Package com.lowagie.text.pdf.hyphenation
Class HyphenationTree
java.lang.Object
com.lowagie.text.pdf.hyphenation.TernaryTree
com.lowagie.text.pdf.hyphenation.HyphenationTree
- All Implemented Interfaces:
PatternConsumer
,Serializable
,Cloneable
This tree structure stores the hyphenation patterns in an efficient way for fast lookup. It provides the provides the
method to hyphenate a word.
- See Also:
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Nested Class Summary
Nested classes/interfaces inherited from class com.lowagie.text.pdf.hyphenation.TernaryTree
TernaryTree.Iterator
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected TernaryTree
This map stores the character classesprivate TernaryTree
Temporary map to store interletter values on pattern loading.private static final long
This map stores hyphenation exceptionsprotected ByteVector
value space: stores the interletter valuesFields inherited from class com.lowagie.text.pdf.hyphenation.TernaryTree
BLOCK_SIZE, eq, freenode, hi, kv, length, lo, root, sc
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
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.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 shyphenate
(char[] w, int offset, int len, int remainCharCount, int pushCharCount) Hyphenate word and return an array of hyphenation points.Hyphenate word and return a Hyphenation object.void
loadSimplePatterns
(InputStream stream) 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
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)
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Field Details
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serialVersionUID
private static final long serialVersionUID- See Also:
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vspace
value space: stores the interletter values -
stoplist
This map stores hyphenation exceptions -
classmap
This map stores the character classes -
ivalues
Temporary map to store interletter values on pattern loading.
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Constructor Details
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HyphenationTree
public HyphenationTree()
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Method Details
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packValues
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.
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unpackValues
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loadSimplePatterns
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findPattern
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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
- The first String to comparesi
- The index to start at on String st
- The second String to compareti
- The index to start at on String t- Returns:
- 0 if equal or
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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<patterns.length; i++) { if ( word.substring(index).startsWidth(patterns[i]) ) { update_interletter_values(patterns[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 matchindex
- start index from wordil
- interletter values array to update
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hyphenate
Hyphenate word and return a Hyphenation object.- Parameters:
word
- the word to be hyphenatedremainCharCount
- 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.
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hyphenate
Hyphenate word and return an array of hyphenation points.- Parameters:
w
- char array that contains the wordoffset
- Offset to first character in wordlen
- Length of wordremainCharCount
- 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.
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addClass
Add a character class to the tree. It is used bySimplePatternParser
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 interfacePatternConsumer
- Parameters:
chargroup
- character group
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addException
Add an exception to the tree. It is used bySimplePatternParser
class as callback to store the hyphenation exceptions.- Specified by:
addException
in interfacePatternConsumer
- Parameters:
word
- normalized wordhyphenatedword
- a vector of alternating strings andhyphen
objects.
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addPattern
Add a pattern to the tree. Mainly, to be used bySimplePatternParser
class as callback to add a pattern to the tree.- Specified by:
addPattern
in interfacePatternConsumer
- Parameters:
pattern
- the hyphenation patternivalue
- 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').
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printStats
public void printStats()- Overrides:
printStats
in classTernaryTree
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