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Sample generic containers with macros

I am trying to create a type-related generic list of links in C using macros. It should work similarly to how templates work in C ++. For instance,

LIST(int) *list = LIST_CREATE(int);

My first attempt was to #define LIST(TYPE)(the macro I used above) to determine struct _List_##TYPE {...}. This, however, did not work, because the structure would be redefined every time I declare a new list. I fixed the problem by following these steps:

/* You would first have to use this macro, which will define
   the `struct _List_##TYPE`...                               */
DEFINE_LIST(int);

int main(void)
{
    /* ... And this macro would just be an alias for the struct, it
       wouldn't actually define it.                                  */
    LIST(int) *list = LIST_CREATE(int);
    return 0;
}

/* This is how the macros look like */

#define DEFINE_LIST(TYPE)    \
    struct _List_##TYPE      \
    {                        \
        ...                  \
    }

#define LIST(TYPE)       \
    struct _List_##TYPE

But another problem is that when I have several files that use DEFINE_LIST(int), for example, and some of them include each other, then there will still be several definitions of the same structure. Is there any way to do a DEFINE_LISTcheck to see if a structure has already been defined?

/* one.h */
DEFINE_LIST(int);

/* two.h */
#include "one.h"
DEFINE_LIST(int); /* Error: already defined in one.h */
+5
6

C , ++ , .

-of-T , . "" "" , . , , --T.

, , , @immortal, .h .c T. , , -T , , list_type.inl, list_type.inl - list_float.h list_float.c - -float. -of-int, list-of-list-of-float, list-of-vector-of-list-of-double, .

. .

-. , T = list-of-thingummy list-of-T. , POD . -of-thingummy - , , . , , . , POD.

, -T , T = . , T -POD - , , - . C :

  • : T- , .

  • : T .

-T, -T , , . , .

, set-of-T map-of-T1-to-T2, -T. -POD- T T1, , . , memcmp() .

, -T ; API const.

, , , , . , macro_kit.h, :

#ifndef MACRO_KIT_H
#define MACRO_KIT_H

/* macro_kit.h */

#define _CAT2(x,y) x##y

// Concatenate 2 tokens x and y
#define CAT2(x,y) _CAT2(x,y)
// Concatenate 3 tokens x, y and z
#define CAT3(x,y,z) CAT2(x,CAT2(y,z))

// Join 2 tokens x and y with '_' = x_y
#define JOIN2(x,y) CAT3(x,_,y)
// Join 3 tokens x, y and z with '_' = x_y_z
#define JOIN3(x,y,z) JOIN2(x,JOIN2(y,z))
// Compute the memory footprint of n T's
#define SPAN(n,T)   ((n) * sizeof(T))

#endif

, list_type.inl:

//! There is intentionally no idempotence guard on this file
#include "macro_kit.h"
#include <stddef.h>

#ifndef INCLUDE_LIST_TYPE_INL
#error This file should only be included from headers \
that define INCLUDE_LIST_TYPE_INL
#endif

#ifndef LIST_ELEMENT_TYPE
#error Need a definition for LIST_ELEMENT_TYPE
#endif

/* list_type.inl

    Defines and implements a generic list-of-T container
    for T the current values of the macros:

    - LIST_ELEMENT_TYPE: 
        - must have a definition = the datatype (or typedef alias) for \
        which a list container is required.

    - LIST_ELEMENT_COPY_INITOR:
        - If undefined, then LIST_ELEMENT_TYPE is assumed to be copy-
        initializable by the assignment operator. Otherwise must be defined
        as the name of a copy initialization function having a prototype of
        the form:

        LIST_ELEMENT_TYPE * copy_initor_name(LIST_ELEMENT_TYPE *pdest,
                                            LIST_ELEMENT_TYPE *psrc);

        that will attempt to copy the LIST_ELEMENT_TYPE at `psrc` into the
        uncommitted memory at `pdest`, returning `pdest` on success and NULL
        on failure.

        N.B. This file itself defines the copy initializor for the list-type
        that it generates.

    - LIST_ELEMENT_DISPOSE
        If undefined, then LIST_ELEMENT_TYPE is assumed to need no
        destruction. Otherwise the name of a destructor function having a
        protoype of the form:

        void dtor_name(LIST_ELEMENT_TYPE pt*);

        that appropriately destroys the LIST_ELEMENT_TYPE at `pt`.

