bnf.g

一个非常好的检索工具

%Options la=2,gp=java,act,an=bnfact.java,hn=bnfhdr.java,tab=space,fp=bnf,prefix=TK_,
%Options nogoto-default,output-size=125,names=max,error-maps
%Define
-- This software is subject to the terms of the IBM Jikes Parser
-- Generator License Agreement available at the following URL:
-- http://www.ibm.com/research/jikes.
-- Copyright (C) 1983, 1999, International Business Machines Corporation
-- and others.  All Rights Reserved.
-- You must accept the terms of that agreement to use this software.

-- This grammar has been augmented with productions that captures
-- most errors that a user is likely to make. This saves the need
-- to have an error recovery system.

-- 
-- This macro is used to initialize the rule_action array
-- to the null_action function.
--
%null_action
/.
        new NullAction(),
./
 
-- 
-- This macro is used to initialize the rule_action array
-- to the no_action function.
--
%no_action
/.
        new NoAction(),
./
 
%Terminals

    SYMBOL PRODUCES OR EOF ERROR

%Alias

    '::='  ::= PRODUCES
    '|'    ::= OR
    %EOF   ::= EOF
    %ERROR ::= ERROR

%Rules
/:
class bnfhdr extends bnfact
{
    Action rule_action[] = {
        null, // no element 0
:/

/.
class bnfact
{
    Parser parser;

    bnfact(Parser parser)
    {
        this.parser = parser;
    }

    void print_rule(int rule_no)
    {
        String rule = new String();
        rule = parser.name[parser.non_terminal_index[parser.lhs[rule_no]]] + " ::=";
        if (parser.rhs[rule_no] == 0)
            rule += " %empty";
        else
        {
            for (int i = 1; i <= parser.rhs[rule_no]; i++)
            {
                int non_term = parser.SYM(i),
                    term = parser.lex_stream.Kind(parser.TOKEN(i));
                rule += (" " + (non_term == 0 ? parser.name[parser.terminal_index[term]]
                                              : parser.name[parser.non_terminal_index[non_term]]));
            }
        }

        System.out.println("Reducing rule number " + rule_no + ": " + rule);

        return;
    }

    interface Action
    {
        public void action();
    }

    final class NoAction implements Action
    {
        public void action() {}
    }

    final class NullAction implements Action
    {
        public void action()
        {
            System.out.println("A null production");
        }
    }
./

bnf ::= %empty
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

bnf ::= bnf rules
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

rules ::= rule
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

rules ::= rules '|' symbol_list
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

rule ::= SYMBOL '::=' symbol_list
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

symbol_list ::= %empty
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

symbol_list ::= symbol_list SYMBOL
  /:        new act%rule_number(),:/
  /.
    // 
    // Rule %rule_number:  %rule_text
    //
    final class act%rule_number implements Action
    {
        public void action()
        {
            print_rule(%rule_number);
            parser.setSYM1((int) parser.lhs[%rule_number]);
        }
    }
  ./

/:
    };

    bnfhdr(Parser parser)
    {
        super(parser);
    }
}
:/

/.
}
./
%End