/**

 * @file expGperf.c

 *

 *  Create a perfect hash function program and use it to compute

 *  index values for a list of provided names.  It also documents how

 *  to incorporate that hashing function into a generated C program.

 *

 * @addtogroup autogen

 * @{

 */

/*

 *  This file is part of AutoGen.

 *  Copyright (C) 1992-2016 Bruce Korb - all rights reserved

 *

 * AutoGen 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.

 *

 * AutoGen 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 <http://www.gnu.org/licenses/>.

 */

#ifndef SHELL_ENABLED

HIDE_FN(SCM ag_scm_make_gperf(SCM name, SCM hlist))

{

    return SCM_UNDEFINED;

}

HIDE_FN(SCM ag_scm_gperf(SCM name, SCM str))

{

    return SCM_UNDEFINED;

}

#else

/*=gfunc make_gperf

 *

 * what:   build a perfect hash function program

 * general_use:

 *

 * exparg: name , name of hash list

 * exparg: strings , list of strings to hash ,, list

 *

 * doc:  Build a program to perform perfect hashes of a known list of input

 *       strings.  This function produces no output, but prepares a program

 *       named, @file{gperf_<name>} for use by the gperf function

 *       @xref{SCM gperf}.

 *

 *       This program will be obliterated as AutoGen exits.

 *       However, you may incorporate the generated hashing function

 *       into your C program with commands something like the following:

 *

 *       @example

 *       [+ (shellf "sed '/^int main(/,$d;/^#line/d' $@{gpdir@}/%s.c"

 *                  name ) +]

 *       @end example

 *

 *       where @code{name} matches the name provided to this @code{make-perf}

 *       function.  @code{gpdir} is the variable used to store the name of the

 *       temporary directory used to stash all the files.

=*/

SCM

ag_scm_make_gperf(SCM name, SCM hlist)

{

    static bool do_cleanup = true;

    char const * gp_nam = ag_scm2zchars(name, "gp nm");

    char const * h_list;

    SCM          nl_scm = scm_from_latin1_stringn(NEWLINE, (size_t)1);

    if (! scm_is_string(name))

        return SCM_UNDEFINED;

    /*

     *  Construct the newline separated list of values

     */

    hlist  = ag_scm_join(nl_scm, hlist);

    h_list = ag_scm2zchars(hlist, "hash list");

    /*

     *  Stash the concatenated list somewhere, hopefully without an alloc.

     */

    {

        char * cmd = aprf(MK_GPERF_SCRIPT, make_prog, gp_nam, h_list);

        /*

         *  Run the command and ignore the results.

         *  In theory, the program should be ready.

         */

        h_list = shell_cmd(cmd);

        AGFREE(cmd);

        if (h_list != NULL)

            free(VOIDP(h_list));

    }

    if (do_cleanup) {

        SCM_EVAL_CONST(MAKE_GPERF_CLEANUP);

        do_cleanup = false;

    }

    return SCM_BOOL_T;

}

/*=gfunc gperf

 *

 * what:   perform a perfect hash function

 * general_use:

 *

 * exparg: name , name of hash list

 * exparg: str  , string to hash

 *

 * doc:  Perform the perfect hash on the input string.  This is only useful if

 *       you have previously created a gperf program with the @code{make-gperf}

 *       function @xref{SCM make-gperf}.  The @code{name} you supply here must

 *       match the name used to create the program and the string to hash must

 *       be one of the strings supplied in the @code{make-gperf} string list.

 *       The result will be a perfect hash index.

 *

 *       See the documentation for @command{gperf(1GNU)} for more details.

=*/

SCM

ag_scm_gperf(SCM name, SCM str)

{

    char const * cmd;

    char const * key2hash = ag_scm2zchars(str,  "key-to-hash");

    char const * gp_name  = ag_scm2zchars(name, "gperf name");

    /*

     *  Format the gperf command and check the result.  If it fits in

     *  scribble space, use that.

     *  (If it does fit, then the test string fits already).

     */

    cmd = aprf(RUN_GPERF_CMD, gp_name, key2hash);

    key2hash = shell_cmd(cmd);

    if (*key2hash == NUL)

        str = SCM_UNDEFINED;

    else

        str = scm_from_latin1_string(key2hash);

    AGFREE(cmd);

    AGFREE(key2hash);

    return str;

}

#endif

/**

 * @}

 *

 * Local Variables:

 * mode: C

 * c-file-style: "stroustrup"

 * indent-tabs-mode: nil

 * End:

 * end of agen5/expGperf.c */