3 files changed, 145 insertions, 0 deletions

diff --git a/src/crepe/facade/CMakeLists.txt b/src/crepe/facade/CMakeLists.txt
index c79e16f..4cc53bc 100644
--- a/src/crepe/facade/CMakeLists.txt
+++ b/src/crepe/facade/CMakeLists.txt
@@ -2,11 +2,13 @@ target_sources(crepe PUBLIC
 	Sound.cpp
 	SoundContext.cpp
 	SDLContext.cpp
+	DB.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Sound.h
 	SoundContext.h
 	SDLContext.h
+	DB.h
 )
 
diff --git a/src/crepe/facade/DB.cpp b/src/crepe/facade/DB.cpp
new file mode 100644
index 0000000..c885560
--- /dev/null
+++ b/src/crepe/facade/DB.cpp
@@ -0,0 +1,68 @@
+#include <cstring>
+
+#include "util/log.h"
+#include "Exception.h"
+
+#include "DB.h"
+
+using namespace std;
+using namespace crepe;
+
+DB::DB(const string & path) {
+	dbg_trace();
+	int ret;
+
+	// init database struct
+	libdb::DB * db;
+	if ((ret = libdb::db_create(&db, NULL, 0)) != 0)
+		throw Exception("db_create: %s", libdb::db_strerror(ret));
+	this->db = { db, [] (libdb::DB * db) { db->close(db, 0); } };
+
+	// load or create database file
+	if ((ret = this->db->open(this->db.get(), NULL, path.c_str(), NULL, libdb::DB_BTREE, DB_CREATE, 0)) != 0)
+		throw Exception("db->open: %s", libdb::db_strerror(ret));
+
+	// create cursor
+	libdb::DBC * cursor;
+	if ((ret = this->db->cursor(this->db.get(), NULL, &cursor, 0)) != 0)
+		throw Exception("db->cursor: %s", libdb::db_strerror(ret));
+	this->cursor = { cursor, [] (libdb::DBC * cursor) { cursor->close(cursor); } };
+}
+
+
+libdb::DBT DB::to_thing(const string & thing) const noexcept {
+	libdb::DBT thang;
+	memset(&thang, 0, sizeof(libdb::DBT));
+	thang.data = (void *) thing.data();
+	thang.size = thing.size();
+	return thang;
+}
+
+string DB::get(const string & key) {
+	libdb::DBT db_key = this->to_thing(key);
+	libdb::DBT db_val;
+	memset(&db_val, 0, sizeof(libdb::DBT));
+
+	int ret = this->cursor->get(this->cursor.get(), &db_key, &db_val, DB_FIRST);
+	if (ret != 0)
+		throw Exception("cursor->get: %s", libdb::db_strerror(ret));
+	return { static_cast<char *>(db_val.data), db_val.size };
+}
+
+void DB::set(const string & key, const string & value) {
+	libdb::DBT db_key = this->to_thing(key);
+	libdb::DBT db_val = this->to_thing(value);
+	int ret = this->db->put(this->db.get(), NULL, &db_key, &db_val, 0);
+	if (ret != 0)
+		throw Exception("cursor->get: %s", libdb::db_strerror(ret));
+}
+
+bool DB::has(const std::string & key) noexcept {
+	try {
+		this->get(key);
+	} catch (...) {
+		return false;
+	}
+	return true;
+}
+
diff --git a/src/crepe/facade/DB.h b/src/crepe/facade/DB.h
new file mode 100644
index 0000000..b62a974
--- /dev/null
+++ b/src/crepe/facade/DB.h
@@ -0,0 +1,75 @@
+#pragma once
+
+#include <string>
+#include <functional>
+#include <memory>
+
+namespace libdb {
+extern "C" {
+#include <db.h>
+}
+}
+
+namespace crepe {
+
+/**
+ * \brief Berkeley DB facade
+ *
+ * Berkeley DB is a simple key-value database that stores arbitrary data as
+ * both key and value. This facade uses STL strings as keys/values.
+ */
+class DB {
+public:
+	/**
+	 * \param path  The path of the database (created if nonexistant)
+	 */
+	DB(const std::string & path);
+	virtual ~DB() = default;
+
+public:
+	/**
+	 * \brief Get a value from the database, or throw an exception
+	 *
+	 * \param key  The value key
+	 *
+	 * \return The value
+	 *
+	 * \throws Exception if value is not found in DB or other error occurs
+	 */
+	std::string get(const std::string & key);
+	/**
+	 * \brief Set (create or overwrite) a value in the database
+	 *
+	 * \param key  The value key
+	 * \param value  The value to store
+	 *
+	 * \throws Exception if an error occurs
+	 */
+	void set(const std::string & key, const std::string & value);
+	/**
+	 * \brief Check if a key exists in the database
+	 *
+	 * \param key  The value key
+	 *
+	 * \returns True if the key exists, or false if it does not
+	 */
+	bool has(const std::string & key) noexcept;
+
+private:
+	//! RAII wrapper around \c DB struct
+	std::unique_ptr<libdb::DB, std::function<void(libdb::DB *)>> db;
+	//! RAII wrapper around \c DBC struct
+	std::unique_ptr<libdb::DBC, std::function<void(libdb::DBC *)>> cursor;
+
+private:
+	/**
+	 * \brief Convert an STL string to DBT (data base thang)
+	 *
+	 * \param thing  Input data
+	 * \return \c DBT with the same data as input \c thing
+	 */
+	libdb::DBT to_thing(const std::string & thing) const noexcept;
+};
+
+}
+