MySQL 8.0.30
Source Code Documentation
tables_contained_in.h
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23
24#ifndef TABLES_CONTAINED_IN_H_
25#define TABLES_CONTAINED_IN_H_
26
27#include <string.h>
28
29#include "my_inttypes.h"
30#include "sql/sql_optimizer.h"
31
32#ifdef _MSC_VER
33#include <intrin.h>
34#pragma intrinsic(_BitScanForward64)
35#endif
36
37// A utility class to loop over all set bits in the given map.
38// Use as:
39//
40// qep_tab_map = ...;
41// for (QEP_TAB *qep_tab : TablesContainedIn(join, qep_tab_map)) {
42// ...
43// }
45 public:
46 class iterator {
47 private:
48 const JOIN *const m_join;
50
51 public:
54 bool operator==(const iterator &other) const {
55 assert(m_join == other.m_join);
56 return m_bits_left == other.m_bits_left;
57 }
58 bool operator!=(const iterator &other) const {
59 assert(m_join == other.m_join);
60 return m_bits_left != other.m_bits_left;
61 }
62 QEP_TAB *operator*() const {
63 // Find the QEP_TAB that corresponds to the lowest set bit.
64 assert(m_bits_left != 0);
65#ifdef _MSC_VER
66 unsigned long idx;
67 _BitScanForward64(&idx, m_bits_left);
68#else
69 size_t idx = ffsll(m_bits_left) - 1;
70#endif
71 assert(idx < m_join->tables);
72 return &m_join->qep_tab[idx];
73 }
75 // Clear the lowest set bit.
76 assert(m_bits_left != 0);
77 m_bits_left &= (m_bits_left - 1);
78 return *this;
79 }
80 };
81
84
85 iterator begin() const { return {m_join, m_initial_map}; }
86 iterator end() const { return {m_join, 0}; }
87
88 private:
89 const JOIN *const m_join;
91};
92
93#endif // TABLES_CONTAINED_IN_H_
Definition: sql_optimizer.h:125
QEP_TAB * qep_tab
Array of QEP_TABs.
Definition: sql_optimizer.h:148
Definition: sql_executor.h:259
Definition: tables_contained_in.h:46
iterator(const JOIN *join, qep_tab_map map)
Definition: tables_contained_in.h:52
QEP_TAB * operator*() const
Definition: tables_contained_in.h:62
bool operator==(const iterator &other) const
Definition: tables_contained_in.h:54
bool operator!=(const iterator &other) const
Definition: tables_contained_in.h:58
iterator & operator++()
Definition: tables_contained_in.h:74
qep_tab_map m_bits_left
Definition: tables_contained_in.h:49
const JOIN *const m_join
Definition: tables_contained_in.h:48
Definition: tables_contained_in.h:44
iterator end() const
Definition: tables_contained_in.h:86
const qep_tab_map m_initial_map
Definition: tables_contained_in.h:90
iterator begin() const
Definition: tables_contained_in.h:85
const JOIN *const m_join
Definition: tables_contained_in.h:89
TablesContainedIn(const JOIN *join, qep_tab_map map)
Definition: tables_contained_in.h:82
Some integer typedefs for easier portability.
uint64_t qep_tab_map
Definition: my_table_map.h:31
std::string join(Container cont, const std::string &delim)
join elements of an container into a string separated by a delimiter.
Definition: string.h:150
std::map< Key, Value, Compare, ut::allocator< std::pair< const Key, Value > > > map
Specialization of map which uses ut_allocator.
Definition: ut0new.h:2873
Classes used for query optimizations.