org.apache.fop.hyphenation

## Class HyphenationTree

- java.lang.Object
- - org.apache.fop.hyphenation.TernaryTree
  - - org.apache.fop.hyphenation.HyphenationTree

- All Implemented Interfaces:
    Serializable, Cloneable, PatternConsumer

      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. This work was originally authored by Carlos Villegas cav@uniscope.co.jp
  See Also:
    Serialized Form

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.fop.hyphenation.TernaryTree

      `TernaryTree.Iterator`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected TernaryTree` | `classmap` This map stores the character classes
    `protected HashMap` | `stoplist` This map stores hyphenation exceptions
    `protected ByteVector` | `vspace` value space: stores the interletter values

    - ### Fields inherited from class org.apache.fop.hyphenation.TernaryTree

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

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `HyphenationTree()` Default constructor.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addClass(String chargroup)` 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.
    `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(InputSource source)` Read hyphenation patterns from an XML file.
    `void` | `loadPatterns(String filename)` Read hyphenation patterns from an XML file.
    `static void` | `main(String[] argv)` Main entry point for this hyphenation utility application.
    `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` | `printStats()` Print statistics.
    `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 org.apache.fop.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 HashMap 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

      Read hyphenation patterns from an XML file.
      Parameters:
        `filename` - the filename
      Throws:
        `HyphenationException` - In case the parsing fails

    - #### loadPatterns

          public void loadPatterns(InputSource source)
                            throws HyphenationException

      Read hyphenation patterns from an XML file.
      Parameters:
        `source` - the InputSource for the file
      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<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 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 `PatternConsumer`
      Parameters:
        `chargroup` - a character class (group)

    - #### addException

          public void addException(String word,
                                   ArrayList 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 `PatternConsumer`
      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 `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()

      Print statistics.
      Overrides:
        `printStats` in class `TernaryTree`

    - #### main

          public static void main(String[] argv)
                           throws Exception

      Main entry point for this hyphenation utility application.
      Parameters:
        `argv` - array of command linee arguments
      Throws:
        `Exception` - in case an exception is raised but not caught

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