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conky/src/setting.hh

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/* -*- mode: c++; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: t -*-
* vim: ts=4 sw=4 noet ai cindent syntax=cpp
*
* Conky, a system monitor, based on torsmo
*
* Please see COPYING for details
*
* Copyright (C) 2010 Pavel Labath et al.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 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 General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef SETTING_HH
#define SETTING_HH
#include <string>
#include <type_traits>
#include <unordered_map>
#include "logging.h"
#include "luamm.hh"
namespace conky {
// performs the assignment without any error checking
void simple_lua_setter(lua::state *l, bool init);
// converts standard lua types to C types
template<typename T,
bool integral = std::is_integral<T>::value,
bool floating_point = std::is_floating_point<T>::value>
struct simple_getter {
// integral is here to force the compiler to evaluate the assert at instantiation time
static_assert(integral && false,
"Only specializations for string, integral and floating point types are available");
};
// Specialization for integral type.
template<typename T>
struct simple_getter<T, true, false> {
static T do_it_def(lua::state *l, T def)
{
if(l->isnil(-1))
return def;
T t = l->tointeger(-1);
l->pop();
return t;
}
static T do_it(lua::state *l)
{ return do_it_def(l, static_cast<T>(0)); }
};
// specialization for floating point types
template<typename T>
struct simple_getter<T, false, true> {
static T do_it_def(lua::state *l, T def)
{
if(l->isnil(-1))
return def;
T t = l->tonumber(-1);
l->pop();
return t;
}
static T do_it(lua::state *l)
{ return do_it_def(l, T(0)); }
};
// specialization for std::string
template<>
struct simple_getter<std::string, false, false> {
static std::string do_it_def(lua::state *l, const std::string &def)
{
if(l->isnil(-1))
return def;
std::string t = l->tostring(-1);
l->pop();
return t;
}
static std::string do_it(lua::state *l)
{ return do_it_def(l, std::string()); }
};
namespace priv {
class config_setting_base {
public:
typedef std::function<void (lua::state *l, bool init)> lua_setter_t;
const std::string name;
const lua_setter_t lua_setter;
config_setting_base(const std::string &name_, const lua_setter_t &lua_setter_);
virtual ~config_setting_base() {}
/*
* Set the setting manually.
* stack on entry: | ... new_value |
* stack on exit: | ... |
*/
void lua_set(lua::state &l);
};
typedef std::unordered_map<std::string, config_setting_base *> config_settings_t;
extern config_settings_t *config_settings;
}
/*
* Declares a setting <name> in the conky.config table.
* Getter function is used to translate the lua value into C++. It recieves the value on the
* lua stack. It should pop it and return the C++ value. In case the value is nil, it should
* return a predefined default value. Translation into basic types is provided with the
* default simple_getter::do_it functions.
* The lua_setter function is called when someone tries to set the value.
* It recieves the new and the old value on the stack (old one is on top). It should return
* the new value for the setting. It doesn't have to be the value the user set, if e.g. the
* value doesn't make sense. The second parameter is true if the assignment occurs during the
* initial parsing of the config file, and false afterwards. Some settings obviously cannot
* be changed (easily?) when conky is running, but some (e.g. x/y position of the window)
* can.
*/
template<typename T>
class config_setting: public priv::config_setting_base {
public:
typedef std::function<T (lua::state *l)> getter_t;
config_setting(const std::string &name_,
const getter_t &getter_ = &simple_getter<T>::do_it,
const lua_setter_t &lua_setter_ = &simple_lua_setter)
: config_setting_base(name_, lua_setter_), getter(getter_)
{}
T get(lua::state &l);
private:
getter_t getter;
};
template<typename T>
T config_setting<T>::get(lua::state &l)
{
lua::stack_sentry s(l);
l.checkstack(2);
l.getglobal("conky");
l.getfield(-1, "config");
l.replace(-2);
l.getfield(-1, name.c_str());
l.replace(-2);
return getter(&l);
}
template<typename T>
class enum_config_setting: public config_setting<T> {
// In theory, this class may be useful for other types too. If you think think you have a
// use for that, remove this assert.
static_assert(std::is_enum<T>::value, "Only enum types allowed");
typedef config_setting<T> Base;
std::pair<T, bool> convert(lua::state *l, int index);
T enum_getter(lua::state *l);
void enum_lua_setter(lua::state *l, bool init);
public:
typedef std::initializer_list<std::pair<std::string, T>> Map;
enum_config_setting(const std::string &name_, Map map_, bool modifiable_, T default_value_)
: Base(name_,
std::bind(&enum_config_setting::enum_getter, this, std::placeholders::_1),
std::bind(&enum_config_setting::enum_lua_setter, this, std::placeholders::_1,
std::placeholders::_2)),
map(map_), modifiable(modifiable_), default_value(default_value_)
{}
private:
Map map;
bool modifiable;
T default_value;
};
template<typename T>
std::pair<T, bool> enum_config_setting<T>::convert(lua::state *l, int index)
{
if(l->isnil(index))
return {default_value, true};
std::string val = l->tostring(index);
for(auto i = map.begin(); i != map.end(); ++i) {
if(i->first == val)
return {i->second, true};
}
std::string msg = "Invalid value '" + val + "' for setting '"
+ Base::name + "'. Valid values are: ";
for(auto i = map.begin(); i != map.end(); ++i) {
if(i != map.begin())
msg += ", ";
msg += "'" + i->first + "'";
}
msg += ".";
NORM_ERR("%s", msg.c_str());
return {default_value, false};
}
template<typename T>
T enum_config_setting<T>::enum_getter(lua::state *l)
{
lua::stack_sentry s(*l, -1);
auto ret = convert(l, -1);
l->pop();
// setter function should make sure the value is valid
assert(ret.second);
return ret.first;
}
template<typename T>
void enum_config_setting<T>::enum_lua_setter(lua::state *l, bool init)
{
lua::stack_sentry s(*l, -2);
if(!init && !modifiable) {
NORM_ERR("Setting '%s' is not modifiable", Base::name.c_str());
l->replace(-2);
} else {
auto ret = convert(l, -2);
if(ret.second)
l->pop();
else
l->replace(-2);
}
++s;
}
void check_config_settings(lua::state &l);
/////////// example settings, remove after real settings are available ///////
extern config_setting<std::string> asdf;
}
#endif /* SETTING_HH */