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handle.cc
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handle.cc
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#define ICI_CORE
#include "handle.h"
#include "array.h"
#include "cfunc.h"
#include "fwd.h"
#include "int.h"
#include "map.h"
#include "null.h"
#include "object.h"
#include "str.h"
namespace ici
{
static handle ici_handle_proto;
/*
* Return a handle object corresponding to the given C data 'ptr', with the
* ICI type 'name' (which may be nullptr), and with the given 'super' (which
* may be nullptr).
*
* The returned handle will have had its reference count inceremented.
*
* ICI handle objects are generic wrapper/interface objects around some C data
* structure. They act, on the ICI side, as objects with the type 'name'.
* When you are passed a handle back from ICI code, you can check this name
* to prevent the ICI program from giving you some other data type's handle.
* (You can't make handles at the script level, so you are safe from all
* except other native code mimicing your type name.)
*
* Handles are intrinsicly atomic with respect to the 'ptr' and 'name'. So
* this function actually just finds the existing handle of the given data
* object if that handle already exists.
*
* Handle's will, of course, be garbage collected as usual. If your C data is
* dependent on the handle, you should store a pointer to a free function
* for your data in the 'h_pre_free' field of the handle. It will be called
* just before the gardbage collector frees the memory of the handle.
*
* If, on the other hand, your C data structure is the master structure and it
* might be freed by some other aspect of your code, you must consider that
* its handle object may still be referenced from ICI code. You don't want to
* have it passed back to you and inadvertently try to access your freed data.
* To prevent this you can set the handle::CLOSED flag in the handle's object header
* when you free the C data (see 'handle_probe()'). Note that in
* callbacks where you are passed the handle object directly, you are
* reponsible to checking handle::CLOSED. Also, once you use this mechanism, you
* must *clear* the handle::CLOSED field after a real new handle allocation (because
* you might be reusing the old memory, and this function might be returning
* to you a zombie handle).
*
* Handles can support assignment to fields "just like a struct" by
* the automatic creation of a private struct to store such values in upon
* first assignment. This mechanism is, by default, only enabled if you
* supply a non-nullptr super. But you can enable it even with a nullptr super
* by setting O_SUPER in the handle's object header at any time. (Actually,
* it is an historical accident that 'super' was ever an argument to this
* function.)
*
* Handles can support an interface function that allows C code to implement
* fetch and assign operations, as well as method invocation on fields of the
* handle. See the 'h_member_intf' in the 'handle' type description
* (and the 'Common tasks' section of this chapter.)
*
* Handles can also be used as instances of an ICI class. Typically the class
* will have the methods that operate on the handle. In this case you will
* pass the class in 'super'. Instance variables will be supported by the
* automatic creation of the private struct to hold them (which allows the
* class to be extended in ICI with additional instance data that is not part
* of your C code). However, note that these instance variables are not
* "magic". Your C code does not notice them getting fetched or assigned to.
*
* This --func-- forms part of the --ici-api--.
*/
handle *new_handle(void *ptr, str *name, objwsup *super, void (*prefree)(handle *))
{
handle *h;
object **po;
ici_handle_proto.h_ptr = ptr;
ici_handle_proto.h_name = name;
ici_handle_proto.o_super = super;
if (auto x = atom_probe2(&ici_handle_proto, &po))
{
h = handleof(x);
incref(h);
return h;
}
++supress_collect;
if ((h = ici_talloc(handle)) == nullptr)
{
return nullptr;
}
set_tfnz(h, TC_HANDLE, (super != nullptr ? object::O_SUPER : 0) | object::O_ATOM, 1, 0);
h->h_ptr = ptr;
h->h_name = name;
h->o_super = super;
h->h_pre_free = prefree;
h->h_member_map = nullptr;
h->h_member_intf = nullptr;
h->h_general_intf = nullptr;
rego(h);
--supress_collect;
store_atom_and_count(po, h);
return h;
}
/*
* If it exists, return a pointer to the handle corresponding to the C data
* structure 'ptr' with the ICI type 'name'. If it doesn't exist, return
* nullptr. The handle (if returned) will have been increfed.
*
* This function can be used to probe to see if there is an ICI handle
* associated with your C data structure in existence, but avoids allocating
* it if does not exist already (as 'new_handle()' would do). This can be
* useful if you want to free your C data structure, and need to mark any ICI
* reference to the data by setting handle::CLOSED in the handle's object header.
