Table of Contents

Class HyphenationTree

Namespace
iTextSharp.text.pdf.hyphenation
Assembly
iTextSharp.LGPLv2.Core.dll

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 : TernaryTree, ICloneable, IPatternConsumer
Inheritance
HyphenationTree
Implements
Inherited Members

Constructors

HyphenationTree() 

public HyphenationTree()

Fields

Classmap

This map stores the character classes

protected TernaryTree Classmap

Field Value

TernaryTree

Stoplist

This map stores hyphenation exceptions

protected INullValueDictionary<string, List<object>> Stoplist

Field Value

INullValueDictionary<string, List<object>>

Vspace

value space: stores the inteletter values

protected ByteVector Vspace

Field Value

ByteVector

Methods

AddClass(string)

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)

Parameters

chargroup string

AddException(string, List<object>)

Add an exception to the tree. It is used by {@link SimplePatternParser SimplePatternParser} class as callback to store the hyphenation exceptions. {@link Hyphen hyphen} objects.

public void AddException(string word, List<object> hyphenatedword)

Parameters

word string

normalized word

hyphenatedword List<object>

a vector of alternating strings and

AddPattern(string, string)

Add a pattern to the tree. Mainly, to be used by {@link SimplePatternParser SimplePatternParser} class as callback to add a pattern to the tree. 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 values)

Parameters

pattern string

the hyphenation pattern

values string

interletter weight values indicating the

FindPattern(string) 

public string FindPattern(string pat)

Parameters

pat string

Returns

string

GetValues(int) 

protected byte[] GetValues(int k)

Parameters

k int

Returns

byte[]

Hstrcmp(char[], int, char[], int)

String compare, returns 0 if equal or t is a substring of s

protected static int Hstrcmp(char[] s, int si, char[] t, int ti)

Parameters

s char[]
si int
t char[]
ti int

Returns

int

Hyphenate(char[], int, int, int, int)

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

public Hyphenation Hyphenate(char[] w, int offset, int len, int remainCharCount, int pushCharCount)

Parameters

w char[]

char array that contains the word

offset int

Offset to first character in word

len int

Length of word

remainCharCount int

Minimum number of characters allowed

pushCharCount int

Minimum number of characters allowed after

Returns

Hyphenation

a {@link Hyphenation Hyphenation} object representing

Hyphenate(string, int, int)

Hyphenate word and return a Hyphenation object. before the hyphenation point. the hyphenation point. the hyphenated word or null if word is not hyphenated.

public Hyphenation Hyphenate(string word, int remainCharCount, int pushCharCount)

Parameters

word string

the word to be hyphenated

remainCharCount int

Minimum number of characters allowed

pushCharCount int

Minimum number of characters allowed after

Returns

Hyphenation

a {@link Hyphenation Hyphenation} object representing

LoadSimplePatterns(Stream) 

public void LoadSimplePatterns(Stream stream)

Parameters

stream Stream

PackValues(string)

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. interletter values. are stored.

protected int PackValues(string values)

Parameters

values string

a string of digits from '0' to '9' representing the

Returns

int

the index into the vspace array where the packed values

PrintStats() 

public override void PrintStats()

SearchPatterns(char[], int, byte[])

Search for all possible partial matches of word starting at index an update interletter values. 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

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

Parameters

word char[]

null terminated word to match

index int

start index from word

il byte[]

interletter values array to update

UnpackValues(int) 

protected string UnpackValues(int k)

Parameters

k int

Returns

string