Cdt - container data types
#include <cdt.h>
Dt_t;
Dtdisc_t;
Dtmethod_t;
Dtlink_t;
Dtstat_t;
Dt_t* dtopen(const Dtdisc_t* disc, const Dtmethod_t* meth);
int dtclose(Dt_t* dt);
void dtclear(dt);
Dtmethod_t* dtmethod(Dt_t* dt, const Dtmethod_t* meth);
Dtdisc_t* dtdisc(Dt_t* dt, const Dtdisc_t* disc, int type);
Dt_t* dtview(Dt_t* dt, Dt_t* view);
Dtmethod_t* Dtset;
Dtmethod_t* Dtbag;
Dtmethod_t* Dtoset;
Dtmethod_t* Dtobag;
Dtmethod_t* Dtlist;
Dtmethod_t* Dtstack;
Dtmethod_t* Dtqueue;
Dtmethod_t* Dtdeque;
#define DTOFFSET(struct_s,member)
#define DTDISC(disc,key,size,link,makef,freef,comparf,hashf,memoryf,eventf)
typedef void* (*Dtmake_f)(Dt_t*, void*, Dtdisc_t*);
typedef void (*Dtfree_f)(Dt_t*, void*, Dtdisc_t*);
typedef int (*Dtcompar_f)(Dt_t*, void*, void*, Dtdisc_t*);
typedef unsigned int (*Dthash_f)(Dt_t*, void*, Dtdisc_t*);
typedef void* (*Dtmemory_f)(Dt_t*, void*, size_t, Dtdisc_t*);
typedef int (*Dtevent_f)(Dt_t*, int, void*, Dtdisc_t*);
void* dtinsert(Dt_t* dt, void* obj);
void* dtappend(Dt_t* dt, void* obj);
void* dtdelete(Dt_t* dt, void* obj);
void* dtattach(Dt_t* dt, void* obj);
void* dtdetach(Dt_t* dt, void* obj);
void* dtsearch(Dt_t* dt, void* obj);
void* dtmatch(Dt_t* dt, void* key);
void* dtfirst(Dt_t* dt);
void* dtnext(Dt_t* dt, void* obj);
void* dtlast(Dt_t* dt);
void* dtprev(Dt_t* dt, void* obj);
void* dtfinger(Dt_t* dt);
void* dtrenew(Dt_t* dt, void* obj);
int dtwalk(Dt_t* dt, int (*userf)(Dt_t*, void*, void*), void*);
Dtlink_t* dtflatten(Dt_t* dt);
Dtlink_t* dtlink(Dt_t*, Dtlink_t* link);
void* dtobj(Dt_t* dt, Dtlink_t* link);
Dtlink_t* dtextract(Dt_t* dt);
int dtrestore(Dt_t* dt, Dtlink_t* link);
#define DTTREESEARCH(Dt_t* dt, void* obj, action)
#define DTTREEMATCH(Dt_t* dt, void* key, action)
Dt_t* dtvnext(Dt_t* dt);
int dtvcount(Dt_t* dt);
Dt_t* dtvhere(Dt_t* dt);
int dtsize(Dt_t* dt);
int dtstat(Dt_t* dt, Dtstat_t*, int all);
unsigned int dtstrhash(unsigned int h, char* str, int n);
unsigned int dtcharhash(unsigned int h, unsigned char c);
Cdt manages run-time dictionaries using standard container data types:
unordered set/multiset, ordered set/multiset, list, stack, and queue.
This is the type of a dictionary handle.
This defines the type of a discipline structure which describes object lay-out
and manipulation functions.
This defines the type of a container method.
This is the type of a dictionary object holder (see dtdisc().)
This is the type of a structure to return dictionary statistics (see dtstat().)
This creates a new dictionary. disc is a discipline structure to describe object
format. meth specifies a manipulation method. dtopen() returns the new
dictionary or NULL on error. See also the events DT_OPEN and DT_ENDOPEN below.
This deletes dt and its objects. Note that dtclose() fails if dt is being viewed
by some other dictionaries (see dtview()). dtclose() returns 0 on success and
-1 on error. See also the events DT_CLOSE and DT_ENDCLOSE below.
This deletes all objects in dt without closing dt.
If meth is NULL, dtmethod() returns the current method. Otherwise, it changes
the storage method of dt to meth. Object order remains the same during a
method switch among Dtlist, Dtstack, Dtqueue and Dtdeque. Switching to and
from Dtset/Dtbag and Dtoset/Dtobag may cause objects to be rehashed,
reordered, or removed as the case requires. dtmethod() returns the previous
method or NULL on error.
