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1 : : /***********************************************************************\
2 : : * gnc-sql-result.hpp: Encapsulate the results of a SQL query. *
3 : : * *
4 : : * Copyright 2016 John Ralls <jralls@ceridwen.us> *
5 : : * *
6 : : * This program is free software; you can redistribute it and/or *
7 : : * modify it under the terms of the GNU General Public License as *
8 : : * published by the Free Software Foundation; either version 2 of *
9 : : * the License, or (at your option) any later version. *
10 : : * *
11 : : * This program is distributed in the hope that it will be useful, *
12 : : * but WITHOUT ANY WARRANTY; without even the implied warranty of *
13 : : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
14 : : * GNU General Public License for more details. *
15 : : * *
16 : : * You should have received a copy of the GNU General Public License *
17 : : * along with this program; if not, contact: *
18 : : * *
19 : : * Free Software Foundation Voice: +1-617-542-5942 *
20 : : * 51 Franklin Street, Fifth Floor Fax: +1-617-542-2652 *
21 : : * Boston, MA 02110-1301, USA gnu@gnu.org *
22 : : \***********************************************************************/
23 : :
24 : : #ifndef __GNC_SQL_RESULT_HPP__
25 : : #define __GNC_SQL_RESULT_HPP__
26 : :
27 : : #include <qof.h>
28 : :
29 : : #include <cstdint>
30 : : #include <optional>
31 : : #include <string>
32 : : #include <vector>
33 : :
34 : : class GncSqlRow;
35 : : /**
36 : : * Pure virtual class to iterate over a query result set.
37 : : */
38 : :
39 : : class GncSqlResult
40 : : {
41 : : public:
42 : 0 : virtual ~GncSqlResult() = default;
43 : : virtual uint64_t size() const noexcept = 0;
44 : : virtual GncSqlRow& begin() = 0;
45 : : virtual GncSqlRow& end() = 0;
46 : : friend GncSqlRow;
47 : : protected:
48 : : class IteratorImpl {
49 : : public:
50 : 0 : virtual ~IteratorImpl() = default;
51 : : virtual GncSqlRow& operator++() = 0;
52 : : virtual GncSqlResult* operator*() = 0;
53 : : virtual std::optional<int64_t> get_int_at_col (const char* col) const = 0;
54 : : virtual std::optional<double> get_float_at_col (const char* col) const = 0;
55 : : virtual std::optional<double> get_double_at_col (const char* col) const = 0;
56 : : virtual std::optional<std::string> get_string_at_col (const char* col) const = 0;
57 : : virtual std::optional<time64> get_time64_at_col (const char* col) const = 0;
58 : : virtual bool is_col_null (const char* col) const noexcept = 0;
59 : : };
60 : : };
61 : :
62 : : /**
63 : : * Row of SQL Query results.
64 : : *
65 : : * This is a "pointer" class of a pimpl pattern, the implementation being
66 : : * GncSqlResult::IteratorImpl. It's designed to present a std::forward_iterator
67 : : * like interface for use with range-for while allowing for wrapping a C API.
68 : : *
69 : : * Important Implementation Note: Operator++() as written requires that the
70 : : * sentinel GncSqlRow returned by GncSqlResult::end() has m_impl = nullptr in
71 : : * order to terminate the loop condition. This is a bit of a hack and might be a
72 : : * problem with a different SQL interface library from libdbi.
73 : : *
74 : : * Note that GncSqlResult::begin and GncSqlRow::operator++() return
75 : : * GncSqlRow&. This is necessary for operator++() to be called: Using operator
76 : : * ++() on a pointer performs pointer arithmetic rather than calling the
77 : : * pointed-to-class's operator++() and C++'s range-for uses operator++()
78 : : * directly on whatever begin() gives it.
79 : : */
80 : : class GncSqlRow
81 : : {
82 : : public:
83 : 0 : GncSqlRow (GncSqlResult::IteratorImpl* iter) : m_iter{iter} {}
84 : 0 : ~GncSqlRow() { }
85 : : GncSqlRow& operator++();
86 : 275 : GncSqlRow& operator*() { return *this; }
87 : : friend bool operator!=(const GncSqlRow&, const GncSqlRow&);
88 : 778 : std::optional<int64_t> get_int_at_col (const char* col) const {
89 : 778 : return m_iter->get_int_at_col (col); }
90 : 58 : std::optional<double> get_float_at_col (const char* col) const {
91 : 58 : return m_iter->get_float_at_col (col); }
92 : 52 : std::optional<double> get_double_at_col (const char* col) const {
93 : 52 : return m_iter->get_double_at_col (col); }
94 : 1175 : std::optional<std::string> get_string_at_col (const char* col) const {
95 : 1175 : return m_iter->get_string_at_col (col); }
96 : 0 : std::optional<time64> get_time64_at_col (const char* col) const {
97 : 0 : return m_iter->get_time64_at_col (col); }
98 : 71 : bool is_col_null (const char* col) const noexcept {
99 : 71 : return m_iter->is_col_null (col); }
100 : : private:
101 : : GncSqlResult::IteratorImpl* m_iter;
102 : : };
103 : :
104 : 745 : inline bool operator!=(const GncSqlRow& lr, const GncSqlRow& rr) {
105 : 745 : return lr.m_iter != rr.m_iter;
106 : : }
107 : :
108 : 26 : inline bool operator==(const GncSqlRow& lr, const GncSqlRow& rr) {
109 : 26 : return !(lr != rr);
110 : : }
111 : :
112 : :
113 : : #endif //__GNC_SQL_RESULT_HPP__
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