item.h

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#ifndef REDUCT_ITEM_H
#define REDUCT_ITEM_H 1
 
#include "atom.h"
#include "closure.h"
#include "defs.h"
#include "function.h"
#include "list.h"
 
/**
 * @file item.h
 * @brief Item management.
 * @defgroup item Item
 *
 * An item is a generic container for all data types and heap alloacted structures within Reduct.
 *
 * To optimize memory cacheing and reduce fragmentation, all items are 64 bytes and aligned to cache lines.
 *
 * @{
 */
 
/**
 * @brief Item type enumeration.
 */
typedef reduct_uint8_t reduct_item_type_t;
#define REDUCT_ITEM_TYPE_NONE 0      ///< No type.
#define REDUCT_ITEM_TYPE_ATOM 1      ///< An atom.
#define REDUCT_ITEM_TYPE_LIST 2      ///< A list.
#define REDUCT_ITEM_TYPE_FUNCTION 3  ///< A function.
#define REDUCT_ITEM_TYPE_CLOSURE 4   ///< A closure.
#define REDUCT_ITEM_TYPE_LIST_NODE 5 ///< A list node.
 
/**
 * @brief Item flags enumeration.
 */
typedef reduct_uint8_t reduct_item_flags_t;
#define REDUCT_ITEM_FLAG_NONE 0                ///< No flags.
#define REDUCT_ITEM_FLAG_FALSY (1 << 0)        ///< Item is falsy.
#define REDUCT_ITEM_FLAG_INT_SHAPED (1 << 1)   ///< Item is an integer shaped atom.
#define REDUCT_ITEM_FLAG_FLOAT_SHAPED (1 << 2) ///< Item is a float shaped atom.
#define REDUCT_ITEM_FLAG_INTRINSIC (1 << 3)    ///< Item is an atom and a intrinsic.
#define REDUCT_ITEM_FLAG_NATIVE (1 << 4)       ///< Item is an atom and a native function.
#define REDUCT_ITEM_FLAG_QUOTED (1 << 5)       ///< Item is a quoted atom.
#define REDUCT_ITEM_FLAG_GC_MARK (1 << 6)      ///< Item is marked by GC.
 
#define REDUCT_ITEM_PAYLOAD_MAX 48 ///< The maximum size of the item payload.
 
/**
 * @brief Item structure.
 * @struct reduct_item_t
 *
 * Should be exactly 64 bytes for caching.
 *
 * @see handle
 */
typedef struct reduct_item
{
    struct reduct_input* input;  ///< The parsed input that created this item.
    reduct_uint32_t position;    ///< The position in the input buffer where the item was parsed.
    reduct_item_flags_t flags;   ///< Flags for the item.
    reduct_item_type_t type;     ///< The type of the item.
    reduct_uint16_t retainCount; ///< The reference count for GC retention.
    union {
        reduct_uint32_t
            length;         ///< Common length for the item. (Stored in the union to save space due to padding rules.)
        reduct_atom_t atom; ///< An atom.
        reduct_list_t list; ///< A list.
        reduct_list_node_t node;    ///< A list node.
        reduct_function_t function; ///< A function.
        reduct_closure_t closure;   ///< A closure.
        struct reduct_item* free;   ///< The next free item in the free list.
        uint8_t _raw[REDUCT_ITEM_PAYLOAD_MAX];
    };
} reduct_item_t;
 
#ifdef _Static_assert
_Static_assert(sizeof(reduct_item_t) == 64, "reduct_item_t must be 64 bytes");
#endif
 
#define REDUCT_ITEM_BLOCK_MAX 255 ///< The maximum number of items in a block.
 
/**
 * @brief Item block structure.
 * @struct reduct_item_block_t
 *
 * Should be a power of two size as that should help most memory allocators.
 */
typedef struct reduct_item_block
{
    struct reduct_item_block* next;
    reduct_uint8_t _padding[sizeof(reduct_item_t) - sizeof(struct reduct_item_block*)];
    reduct_item_t items[REDUCT_ITEM_BLOCK_MAX];
} reduct_item_block_t;
 
#ifdef _Static_assert
_Static_assert((sizeof(reduct_item_block_t) & (sizeof(reduct_item_block_t) - 1)) == 0,
    "reduct_item_block_t must be a power of two");
#endif
 
/**
 * @brief Allocate a new Reduct item.
 *
 * @param reduct Pointer to the Reduct structure.
 * @return A pointer to the newly created item.
 */
REDUCT_API reduct_item_t* reduct_item_new(struct reduct* reduct);
 
/**
 * @brief Free an Reduct item.
 *
 * @param reduct Pointer to the Reduct structure.
 * @param item Pointer to the item to free.
 */
REDUCT_API void reduct_item_free(struct reduct* reduct, reduct_item_t* item);
 
/**
 * @brief Get the integer value of an item if it is number shaped.
 *
 * @param item Pointer to the item.
 * @return The integer value, or 0 if not number shaped.
 */
REDUCT_API reduct_int64_t reduct_item_get_int(reduct_item_t* item);
 
/**
 * @brief Get the float value of an item if it is number shaped.
 *
 * @param item Pointer to the item.
 * @return The float value, or 0.0 if not number shaped.
 */
REDUCT_API reduct_float_t reduct_item_get_float(reduct_item_t* item);
 
/**
 * @brief Get the string representation of an Reduct item type.
 *
 * @param type The item type.
 * @return The string representation of the item type.
 */
REDUCT_API const char* reduct_item_type_str(reduct_item_type_t type);
 
/** @} */
 
#endif