If disc is NULL, dtdisc() returns the current discipline. Otherwise, it changes
the discipline of dt to disc. Objects may be rehashed, reordered, or removed
as appropriate. type can be any bit combination of DT_SAMECMP and DT_SAMEHASH.
DT_SAMECMP means that objects will compare exactly the same as before thus
obviating the need for reordering or removing new duplicates. DT_SAMEHASH
means that hash values of objects remain the same thus obviating the need to
rehash. dtdisc() returns the previous discipline on success and NULL on error.
A viewpath allows a search or walk starting from a dictionary to continue to
another. dtview() first terminates any current view from dt to another
dictionary. Then, if view is NULL, dtview returns the terminated view
dictionary. If view is not NULL, a viewpath from dt to view is established.
dtview() returns dt on success and NULL on error.
It is an error to have dictionaries on a viewpath with different storage
methods. In addition, dictionaries on the same view path should treat objects
in a consistent manner with respect to comparison or hashing. If not,
undefined behaviors may result.
Storage methods are of type Dtmethod_t*.
Cdt supports the following
methods:
Objects are ordered by comparisons. Dtoset keeps unique objects. Dtobag allows
repeatable objects.
Objects are unordered. Dtset keeps unique objects. Dtbag allows repeatable
objects and always keeps them together (note the effect on dictionary
walking.) These methods use a hash table with chaining to manage the objects.
See also the event DT_HASHSIZE below on how to manage hash table resizing when
objects are inserted.
Objects are kept in a list. The call dtinsert() inserts a new object in front of
the current object (see dtfinger()) if it is defined or at list front
if no current object is defined. Similarly, the call dtappend() appends a new
object after
the current object (see dtfinger()) if it is defined or at
list end if no current object is defined.
Objects are kept in a deque. This is similar to Dtlist except that objects are
always inserted at the front and appended at the tail of the list.
Objects are kept in a stack, i.e., in reverse order of insertion. Thus, the last
object inserted is at stack top and will be the first to be deleted.
Objects are kept in a queue, i.e., in order of insertion. Thus, the first object
inserted is at queue head and will be the first to be deleted.
Object format and associated management functions are defined in the type
Dtdisc_t:
typedef struct
{ int key, size;
int link;
Dtmake_f makef;
Dtfree_f freef;
Dtcompar_f comparf;
Dthash_f hashf;
Dtmemory_f memoryf;
Dtevent_f eventf;
} Dtdisc_t;
Each object obj is identified by a key used for object comparison or hashing.
key should be non-negative and defines an offset into obj. If size is
negative, the key is a null-terminated string with starting address
*(void**)((char*)obj+key). If size is zero, the key is a null-terminated
string with starting address (void*)((char*)obj+key). Finally, if size is
positive, the key is a byte array of length size starting at
(void*)((char*)obj+key).
Let obj be an object to be inserted into dt as discussed below. If link is
negative, an internally allocated object holder is used to hold obj.
Otherwise, obj should have a Dtlink_t structure embedded link bytes into it,
i.e., at address (Dtlink_t*)((char*)obj+link).
If makef is not NULL, dtinsert(dt,obj) or dtappend() will call it to make a copy
of obj suitable for insertion into dt. If makef is NULL, obj itself will be
inserted into dt.
If not NULL, freef is used to destroy data associated with obj.
If not NULL, comparf is used to compare two keys. Its return value should be
<0, =0, or >0 to indicate whether key1 is smaller, equal to, or larger
than key2. All three values are significant for method Dtoset and Dtobag. For
other methods, a zero value indicates equality and a non-zero value indicates
inequality. If (*comparf)() is NULL, an internal function is used to compare
the keys as defined by the Dtdisc_t.size field.
If not NULL, hashf is used to compute the hash value of key. It is required that
keys compared equal will also have same hash values. If hashf is NULL, an
internal function is used to hash the key as defined by the Dtdisc_t.size
field.
If not NULL, memoryf is used to allocate and free memory. When addr is NULL, a
memory segment of size size is requested. If addr is not NULL and size is
zero, addr is to be freed. If addr is not NULL and size is positive, addr is
to be resized to the given size. If memoryf is NULL,
malloc(3) is used.
