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Java Lookahead Parser Generator. Generator produces LALR(k) parsers. Grammar rules are entered using annotations. Rule annotation can be attached to reducer method, which keeps rule and it's action together.

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/*
 * Copyright (C) 2012 Timo Vesalainen
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.vesalainen.parser.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Use Rule annotation to add a rule to a grammar. Field left is the rule nonterminal.
 * Default value for left is the method name.
 * Field value is the rule right hand side. Right hand side value is either a nonterminal
 * name, a terminal name or anonymous terminal. Anonymous terminals are used for terminals
 * that doesn't need reducer methods. Separators like /,.: are examples of anonymous
 * terminals. Anonymous terminal regular expression is quoted with apostrophe (').
 *
 * Example.
 * 
EXPRESSION ::= EXPRESSION + TERM
 * 
     @Rule(left="Expression", value={"Expression", "PLUS", "Term"})
    public long plusExpression(long expr, long term)
    {
        return expr + term;
    }
 * 
 *
 * 
Nonterminal names are like (us-ascii) method names. At right hand side it is
 * also possible to use grouping and quantifiers. Example:
 * 
    @Rule({"prolog", "element", "misc*"})
    protected void document(@ParserContext DefaultHandler2 handler)
    {

    }
 * 
 * 
For misc* nonterminal two rules are added to the grammar.
 * 
 * misc* ::=
 * misc* ::= misc* misc
 * 
 *
 * 
Quantifiers +, ? and * are allowed.
 *
 * Nonterminals can be grouped with or without quantifiers. Example:
 * 
    @Rule({"a1", "(a2 misc*)?"})
    protected void lhs()
    {

    }
 * 
 * 
Note! If grouping contains anonymous terminals, use \x20 for space.
 * 
 * 
doc is the rule documentation
 * 
 * 
left is the nonterminal of the rule
 * 
 * 
value is the rigth hand side of rule. Can be empty is rule accepts empty input.
 * 
 * reducer method in text form. Used only with class annotation. Format is
 * <canonical name of method class> ' ' <method name> '(' arguments ')'
 * 
 * Arguments is a comma separated list of argument type names. Argument type name
 * is canonical name of argument class. Arrays however are printed with leading '['.
 * Example T0.class.getDeclaredMethod("m1", String.class, int.class, long[].class) 
 * produces "org.vesalainen.bcc.T0 m1(java.lang.String,int,[long)"
 * @author tkv
 */
@Repeatable(Rules.class)
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.METHOD, ElementType.TYPE})
public @interface Rule
{
    String doc() default "";
    String left() default "";
    String[] value() default {};
    String reducer() default "";
}