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variables.c

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/*
 *      Copyright (c) 1989 by the Massachusetts Institute of Technology.
 *      For copying and distribution information, see the file
 *      "mit-copyright.h".
 *
 *      Modified for jwgc by Daniel Henninger.
 */

#include "mit-copyright.h"

/****************************************************************************/
/* */
/* Module containing code to deal with description langauge variables:    */
/* */
/****************************************************************************/

#include "notice.h"
#include "string_dictionary_aux.h"
#include "variables.h"

/*
 * fields_data[_length] - these point to the field data that the number
 *                        variables were last set to using
 *                        var_set_number_variables_to_fields.
 */

static char *fields_data;
static int fields_data_length = 0;

/*
 * [non_]number_variable_dict - contains the values of all the [non-]number
 *                              variables that have been set since the last
 *                              var_clear_all_variables call or (for numbers
 *                              only) var_set_number_variables_to_fields call.
 */

static string_dictionary non_number_variable_dict = NULL;
static string_dictionary number_variable_dict = NULL;

/*
 *  Internal Routine:
 *
 *    int is_digits(string text)
 *        Effects: Returns true iff text matches [0-9]*.  ("" matches...)
 */

static int 
is_digits(text)
        string text;
{
        for (; *text; text++)
                if (!isdigit(*text))
                        return (0);

        return (1);
}

/*
 *  Internal Routine:
 *
 *    int is_number_variable(string text)
 *        Effects: Returns true iff text matches [0-9]+.
 */

#define  is_number_variable(x)      (isdigit(*(x)) && is_digits((x)))

/*
 *    void var_clear_all_variables()
 *        Requires: This routine must be called before any other
 *                  var module routine is called.
 *        Modifies: All description language variables
 *        Effects: Sets all description langauge variables to "".
 */

void 
var_clear_all_variables()
{
        if (non_number_variable_dict) {
                string_dictionary_SafeDestroy(non_number_variable_dict);
                string_dictionary_SafeDestroy(number_variable_dict);
        }

        non_number_variable_dict = string_dictionary_Create(101);
        number_variable_dict = string_dictionary_Create(11);
        fields_data_length = 0;
}

/*
 *    string var_get_variable(string name)
 *        Requires: var_clear_all_variables has been called
 *        Effects: Returns the value of the description langauge variable
 *                 named name.  The returned string is read-only and is
 *                 guarenteed to last only until the next var module
 *                 call.  DO NOT FREE THIS STRING.
 */

string 
var_get_variable(name)
        string name;
{
        char *result;
        int field_to_get;
        static string last_get_field_call_result = NULL;

        if (is_number_variable(name)) {
                if ((result = string_dictionary_Fetch(number_variable_dict, name)))
                        return (result);

                /*
                 * Convert name to an integer avoiding overflow:
                 */
                while (*name == '0')
                        name++;
                if (strlen(name) > 12)
                        field_to_get = 0;       /* no way we'll have > 1
                                                 * trillian fields... */
                else
                        field_to_get = atoi(name);

                if (!field_to_get)
                        return ("");
                if (last_get_field_call_result)
                        free(last_get_field_call_result);
                last_get_field_call_result = get_field(fields_data,
                                                       fields_data_length,
                                                       field_to_get);
                return (last_get_field_call_result);
        }

        if (!(result = string_dictionary_Fetch(non_number_variable_dict, name)))
                result = "";

        return (result);
}

/*
 *    void var_set_variable(string name, value)
 *        Requires: var_clear_all_variables has been called
 *        Modifies: The value of description langauge variable
 *                  named name.
 *        Effects: Sets the description langauge variable named name
 *                 to have the value value.
 */

void 
var_set_variable(name, value)
        string name;
        string value;
{
        string_dictionary_Set(is_number_variable(name) ? number_variable_dict
                              : non_number_variable_dict, name, value);
}

/*
 *    void var_set_variable_to_number(string name; int number)
 *        Requires: var_clear_all_variables has been called
 *        Modifies: The value of description langauge variable
 *                  named name.
 *        Effects: Sets the description langauge variable named name
 *                 to have as its value number's ascii representation.
 */

void 
var_set_variable_to_number(name, number)
        string name;
        int number;
{
        char buffer[20];

        sprintf(buffer, "%d", number);
        var_set_variable(name, buffer);
}

/*
 *    void var_set_variable_then_free_value(string name, value)
 *        Requires: var_clear_all_variables has been called, value is
 *                  on the heap.
 *        Modifies: The value of description langauge variable
 *                  named name, value
 *        Effects: Sets the description langauge variable named name
 *                 to have the value value then frees value.  This
 *                 routine is slightly faster than calling var_set_variable
 *                 then freeing value.  It is provided mainly for
 *                 convenience reasons.
 */

void 
var_set_variable_then_free_value(name, value)
        string name;
        string value;
{
        string_dictionary_binding *binding;
        int exists;

        if (is_number_variable(name)) {
                var_set_variable(name, value);
                free(value);
                return;
        }

        binding = string_dictionary_Define(non_number_variable_dict, name,
                                           &exists);
        if (exists)
                free(binding->value);
        binding->value = value;
}

/*
 *    void var_set_number_variables_to_fields(char *data, int length)
 *        Requires: var_clear_all_variables has been called
 *        Modifies: All numeric description language variables
 *        Effects: Treats data[0]..data[length-1] as a series of
 *                 null-seperated fields.  Sets $<number> (<number>
 *                 here means [0-9]+ to field # <number> in data.
 *                 Field 0 is defined to be "" as are all field #'s
 *                 greater than the number of fields in data.
 *                 Data[0]..data[length-1] must not be changed (or freed)
 *                 until either this call is made again with different
 *                 data or var_clear_all_variables is called.
 */

void 
var_set_number_variables_to_fields(data, length)
        char *data;
        int length;
{
        fields_data = data;
        fields_data_length = length;

        string_dictionary_SafeDestroy(number_variable_dict);
        number_variable_dict = string_dictionary_Create(11);
}

Last updated at Tue Dec 18 21:07:42 PST 2007.

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