JparsecSample.java

package sample.jparsec;

import static org.junit.Assert.assertEquals;

import java.util.List;
import org.codehaus.jparsec.*;
import org.codehaus.jparsec.functors.*;
import org.junit.Test;

public class JparsecSample {
    public static Parser<String> str(String s) {
        return Scanners.string(s).source();
    }
    @Test
    public void recursiveTest() {
        // <a1star> ::= { "a" "1" }
        Parser<String> a1star = Parsers.sequence(
            str("a"), str("1"),
            new Map2<String, String, String>() {
                public String map(String s1,String s2) {
                    return s1 + s2;
                }
            }
        ).many().map(new Map<List<String>, String>() {
            public String map(List<String> strings) {
                String acc = "";
                for (String s :strings) {
                    acc += s;
                }
                return acc;
            }
        });
        // <a> ::= [ "a" ]
        Parser<String> a = str("a").optional("");
        // <p4> ::= <a1star> <a>
        Parser<String> p4 = Parsers.sequence(
            a1star, a,
            new Map2<String, String, String>() {
                public String map(String s1,String s2) {
                    return s1 + s2;
                }
            }
        );
        assertEquals("a1", p4.parse("a1")); // OK
        assertEquals("a1a1a1", p4.parse("a1a1a1")); // OK
        assertEquals("a1a", p4.parse("a1a")); // NG...?
/*
org.codehaus.jparsec.error.ParserException: line 1, column 4:
1 expected, EOF encountered.
    at org.codehaus.jparsec.Parsers.parse(Parsers.java:98)
...
*/
    }
}