Configuration3

Usage

#include <Configuration.h>
Configuration config;
ConfigDefault config_defaults = {
  { "verbose", "true" },
  { 0, 0 }
};
config.Defaults(config_defaults);
config.Read("/spare2/myconfig") ;
config.Add("sync", "false");
if(config["sync"]) ...
if(config.Value("rate") < 50) ...
if(config.Boolean("sync")) ...

Overview

The primary purpose of the Configuration class is to parse a configuration file and allow the application to modify the internal data structure produced. All values are strings and are converted by the appropriate accessors. For instance the Boolean method will return numerical true (not zero) if the string either contains a number that is different from zero or the string true

The ConfigDefaults type is a structure of two char pointers: the name of the configuration attribute and it's value. The end of the array is the first entry that contains a null pointer instead of the attribute name. Numerical values must be in strings. For instance:

ConfigDefault* config_defaults = {
  { "wordlist_compress", "true" },
  { "wordlist_page_size", "8192" },
  { 0, 0 }
};

The additional fields of the ConfigDefault are purely informative.

File format

The configuration file is a plain ASCII text file. Each line in the file is either a comment or an attribute. Comment lines are blank lines or lines that start with a '#'. Attributes consist of a variable name and an associated value:

<name>:<whitespace><value><newline>

The <name> contains any alphanumeric character or underline (_) The <value> can include any character except newline. It also cannot start with spaces or tabs since those are considered part of the whitespace after the colon. It is important to keep in mind that any trailing spaces or tabs will be included.

It is possible to split the <value> across several lines of the configuration file by ending each line with a backslash (. The effect on the value is that a space is added where the line split occurs.

A configuration file can include another file, by using the special <name>, <tt>include</tt>. The <value> is taken as the file name of another configuration file to be read in at this point. If the given file name is not fully qualified, it is taken relative to the directory in which the current configuration file is found. Variable expansion is permitted in the file name. Multiple include statements, and nested includes are also permitted.

include: common.conf

Methods

Configuration()

Constructor

~Configuration()

Destructor

void Add(const String& str)

Add configuration item str to the configuration. The value associated with it is undefined.

void Add(const String& name, const String& value)

Add configuration item name to the configuration and associate it with value

int Remove(const String& name)

Remove the name from the configuration.

void NameValueSeparators(const String& s)

Let the Configuration know how to parse name value pairs. Each character of string s is a valid separator between the name and the value.

virtual int Read(const String& filename)

Read name/value configuration pairs from the file filename

const String Find(const String& name) const

Return the value of configuration attribute name as a String

const String operator[](const String& name) const

Alias to the Find method.

int Value(const String& name, int default_value = 0) const

Return the value associated with the configuration attribute name , converted to integer using the atoi(3) function. If the attribute is not found in the configuration and a default_value is provided, return it.

double Double(const String& name, double default_value = 0) const

Return the value associated with the configuration attribute name , converted to double using the atof(3) function. If the attribute is not found in the configuration and a default_value is provided, return it.

int Boolean(const String& name, int default_value = 0) const

Return 1 if the value associated to name is either 1, yes or true Return 0 if the value associated to name is either 0, no or false

void Defaults(const ConfigDefaults *array)

Load configuration attributes from the name and value members of the array argument.