query.hpp

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/*##############################################################################
 VSQLite++ - virtuosic bytes SQLite3 C++ wrapper
 
 Copyright (c) 2006-2014 Vinzenz Feenstra vinzenz.feenstra@gmail.com
 All rights reserved.
 
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 are permitted provided that the following conditions are met:
 
 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
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 * Neither the name of virtuosic bytes nor the names of its contributors may
   be used to endorse or promote products derived from this software without
   specific prior written permission.
 
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 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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##############################################################################*/
#ifndef GUARD_SQLITE_QUERY_HPP_INCLUDED
#define GUARD_SQLITE_QUERY_HPP_INCLUDED
 
#include <iterator>
#include <memory>
#include <stdexcept>
#include <string>
#include <string_view>
#include <unordered_map>
#include <vector>
#include <type_traits>
#include <memory>
#include <sqlite/command.hpp>
#include <sqlite/result.hpp>

namespace sqlite {
inline namespace v2 {

    struct query : command {
        query(connection &con, std::string const &sql);

        virtual ~query();
 
        class result_range {
        public:
            struct column_cache {
                std::vector<std::string> names;
                std::unordered_map<std::string, int> lookup;
                int index_of(std::string_view name) const;
            };
 
            class row_view {
            public:
                row_view() = default;
                row_view(result *res, std::shared_ptr<column_cache> cache) :
                    res_(res), cache_(std::move(cache)) {}
 
                bool valid() const noexcept {
                    return res_ != nullptr;
                }
 
                result &raw() const {
                    if (!res_) {
                        throw std::runtime_error("row_view is not bound to a row");
                    }
                    return *res_;
                }
 
                template <typename T> T get(std::string_view name) const {
                    return raw().get<T>(column(name));
                }
 
                template <typename T> T get(int idx) const {
                    return raw().get<T>(idx);
                }
 
                template <typename T> T operator[](std::string_view name) const {
                    return get<T>(name);
                }
 
            private:
                int column(std::string_view name) const;
 
                result *res_ = nullptr;
                std::shared_ptr<column_cache> cache_;
            };
 
            class iterator {
            public:
                using iterator_category = std::input_iterator_tag;
                using value_type        = row_view;
                using difference_type   = std::ptrdiff_t;
                using pointer           = row_view *;
                using reference         = row_view &;
 
                iterator();
                iterator(result_type res, std::shared_ptr<column_cache> cache, bool end);
                reference operator*() const;
                pointer operator->() const;
                iterator &operator++();
                iterator operator++(int);
                bool operator==(iterator const &other) const;
                bool operator!=(iterator const &other) const;
 
            private:
                void advance();
                void prime_cache();
                result_type result_;
                bool end_ = true;
                std::shared_ptr<column_cache> cache_;
                row_view current_;
            };
 
            result_range();
            explicit result_range(result_type res);
 
            iterator begin();
            iterator end() const;
 
        private:
            result_type result_;
            bool begin_called_ = false;
            std::shared_ptr<column_cache> cache_;
        };

        VSQLITE_DEPRECATED result_type emit_result();

        result_type get_result();

        result_range each();

        template <typename... Args, typename = std::enable_if_t<(sizeof...(Args) > 0)>>
        result_range each(Args &&...args) {
            ((void)(*this % std::forward<Args>(args)), ...);
            return each();
        }
 
    private:
        friend struct result;
        void access_check();
        bool step();
    };
} // namespace v2
} // namespace sqlite
 
#endif // GUARD_SQLITE_QUERY_HPP_INCLUDED