If not NULL, eventf announces various events. Each event may have particular
handling of the return values from eventf. But a negative return value
typically means failure. Following are the events:
- DT_OPEN:
- dt is being opened. If eventf returns negative, the opening
process terminates with failure. If eventf returns zero, the opening
process proceeds in a default manner. A positive return value indicates
special treatment of memory as follows. If *(void**)data is set to point
to some memory segment as discussed in memoryf, that segment of memory is
used to start the dictionary. If *(void**)data is NULL, all memory
including that of the dictionary handle itself will be allocated via
memoryf.
- DT_ENDOPEN:
- This event announces that dtopen() has successfully opened
a dictionary and is about to return. The data argument of eventf should be
the new dictionary handle itself.
- DT_CLOSE:
- dt is about to be closed. If eventf returns negative, the
closing process stops immediately and dtclose() returns -1. Objects in the
dictionary are deleted only if eventf returns zero. The dictionary handle
itself is processed as follows. If it was allocated via malloc(), it will
be freed. If it was allocated via memoryf (see dtopen()) and eventf
returns 0, a call to memoryf will be issued to attempt freeing the handle.
Otherwise, nothing will be done to its memory.
As should be clear from their description, the events DT_OPEN and DT_CLOSE
are designed to be used along with memoryf to manage the allocation and
deallocation of dictionary and object memory across dictionaries. In fact,
they can be used to manage dictionaries based on shared and/or persistent
memory.
- DT_ENDCLOSE:
- This event announces that dtclose() has successfully closed
a dictionary and is about to return.
- DT_DISC:
- The discipline of dt is being changed to a new one given in
(Dtdisc_t*)data.
- DT_METH:
- The method of dt is being changed to a new one given in
(Dtmethod_t*)data.
- DT_HASHSIZE:
- The hash table (for Dtset and Dtbag) is being resized. In
this case, *(int*)data has the current size of the table. The application
can set the new table size by first changing *(int*)data to the desired
size, then return a positive value. The application can also fix the table
size at the current value forever by setting *(int*)data to a negative
value, then again return a positive value. A non-positive return value
from the event handling function means that Cdt will be responsible for
choosing the hash table size.
This macro function computes the offset of member from the start of structure
struct_s. It is useful for getting the offset of a Dtlink_t embedded inside an
object.
This macro function initializes the discipline pointed to by disc with the given
values.
These functions add an object prototyped by obj into dt. dtinsert() and
dtappend() perform the same function for all methods except for Dtlist. See
Dtlist for details. If there is an existing object in dt matching obj and the
storage method is Dtset or Dtoset, dtinsert() and dtappend() will simply
return the matching object. Otherwise, a new object is inserted according to
the method in use. See Dtdisc_t.makef for object construction. The new object
or a matching object as noted will be returned on success while NULL is
returned on error.
If obj is NULL, methods Dtstack and Dtqueue delete respectively stack top or
queue head while other methods do nothing. If obj is not NULL, there are two
cases. If the method in use is not Dtbag or Dtobag, the first object matching
obj is deleted. On the other hand, if the method in use is Dtbag or Dtobag,
the library check to see if obj is in the dictionary and delete it. If obj is
not in the dictionary, some object matching it will be deleted. See
Dtdisc_t.freef for object destruction. dtdelete() returns the deleted object
(even if it was deallocated) or NULL on error.
This function is similar to dtinsert() but obj itself will be inserted into dt
even if a discipline function makef is defined.
This function is similar to dtdelete() but the object to be deleted from dt will
not be freed (via the discipline freef function).
These functions find an object matching obj or key either from dt or from some
dictionary accessible from dt via a viewpath (see dtview().) dtsearch() and
dtmatch() return the matching object or NULL on failure.
dtfirst() returns the first object in dt. dtnext() returns the object following
obj. Objects are ordered based on the storage method in use. For Dtoset and
Dtobag, objects are ordered by object comparisons. For Dtstack, objects are
ordered in reverse order of insertion. For Dtqueue, objects are ordered in
order of insertion. For Dtlist, objects are ordered by list position. For
Dtset and Dtbag, objects are ordered by some internal order (more below).
Thus, objects in a dictionary or a viewpath can be walked using a for(;;) loop
as below.
for(obj = dtfirst(dt); obj; obj = dtnext(dt,obj))
When a dictionary uses Dtset or Dtbag, the object order is determined upon a
call to dtfirst()/dtlast(). This order is frozen until a call
dtnext()/dtprev() returns NULL or when these same functions are called with a
NULL object argument. It is important that a dtfirst()/dtlast() call be
balanced by a dtnext()/dtprev() call as described. Nested loops will require
multiple balancing, once per loop. If loop balancing is not done carefully,
either performance is degraded or unexpected behaviors may result.
dtlast() and dtprev() are like dtfirst() and dtnext() but work in reverse order.
