package edu.northwestern.at.utils.corpuslinguistics.tokenizer;
/* Please see the license information at the end of this file. */
import java.util.*;
import java.util.regex.*;
import java.util.StringTokenizer.*;
import java.text.*;
import edu.northwestern.at.utils.*;
/** Default word tokenizer. */
public class DefaultWordTokenizer
extends AbstractWordTokenizer
implements WordTokenizer
{
/** Create a simple word tokenizer.
*/
public DefaultWordTokenizer()
{
super();
}
/** Break text into word tokens.
*
* @param text Text to break into word tokens.
*
* @return List of word tokens.
*
* <p>
* Word tokens may be words, numbers, punctuation, etc.
* </p>
*/
public List<String> extractWords( String text )
{
// List of extracted words.
List<String> result = ListFactory.createNewList();
// Create string tokenizer which
// splits preTokenizer text at
// white space boundaries.
String pretokenizedText = preTokenizer.pretokenize( text );
StringTokenizer tokenizer =
new StringTokenizer( pretokenizedText );
// While there are tokens left to get ...
while ( tokenizer.hasMoreTokens() )
{
// Extract next token.
String token = tokenizer.nextToken();
// Preprocess token.
token = preprocessToken( token , result );
// Check if we have to split off a
// leading character, Some like a
// leading percent are
// always split off. For others,
// when the token appears in the
// list of contracted forms, leave
// the character alone, otherwise split off
// the leading character.
boolean doneLeading = false;
while ( ( token.length() > 0 ) && ( !doneLeading ) )
{
hyphensMatcher.reset( token );
if ( hyphensMatcher.matches() )
{
doneLeading = true;
}
else if ( token.charAt( 0 ) == '&' )
{
if ( contractions.containsString( token ) )
{
doneLeading = true;
}
else
{
addWordToSentence( result , "&" );
token = token.substring( 1 );
}
}
else if ( !apostropheCanBeQuote &&
CharUtils.isApostrophe( token.charAt( 0 ) ) )
{
doneLeading = true;
}
else if ( isSingleOpeningQuote( token.charAt( 0 ) ) )
{
if ( contractions.containsString( token ) )
{
doneLeading = true;
}
else
{
addWordToSentence( result , token.charAt( 0 ) + "" );
token = token.substring( 1 );
}
}
else if ( CharUtils.isOpeningQuote( token.charAt( 0 ) ) )
{
addWordToSentence( result , token.charAt( 0 ) + "" );
token = token.substring( 1 );
}
else if ( token.charAt( 0 ) == '%' )
{
addWordToSentence( result , "%" );
token = token.substring( 1 );
}
else if ( token.charAt( 0 ) == '*' )
{
addWordToSentence( result , "*" );
token = token.substring( 1 );
}
// else if ( CharUtils.isDash( token.charAt( 0 ) ) )
else if ( CharUtils.isBreakingDash( token.charAt( 0 ) ) )
{
if ( token.length() > 1 )
{
if ( !CharUtils.isNumber( token.substring( 1 ) ) )
{
addWordToSentence(
result , token.charAt( 0 ) + "" );
token = token.substring( 1 );
}
else
{
doneLeading = true;
}
}
else
{
doneLeading = true;
}
}
else
{
doneLeading = true;
}
}
int l = token.length();
String endDelims = "";
// If token is all dashes, leave it
// intact.
hyphensMatcher.reset( token );
if ( !hyphensMatcher.matches() )
{
// See if we have to split off
// trailing delimiter characters.
boolean doneEnding = false;
while ( ( l > 1 ) && !doneEnding )
{
// If character is colon, dash, or single
// quote, assume we should split
// off that character.
if ( ( token.charAt( l - 1 ) == ':' ) ||
// ( CharUtils.isDash( token.charAt( l - 1 ) ) ) ||
( CharUtils.isBreakingDash( token.charAt( l - 1 ) ) ) ||
( isClosingQuote( token.charAt( l - 1 ) ) )
)
{
endDelims = token.charAt( l - 1 ) + endDelims;
token =
token.substring( 0 , token.length() - 1 );
}
// See if we should split off a
// trailing question or exclamation.
else if ( ( token.charAt( l - 1 ) == '!' ) ||
( token.charAt( l - 1 ) == '?' )
)
{
if ( Abbreviations.isAbbreviation( token ) )
{
doneEnding = true;
}
else
{
endDelims =
token.charAt( l - 1 ) + endDelims;
token =
token.substring( 0 , token.length() - 1 );
}
}
// See if we should split off a
// trailing period.
