Source: ../../policy/code_generator.hh

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// -*- c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t -*-
// vim:set sts=4 ts=8:

// Copyright (c) 2001-2008 XORP, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software")
// to deal in the Software without restriction, subject to the conditions
// listed in the XORP LICENSE file. These conditions include: you must
// preserve this copyright notice, and you cannot mention the copyright
// holders in advertising related to the Software without their permission.
// The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
// notice is a summary of the XORP LICENSE file; the license in that file is
// legally binding.

// $XORP: xorp/policy/code_generator.hh,v 1.9 2008/07/23 05:11:18 pavlin Exp $

#ifndef __POLICY_CODE_GENERATOR_HH__
#define __POLICY_CODE_GENERATOR_HH__

#include "policy/common/varrw.hh"
#include "policy/common/policy_exception.hh"
#include "var_map.hh"
#include "visitor.hh"
#include "code.hh"
#include "policy_statement.hh"
#include "node.hh"
#include <sstream>
#include <string>

/**
 * @short Generic code generator. It is suitable for import filters.
 *
 * This class visits a structure of Nodes and generates appropriate code.
 */
class CodeGenerator : public Visitor {
public:
    /**
     * @short Exception thrown if code generation fails.
     *
     * This may occur for example, if an import policy has a dest part. The
     * semantic check should however get rid of all errors.
     */
    class CodeGeneratorErr : public PolicyException {
    public:
        CodeGeneratorErr(const char* file, size_t line, 
			 const string& init_why = "")
            : PolicyException("CodeGeneratorErr", file, line, init_why) {}   
    };

    CodeGenerator(const VarMap& varmap); // used by source match code generator.
    
    /**
     * Generate code for a specific protocol and filter [target]/
     *
     * This construct is mainly used by derived classes to set the code target.a
     *
     * @param proto target protocol.
     * @param filter target filter type.
     * @param varmap varmap.
     */
    CodeGenerator(const string& proto, const filter::Filter& filter,
		  const VarMap& varmap);
    
    /**
     * Initialize code generation for an import of a specific protocol.
     *
     * @param proto target protocol.
     * @param varmap varmap.
     */
    CodeGenerator(const string& proto, const VarMap& varmap);

    virtual ~CodeGenerator();

    const Element* visit(NodeUn& node);
    const Element* visit(NodeBin& node);
    const Element* visit(NodeAssign& node);
    const Element* visit(NodeElem& node);
    const Element* visit(NodeVar& node);
    const Element* visit(NodeSet& node);
    const Element* visit(NodeAccept& node);
    const Element* visit(NodeReject& node);
    
    const Element* visit(PolicyStatement& policy); 
    const Element* visit(Term& policy); 
    const Element* visit(NodeProto& policy); 

    /**
     * @return code generated.
     */
    const Code& code();

protected:
    // may not overload virtual functions =(
    // yes it is a triple dispatch... but we will get there eventually =D
    virtual const Element* visit_policy(PolicyStatement& policy);
    virtual const Element* visit_term(Term& term);
    virtual const Element* visit_proto(NodeProto& node);

    virtual const string& protocol();

    Code _code;
    ostringstream _os;
    const VarMap& _varmap;

private:
    string _protocol;
};

#endif // __POLICY_CODE_GENERATOR_HH__