A simple configuration file library.
To read values load and use the get_value API.
cfg::Config config;
config.load("user.cfg");
unsigned int width = config.get_value<unsigned int>("graphic", width, 800);
To save values use the set_value and save API.
cfg::Config config;
config.set_value("graphic", width, 800);
config.save();
The library is accessed through the cfg::Config class. It has the following API:
void load(const std::string& file)
The function load loads a configuration file. It a parsing error occurs,
an std::runtime_error is raised with the location and cause of the error.
void save(std::string file)
The function save writes a configuration file. If the function encounters a
write error, the exception std::runtime_error is raised.
bool has_value(const std::string& section, const std::string& name);
The function has_value checks the presense of a value.
const std::string get_value(const std::string& section, const std::string& name) const;
template <typename Type>
Type get_value(const std::string& section, const std::string& name) const;
std::string get_value(const std::string& section, const std::string& name, const std::string& fallback);
template <typename Type>
Type get_value(const std::string& section, const std::string& name, const Type& fallback);
The function get_value read a value from the configuration. The functions
can either have a fallback value set or raise a std::logic_error if the
value was not found.
For convenience a type template parameter can be set that converts the internal string to the desired type. Note: The type mus be standard streamable.
void set_value(const std::string& section, const std::string& name, const std::string& value);
template <typename Type>
void set_value(const std::string& section, const std::string& name, const Type& value);
The function set_value sets a given value. If the value does not yet exist,
it is created.
For convenience a type template parameter can be set that converts the given value to the internal text representation. Note: The type mus be standard streamable.
The configuration file format loosely follows the INI conversion, but the format is stricter.
An example format is as follows:
# This is a comment
[SectionOne]
valueOne = "This is a string."
value_two = 123.5
[SectionTwo]
boolValue = true
A few significant different to INI are:
- No values outside of a section.
- All values must be either a identifier, number or string.
- String must be contained within one line.
The formal syntax is as follows:
file := preamble* section*;
preamble := blank | comment;
blank := ws* nl;
comment := ws* "#" [^\r\n]* nl;
section := shead lines;
shead := ws* "[" ws* identifier ws* "]" ws* nl
lines := blank | comment | key_value;
key_value := ws* identifier ws* "=" ws* value ws* nl;
value: identifier | number | string;
identifier := [a-zA-Z_-][0-9a-zA-Z_-]*;
number := (+|-)?[0-9]+(\.[0-9]+)?
string := \"[^"\r\n]*\"
ws := " " | "\t";
nl := "\n" | "\r" | "\r\n";
cfg - A simple configuration file library.
Copyright (c) 2015-2017 Sean Farrell <sean.farrell@rioki.org>
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