hyphenNode)` Hyphenate a single word.
`protected boolean`	`isCompressed()` Getter for compressed.
`protected void`	`setCompressed()` Setter for compressed.

Methods inherited from class de.dante.extex.language.hyphenation.base.BaseHyphenationTable

addHyphenation, createHyphenation, findWord, getLeftHyphenmin, getLigature, getName, getRightHyphenmin, insertLigatures, insertShy, isHyphenActive, normalize, readResolve, setHyphenActive, setLeftHyphenmin, setLigatureBuilder, setName, setRightHyphenmin, setWordTokenizer

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

protected static final long serialVersionUID

The constant serialVersionUID contains the id for serialization.

See Also:: Constant Field Values

Constructor Detail