C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_200/231_01/class.c

C/C++ Source or Header | 1987-06-15 | 5.1 KB | 205 lines

/*
    Little Smalltalk
        class instance creation and deletion

        timothy a. budd  10/84
*/
/*
    The source code for the Little Smalltalk System may be freely
    copied provided that the source of all files is acknowledged
    and that this condition is copied with each file.

    The Little Smalltalk System is distributed without responsibility
    for the performance of the program and without any guarantee of
    maintenance.

    All questions concerning Little Smalltalk should be addressed to:

        Professor Tim Budd
        Department of Computer Science
        Oregon State University
        Corvallis, Oregon
        97331
        USA
*/
# include <stdio.h>
# include "object.h"
# include "file.h"
# include "number.h"
# include "symbol.h"
# include "string.h"
# include "primitive.h"
# define streq(x,y) (strcmp(x,y) == 0)

extern class *Array, *ArrayedCollection;

extern object *o_object, *o_empty, *o_number, *o_magnitude;
extern object *o_smalltalk, *o_acollection;

static mstruct *fr_class = 0;
int ca_class = 0;    /* count class allocations */

# define CLASSINITMAX 30

static class cl_table[CLASSINITMAX];

class_init()
{    class *p;
    mstruct *new;
    int i;

    for (p = cl_table, i = 0; i < CLASSINITMAX; i++, p++) {
        new = (mstruct *) p;
        new->mlink = fr_class;
        fr_class = new;
        }
}

class *new_class()
{    class *new;

    if (fr_class) {
        new = (class *) fr_class;
        fr_class = fr_class->mlink;
        }
    else {
        new = structalloc(class);
        ca_class++;
        }

    new->c_ref_count = 0;
    new->c_size = CLASSSIZE;
    sassign(new->file_name, o_nil);
    sassign(new->class_name, o_nil);
    new->super_class = (object *) 0;
    sassign(new->c_inst_vars, o_nil);
    new->context_size = 0;
    sassign(new->message_names, o_nil);
    sassign(new->methods, o_nil);
    return(new);
}

class *mk_class(classname, args)
char *classname;
object **args;
{    class *new;
    object *new_iarray();

    new = new_class();
    assign(new->class_name, args[0]);
    if (! streq(classname, "Object"))
        sassign(new->super_class, args[1]);
    assign(new->file_name, args[2]);
    assign(new->c_inst_vars, args[3]);
    assign(new->message_names, args[4]);
    assign(new->methods, args[5]);
    new->context_size = int_value(args[6]);
    new->stack_max = int_value(args[7]);

    if (streq(classname, "Array")) {
        assign(Array, new);
        assign(o_empty, new_iarray(0));
        }
    else if (streq(classname, "ArrayedCollection")) {
        assign(ArrayedCollection, new);
        assign(o_acollection, new_inst(new));
        assign(o_empty, new_iarray(0));
        }
    else if (streq(classname, "False"))
        assign(o_false, new_inst(new))
    else if (streq(classname, "Magnitude"))
        assign(o_magnitude, new_inst(new))
    else if (streq(classname, "Number"))
        assign(o_number, new_inst(new))
    else if (streq(classname, "Object"))
        assign(o_object, new_inst(new))
    else if (streq(classname, "Smalltalk"))
        assign(o_smalltalk, new_inst(new))
    else if (streq(classname, "True"))
        assign(o_true, new_inst(new))
    else if (streq(classname, "UndefinedObject"))
        assign(o_nil, new_inst(new))
    return(new);
}

/* new_sinst - new instance with explicit super object */
object *new_sinst(aclass, super)
class *aclass;
object *super;
{    object *new;
    char *classname, buffer[80];

    if (! is_class(aclass))
        cant_happen(4);
    classname = symbol_value(aclass->class_name);
    if (    streq(classname, "Block") ||
        streq(classname, "Char") ||
        streq(classname, "Class") ||
        streq(classname, "Float") ||
        streq(classname, "Integer") ||
        streq(classname, "Process") ||
        streq(classname, "Symbol") ) {
        sprintf(buffer,"%s: does not respond to new", classname);
        sassign(new, new_str(buffer));
        primitive(ERRPRINT, 1, &new);
        obj_dec(new);
        if (super) /* get rid of unwanted object */
            {obj_inc((object *) super);
             obj_dec((object *) super);}
        new = o_nil;
        }
    else if (streq(classname, "File")) {
        new = new_file();
        if (super) /* get rid of unwanted object */
            {obj_inc((object *) super);
             obj_dec((object *) super);}
        }
    else if (streq(classname, "String")) {
        new = new_str("");
        if (super)
            assign(((string *) new)->s_super_obj, super);
        }
    else {
        new = new_obj(aclass, (aclass->c_inst_vars)->size, 1);
        if (super)
            sassign(new->super_obj, super);
        }
    return(new);
}

object *new_inst(aclass)
class *aclass;
{    object *super, *sp_class_name, *lookup_class();
    class *super_class;

    if (! is_class(aclass))
        cant_happen(4);
    if (aclass == o_object->class)
        return(o_object);
    super = (object *) 0;
    sp_class_name = aclass->super_class;
    if (sp_class_name && is_symbol(sp_class_name)) {
        super_class = (class *)
            lookup_class(symbol_value(sp_class_name));
        if (super_class && is_class(super_class))
            super = new_inst(super_class);
        }
    return(new_sinst(aclass, super));
}

free_class(c)
class *c;
{
    if (! is_class(c))
        cant_happen(8);
    obj_dec(c->class_name);
    if (c->super_class)
        obj_dec((object *) c->super_class);
    obj_dec(c->file_name);
    obj_dec(c->c_inst_vars);
    obj_dec(c->message_names);
    obj_dec(c->methods);
    ((mstruct *) c )->mlink = fr_class;
    fr_class = (mstruct *) c;
}