*
* This --func-- forms part of the --ici-api--.
*/
handle *handle_probe(void *ptr, str *name)
{
handle *h;
ici_handle_proto.h_ptr = ptr;
ici_handle_proto.h_name = name;
if ((h = handleof(atom_probe(&ici_handle_proto))) != nullptr)
{
incref(h);
}
return h;
}
/*
* Verify that a method on a handle has been invoked correctly. In
* particular, that 'inst' is not nullptr and is a handle with the given 'name'.
* If OK and 'h' is non-nullptr, the handle is stored through it. If 'p' is
* non-nullptr, the associted pointer ('h_ptr') is stored through it. Return 1
* on error and sets error, else 0.
*
* For example, a typical method where the instance should be a handle
* of type 'XML_Parse' might look like this:
*
* static int
* ici_xml_SetBase(object *inst)
* {
* char *s;
* XML_Parser p;
*
* if (handle_method_check(inst, ICIS(XML_Parser), nullptr, &p))
* return 1;
* if (typecheck("s", &s))
* return 1;
* if (!XML_SetBase(p, s))
* return ici_xml_error(p);
* return null_ret();
* }
*
*
* This --func-- forms part of the --ici-api--.
*/
int handle_method_check(object *inst, str *name, handle **h, void **p)
{
char n1[objnamez];
char n2[objnamez];
if (method_check(inst, TC_HANDLE))
{
return 1;
}
if (handleof(inst)->h_name != name)
{
return set_error("attempt to apply method %s to %s", objname(n1, os.a_top[-1]), objname(n2, inst));
}
if (h != nullptr)
{
*h = handleof(inst);
}
if (p != nullptr)
{
*p = handleof(inst)->h_ptr;
}
return 0;
}
/*
* The function used to field method calls that go through the memeber map
* mechanism. Checks conditions and transfers to the h_memeber_intf function
* of the handle.
*/
static int ici_handle_method(object *inst)
{
object *r;
char n1[objnamez];
char n2[objnamez];
long id;
if (method_check(inst, TC_HANDLE))
{
return 1;
}
if (inst->hasflag(handle::CLOSED))
{
return set_error("attempt to apply method %s to %s which is dead", objname(n1, os.a_top[-1]),
objname(n2, inst));
}
r = nullptr;
id = (long)cfuncof(os.a_top[-1])->cf_arg1;
if ((*handleof(inst)->h_member_intf)(handleof(inst)->h_ptr, id, nullptr, &r))
{
return 1;
}
if (r == nullptr)
{
return set_error("attempt to apply method %s to %s", objname(n1, os.a_top[-1]), objname(n2, inst));
}
return ret_no_decref(r);
}
/*
* Build the map that 'handle' objects use to map a member name (used in
* ICI code) to an integer ID (used in the C code). The returned map is actually
* an ICI struct. It is returned with 1 refernce count.
*
* The argument 'ni' should be a pointer to the first element of an arrary
* of 'name_id' structs that contain the names of members and the integer
* IDs that your code would like to refere to them by. All members that are
* to be invoked as methods calls must include the flag handle::METHOD in the ID.
* (This flag is removed from the ID when it is passed back to your code. handle::METHOD
* is the most significant bit in the 32 bit ID.) The list is terminated by an
* entry with a name of nullptr.
*
* For example:
*
* enum {P_Property1, P_Property2, M_Method1, M_Method2, ...};
*
* static name_id member_name_ids[] =
* {
* {"Property1", P_Property1},
* {"Property2", P_Property1},
* {"Method1", M_Method1},
* {"Method2", M_Method2},
* {nullptr},
* }
*
* object *ici_member_map;
*
* ...
* member_map = make_handle_member_map(member_name_ids)
* if (member_map == nullptr)
* ...
*
* This --func-- forms part of the --ici-api--.
