Javaで始めるパーザコンビネータの作り方（5）~補足 ref: http://qiita.com/kmizu/items/d3d0f9511f631635d4b2

file0.java

package parser;
public class Main {
    public static void main(String[] args) {
        Parser<List<String>> hellos = Parser.string("Hello").many();
        System.out.println(hellos.invoke("Hello, World!"));
    }
}

file1.txt

Success([Hello], , World!)

file2.java

package parser;
public class EOFParser implements Parser<String> {
    @Override
    public ParseResult<String> invoke(String input) {
        if(input.length() != 0) {
            return new ParseResult.Failure<>("expected: EOF, actual: " + input.charAt(0), input);
        } else {
            return new ParseResult.Success<String>("", "");
    }
    }
}

file3.java

package parser;
public interface Parser<T> {
    ParseResult<T> invoke(String input);
    static Parser<String> string(String literal) {
        return new StringParser(literal);
    }
    default Parser<T> or(Parser<T> rhs) {
        return new Or<>(this, rhs);
    }
    default <U> Parser<Tuple2<T, U>> cat(Parser<U> rhs) {
        return new Cat<>(this, rhs);
    }
    default Parser<List<T>> many() {
        return new ManyParser<T>(this);
    }
    static Parser<String> EOF() {
        return new EOFParser();
    }
}

file4.java

public class Main {
    public static void main(String[] args) {
        Parser<Tuple2<List<String>, String>> hellos = Parser.string("Hello").many().cat(Parser.EOF());
        System.out.println(hellos.invoke("Hello"));
        System.out.println(hellos.invoke("Hello, World!"));
    }
}

file5.txt

Success(Tuple2{item1=[Hello], item2=}, )
Failure(expected: EOF, actual: ,, , World!