else if ( token.charAt( l - 1 ) == '.' )
{
// If this is currency, split off the
// trailing period if there is
// a previous period in the token.
if ( token.charAt( 0 ) == '$' )
{
if ( token.length() > 2 )
{
if ( token.substring( 1 , l - 2 ).indexOf(
'.' ) >= 0 )
{
endDelims = "." + endDelims;
token =
token.substring(
0 , token.length() - 1 );
}
}
doneEnding = true;
}
// If we have an apparent abbreviation,
// leave the period attached to the
// token. Split it off otherwise.
else if ( isLetterOrSingleQuote(
token.charAt( l - 2 ) ) )
{
if ( Abbreviations.isAbbreviation( token ) )
{
doneEnding = true;
}
else
{
endDelims = "." + endDelims;
token =
token.substring(
0 , token.length() - 1 );
}
}
// All periods? Leave it alone.
else if ( CharUtils.isAllPeriods( token ) )
{
doneEnding = true;
}
// Leave trailing period attached
// to number.
else if ( CharUtils.isNumber( token ) )
{
doneEnding = true;
}
// Leave trailing period attached
// to Roman numeral.
else if ( RomanNumeralUtils.isLooseRomanNumeral(
token ) )
{
doneEnding = true;
}
else
{
endDelims = "." + endDelims;
token =
token.substring( 0 , token.length() - 1 );
}
}
else
{
doneEnding = true;;
}
l = token.length();
}
}
// If we have just "--" or "---" and the
// previous token was just a single letter,
// append the dashes to the previous token.
if ( isMultipleHyphens( token ) )
{
if ( result.size() > 0 )
{
String previousToken =
(String)result.get( result.size() - 1 );
if ( CharUtils.isLetter( previousToken ) )
{
previousToken = previousToken + token;
result.set( result.size() - 1 , previousToken );
token = "";
}
}
}
// If we have a 's or 'S, and the previous
// token was just dashes or asterisks,
// append the 's to the previous token.
if ( token.equals( "'s" ) || token.equals( "'S" ) )
{
if ( result.size() > 0 )
{
String previousToken =
(String)result.get( result.size() - 1 );
if ( previousToken.matches(
"([A-Za-z]){0,1}(--|---|\u2011\u2011|\u2011\u2011\u2011|(\\*+))" ) )
{
previousToken = previousToken + token;
result.set( result.size() - 1 , previousToken );
token = "";
}
}
}
// If the token is not empty,
// add it to the sentence.
if ( token.length() > 0 )
{
// Check if we need to split a token
// containing an internal period.
String[] tokens = splitToken( token );
for ( int k = 0 ; k < tokens.length ; k++ )
{
if ( tokens[ k ].length() > 0 )
{
addWordToSentence( result , tokens[ k ] );
}
}
}
// Add the trailing delimiters.
for ( int k = 0 ; k < endDelims.length() ; k++ )
{
String delimToken = endDelims.charAt( k ) + "";
addWordToSentence( result , delimToken );
}
}
// Return list of words to caller.
return result;
}
/** Add word to list of words in sentence.
*
* @param sentence Result sentence.
* @param word Word to add.
*/
public void addWordToSentence( List<String> sentence , String word )
{
boolean coalesce =
( sentence.size() > 0 ) &&
( ( coalesceHyphens && word.equals( "-" ) ) ||
( coalesceAsterisks && word.equals( "*" ) )
);
if ( coalesce )
{
String previousWord = sentence.get( sentence.size() - 1 );
if ( previousWord.endsWith( word ) )
{
previousWord = previousWord + word;
sentence.set( sentence.size() - 1 , previousWord );
}
else
{
sentence.add( word );
}
}
else
{
//$$$PIB$$$ Kluge to handle Roman numerals enclosed in periods.
//
// sentence.add( word );
//
if ( word.equals( "." ) && ( sentence.size() > 0 ) )
{
String prevWord = sentence.get( sentence.size() - 1 );
if ( ( prevWord.charAt( 0 ) == '.' ) &&
( RomanNumeralUtils.isLooseRomanNumeral(
prevWord )
)
)
{
prevWord = prevWord + ".";
sentence.set( sentence.size() - 1 , prevWord );
}
else
{
sentence.add( word );
}
}
else
{
sentence.add( word );
}
}
}
}
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