indexed_column.h

#pragma once

#include <string>  //  std::string
#include <utility>  //  std::move

#include "functional/cxx_universal.h"
#include "ast/where.h"

namespace sqlite_orm {

    namespace internal {

        template<class C>
        struct indexed_column_t {
            using column_type = C;

#ifndef SQLITE_ORM_AGGREGATE_NSDMI_SUPPORTED
            indexed_column_t(column_type _column_or_expression) :
                column_or_expression(std::move(_column_or_expression)) {}
#endif

            column_type column_or_expression;
            std::string _collation_name;
            int _order = 0;  //  -1 = desc, 1 = asc, 0 = not specified

            indexed_column_t<column_type> collate(std::string name) {
                auto res = std::move(*this);
                res._collation_name = std::move(name);
                return res;
            }

            indexed_column_t<column_type> asc() {
                auto res = std::move(*this);
                res._order = 1;
                return res;
            }

            indexed_column_t<column_type> desc() {
                auto res = std::move(*this);
                res._order = -1;
                return res;
            }
        };

        template<class C>
        indexed_column_t<C> make_indexed_column(C col) {
            return {std::move(col)};
        }

        template<class C>
        where_t<C> make_indexed_column(where_t<C> wher) {
            return std::move(wher);
        }

        template<class C>
        indexed_column_t<C> make_indexed_column(indexed_column_t<C> col) {
            return std::move(col);
        }
    }

    /**
     * Use this function to specify indexed column inside `make_index` function call.
     * Example: make_index("index_name", indexed_column(&User::id).asc())
     */
    template<class C>
    internal::indexed_column_t<C> indexed_column(C column_or_expression) {
        return {std::move(column_or_expression)};
    }

}