wrapper.h

Go to the documentation of this file.

 
#include "common.h"
#include "debug.h"
 
#ifdef ONLY_FOR_DOXYGEN
#include "node.h"
#endif //ONLY_FOR_DOXYGEN
 
 
#ifndef RBT_WRAPPER_H_PREFIX_
#error RBT_WRAPPER_H_PREFIX_ is not defined.
#endif // RBT_WRAPPER_H_PREFIX_
 
#ifndef RBT_KEY_T
#error RBT_KEY_T is not defined.
#endif // RBT_KEY_T
 
#ifndef RBT_KEY_COUNT_BITS
#error RBT_KEY_COUNT_BITS is not defined.
#endif // RBT_KEY_COUNT_BITS
 
#ifndef RBT_KEY_PTR
#error RBT_KEY_PTR is not defined.
#endif // RBT_KEY_PTR
 
#ifndef RBT_KEY_FPRINT
#error RBT_KEY_FPRINT is not defined.
#endif // RBT_KEY_FPRINT
 
typedef RBT_KEY_T RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, key_t);
 
#undef RBT_NODE_QUERY_WRAPPER
#define RBT_NODE_QUERY_WRAPPER RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, node_query_wrapper)
 
#undef RBT_DELETE
#define RBT_DELETE   RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, delete)
 
#undef RBT_HAS_KEY
#define RBT_HAS_KEY  RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, has_key)
 
#undef RBT_INSERT
#define RBT_INSERT   RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, insert)
 
#undef RBT_RETRIEVE
#define RBT_RETRIEVE RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, retrieve)
 
#undef RBT_SWAP
#define RBT_SWAP     RBT_TOKEN_2_W(RBT_WRAPPER_H_PREFIX_, swap)
 
/*
  When a given key type is cast into the internal key type, care must be taken
  to prevent reads past the boundary of allocated memory. This is best
  illustrated with an example, however contrived.
 
  If the user chooses an internal key type that uses arrays of `unsigned int`s
  (either by explicit choice or by using e.g. uint_fast8_t on some platform),
  but then chooses a key type of "char", then the following situation would
  arise, where "x" represents an allocated byte and "." an unallocated byte, and
  `int`s are 32 bits:
 
      key:          x...
      internal key: xxxx
 
  Even if the various functions will only ever compare the first 8 bits, casting
  the key to an internal key will dereference 3 unallocated bytes. The behavior
  is undefined. If there were a guarantee that it would never segfault then it
  would not be a problem, because the value of those bits will never be directly
  accessed.
 
  Unfortunately, segfaults may occur, so the best solution is to allocate memory
  and copy over the allocated bytes from the key. The rest of the bytes can be
  left uninitialized as they have no effect.
 
  Of course, if the internal key is an array of single-byte elements then this
  is never a concern, nor is it a concern if the two types share a common factor
  greater than 1, as a cast will not run past the bountary in that case.
*/
 
#undef RBT_PINS_FIXED
#undef RBT_PINS_FIXED
#define RBT_PINS_FIXED ((RBT_KEY_SIZE_FIXED + (RBT_PIN_SIZE - 1)) / RBT_PIN_SIZE)
 
#undef _RBT_NODE_QUERY_WITH_CAST_KEY
#ifdef RBT_KEY_SIZE_FIXED
  #define _RBT_NODE_QUERY_WITH_CAST_KEY(node, key, bits, action, value) \
    do \
    { \
      if (RBT_PIN_SIZE != 1) \
      { \
        if (RBT_KEY_SIZE_FIXED % RBT_PIN_SIZE) \
        { \
          RBT_PIN_T cast_key[RBT_PINS_FIXED]; \
          memset(cast_key, 0, sizeof(cast_key)); \
          memcpy(cast_key, RBT_KEY_PTR(key), RBT_KEY_SIZE_FIXED); \
          bits = sizeof(cast_key) * BITS_PER_BYTE; \
          return RBT_NODE_QUERY(node, cast_key, bits, action, value); \
        } \
        else \
        { \
          return RBT_NODE_QUERY(node, (RBT_PIN_T *) RBT_KEY_PTR(key), bits, action, value); \
        } \
      } \
      else \
      { \
        return RBT_NODE_QUERY(node, (RBT_PIN_T *) RBT_KEY_PTR(key), bits, action, value); \
      } \
    } \
    while (0)
 
#else
  #define _RBT_NODE_QUERY_WITH_CAST_KEY(node, key, bits, action, value) \
    do \
    { \
      if (RBT_PIN_SIZE != 1) \
      { \
        int q; \
        int r; \
        RBT_DIVMOD(bits, RBT_PIN_SIZE_BITS, q, r); \
        if (r) \
        { \
          q ++; \
          RBT_PIN_T cast_key[q]; \
          memset(cast_key, 0, sizeof(cast_key)); \
          memcpy(cast_key, RBT_KEY_PTR(key), (bits + (BITS_PER_BYTE - 1)) / BITS_PER_BYTE); \
          bits = q * RBT_PIN_SIZE_BITS; \
          return RBT_NODE_QUERY(node, cast_key, bits, action, value); \
        } \
        else \
        { \
          return RBT_NODE_QUERY(node, (RBT_PIN_T *) RBT_KEY_PTR(key), bits, action, value); \
        } \
      } \
      else \
      { \
        return RBT_NODE_QUERY(node, (RBT_PIN_T *) RBT_KEY_PTR(key), bits, action, value); \
      } \
    } \
    while (0)
#endif //RBT_KEY_SIZE_FIXED
 
RBT_VALUE_T
RBT_NODE_QUERY_WRAPPER(
  RBT_NODE_T * node,
  RBT_KEY_T key,
  rbt_query_action_t action,
  RBT_VALUE_T value
)
{
  RBT_KEY_SIZE_T bits;
  bits = RBT_KEY_COUNT_BITS(key);
//   _RBT_NODE_QUERY_WITH_CAST_KEY(cast_key, key, bits);
//   return RBT_NODE_QUERY(node, cast_key, bits, action, value);
  _RBT_NODE_QUERY_WITH_CAST_KEY(node, key, bits, action, value);
}
 
 
 
RBT_VALUE_T
RBT_INSERT(
  RBT_NODE_T * node,
  RBT_KEY_T key,
  RBT_VALUE_T value
)
{
  return RBT_NODE_QUERY_WRAPPER(node, key, RBT_QUERY_ACTION_INSERT, value);
}
 
 
 
RBT_VALUE_T
RBT_RETRIEVE(
  RBT_NODE_T * node,
  RBT_KEY_T key
)
{
  return RBT_NODE_QUERY_WRAPPER(node, key, RBT_QUERY_ACTION_RETRIEVE, RBT_VALUE_NULL);
}
 
 
 
RBT_VALUE_T
RBT_DELETE(
  RBT_NODE_T * node,
  RBT_KEY_T key
)
{
  return RBT_NODE_QUERY_WRAPPER(node, key, RBT_QUERY_ACTION_DELETE, RBT_VALUE_NULL);
}
 
 
 
RBT_VALUE_T
RBT_SWAP(
  RBT_NODE_T * node,
  RBT_KEY_T key,
  RBT_VALUE_T value
)
{
  return RBT_NODE_QUERY_WRAPPER(node, key, RBT_QUERY_ACTION_SWAP, value);
}
 
 
 
 
 
int
RBT_HAS_KEY(RBT_NODE_T * node, RBT_KEY_T key)
{
  return !RBT_VALUE_IS_NULL(RBT_RETRIEVE(node, key));
}