vos/corelibs/typechain/handlers/externaltypehandler.hh

Go to the documentation of this file.

/* $Id: externaltypehandler.hh,v 1.6 2003/05/29 23:24:47 reed Exp $ */

/** @file typehandler.hh    defines a basic type handler from which
    you may derive specific type handlers.
    @author Reed sept 2001
*/

/*
    This file is part of the Virtual Object System of
    the Interreality project (http://interreality.org).

    Copyright (C) 2001, 2002 Reed Hedges <reed@zerohour.net>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
*/

#ifndef _EXTERNALTYPEHANDLER_HH_
#define _EXTERNALTYPEHANDLER_HH_

#include <string>
#include <map>
#include <stdio.h>
#include "../typechain.hh"


typedef map<string,string> TypeParams;


/** This class calls an external program or "helper application" to decode
    stuff. The helper program must accept input data via standard input,
    and write to standard output.
    @bug    If there is an error running the external program, you will receve a SIGPIPE (Broken Pipe) signal.
    */
class ExternalTypeHandler : public TypeHandler {

private:

    char **decoder_command; // stores program name for deconding (element 0) and arguments  (0-terminated)
    char **encoder_command; // stores program name and arguments for encoding
    bool needtofreecommands;    // decoder_command and encoder_command were malloc'ed by the constructor, and need to be freed in the destructor


    /* private method for spawning child process and getting some file pointers to talk to it with. */
    int exec_child_io(char *cmd, char **argv, FILE **readpipe, FILE **writepipe);

    /* run external command command, pass data as stdin, return stdout. 
     * On Windows, a Null implementation.
     * On others, implemented as a wrapper around exec_child_io. 
     */
    void run_external(string& data, char **command) ;

public:

    /** Constructor:  given a program name and arguments. data to decode is
        passed through given command with arguments: program name should be
        in decmd[0]. (PATH environment variable will be searched for program
        to run)
        @param decmd program name and arguments for decoding
        @param encmd program name and arguments for encoding
        @param file_ext "Filename extension" for this type.
    */
    ExternalTypeHandler(string name, char **decmd, char **encmd = 0, string file_ext = "?" );

    /** simpler version of ExternalTypeHandler(char *decmd[]);
        takes a program name with no arguments.
        @param decmd program for decoding.
        @param encmd program for encoding.
        @param file_ext Filename "extension" for this type.
    */
    ExternalTypeHandler(string name, char *decmd, char *encmd = 0, string file_ext = "?");

    /** Destructor. Frees internally allocated memory. */
    virtual ~ExternalTypeHandler();


    /** Call the external program to decode the data.
        @param data data to pass to external program to decode.
        @param params Map of parameters from type identifier.
        @return the new data.

    */

    virtual void decode(string& data, TypeParams& params) ;

    /** Call external program to encode data.
        @param data data to pass to external program to encode
        @param params parameters
        @return the new data.
    */

    virtual void encode(string& data, TypeParams& params);

};




#endif

---