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140 lines
4.1 KiB
140 lines
4.1 KiB
///
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/// Copyright 2015-2018 Oliver Giles
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///
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/// This file is part of Laminar
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///
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/// Laminar is free software: you can redistribute it and/or modify
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/// it under the terms of the GNU General Public License as published by
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/// the Free Software Foundation, either version 3 of the License, or
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/// (at your option) any later version.
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///
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/// Laminar is distributed in the hope that it will be useful,
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/// but WITHOUT ANY WARRANTY; without even the implied warranty of
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/// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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/// GNU General Public License for more details.
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///
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/// You should have received a copy of the GNU General Public License
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/// along with Laminar. If not, see <http://www.gnu.org/licenses/>
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///
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#include "database.h"
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#include <sqlite3.h>
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#include <string.h>
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#include <math.h>
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#include <cstdint>
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struct StdevCtx {
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double mean;
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double M2;
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int64_t count;
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};
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static void stdevStep(sqlite3_context *ctx, int, sqlite3_value **args)
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{
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StdevCtx* p = static_cast<StdevCtx*>(sqlite3_aggregate_context(ctx, sizeof(StdevCtx)));
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// Welford's Online Algorithm
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if(sqlite3_value_numeric_type(args[0]) != SQLITE_NULL) {
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p->count++;
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double val = sqlite3_value_double(args[0]);
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double delta = val - p->mean;
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p->mean += delta / p->count;
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p->M2 += delta * (val - p->mean);
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}
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}
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static void stdevFinalize(sqlite3_context *context){
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StdevCtx* p = static_cast<StdevCtx*>(sqlite3_aggregate_context(context, 0));
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if(p && p->count > 1)
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sqlite3_result_double(context, sqrt(p->M2 / (p->count-1)));
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else
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sqlite3_result_null(context);
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}
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Database::Database(const char *path) {
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sqlite3_open(path, &hdl);
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int create_func_flags = SQLITE_UTF8;
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#if SQLITE_VERSION_NUMBER >= 3008003
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create_func_flags |= SQLITE_DETERMINISTIC;
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#endif
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sqlite3_create_function(hdl, "STDEV", 1, create_func_flags, NULL, NULL, stdevStep, stdevFinalize);
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}
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Database::~Database() {
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sqlite3_close(hdl);
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}
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Database::Statement::Statement(sqlite3 *db, const char *query) :
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stmt(nullptr)
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{
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sqlite3_prepare_v2(db, query, -1, &stmt, nullptr);
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}
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Database::Statement::~Statement() {
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sqlite3_finalize(stmt);
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}
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bool Database::Statement::exec() {
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return sqlite3_step(stmt) == SQLITE_DONE;
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}
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void Database::Statement::bindValue(int i, int e) {
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sqlite3_bind_int(stmt, i, e);
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}
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void Database::Statement::bindValue(int i, uint e) {
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sqlite3_bind_int(stmt, i, static_cast<int32_t>(e));
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}
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void Database::Statement::bindValue(int i, long e) {
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sqlite3_bind_int64(stmt, i, e);
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}
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void Database::Statement::bindValue(int i, ulong e) {
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sqlite3_bind_int64(stmt, i, static_cast<int64_t>(e));
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}
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void Database::Statement::bindValue(int i, const char* e) {
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sqlite3_bind_text(stmt, i, e, -1, nullptr);
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}
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void Database::Statement::bindValue(int i, const std::string& e) {
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sqlite3_bind_text(stmt, i, e.data(), static_cast<int>(e.size()), nullptr);
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}
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template<> std::string Database::Statement::fetchColumn(int col) {
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uint sz = static_cast<uint>(sqlite3_column_bytes(stmt, col)); // according to documentation will never be negative
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std::string res(sz, '\0');
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memcpy(&res[0], sqlite3_column_text(stmt, col), sz);
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return res;
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}
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template<> const char* Database::Statement::fetchColumn(int col) {
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// while sqlite3_column_text maybe more correctly returns an unsigned const char*, signed const char* is more consistent
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return reinterpret_cast<const char*>(sqlite3_column_text(stmt, col));
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}
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template<> int Database::Statement::fetchColumn(int col) {
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return sqlite3_column_int(stmt, col);
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}
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template<> uint Database::Statement::fetchColumn(int col) {
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return static_cast<uint>(sqlite3_column_int(stmt, col));
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}
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template<> long Database::Statement::fetchColumn(int col) {
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return static_cast<long>(sqlite3_column_int64(stmt, col));
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}
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template<> ulong Database::Statement::fetchColumn(int col) {
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return static_cast<ulong>(sqlite3_column_int64(stmt, col));
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}
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template<> double Database::Statement::fetchColumn(int col) {
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return sqlite3_column_double(stmt, col);
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}
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bool Database::Statement::row() {
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return sqlite3_step(stmt) == SQLITE_ROW;
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}
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