Package org.apache.uima.internal.util

Class TextStringTokenizer

java.lang.Object
org.apache.uima.internal.util.TextStringTokenizer
public class TextStringTokenizer extends Object
An implementation of a text tokenizer for whitespace separated natural language text.

The tokenizer knows about four different character classes: regular word characters, whitespace characters, sentence delimiters and separator characters. Tokens can consist of

  • sequences of word characters and sentence delimiters where the last character is a word character,
  • sentence delimiter characters (if they do not precede a word character),
  • sequences of whitespace characters,
  • and individual separator characters.

The character classes are completely user definable. By default, whitespace characters are the Unicode whitespace characters. All other characters are word characters. The two separator classes are empty by default. The different classes may have non-empty intersections. When determining the class of a character, the user defined classes are considered in the following order: end-of-sentence delimiter before other separators before whitespace before word characters. That is, if a character is defined to be both a separator and a whitespace character, it will be considered to be a separator.

By default, the tokenizer will return all tokens, including whitespace. That is, appending the sequence of tokens will recover the original input text. This behavior can be changed so that whitespace and/or separator tokens are skipped.

A tokenizer provides a standard iterator interface similar to StringTokenizer. The validity of the iterator can be queried with hasNext(), and the next token can be queried with nextToken(). In addition, getNextTokenType() returns the type of the token as an integer. NB that you need to call getNextTokenType() before calling nextToken(), since calling nextToken() will advance the iterator.

Version:
$Id: TextStringTokenizer.java,v 1.6 2003/04/07 14:50:11 goetz Exp $

  • Field Details

  • Constructor Details

    • TextStringTokenizer

      public TextStringTokenizer(String string)
      Construct a tokenizer from a Java string.
      Parameters:
      string - The string to tokenize.

  • Method Details

    • setShowWhitespace

      public void setShowWhitespace(boolean b)
      Set the flag for showing whitespace tokens.
      Parameters:
      b - The whitespace flag.

    • setShowSeparators

      public void setShowSeparators(boolean b)
      Set the flag for showing separator tokens.
      Parameters:
      b - The flag.

    • setEndOfSentenceChars

      public void setEndOfSentenceChars(String chars)
      Set the set of sentence delimiters.
      Parameters:
      chars - A string containing EOS chars.

    • addToEndOfSentenceChars

      public void addToEndOfSentenceChars(String chars)
      Add to the set of sentence delimiters.
      Parameters:
      chars - A string containing EOS chars.

    • setSeparators

      public void setSeparators(String chars)
      Set the set of separator characters.
      Parameters:
      chars - The separator chars.

    • addSeparators

      public void addSeparators(String chars)
      Add to the set of separator characters.
      Parameters:
      chars - Separator chars.

    • setWhitespaceChars

      public void setWhitespaceChars(String chars)
      Set the set of whitespace characters (in addition to the Unicode whitespace chars).
      Parameters:
      chars - Whitespace chars.

    • addWhitespaceChars

      public void addWhitespaceChars(String chars)
      Add to the set of whitespace characters.
      Parameters:
      chars - Whitespace chars.

    • setWordChars

      public void setWordChars(String chars)
      Set the set of word characters.
      Parameters:
      chars - Word chars.

    • addWordChars

      public void addWordChars(String chars)
      Add to the set of word characters.
      Parameters:
      chars - Word chars.

    • getTokenType

      public int getTokenType()
      Get the type of the token returned by the next call to nextToken().
      Returns:
      The token type, or -1 if there is no next token.

    • isValid

      public boolean isValid()
      Return true iff there is a next token.
      Returns:
      true iff there is a next token.

    • setToFirst

      public void setToFirst()
      Reset the tokenizer at any time.

    • getToken

      public String getToken()
      Return the next token.
      Returns:
      The next token.

    • getTokenStart

      public int getTokenStart()
      Get the start of the token.
      Returns:
      The start of the token.

    • getTokenEnd

      public int getTokenEnd()
      Get the end of the token.
      Returns:
      The token end.

    • setToNext

      public void setToNext()
      Compute the next token.

    • getCharType

      public int getCharType(char c)
      Get the type of an individual character.
      Parameters:
      c - -
      Returns:
      The char type.