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

   1 /* Licensed under LGPLv3+ - see LICENSE file for details */
   2 #ifndef CCAN_FOREACH_H
   3 #define CCAN_FOREACH_H
   4 #include "config.h"
   5 #include <stddef.h>
   6 #include <assert.h>
   7 #include <stdbool.h>
   8
   9 #if HAVE_COMPOUND_LITERALS
  10 #if HAVE_FOR_LOOP_DECLARATION
  11 /**
  12  * foreach_int - iterate over a fixed series of integers
  13  * @i: the int-compatible iteration variable
  14  * ...: one or more integer-compatible values
  15  *
  16  * This is a convenient wrapper function for setting a variable to one or
  17  * more explicit values in turn.  continue and break work as expected.
  18  *
  19  * Example:
  20  *      int i;
  21  *      foreach_int(i, 0, -1, 100, 0, -99) {
  22  *              printf("i is %i\n", i);
  23  *      }
  24  */
  25 #define foreach_int(i, ...)                                             \
  26         for (unsigned _foreach_i = (((i) = ((int[]) { __VA_ARGS__ })[0]), 0); \
  27              _foreach_i < sizeof((int[]) { __VA_ARGS__ })/sizeof(int);  \
  28              (i) = ((int[]) { __VA_ARGS__, 0 })[++_foreach_i])
  29
  30 /**
  31  * foreach_ptr - iterate over a non-NULL series of pointers
  32  * @i: the pointer iteration variable
  33  * ...: one or more compatible pointer values
  34  *
  35  * This is a convenient wrapper function for setting a variable to one
  36  * or more explicit values in turn.  None of the values can be NULL;
  37  * that is the termination condition (ie. @i will be NULL on
  38  * completion).  continue and break work as expected.
  39  *
  40  * Example:
  41  *      const char *p;
  42  *      foreach_ptr(p, "Hello", "world") {
  43  *              printf("p is %s\n", p);
  44  *      }
  45  */
  46 #define foreach_ptr(i, ...)                                     \
  47         for (unsigned _foreach_i                                \
  48              = (((i) = (void *)((FOREACH_TYPEOF(i)[]){ __VA_ARGS__ })[0]), 0); \
  49              (i);                                                       \
  50              (i) = (void *)((FOREACH_TYPEOF(i)[])                       \
  51                      { __VA_ARGS__, NULL})[++_foreach_i],               \
  52                 _foreach_no_nullval(_foreach_i, i,                      \
  53                                     ((const void *[]){ __VA_ARGS__})))
  54 #else /* !HAVE_FOR_LOOP_DECLARATION */
  55 /* GCC in C89 mode still has compound literals, but no for-declarations */
  56 #define foreach_int(i, ...)                                             \
  57         for ((i) = ((int[]){ __VA_ARGS__ })[0], _foreach_iter_init(&(i)); \
  58              _foreach_iter(&(i)) < sizeof((int[]) { __VA_ARGS__ })      \
  59                            / sizeof(int);                               \
  60              (i) = (int[]) { __VA_ARGS__, 0 }[_foreach_iter_inc(&(i))])
  61
  62 #define foreach_ptr(i, ...)                                             \
  63         for ((i) = (void *)((FOREACH_TYPEOF(i)[]){ __VA_ARGS__ })[0],   \
  64                      _foreach_iter_init(&(i));                          \
  65              (i);                                                       \
  66              (i) = (void *)((FOREACH_TYPEOF(i)[]){ __VA_ARGS__, NULL }) \
  67                      [_foreach_iter_inc(&(i))],                         \
  68                  _foreach_no_nullval(_foreach_iter(&(i)), i,            \
  69                                      ((const void *[]){ __VA_ARGS__})))
  70
  71 void _foreach_iter_init(const void *i);
  72 unsigned int _foreach_iter(const void *i);
  73 unsigned int _foreach_iter_inc(const void *i);
  74
  75 #endif /* !HAVE_FOR_LOOP_DECLARATION */
  76
  77 /* Make sure they don't put NULL values into array! */
  78 #define _foreach_no_nullval(i, p, arr)                          \
  79         assert((i) >= sizeof(arr)/sizeof(arr[0]) || (p))
  80
  81 #if HAVE_TYPEOF
  82 #define FOREACH_TYPEOF(i) __typeof__(i)
  83 #else
  84 #define FOREACH_TYPEOF(i) const void *
  85 #endif
  86
  87 #else /* !HAVE_COMPOUND_LITERALS */
  88
  89 /* No compound literals, but it's still (just) possible. */
  90 #define foreach_int(i, ...)                                             \
  91         for (i = _foreach_intval_init(&(i), __VA_ARGS__, _foreach_term); \
  92              !_foreach_intval_done(&i);                                 \
  93              i = _foreach_intval_next(&(i), __VA_ARGS__, _foreach_term))
  94
  95 #define foreach_ptr(i, ...)                                             \
  96         for (i = _foreach_ptrval_init(&(i), __VA_ARGS__, NULL);         \
  97              (i);                                                       \
  98              i = _foreach_ptrval_next(&(i), __VA_ARGS__, NULL))
  99
 100 extern int _foreach_term;
 101 int _foreach_intval_init(const void *i, int val, ...);
 102 bool _foreach_intval_done(const void *i);
 103 int _foreach_intval_next(const void *i, int val, ...);
 104 void *_foreach_ptrval_init(const void *i, const void *val, ...);
 105 void *_foreach_ptrval_next(const void *i, const void *val, ...);
 106 #endif /* !HAVE_COMPOUND_LITERALS */
 107
 108 #endif /* CCAN_FOREACH_H */