Acceptor.java

package org.softlang.company.features.recognizer;

import static org.softlang.company.features.recognizer.Token.*;

import java.io.FileNotFoundException;

/**
 * An acceptor only.
 * See class Parser for an elaboration that allows for injection of semantic actions.
 */
public class Acceptor {

    private Lexer lexer;
    private Token lookahead;

    // Parse a file
    public void accept(String s) throws FileNotFoundException {
        lexer = new Lexer(s);
        company();
        match(EOF);
    }

    //
    // Match expected with actual tokem.
    // Consume the token if successful.
    // Throw exception if not successful.
    //
    private String match(Token token) {
        if (test(token)) {
            lookahead = null;
            return lexer.getLexeme();
        }
        else
            throw new RecognitionException("Expected: " + token + "; Found: " + lookahead);
    }

    // Test actual token
    private boolean test(Token token) {
        if (lookahead==null)
            lookahead = lexer.next();
        return (lookahead==token);
    }

    // Parse companies
    private final void company() {
        match(COMPANY);
        match(STRING);
        match(OPEN);
        while (test(DEPARTMENT))
            department();
        match(CLOSE);
    }

    // Parse departments
    private final void department() {
        match(DEPARTMENT);
        match(STRING);
        match(OPEN);
        match(MANAGER);
        employee();
        while (test(EMPLOYEE)) {
            match(EMPLOYEE);
            employee();
        }
        while (test(DEPARTMENT))
            department();
        match(CLOSE);
    }

    // Parse employees
    private final void employee() {
        match(STRING);
        match(OPEN);
        match(ADDRESS);
        match(STRING); 
        match(SALARY);
        match(FLOAT); 
        match(CLOSE);
    }

}