/*
 * dstatic.d
 *
 * This module implements the static subset of D.
 *
 */

module runtime.dstatic;

import runtime.util;
import runtime.common;

extern(C):

/******************************************
 * Given a pointer:
 *		If it is an Object, return that Object.
 *		If it is an interface, return the Object implementing the interface.
 *		If it is null, return null.
 *		Else, undefined crash
 */

Object _d_toObject(void* p) {
	Object o;

	if (p) {
		o = cast(Object)p;
		ClassInfo oc = o.classinfo;
		Interface *pi = **cast(Interface ***)p;

		/* Interface.offset lines up with ClassInfo.name.ptr,
		 * so we rely on pointers never being less than 64K,
		 * and Objects never being greater.
		 */
		if (pi.offset < 0x10000) {
			//printf("\tpi.offset = %d\n", pi.offset);
			o = cast(Object)(p - pi.offset);
		}
	}
	return o;
}

/*************************************
 * Attempts to cast Object o to class c.
 * Returns o if successful, null if not.
 */

Object _d_interface_cast(void* p, ClassInfo c) {
	Object o;

	//printf("_d_interface_cast(p = %p, c = '%.*s')\n", p, c.name);
	if (p) {
		Interface *pi = **cast(Interface ***)p;

		//printf("\tpi.offset = %d\n", pi.offset);
		o = cast(Object)(p - pi.offset);
		return _d_dynamic_cast(o, c);
	}
	return o;
}

Object _d_dynamic_cast(Object o, ClassInfo c) {
	ClassInfo oc;
	size_t offset = 0;

	//printf("_d_dynamic_cast(o = %p, c = '%.*s')\n", o, c.name);

	if (o) {
		oc = o.classinfo;
		if (_d_isbaseof2(oc, c, offset)) {
			//printf("\toffset = %d\n", offset);
			o = cast(Object)(cast(void*)o + offset);
		}
		else
			o = null;
	}
	//printf("\tresult = %p\n", o);
	return o;
}

int _d_isbaseof2(ClassInfo oc, ClassInfo c, inout size_t offset) {
	int i;

	if (oc is c)
		return 1;
	do {
		if (oc.base is c)
			return 1;
		for (i = 0; i < oc.interfaces.length; i++) {
			ClassInfo ic;

			ic = oc.interfaces[i].classinfo;
			if (ic is c) {
				offset = oc.interfaces[i].offset;
				return 1;
			}
		}
		for (i = 0; i < oc.interfaces.length; i++) {
			ClassInfo ic;

			ic = oc.interfaces[i].classinfo;
			if (_d_isbaseof2(ic, c, offset)) {
				offset = oc.interfaces[i].offset;
				return 1;
			}
		}
		oc = oc.base;
	} while (oc);
	return 0;
}

int _d_isbaseof(ClassInfo oc, ClassInfo c) {
	int i;

	if (oc is c)
		return 1;
	do {
		if (oc.base is c)
			return 1;
		for (i = 0; i < oc.interfaces.length; i++) {
			ClassInfo ic;

			ic = oc.interfaces[i].classinfo;
			if (ic is c || _d_isbaseof(ic, c))
				return 1;
		}
		oc = oc.base;
	} while (oc);
	return 0;
}

/*********************************
 * Find the vtbl[] associated with Interface ic.
 */

void *_d_interface_vtbl(ClassInfo ic, Object o) {
	int i;
	ClassInfo oc;

	//printf("__d_interface_vtbl(o = %p, ic = %p)\n", o, ic);

	assert(o);

	oc = o.classinfo;
	for (i = 0; i < oc.interfaces.length; i++) {
		ClassInfo oic;

		oic = oc.interfaces[i].classinfo;
		if (oic is ic) {
			return cast(void *)oc.interfaces[i].vtbl;
		}
	}
	assert(0);
}

int _d_obj_eq(Object o1, Object o2) {
    return o1 is o2 || (o1 && o1.opEquals(o2));
}

int _d_obj_cmp(Object o1, Object o2) {
    return o1.opCmp(o2);
}