        N.B. This file itself defines the destructor for the list-type that
        it generates.
*/

/* Define the names of the list-type to generate, 
    e.g. list_int, list_float
*/
#define LIST_TYPE JOIN2(list,LIST_ELEMENT_TYPE)

/* Define the function-names of the LIST_TYPE API.
    Each of the API macros LIST_XXXX generates a function name in
    which LIST becomes the value of LIST_TYPE and XXXX becomes lowercase,
    e.g list_int_new
*/
#define LIST_NEW JOIN2(LIST_TYPE,new)
#define LIST_NODE JOIN2(LIST_TYPE,node)
#define LIST_DISPOSE JOIN2(LIST_TYPE,dispose)
#define LIST_COPY_INIT JOIN2(LIST_TYPE,copy_init)
#define LIST_COPY JOIN2(LIST_TYPE,copy)
#define LIST_BEGIN JOIN2(LIST_TYPE,begin)
#define LIST_END JOIN2(LIST_TYPE,end)
#define LIST_SIZE JOIN2(LIST_TYPE,size)
#define LIST_INSERT_BEFORE JOIN3(LIST_TYPE,insert,before)
#define LIST_DELETE_BEFORE JOIN3(LIST_TYPE,delete,before)
#define LIST_PUSH_BACK JOIN3(LIST_TYPE,push,back)
#define LIST_PUSH_FRONT JOIN3(LIST_TYPE,push,front)
#define LIST_POP_BACK JOIN3(LIST_TYPE,pop,back)
#define LIST_POP_FRONT JOIN3(LIST_TYPE,pop,front)
#define LIST_NODE_GET JOIN2(LIST_NODE,get)
#define LIST_NODE_NEXT JOIN2(LIST_NODE,next)
#define LIST_NODE_PREV JOIN2(LIST_NODE,prev)

/* Define the name of the structure used to implement a LIST_TYPE.
    This structure is not exposed to user code.
*/
#define LIST_STRUCT JOIN2(LIST_TYPE,struct)

/* Define the name of the structure used to implement a node of a LIST_TYPE.
    This structure is not exposed to user code.
*/
#define LIST_NODE_STRUCT JOIN2(LIST_NODE,struct)

/* The LIST_TYPE API... */


// Define the abstract list type
typedef struct LIST_STRUCT * LIST_TYPE;

// Define the abstract list node type
typedef struct LIST_NODE_STRUCT * LIST_NODE;

/* Return a pointer to the LIST_ELEMENT_TYPE in a LIST_NODE `node`,
    or NULL if `node` is null
*/
extern LIST_ELEMENT_TYPE * LIST_NODE_GET(LIST_NODE node);

/* Return the LIST_NODE successor of a LIST_NODE `node`,
    or NULL if `node` is null.
*/ 
extern LIST_NODE LIST_NODE_NEXT(LIST_NODE node);

/* Return the LIST_NODE predecessor of a LIST_NODE `node`,
    or NULL if `node` is null.
*/
extern LIST_NODE LIST_NODE_PREV(LIST_NODE node);


/* Create a new LIST_TYPE optionally initialized with elements copied from
    `start` and until `end`.

    If `end` is null it is assumed == `start` + 1.

    If `start` is not NULL then elements will be appended to the
    LIST_TYPE until `end` or until an element cannot be successfully copied.
    The size of the LIST_TYPE will be the number of successfully copied
    elements. 
*/ 
extern LIST_TYPE LIST_NEW(LIST_ELEMENT_TYPE *start, LIST_ELEMENT_TYPE *end);

/* Dispose of a LIST_TYPE
    If the pointer to LIST_TYPE `plist` is not null and addresses
    a non-null LIST_TYPE then the LIST_TYPE it addresses is
    destroyed and set NULL.
*/ 
extern void LIST_DISPOSE(LIST_TYPE * plist);

/* Copy the LIST_TYPE at `psrc` into the LIST_TYPE-sized region at `pdest`,
    returning `pdest` on success, else NULL.

    If copying is unsuccessful the LIST_TYPE-sized region at `pdest is
    unchanged.
*/
extern LIST_TYPE * LIST_COPY_INIT(LIST_TYPE *pdest, LIST_TYPE *psrc);

/* Return a copy of the LIST_TYPE `src`, or NULL if `src` cannot be
    successfully copied.
*/
extern LIST_TYPE LIST_COPY(LIST_TYPE src);

/* Return a LIST_NODE referring to the  start of the
    LIST_TYPE `list`, or NULL if `list` is null.
*/
extern LIST_NODE LIST_BEGIN(LIST_TYPE list);

/* Return a LIST_NODE referring to the end of the
    LIST_TYPE `list`, or NULL if `list` is null.
*/
extern LIST_NODE LIST_END(LIST_TYPE list);

/* Return the number of LIST_ELEMENT_TYPEs in the LIST_TYPE `list`
    or 0 if `list` is null.
*/
extern size_t LIST_SIZE(LIST_TYPE list);

/* Etc. etc. - extern prototypes for all API functions.
    ...
    ...
*/

/* If LIST_IMPLEMENT is defined then the implementation of LIST_TYPE is
    compiled, otherwise skipped. #define LIST_IMPLEMENT to include this
    file in the .c file that implements LIST_TYPE. Leave it undefined
    to include this file in the .h file that defines the LIST_TYPE API.
*/
#ifdef LIST_IMPLEMENT
// Implementation code now included.

// Standard library #includes...?

