cpython/Objects/object.c

/* Generic object operations; and implementation of None (NoObject) */

#include "allobjects.h"

#ifdef REF_DEBUG
long ref_total;
#endif

/* Object allocation routines used by NEWOBJ and NEWVAROBJ macros.
   These are used by the individual routines for object creation.
   Do not call them otherwise, they do not initialize the object! */

object *
newobject(tp)
	typeobject *tp;
{
	object *op = (object *) malloc(tp->tp_basicsize);
	if (op == NULL)
		return err_nomem();
	NEWREF(op);
	op->ob_type = tp;
	return op;
}

#if 0 /* unused */

varobject *
newvarobject(tp, size)
	typeobject *tp;
	unsigned int size;
{
	varobject *op = (varobject *)
		malloc(tp->tp_basicsize + size * tp->tp_itemsize);
	if (op == NULL)
		return err_nomem();
	NEWREF(op);
	op->ob_type = tp;
	op->ob_size = size;
	return op;
}

#endif

int StopPrint; /* Flag to indicate printing must be stopped */

static int prlevel;

void
printobject(op, fp, flags)
	object *op;
	FILE *fp;
	int flags;
{
	/* Hacks to make printing a long or recursive object interruptible */
	/* XXX Interrupts should leave a more permanent error */
	prlevel++;
	if (!StopPrint && intrcheck()) {
		fprintf(fp, "\n[print interrupted]\n");
		StopPrint = 1;
	}
	if (!StopPrint) {
		if (op == NULL) {
			fprintf(fp, "<nil>");
		}
		else {
			if (op->ob_refcnt <= 0)
				fprintf(fp, "(refcnt %d):", op->ob_refcnt);
			if (op->ob_type->tp_print == NULL) {
				fprintf(fp, "<%s object at %lx>",
					op->ob_type->tp_name, (long)op);
			}
			else {
				(*op->ob_type->tp_print)(op, fp, flags);
			}
		}
	}
	prlevel--;
	if (prlevel == 0)
		StopPrint = 0;
}

object *
reprobject(v)
	object *v;
{
	object *w = NULL;
	/* Hacks to make converting a long or recursive object interruptible */
	prlevel++;
	if (!StopPrint && intrcheck()) {
		StopPrint = 1;
		err_set(KeyboardInterrupt);
	}
	if (!StopPrint) {
		if (v == NULL) {
			w = newstringobject("<NULL>");
		}
		else if (v->ob_type->tp_repr == NULL) {
			char buf[100];
			sprintf(buf, "<%.80s object at %lx>",
				v->ob_type->tp_name, (long)v);
			w = newstringobject(buf);
		}
		else {
			w = (*v->ob_type->tp_repr)(v);
		}
		if (StopPrint) {
			XDECREF(w);
			w = NULL;
		}
	}
	prlevel--;
	if (prlevel == 0)
		StopPrint = 0;
	return w;
}

int
cmpobject(v, w)
	object *v, *w;
{
	typeobject *tp;
	if (v == w)
		return 0;
	if (v == NULL)
		return -1;
	if (w == NULL)
		return 1;
	if ((tp = v->ob_type) != w->ob_type)
		return strcmp(tp->tp_name, w->ob_type->tp_name);
	if (tp->tp_compare == NULL)
		return (v < w) ? -1 : 1;
	return ((*tp->tp_compare)(v, w));
}

object *
getattr(v, name)
	object *v;
	char *name;
{
	if (v->ob_type->tp_getattr == NULL) {
		err_setstr(TypeError, "attribute-less object");
		return NULL;
	}
	else {
		return (*v->ob_type->tp_getattr)(v, name);
	}
}

int
setattr(v, name, w)
	object *v;
	char *name;
	object *w;
{
	if (v->ob_type->tp_setattr == NULL) {
		if (v->ob_type->tp_getattr == NULL)
			err_setstr(TypeError, "attribute-less object");
		else
			err_setstr(TypeError, "object has read-only attributes");
		return -1;
	}
	else {
		return (*v->ob_type->tp_setattr)(v, name, w);
	}
}


/*
NoObject is usable as a non-NULL undefined value, used by the macro None.
There is (and should be!) no way to create other objects of this type,
so there is exactly one (which is indestructible, by the way).
*/

static void
none_print(op, fp, flags)
	object *op;
	FILE *fp;
	int flags;
{
	fprintf(fp, "None");
}

static object *
none_repr(op)
	object *op;
{
	return newstringobject("None");
}

static typeobject Notype = {
	OB_HEAD_INIT(&Typetype)
	0,
	"None",
	0,
	0,
	0,		/*tp_dealloc*/ /*never called*/
	none_print,	/*tp_print*/
	0,		/*tp_getattr*/
	0,		/*tp_setattr*/
	0,		/*tp_compare*/
	none_repr,	/*tp_repr*/
	0,		/*tp_as_number*/
	0,		/*tp_as_sequence*/
	0,		/*tp_as_mapping*/
};

object NoObject = {
	OB_HEAD_INIT(&Notype)
};


#ifdef TRACE_REFS

static object refchain = {&refchain, &refchain};

NEWREF(op)
	object *op;
{
	ref_total++;
	op->ob_refcnt = 1;
	op->_ob_next = refchain._ob_next;
	op->_ob_prev = &refchain;
	refchain._ob_next->_ob_prev = op;
	refchain._ob_next = op;
}

UNREF(op)
	register object *op;
{
	register object *p;
	if (op->ob_refcnt < 0) {
		fprintf(stderr, "UNREF negative refcnt\n");
		abort();
	}
	for (p = refchain._ob_next; p != &refchain; p = p->_ob_next) {
		if (p == op)
			break;
	}
	if (p == &refchain) { /* Not found */
		fprintf(stderr, "UNREF unknown object\n");
		abort();
	}
	op->_ob_next->_ob_prev = op->_ob_prev;
	op->_ob_prev->_ob_next = op->_ob_next;
}

DELREF(op)
	object *op;
{
	UNREF(op);
	(*(op)->ob_type->tp_dealloc)(op);
}

printrefs(fp)
	FILE *fp;
{
	object *op;
	fprintf(fp, "Remaining objects:\n");
	for (op = refchain._ob_next; op != &refchain; op = op->_ob_next) {
		fprintf(fp, "[%d] ", op->ob_refcnt);
		printobject(op, fp, 0);
		putc('\n', fp);
	}
}

#endif