Add MapSettingsManager and new mapgen setting script API functions

This commit refactors the majority of the Mapgen settings system.
- MapgenParams is now owned by MapSettingsManager, itself a part of ServerMap,
  instead of the EmergeManager.
- New Script API functions added:
    core.get_mapgen_setting
    core.get_mapgen_setting_noiseparams,
    core.set_mapgen_setting, and
    core.set_mapgen_setting_noiseparams.
- minetest.get/set_mapgen_params are deprecated by the above new functions.
- It is now possible to view and modify any arbitrary mapgen setting from a mod,
  rather than the base MapgenParams structure.
- MapgenSpecificParams has been removed.

src/map_settings_manager.cpp

@@ -0,0 +1,194 @@
+/*
+Minetest
+Copyright (C) 2010-2013 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "debug.h"
+#include "filesys.h"
+#include "log.h"
+#include "mapgen.h"
+#include "settings.h"
+
+#include "map_settings_manager.h"
+
+MapSettingsManager::MapSettingsManager(
+	Settings *user_settings, const std::string &map_meta_path)
+{
+	m_map_meta_path = map_meta_path;
+	m_user_settings = user_settings;
+	m_map_settings  = new Settings;
+	mapgen_params   = NULL;
+
+	assert(m_user_settings != NULL);
+}
+
+
+MapSettingsManager::~MapSettingsManager()
+{
+	delete m_map_settings;
+	delete mapgen_params;
+}
+
+
+bool MapSettingsManager::getMapSetting(
+	const std::string &name, std::string *value_out)
+{
+	if (m_map_settings->getNoEx(name, *value_out))
+		return true;
+
+	// Compatibility kludge
+	if (m_user_settings == g_settings && name == "seed")
+		return m_user_settings->getNoEx("fixed_map_seed", *value_out);
+
+	return m_user_settings->getNoEx(name, *value_out);
+}
+
+
+bool MapSettingsManager::getMapSettingNoiseParams(
+	const std::string &name, NoiseParams *value_out)
+{
+	return m_map_settings->getNoiseParams(name, *value_out) ||
+		m_user_settings->getNoiseParams(name, *value_out);
+}
+
+
+bool MapSettingsManager::setMapSetting(
+	const std::string &name, const std::string &value, bool override_meta)
+{
+	if (mapgen_params)
+		return false;
+
+	if (override_meta)
+		m_map_settings->set(name, value);
+	else
+		m_map_settings->setDefault(name, value);
+
+	return true;
+}
+
+
+bool MapSettingsManager::setMapSettingNoiseParams(
+	const std::string &name, const NoiseParams *value, bool override_meta)
+{
+	if (mapgen_params)
+		return false;
+
+	m_map_settings->setNoiseParams(name, *value, !override_meta);
+	return true;
+}
+
+
+bool MapSettingsManager::loadMapMeta()
+{
+	std::ifstream is(m_map_meta_path.c_str(), std::ios_base::binary);
+
+	if (!is.good()) {
+		errorstream << "loadMapMeta: could not open "
+			<< m_map_meta_path << std::endl;
+		return false;
+	}
+
+	if (!m_map_settings->parseConfigLines(is, "[end_of_params]")) {
+		errorstream << "loadMapMeta: [end_of_params] not found!" << std::endl;
+		return false;
+	}
+
+	return true;
+}
+
+
+bool MapSettingsManager::saveMapMeta()
+{
+	// If mapgen params haven't been created yet; abort
+	if (!mapgen_params)
+		return false;
+
+	if (!fs::CreateAllDirs(fs::RemoveLastPathComponent(m_map_meta_path))) {
+		errorstream << "saveMapMeta: could not create dirs to "
+			<< m_map_meta_path;
+		return false;
+	}
+
+	std::ostringstream oss(std::ios_base::binary);
+	Settings conf;
+
+	mapgen_params->MapgenParams::writeParams(&conf);
+	mapgen_params->writeParams(&conf);
+	conf.writeLines(oss);
+
+	// NOTE: If there are ever types of map settings other than
+	// those relating to map generation, save them here
+
+	oss << "[end_of_params]\n";
+
+	if (!fs::safeWriteToFile(m_map_meta_path, oss.str())) {
+		errorstream << "saveMapMeta: could not write "
+			<< m_map_meta_path << std::endl;
+		return false;
+	}
+
+	return true;
+}
+
+
+MapgenParams *MapSettingsManager::makeMapgenParams()
+{
+	if (mapgen_params)
+		return mapgen_params;
+
+	assert(m_user_settings != NULL);
+	assert(m_map_settings != NULL);
+
+	// At this point, we have (in order of precedence):
+	// 1). m_mapgen_settings->m_settings containing map_meta.txt settings or
+	//     explicit overrides from scripts
+	// 2). m_mapgen_settings->m_defaults containing script-set mgparams without
+	//     overrides
+	// 3). g_settings->m_settings containing all user-specified config file
+	//     settings
+	// 4). g_settings->m_defaults containing any low-priority settings from
+	//     scripts, e.g. mods using Lua as an enhanced config file)
+
+	// Now, get the mapgen type so we can create the appropriate MapgenParams
+	std::string mg_name;
+	MapgenType mgtype = getMapSetting("mg_name", &mg_name) ?
+		Mapgen::getMapgenType(mg_name) : MAPGEN_DEFAULT;
+	if (mgtype == MAPGEN_INVALID) {
+		errorstream << "EmergeManager: mapgen '" << mg_name <<
+			"' not valid; falling back to " <<
+			Mapgen::getMapgenName(MAPGEN_DEFAULT) << std::endl;
+		mgtype = MAPGEN_DEFAULT;
+	}
+
+	// Create our MapgenParams
+	MapgenParams *params = Mapgen::createMapgenParams(mgtype);
+	if (params == NULL)
+		return NULL;
+
+	params->mgtype = mgtype;
+
+	// Load the rest of the mapgen params from our active settings
+	params->MapgenParams::readParams(m_user_settings);
+	params->MapgenParams::readParams(m_map_settings);
+	params->readParams(m_user_settings);
+	params->readParams(m_map_settings);
+
+	// Hold onto our params
+	mapgen_params = params;
+
+	return params;
+}