*/
object *make_handle_member_map(name_id *ni)
{
object *m;
str *n;
object *id;
if ((m = new_map()) == nullptr)
{
return nullptr;
}
for (; ni->ni_name != nullptr; ++ni)
{
id = nullptr;
if ((n = new_str_nul_term(ni->ni_name)) == nullptr)
{
goto fail;
}
if (ni->ni_id & handle::METHOD)
{
id = new_cfunc(n, (int (*)(...))(ici_handle_method), (void *)(ni->ni_id & ~handle::METHOD), nullptr);
if (id == nullptr)
{
goto fail;
}
}
else
{
if ((id = new_int(ni->ni_id)) == nullptr)
{
goto fail;
}
}
if (ici_assign(m, n, id))
{
goto fail;
}
decref(n);
decref(id);
}
return m;
fail:
if (n != nullptr)
{
decref(n);
}
if (id != nullptr)
{
decref(id);
}
decref(m);
return nullptr;
}
void handle_type::objname(object *o, char p[objnamez])
{
if (handleof(o)->h_name == nullptr)
{
strcpy(p, "handle");
}
else
{
if (handleof(o)->h_name->s_nchars > objnamez - 1)
{
sprintf(p, "%.*s...", objnamez - 4, handleof(o)->h_name->s_chars);
}
else
{
sprintf(p, "%s", handleof(o)->h_name->s_chars);
}
}
}
size_t handle_type::mark(object *o)
{
auto mem = type::mark(o);
if (objwsupof(o)->o_super != nullptr)
{
mem += ici_mark(objwsupof(o)->o_super);
}
if (handleof(o)->h_name != nullptr)
{
mem += ici_mark(handleof(o)->h_name);
}
return mem;
}
int handle_type::cmp(object *o1, object *o2)
{
return handleof(o1)->h_ptr != handleof(o2)->h_ptr || handleof(o1)->h_name != handleof(o2)->h_name;
}
unsigned long handle_type::hash(object *o)
{
return ICI_PTR_HASH(handleof(o)->h_ptr) ^ ICI_PTR_HASH(handleof(o)->h_name);
}
object *handle_type::fetch(object *o, object *k)
{
handle *h;
object *r;
h = handleof(o);
if (h->h_member_map != nullptr && !o->hasflag(handle::CLOSED))
{
object *id;
if ((id = ici_fetch(h->h_member_map, k)) == nullptr)
{
return nullptr;
}
if (iscfunc(id))
{
return id;
}
if (isint(id))
{
r = nullptr;
if ((*h->h_member_intf)(h->h_ptr, intof(id)->i_value, nullptr, &r))
{
return nullptr;
}
if (r != nullptr)
{
return r;
}
}
}
if (h->h_general_intf != nullptr)
{
r = nullptr;
if ((*h->h_general_intf)(h, k, nullptr, &r))
{
return nullptr;
}
if (r != nullptr)
{
return r;
}
}
if (!hassuper(o) || handleof(o)->o_super == nullptr)
{
return fetch_fail(o, k);
}
return ici_fetch(handleof(o)->o_super, k);
}
/*
* Do a fetch where we are the super of some other object that is
* trying to satisfy a fetch. Don't regard the item k as being present
* unless it really is. Return -1 on error, 0 if it was not found,
* and 1 if was found. If found, the value is stored in *v.
*
* If not nullptr, b is a struct that was the base element of this
* assignment. This is used to mantain the lookup lookaside mechanism.
*/
int handle_type::fetch_super(object *o, object *k, object **v, map *b)
{
if (!hassuper(o))
{
fetch_fail(o, k);
return 1;
}
if (handleof(o)->o_super == nullptr)
{
return 0;
}
return ici_fetch_super(handleof(o)->o_super, k, v, b);
}
object *handle_type::fetch_base(object *o, object *k)
{
handle *h;
object *r;
h = handleof(o);
if (h->h_member_map != nullptr && !o->hasflag(handle::CLOSED))
{
object *id;
if ((id = ici_fetch(h->h_member_map, k)) == nullptr)
{
return nullptr;
}
if (iscfunc(id))
{
return id;
}
if (isint(id))
{
r = nullptr;
if ((*h->h_member_intf)(h->h_ptr, intof(id)->i_value, nullptr, &r))
{
return nullptr;
}
if (r != nullptr)
{
return r;
}
}
}
if (h->h_general_intf != nullptr)
{
r = nullptr;
if ((*h->h_general_intf)(h, k, nullptr, &r))
{
return nullptr;
}
if (r != nullptr)
{
return r;
}
}
if (!hassuper(o))
{
return fetch_fail(o, k);
}
if (!o->hasflag(handle::HAS_PRIV_MAP))
{
return null;
}
return ici_fetch_base(h->o_super, k);
}
/*
* Assign a value into a key of object o, but ignore the super chain.
