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package com.wcohen.ss.tokens;
import java.util.*;
import com.wcohen.ss.api.*;
/**
* Simple implementation of a Tokenizer. Tokens are sequences of
* alphanumerics, optionally including single punctuation characters.
*/
public class SimpleTokenizer implements Tokenizer
{
public static final SimpleTokenizer DEFAULT_TOKENIZER = new SimpleTokenizer(true,true);
private boolean ignorePunctuation = true;
private boolean ignoreCase = true;
public SimpleTokenizer(boolean ignorePunctuation,boolean ignoreCase) {
this.ignorePunctuation = ignorePunctuation;
this.ignoreCase = ignoreCase;
}
// parameter setting
public void setIgnorePunctuation(boolean flag) { ignorePunctuation = flag; }
public void setIgnoreCase(boolean flag) { ignoreCase = flag; }
public String toString() { return "[SimpleTokenizer "+ignorePunctuation+";"+ignoreCase+"]"; }
/** Return tokenized version of a string. Tokens are sequences
* of alphanumerics, or any single punctuation character. */
public Token[] tokenize(String input)
{
List tokens = new ArrayList();
int cursor = 0;
while (cursor<input.length()) {
char ch = input.charAt(cursor);
if (Character.isWhitespace(ch)) {
cursor++;
} else if (Character.isLetter(ch)) {
StringBuffer buf = new StringBuffer("");
while (cursor<input.length() && Character.isLetter(input.charAt(cursor))) {
buf.append(input.charAt(cursor));
cursor++;
}
tokens.add(internSomething(buf.toString()));
} else if (Character.isDigit(ch)) {
StringBuffer buf = new StringBuffer("");
while (cursor<input.length() && Character.isDigit(input.charAt(cursor))) {
buf.append(input.charAt(cursor));
cursor++;
}
tokens.add(internSomething(buf.toString()));
} else {
if (!ignorePunctuation) {
StringBuffer buf = new StringBuffer("");
buf.append(ch);
String str = buf.toString();
tokens.add(internSomething(str));
}
cursor++;
}
}
return (Token[]) tokens.toArray(new BasicToken[tokens.size()]);
}
private Token internSomething(String s)
{
return intern( ignoreCase ? s.toLowerCase() : s );
}
//
// 'interning' strings as tokens
//
private int nextId = 0;
private Map tokMap = new TreeMap();
public Token intern(String s)
{
Token tok = (Token)tokMap.get(s);
if (tok==null) {
tok = new BasicToken(++nextId,s);
tokMap.put(s,tok);
}
return tok;
}
public Iterator tokenIterator()
{
return tokMap.values().iterator();
}
public int maxTokenIndex()
{
return nextId;
}
/** Test routine */
public static void main(String[] argv)
{
SimpleTokenizer tokenizer = DEFAULT_TOKENIZER;
int n = 0;
for (int i=0; i<argv.length; i++) {
System.out.println("argument "+i+": '"+argv[i]+"'");
Token[] tokens = tokenizer.tokenize(argv[i]);
for (int j=0; j<tokens.length; j++) {
System.out.println("token "+(++n)+":"
+" id="+tokens[j].getIndex()
+" value: '"+tokens[j].getValue()+"'");
}
}
}
}
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