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      1 #ifndef Py_INTERNAL_HAMT_H
      2 #define Py_INTERNAL_HAMT_H
      3 
      4 
      5 #define _Py_HAMT_MAX_TREE_DEPTH 7
      6 
      7 
      8 #define PyHamt_Check(o) (Py_TYPE(o) == &_PyHamt_Type)
      9 
     10 
     11 /* Abstract tree node. */
     12 typedef struct {
     13     PyObject_HEAD
     14 } PyHamtNode;
     15 
     16 
     17 /* An HAMT immutable mapping collection. */
     18 typedef struct {
     19     PyObject_HEAD
     20     PyHamtNode *h_root;
     21     PyObject *h_weakreflist;
     22     Py_ssize_t h_count;
     23 } PyHamtObject;
     24 
     25 
     26 /* A struct to hold the state of depth-first traverse of the tree.
     27 
     28    HAMT is an immutable collection.  Iterators will hold a strong reference
     29    to it, and every node in the HAMT has strong references to its children.
     30 
     31    So for iterators, we can implement zero allocations and zero reference
     32    inc/dec depth-first iteration.
     33 
     34    - i_nodes: an array of seven pointers to tree nodes
     35    - i_level: the current node in i_nodes
     36    - i_pos: an array of positions within nodes in i_nodes.
     37 */
     38 typedef struct {
     39     PyHamtNode *i_nodes[_Py_HAMT_MAX_TREE_DEPTH];
     40     Py_ssize_t i_pos[_Py_HAMT_MAX_TREE_DEPTH];
     41     int8_t i_level;
     42 } PyHamtIteratorState;
     43 
     44 
     45 /* Base iterator object.
     46 
     47    Contains the iteration state, a pointer to the HAMT tree,
     48    and a pointer to the 'yield function'.  The latter is a simple
     49    function that returns a key/value tuple for the 'Items' iterator,
     50    just a key for the 'Keys' iterator, and a value for the 'Values'
     51    iterator.
     52 */
     53 typedef struct {
     54     PyObject_HEAD
     55     PyHamtObject *hi_obj;
     56     PyHamtIteratorState hi_iter;
     57     binaryfunc hi_yield;
     58 } PyHamtIterator;
     59 
     60 
     61 PyAPI_DATA(PyTypeObject) _PyHamt_Type;
     62 PyAPI_DATA(PyTypeObject) _PyHamt_ArrayNode_Type;
     63 PyAPI_DATA(PyTypeObject) _PyHamt_BitmapNode_Type;
     64 PyAPI_DATA(PyTypeObject) _PyHamt_CollisionNode_Type;
     65 PyAPI_DATA(PyTypeObject) _PyHamtKeys_Type;
     66 PyAPI_DATA(PyTypeObject) _PyHamtValues_Type;
     67 PyAPI_DATA(PyTypeObject) _PyHamtItems_Type;
     68 
     69 
     70 /* Create a new HAMT immutable mapping. */
     71 PyHamtObject * _PyHamt_New(void);
     72 
     73 /* Return a new collection based on "o", but with an additional
     74    key/val pair. */
     75 PyHamtObject * _PyHamt_Assoc(PyHamtObject *o, PyObject *key, PyObject *val);
     76 
     77 /* Return a new collection based on "o", but without "key". */
     78 PyHamtObject * _PyHamt_Without(PyHamtObject *o, PyObject *key);
     79 
     80 /* Find "key" in the "o" collection.
     81 
     82    Return:
     83    - -1: An error occurred.
     84    - 0: "key" wasn't found in "o".
     85    - 1: "key" is in "o"; "*val" is set to its value (a borrowed ref).
     86 */
     87 int _PyHamt_Find(PyHamtObject *o, PyObject *key, PyObject **val);
     88 
     89 /* Check if "v" is equal to "w".
     90 
     91    Return:
     92    - 0: v != w
     93    - 1: v == w
     94    - -1: An error occurred.
     95 */
     96 int _PyHamt_Eq(PyHamtObject *v, PyHamtObject *w);
     97 
     98 /* Return the size of "o"; equivalent of "len(o)". */
     99 Py_ssize_t _PyHamt_Len(PyHamtObject *o);
    100 
    101 /* Return a Keys iterator over "o". */
    102 PyObject * _PyHamt_NewIterKeys(PyHamtObject *o);
    103 
    104 /* Return a Values iterator over "o". */
    105 PyObject * _PyHamt_NewIterValues(PyHamtObject *o);
    106 
    107 /* Return a Items iterator over "o". */
    108 PyObject * _PyHamt_NewIterItems(PyHamtObject *o);
    109 
    110 int _PyHamt_Init(void);
    111 void _PyHamt_Fini(void);
    112 
    113 #endif /* !Py_INTERNAL_HAMT_H */
    114