Class TextStringTokenizer
- java.lang.Object
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- org.apache.uima.internal.util.TextStringTokenizer
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public class TextStringTokenizer extends java.lang.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 withhasNext()
, and the next token can be queried withnextToken()
. In addition,getNextTokenType()
returns the type of the token as an integer. NB that you need to callgetNextTokenType()
before callingnextToken()
, since callingnextToken()
will advance the iterator.- Version:
- $Id: TextStringTokenizer.java,v 1.6 2003/04/07 14:50:11 goetz Exp $
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Constructor Summary
Constructors Constructor Description TextStringTokenizer(java.lang.String string)
Construct a tokenizer from a Java string.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addSeparators(java.lang.String chars)
Add to the set of separator characters.void
addToEndOfSentenceChars(java.lang.String chars)
Add to the set of sentence delimiters.void
addWhitespaceChars(java.lang.String chars)
Add to the set of whitespace characters.void
addWordChars(java.lang.String chars)
Add to the set of word characters.int
getCharType(char c)
Get the type of an individual character.java.lang.String
getToken()
Return the next token.int
getTokenEnd()
Get the end of the token.int
getTokenStart()
Get the start of the token.int
getTokenType()
Get the type of the token returned by the next call tonextToken()
.boolean
isValid()
Returntrue
iff there is a next token.void
setEndOfSentenceChars(java.lang.String chars)
Set the set of sentence delimiters.void
setSeparators(java.lang.String chars)
Set the set of separator characters.void
setShowSeparators(boolean b)
Set the flag for showing separator tokens.void
setShowWhitespace(boolean b)
Set the flag for showing whitespace tokens.void
setToFirst()
Reset the tokenizer at any time.void
setToNext()
Compute the next token.void
setWhitespaceChars(java.lang.String chars)
Set the set of whitespace characters (in addition to the Unicode whitespace chars).void
setWordChars(java.lang.String chars)
Set the set of word characters.
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Field Detail
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EOS
public static final int EOS
Sentence delimiter character/word type.- See Also:
- Constant Field Values
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SEP
public static final int SEP
Separator character/word type.- See Also:
- Constant Field Values
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WSP
public static final int WSP
Whitespace character/word type.- See Also:
- Constant Field Values
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WCH
public static final int WCH
Word character/word type.- See Also:
- Constant Field Values
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Method Detail
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setShowWhitespace
public void setShowWhitespace(boolean b)
Set the flag for showing whitespace tokens.- Parameters:
b
- The whitespace flag.
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setShowSeparators
public void setShowSeparators(boolean b)
Set the flag for showing separator tokens.- Parameters:
b
- The flag.
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setEndOfSentenceChars
public void setEndOfSentenceChars(java.lang.String chars)
Set the set of sentence delimiters.- Parameters:
chars
- A string containing EOS chars.
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addToEndOfSentenceChars
public void addToEndOfSentenceChars(java.lang.String chars)
Add to the set of sentence delimiters.- Parameters:
chars
- A string containing EOS chars.
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setSeparators
public void setSeparators(java.lang.String chars)
Set the set of separator characters.- Parameters:
chars
- The separator chars.
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addSeparators
public void addSeparators(java.lang.String chars)
Add to the set of separator characters.- Parameters:
chars
- Separator chars.
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setWhitespaceChars
public void setWhitespaceChars(java.lang.String chars)
Set the set of whitespace characters (in addition to the Unicode whitespace chars).- Parameters:
chars
- Whitespace chars.
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addWhitespaceChars
public void addWhitespaceChars(java.lang.String chars)
Add to the set of whitespace characters.- Parameters:
chars
- Whitespace chars.
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setWordChars
public void setWordChars(java.lang.String chars)
Set the set of word characters.- Parameters:
chars
- Word chars.
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addWordChars
public void addWordChars(java.lang.String chars)
Add to the set of word characters.- Parameters:
chars
- Word chars.
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getTokenType
public int getTokenType()
Get the type of the token returned by the next call tonextToken()
.- Returns:
- The token type, or
-1
if there is no next token.
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isValid
public boolean isValid()
Returntrue
iff there is a next token.- Returns:
true
iff there is a next token.
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setToFirst
public void setToFirst()
Reset the tokenizer at any time.
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getToken
public java.lang.String getToken()
Return the next token.- Returns:
- The next token.
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getTokenStart
public int getTokenStart()
Get the start of the token.- Returns:
- The start of the token.
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getTokenEnd
public int getTokenEnd()
Get the end of the token.- Returns:
- The token end.
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setToNext
public void setToNext()
Compute the next token.
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getCharType
public int getCharType(char c)
Get the type of an individual character.- Parameters:
c
- -- Returns:
- The char type.
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