mirror of https://github.com/python/cpython
158 lines
6.3 KiB
C
158 lines
6.3 KiB
C
#ifndef Py_DICTOBJECT_H
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#define Py_DICTOBJECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Dictionary object type -- mapping from hashable object to object */
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/* The distribution includes a separate file, Objects/dictnotes.txt,
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describing explorations into dictionary design and optimization.
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It covers typical dictionary use patterns, the parameters for
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tuning dictionaries, and several ideas for possible optimizations.
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*/
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/*
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There are three kinds of slots in the table:
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1. Unused. me_key == me_value == NULL
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Does not hold an active (key, value) pair now and never did. Unused can
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transition to Active upon key insertion. This is the only case in which
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me_key is NULL, and is each slot's initial state.
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2. Active. me_key != NULL and me_key != dummy and me_value != NULL
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Holds an active (key, value) pair. Active can transition to Dummy upon
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key deletion. This is the only case in which me_value != NULL.
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3. Dummy. me_key == dummy and me_value == NULL
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Previously held an active (key, value) pair, but that was deleted and an
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active pair has not yet overwritten the slot. Dummy can transition to
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Active upon key insertion. Dummy slots cannot be made Unused again
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(cannot have me_key set to NULL), else the probe sequence in case of
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collision would have no way to know they were once active.
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Note: .popitem() abuses the me_hash field of an Unused or Dummy slot to
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hold a search finger. The me_hash field of Unused or Dummy slots has no
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meaning otherwise.
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*/
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/* PyDict_MINSIZE is the minimum size of a dictionary. This many slots are
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* allocated directly in the dict object (in the ma_smalltable member).
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* It must be a power of 2, and at least 4. 8 allows dicts with no more
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* than 5 active entries to live in ma_smalltable (and so avoid an
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* additional malloc); instrumentation suggested this suffices for the
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* majority of dicts (consisting mostly of usually-small instance dicts and
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* usually-small dicts created to pass keyword arguments).
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*/
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#define PyDict_MINSIZE 8
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typedef struct {
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/* Cached hash code of me_key. Note that hash codes are C longs.
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* We have to use Py_ssize_t instead because dict_popitem() abuses
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* me_hash to hold a search finger.
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*/
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Py_ssize_t me_hash;
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PyObject *me_key;
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PyObject *me_value;
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} PyDictEntry;
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/*
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To ensure the lookup algorithm terminates, there must be at least one Unused
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slot (NULL key) in the table.
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The value ma_fill is the number of non-NULL keys (sum of Active and Dummy);
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ma_used is the number of non-NULL, non-dummy keys (== the number of non-NULL
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values == the number of Active items).
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To avoid slowing down lookups on a near-full table, we resize the table when
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it's two-thirds full.
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*/
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typedef struct _dictobject PyDictObject;
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struct _dictobject {
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PyObject_HEAD
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Py_ssize_t ma_fill; /* # Active + # Dummy */
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Py_ssize_t ma_used; /* # Active */
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/* The table contains ma_mask + 1 slots, and that's a power of 2.
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* We store the mask instead of the size because the mask is more
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* frequently needed.
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*/
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Py_ssize_t ma_mask;
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/* ma_table points to ma_smalltable for small tables, else to
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* additional malloc'ed memory. ma_table is never NULL! This rule
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* saves repeated runtime null-tests in the workhorse getitem and
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* setitem calls.