// The heap structure of a list node
struct LIST_NODE_STRUCT {
    struct LIST_NODE_STRUCT * _next;
    struct LIST_NODE_STRUCT * _prev;
    LIST_ELEMENT_TYPE _data[1];
};

// The heap structure of a LIST_TYPE
struct LIST_STRUCT {
    size_t _size;
    struct LIST_NODE_STRUCT * _anchor;
};

/* Etc. etc. - implementations for all API functions
    ...
    ...
*/

/*  Undefine LIST_IMPLEMENT whenever it was defined.
    Should never fall through. 
*/
#undef LIST_IMPLEMENT

#endif // LIST_IMPLEMENT 

/*  Always undefine all the LIST_TYPE parameters.
    Should never fall through. 
*/
#undef LIST_ELEMENT_TYPE
#undef LIST_ELEMENT_COPY_INITOR
#undef LIST_ELEMENT_DISPOSE
/* Also undefine the "I really meant to include this" flag. */

#undef INCLUDE_LIST_TYPE_INL

, list_type.inl - mutliple. , - , API- - , .

, , -.

#ifndef LIST_INT_H
#define LIST_INT_H

/* list_int.h*/

#define LIST_ELEMENT_TYPE int
#define INCLUDE_LIST_TYPE_INL
#include "list_type.inl"

#endif

, -of-int :

#ifndef LIST_LIST_INT_H
#define LIST_LIST_INT_H

/* list_list_int.h*/

#define LIST_ELEMENT_TYPE list_int
#define LIST_ELEMENT_COPY_INIT list_int_copy_init
#define LIST_ELEMENT_DISPOSE list_int_dispose
#define INCLUDE_LIST_TYPE_INL
#include "list_type.inl"

#endif

, .

#include "list_int.h"
#include "list_list_int.h"

, LIST_ELEMENT_TYPE , list_type.inl always #undefs , : . .

LIST_IMPLEMENT. undefined, list_type.inl , API- ; . LIST_IMPLEMENT , . , , LIST_IMPLEMENT, API.

, - list_int.c, list_list_int.c, define LIST_IMPLEMENT. , :

/* list_int.c */
#define LIST_IMPLEMENT
#include "list_int.h"


/* list_list_int.c*/
#include "list_int.h"
#define LIST_IMPLEMENT
#include "list_list_int.h"

. " ":

#include "list_int.h"
#include "list_list_int.h"
// etc.

int main(void)
{
    int idata[10] = {1,2,3,4,5,6,7,8,9,10};
    //...
    list_int lint = list_int_new(idata,idata + 10);
    //...
    list_list_int llint = list_list_int_new(&lint,0);
    //...
    list_int_dispose(&lint);
    //...
    list_list_int_dispose(&llint);
    //...
    exit(0);
}

" C", , (!) , .inl , . , , .h .c jiffy .

, ++ , . , , - C .

+8

DEFINE_LIST, "" . :

#define DEFINE_LIST(TYPE, NAME)          \
struct _List_##TYPE_##NAME               \
{                                        \
    TYPE member_1;                       \
    struct _List_##TYPE_##NAME* next;    \
}

:

DEFINE_LIST(int, my_list);
//... more code that uses the "my_list" type

, , , DEFINE_LIST. LIST_CREATE ..

"" , "" . , struct , "name" , . , , , int:

#define GENERIC_LIST_PTR(TYPE) struct _generic_list_type_##TYPE*
#define LIST_CAST_PTR(OBJ, TYPE) (GENERIC_LIST_PTR(TYPE))(OBJ)

void function(GENERIC_LIST_PTR(INT) list)
{
    //...use list as normal (i.e., access it int data-member, etc.)
}

DEFINE_LIST(int, my_list);

int main()
{
    LIST(int, my_list)* list = LIST_CREATE(int, my_list);
    function(LIST_CAST_PTR(list, int));

    //...more code

    return 0;
}

, , , , struct _generic_list_type_XXX - , ( )... .

+1

? GLib, void , , GLib. :

http://pastebin.com/Pc0KsadV

Symbol * (, , ), :

GLIST_INSTANCE(SymbolList, Symbol*, symbol_list);

( ) , , void * .

0

list_template.h, list_TYPE.h list_TYPE.c . , . , .c , .

, ++ ... ...

0

, () . #ifndef DEFINE_LIST(int). , , .

0

. (), , , , - . , , , - . !

, . , , . struct , , . - . C __LINE__ concatenation/stringification ANSI C (C89/C90).

. , , . . , . , , . , __typeof__(), .

OpenGC3, , , :

ccxll(int) list;                      //  declare a list of type int
ccxll_init(list);                     //  initialize the list record

for (int cnt = 8; cnt-- > 0; )        //
    ccxll_push_back(list, rand());    //  insert "rand()" to the end

ccxll_sort(list);                     //  sort with comparator: XLEQ

CCXLL_INCR_AUTO(pnum, list)           //  traverse the list forward:
    printf("num = %d\n", *pnum);      //  access elems through iters

ccxll_free(list);                     //  destroy the list after use

This is very similar to the STL syntax. The type of list is determined upon declaration list. We do not need to worry about type safety, because there is no unsafe type in the list when performing operations.

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