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55  * by Daniel F. Savarese. We appreciate his contributions.
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57
58 import org.apache.oro.text.regex.*;
59
60 /**
61  * This is a test program demonstrating an application of the matchesPrefix()
62  * methods introduced in OROMatcher v1.0.6. This example program shows how
63  * you might tokenize a stream of input using whitespace as a token
64  * separator. Don't forget to use quotes around the input on the command
65  * line, e.g.
66  * java prefixExample "Test to see if 1.0 is real and 2 is an integer"
67  *
68  * If you don't need the power of a full blown lexer generator, you can
69  * easily use regular expressions to create your own tokenization and
70  * simple parsing classes using similar approaches.
71  *
72  @author <a HREF="dfs@savarese.org">Daniel F. Savarese</a>
73  @version $Id: prefixExample.java,v 1.1.1.1 2000/07/23 23:08:48 jon Exp $
74  */

75 public final class prefixExample {
76   public static final int REAL = 0;
77   public static final int INTEGER = 1;
78   public static final int STRING = 2;
79
80   public static final String JavaDoc[] types = { "Real", "Integer", "String" };
81   public static final String JavaDoc whitespace = "\\s+";
82   public static final String JavaDoc[] tokens = {
83     "-?\\d*\\.\\d+(?:[eE][-+]-?\\d+)?(?=\\s|$)", "-?\\d+(?=\\s|$)", "\\S+"
84   };
85   public static final String JavaDoc tokens2 =
86     "(-?\\d*\\.\\d+(?:[eE][-+]-?\\d+)?(?=\\s|$))|(-?\\d+(?=\\s|$))|(\\S+)";
87
88   public static final void main(String JavaDoc args[]) {
89     int token;
90     PatternMatcherInput input;
91     PatternMatcher matcher;
92     PatternCompiler compiler;
93     Pattern[] patterns;
94     Pattern tokenSeparator = null, patterns2 = null;
95
96     if(args.length < 1) {
97       System.err.println("Usage: prefixExample <sample input>");
98       System.exit(1);
99     }
100
101     input = new PatternMatcherInput(args[0]);
102     compiler = new Perl5Compiler();
103     patterns = new Pattern[tokens.length];
104
105     try {
106       tokenSeparator = compiler.compile(whitespace);
107       patterns2 = compiler.compile(tokens2);
108       for(token=0; token < tokens.length; token++)
109     patterns[token] = compiler.compile(tokens[token]);
110     } catch(MalformedPatternException e) {
111       System.err.println("Bad pattern.");
112       e.printStackTrace();
113       System.exit(1);
114     }
115
116     matcher = new Perl5Matcher();
117
118     System.out.println("\nOne approach.\n");
119
120     do {
121       for(token = 0; token < tokens.length; token++)
122     if(matcher.matchesPrefix(input, patterns[token])) {
123       System.out.println(types[token] + ": " + matcher.getMatch());
124       break;
125     }
126     } while(matcher.contains(input, tokenSeparator));
127
128     // An alternative approach using the tokens2 expression which
129
// packs all the token patterns into one regular expression.
130
// As in Perl, there's more than one way to do something in Java.
131
System.out.println("\nAn equivalent alternative.\n");
132
133     input.setCurrentOffset(input.getBeginOffset());
134     do {
135       if(matcher.matchesPrefix(input, patterns2)) {
136     MatchResult result = matcher.getMatch();
137
138     for(token = 1; token <= tokens.length; token++) {
139       if(result.group(token) != null) {
140         System.out.println(types[token - 1] + ": " + result);
141         break;
142       }
143     }
144       }
145     } while(matcher.contains(input, tokenSeparator));
146
147   }
148 }
149
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