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*/
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PyDictEntry *ma_table;
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PyDictEntry *(*ma_lookup)(PyDictObject *mp, PyObject *key, long hash);
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PyDictEntry ma_smalltable[PyDict_MINSIZE];
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};
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PyAPI_DATA(PyTypeObject) PyDict_Type;
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PyAPI_DATA(PyTypeObject) PyDictIterKey_Type;
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PyAPI_DATA(PyTypeObject) PyDictIterValue_Type;
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PyAPI_DATA(PyTypeObject) PyDictIterItem_Type;
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PyAPI_DATA(PyTypeObject) PyDictKeys_Type;
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PyAPI_DATA(PyTypeObject) PyDictItems_Type;
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PyAPI_DATA(PyTypeObject) PyDictValues_Type;
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#define PyDict_Check(op) \
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PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_DICT_SUBCLASS)
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#define PyDict_CheckExact(op) (Py_TYPE(op) == &PyDict_Type)
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#define PyDictKeys_Check(op) (Py_TYPE(op) == &PyDictKeys_Type)
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#define PyDictItems_Check(op) (Py_TYPE(op) == &PyDictItems_Type)
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#define PyDictValues_Check(op) (Py_TYPE(op) == &PyDictValues_Type)
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/* This excludes Values, since they are not sets. */
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# define PyDictViewSet_Check(op) \
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(PyDictKeys_Check(op) || PyDictItems_Check(op))
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PyAPI_FUNC(PyObject *) PyDict_New(void);
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PyAPI_FUNC(PyObject *) PyDict_GetItem(PyObject *mp, PyObject *key);
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PyAPI_FUNC(PyObject *) PyDict_GetItemWithError(PyObject *mp, PyObject *key);
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PyAPI_FUNC(int) PyDict_SetItem(PyObject *mp, PyObject *key, PyObject *item);
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PyAPI_FUNC(int) PyDict_DelItem(PyObject *mp, PyObject *key);
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PyAPI_FUNC(void) PyDict_Clear(PyObject *mp);
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PyAPI_FUNC(int) PyDict_Next(
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PyObject *mp, Py_ssize_t *pos, PyObject **key, PyObject **value);
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PyAPI_FUNC(int) _PyDict_Next(
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PyObject *mp, Py_ssize_t *pos, PyObject **key, PyObject **value, long *hash);
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PyAPI_FUNC(PyObject *) PyDict_Keys(PyObject *mp);
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PyAPI_FUNC(PyObject *) PyDict_Values(PyObject *mp);
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PyAPI_FUNC(PyObject *) PyDict_Items(PyObject *mp);
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PyAPI_FUNC(Py_ssize_t) PyDict_Size(PyObject *mp);
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PyAPI_FUNC(PyObject *) PyDict_Copy(PyObject *mp);
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PyAPI_FUNC(int) PyDict_Contains(PyObject *mp, PyObject *key);
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PyAPI_FUNC(int) _PyDict_Contains(PyObject *mp, PyObject *key, long hash);
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PyAPI_FUNC(PyObject *) _PyDict_NewPresized(Py_ssize_t minused);
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/* PyDict_Update(mp, other) is equivalent to PyDict_Merge(mp, other, 1). */
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PyAPI_FUNC(int) PyDict_Update(PyObject *mp, PyObject *other);
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/* PyDict_Merge updates/merges from a mapping object (an object that
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supports PyMapping_Keys() and PyObject_GetItem()). If override is true,
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the last occurrence of a key wins, else the first. The Python
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dict.update(other) is equivalent to PyDict_Merge(dict, other, 1).
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*/
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PyAPI_FUNC(int) PyDict_Merge(PyObject *mp,
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PyObject *other,
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int override);
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/* PyDict_MergeFromSeq2 updates/merges from an iterable object producing
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iterable objects of length 2. If override is true, the last occurrence
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of a key wins, else the first. The Python dict constructor dict(seq2)
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is equivalent to dict={}; PyDict_MergeFromSeq(dict, seq2, 1).
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*/
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PyAPI_FUNC(int) PyDict_MergeFromSeq2(PyObject *d,
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PyObject *seq2,
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int override);
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PyAPI_FUNC(PyObject *) PyDict_GetItemString(PyObject *dp, const char *key);
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PyAPI_FUNC(int) PyDict_SetItemString(PyObject *dp, const char *key, PyObject *item);
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PyAPI_FUNC(int) PyDict_DelItemString(PyObject *dp, const char *key);
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_DICTOBJECT_H */
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