Note that dictionaries on a viewpath are still walked in order but objects in
each dictionary are walked in reverse order.
This function returns the
current object of dt, if any. The current
object is defined after a successful call to one of dtsearch(), dtmatch(),
dtinsert(), dtfirst(), dtnext(), dtlast(), or dtprev(). As a side effect of
this implementation of
Cdt, when a dictionary is based on Dtoset and
Dtobag, the current object is always defined and is the root of the tree.
This function repositions and perhaps rehashes an object obj after its key has
been changed. dtrenew() only works if obj is the current object (see
dtfinger()).
This function calls (*userf)(walk,obj,data) on each object in dt and other
dictionaries viewable from it. walk is the dictionary containing obj. If
userf() returns a <0 value, dtwalk() terminates and returns the same value.
dtwalk() returns 0 on completion.
Using dtfirst()/dtnext() or dtlast()/dtprev() to walk a single dictionary can
incur significant cost due to function calls. For efficient walking of a
single directory (i.e., no viewpathing), dtflatten() and dtlink() can be used.
Objects in dt are made into a linked list and walked as follows:
for(link = dtflatten(dt); link; link = dtlink(dt,link) )
Note that dtflatten() returns a list of type Dtlink_t*, not void*. That is, it
returns a dictionary holder pointer, not a user object pointer (although both
are the same if the discipline field link is zero.) The macro function
dtlink() returns the dictionary holder object following link. The macro
function dtobj(dt,link) returns the user object associated with link, Beware
that the flattened object list is unflattened on any dictionary operations
other than dtlink().
dtextract() extracts all objects from dt and makes it appear empty. dtrestore()
repopulates dt with objects previously obtained via dtextract(). dtrestore()
will fail if dt is not empty. These functions can be used to share a same dt
handle among many sets of objects. They are useful to reduce dictionary
overhead in an application that creates many concurrent dictionaries. It is
important that the same discipline and method are in use at both extraction
and restoration. Otherwise, undefined behaviors may result.
These macro functions are analogues of dtsearch() and dtmatch() but they can
only be used on a dictionary based on a binary search tree, i.e., Dtoset or
Dtobag.
- obj or key:
- These are used to find a matching object. If there is no
match, the result is NULL.
- action:
- The matching object o (which may be NULL) will be processed
as follow:
action (o);
Since action is used verbatim, it can be any C code fragment combinable with
(o) to form a syntactically correct C statement. For example, suppose that
the matching object is an integer, the below code accumulates the integer
value in a variable total:
DTTREEMATCH(dt, key, total += (int));
This returns the dictionary that dt is viewing, if any.
This returns the number of dictionaries that view dt.
This returns the dictionary v viewable from dt where an object was found from
the most recent search or walk operation.
This function returns the number of objects stored in dt.
This function reports dictionary statistics. If all is non-zero, all fields of
st are filled. Otherwise, only the dt_type and dt_size fields are filled. It
returns 0 on success and -1 on error.
Dtstat_t contains the below fields:
- int dt_type:
- This is one of DT_SET, DT_BAG, DT_OSET, DT_OBAG, DT_LIST,
DT_STACK, and DT_QUEUE.
- int dt_size:
- This contains the number of objects in the dictionary.
- int dt_n:
- For Dtset and Dtbag, this is the number of non-empty chains
in the hash table. For Dtoset and Dtobag, this is the deepest level in the
tree (counting from zero.) Each level in the tree contains all nodes of
equal distance from the root node. dt_n and the below two fields are
undefined for other methods.
- int dt_max:
- For Dtbag and Dtset, this is the size of a largest chain.
For Dtoset and Dtobag, this is the size of a largest level.
- int* dt_count:
- For Dtset and Dtbag, this is the list of counts for chains
of particular sizes. For example, dt_count[1] is the number of chains of
size 1. For Dtoset and Dtobag, this is the list of sizes of the levels.
For example, dt_count[1] is the size of level 1.
These functions compute hash values from bytes or strings. dtcharhash() computes
a new hash value from byte c and seed value h. dtstrhash() computes a new hash
value from string str and seed value h. If n is positive, str is a byte array
of length n; otherwise, str is a null-terminated string.
Dtset and Dtbag are based on hash tables with move-to-front collision chains.
Dtoset and Dtobag are based on top-down splay trees. Dtlist, Dtstack and
Dtqueue are based on doubly linked list.
Kiem-Phong Vo,
[email protected]