git.ozlabs.org Git - ccan/blob - ccan/foreach/foreach.h

   1 #ifndef CCAN_FOREACH_H
   2 #define CCAN_FOREACH_H
   3 #include "config.h"
   4 #include <stddef.h>
   5 #include <assert.h>
   6 #include <stdbool.h>
   7
   8 #if HAVE_COMPOUND_LITERALS
   9 #if HAVE_FOR_LOOP_DECLARATION
  10 /**
  11  * foreach_int - iterate over a fixed series of integers
  12  * @i: the int-compatible iteration variable
  13  * @val: one or more integer-compatible values
  14  *
  15  * This is a convenient wrapper function for setting a variable to one or
  16  * more explicit values in turn.  continue and break work as expected.
  17  *
  18  * Example:
  19  *      int i;
  20  *      foreach_int(i, 0, -1, 100, 0, -99) {
  21  *              printf("i is %i\n", i);
  22  *      }
  23  */
  24 #define foreach_int(i, val, ...)                                        \
  25         for (unsigned _foreach_i = ((i) = val, 0);                      \
  26              _foreach_i < sizeof((int[]) { val, __VA_ARGS__ })/sizeof(val); \
  27              (i) = (int[]) { val, __VA_ARGS__, 0 }[++_foreach_i])
  28
  29 /**
  30  * foreach_ptr - iterate over a non-NULL series of pointers
  31  * @i: the pointer iteration variable
  32  * @val: one or more compatible pointer values
  33  *
  34  * This is a convenient wrapper function for setting a variable to one
  35  * or more explicit values in turn.  None of the values can be NULL;
  36  * that is the termination condition (ie. @i will be NULL on
  37  * completion).  continue and break work as expected.
  38  *
  39  * Example:
  40  *      const char *p;
  41  *      foreach_ptr(p, "Hello", "world") {
  42  *              printf("p is %s\n", p);
  43  *      }
  44  */
  45 #define foreach_ptr(i, val, ...)                                        \
  46         for (unsigned _foreach_i = (unsigned long)((i) = (val), 0);     \
  47              (i);                                                       \
  48              (i) = ((FOREACH_TYPEOF(val)[]){(val), __VA_ARGS__, NULL})  \
  49                      [++_foreach_i])                                    \
  50                 _foreach_no_nullval(_foreach_i, i,                      \
  51                                     ((void *[]){ val, __VA_ARGS__})))
  52 #else /* !HAVE_FOR_LOOP_DECLARATION */
  53 /* GCC in C89 mode still has compound literals, but no for-declarations */
  54 #define foreach_int(i, val, ...)                                        \
  55         for ((i) = (val), _foreach_iter_init(&(i));                     \
  56              _foreach_iter(&(i)) < sizeof((int[]) { (val), __VA_ARGS__ }) \
  57                            / sizeof(int);                               \
  58              (i) = (int[]) { (val), __VA_ARGS__, 0 }[_foreach_iter_inc(&(i))])
  59
  60 #define foreach_ptr(i, val, ...)                                        \
  61         for ((i) = (val), _foreach_iter_init(&(i));                     \
  62              (i);                                                       \
  63              (i) = ((FOREACH_TYPEOF(val)[]){ (val), __VA_ARGS__, 0 })   \
  64                      [_foreach_iter_inc(&(i))],                         \
  65                  _foreach_no_nullval(_foreach_iter(&(i)), i,            \
  66                                      ((void *[]){ val, __VA_ARGS__})))
  67
  68 void _foreach_iter_init(const void *i);
  69 unsigned int _foreach_iter(const void *i);
  70 unsigned int _foreach_iter_inc(const void *i);
  71
  72 #endif /* !HAVE_FOR_LOOP_DECLARATION */
  73
  74 /* Make sure they don't put NULL values into array! */
  75 #define _foreach_no_nullval(i, p, arr)                          \
  76         assert((i) >= sizeof(arr)/sizeof(arr[0]) || (p))
  77
  78 #if HAVE_TYPEOF
  79 #define FOREACH_TYPEOF(val) __typeof__(&*(val))
  80 #else
  81 #define FOREACH_TYPEOF(val) void *
  82 #endif
  83
  84 #else /* !HAVE_COMPOUND_LITERALS */
  85
  86 /* No compound literals, but it's still (just) possible. */
  87 #define foreach_int(i, val, ...)                                        \
  88         for (i = _foreach_intval_init(&(i), val, __VA_ARGS__,   \
  89                                           _foreach_term);               \
  90              !_foreach_intval_done(&i);                         \
  91              i = _foreach_intval_next(&(i), val, __VA_ARGS__,   \
  92                                           _foreach_term))
  93
  94 #define foreach_ptr(i, val, ...)                                        \
  95         for (i = _foreach_ptrval_init(&(i), val, __VA_ARGS__, NULL);    \
  96              (i);                                                       \
  97              i = _foreach_ptrval_next(&(i), val, __VA_ARGS__, NULL))
  98
  99 extern int _foreach_term;
 100 int _foreach_intval_init(const void *i, int val, ...);
 101 bool _foreach_intval_done(const void *i);
 102 int _foreach_intval_next(const void *i, int val, ...);
 103 void *_foreach_ptrval_init(const void *i, const void *val, ...);
 104 void *_foreach_ptrval_next(const void *i, const void *val, ...);
 105 #endif /* !HAVE_COMPOUND_LITERALS */
 106
 107 #endif /* CCAN_FOREACH_H */