* That is, always assign into the lowest level. Usual error coventions.
*/
int handle_type::assign_base(object *o, object *k, object *v)
{
handle *h;
object *r;
h = handleof(o);
if (h->h_member_map != nullptr && !o->hasflag(handle::CLOSED))
{
object *id;
if ((id = ici_fetch(h->h_member_map, k)) == nullptr)
{
return 1;
}
if (isint(id))
{
r = nullptr;
if ((*h->h_member_intf)(h->h_ptr, intof(id)->i_value, v, &r))
{
return 1;
}
if (r != nullptr)
{
return 0;
}
}
}
if (h->h_general_intf != nullptr)
{
r = nullptr;
if ((*h->h_general_intf)(h, k, v, &r))
{
return 1;
}
if (r != nullptr)
{
return 0;
}
}
if (!hassuper(o))
{
return assign_fail(o, k, v);
}
if (!o->hasflag(handle::HAS_PRIV_MAP))
{
objwsup *s;
/*
* We don't yet have a private struct to hold our values.
* Give ourselves one.
*
* This operation disturbs the struct-lookup lookaside mechanism.
* We invalidate all existing entries by incrementing vsver.
*/
if ((s = objwsupof(new_map())) == nullptr)
{
return 1;
}
s->o_super = objwsupof(o)->o_super;
objwsupof(o)->o_super = s;
++vsver;
o->set(handle::HAS_PRIV_MAP);
}
return ici_assign_base(objwsupof(o)->o_super, k, v);
}
/*
* Assign to key k of the object o the value v. Return 1 on error, else 0.
* See the comment on t_assign() in object.h.
*/
int handle_type::assign(object *o, object *k, object *v)
{
handle *h;
object *r;
h = handleof(o);
r = nullptr;
if (h->h_member_map != nullptr && !o->hasflag(handle::CLOSED))
{
object *id;
if ((id = ici_fetch(h->h_member_map, k)) == nullptr)
{
return 1;
}
if (isint(id))
{
if ((*h->h_member_intf)(h->h_ptr, intof(id)->i_value, v, &r))
{
return 1;
}
if (r != nullptr)
{
return 0;
}
}
}
if (h->h_general_intf != nullptr)
{
r = nullptr;
if ((*h->h_general_intf)(h, k, v, &r))
{
return 1;
}
if (r != nullptr)
{
return 0;
}
}
if (!hassuper(o))
{
return assign_fail(o, k, v);
}
if (o->hasflag(handle::HAS_PRIV_MAP))
{
return ici_assign(h->o_super, k, v);
}
/*
* We don't have a base struct of our own yet. Try the super.
*/
if (handleof(o)->o_super != nullptr)
{
switch (ici_assign_super(h->o_super, k, v, nullptr))
{
case -1:
return 1;
case 1:
return 0;
}
}
/*
* We failed to assign the value to a super, and we haven't yet got
* a private struct. Assign it to the base. This will create our
* private struct.
*/
return assign_base(o, k, v);
}
/*
* Do an assignment where we are the super of some other object that
* is trying to satisfy an assign. Don't regard the item k as being
* present unless it really is. Return -1 on error, 0 if not found
* and 1 if the assignment was completed.
*
* If 0 is returned, nothing has been modified during the
* operation of this function.
*
* If not nullptr, b is a struct that was the base element of this
* assignment. This is used to mantain the lookup lookaside mechanism.
*/
int handle_type::assign_super(object *o, object *k, object *v, map *b)
{
if (!hassuper(o))
{
return assign_fail(o, k, v);
}
if (handleof(o)->o_super == nullptr)
{
return 0;
}
return ici_assign_super(handleof(o)->o_super, k, v, b);
}
/*
* Free this object and associated memory (but not other objects).
* See the comments on t_free() in object.h.
*/
void handle_type::free(object *o)
{
if (handleof(o)->h_pre_free != nullptr)
{
(*handleof(o)->h_pre_free)(handleof(o));
}
ici_tfree(o, handle);
}
} // namespace ici