ConfigFileParser

Format

A config file is a text file in ASCII encoding. The following is a specification of the format. The primary construct for a config file is a KeyValue pair. The format is case-sensitive. Spaces and blank lines are ignored.

Key\Value

The key is on the left, followed by an equal sign, followed by the value.

key = "value"

Both the key and value are required. Line breaks are not allowed. The value cannot be redefined for the same key (within the same section).

Key

The key may consist of:

 - Uppercase and lowercase Latin letters
 - Digits
 - Symbols '-' and '_'

The key cannot be of zero length.

number = 0
name = "M3100"

Value

The value can be one of the following types

- Integer number
- Floating-point number
- String
- Boolean variable
- Array of values

Integer

Consists of digits (one or more). A '+' or '-' sign may be added as the first character.

key1 = 1
key2 = -2022
key3 = +128

The possible value will fit in an int32_t.

Floating-point number

Consists of digits (one or more) and a single period. There must be at least one digit before and after the period.

A '+' or '-' sign may be added as the first character.

key1 = 1.23
key2 = -2.77
key3 = -0.0001

String

The string is surrounded by double quotes. It can contain any characters.

key1 = "value"
key2 = "Hello world!"

Boolean value

The literal "true" or "false" is used for boolean values.

key1 = true
key2 = false

Array

The array is surrounded by square brackets []. Elements are separated by commas.

The array can consist of any correct values, not necessarily of the same type.

key1 = [1, 2, 3, 4, 5]
key2 = ["Hello", "world"]
key3 = [[1, 2, 3, 4, 5], ["Hello", "world"]]
key4 = [1, 3.3, "ITMO", [true, false]]

Sections

In addition to the key-value block, the format supports sections. Sections allow sets of key-value pairs to be combined into logical blocks.

A section is defined as a key surrounded by square brackets [].

[name]

After a section declaration, all subsequent key-value pairs belong to that section until the next one is declared.

[section-1]
key1 = 1
key2 = "2"

[section-2]
key1 = 2

Although a section follows the key rules, it can also contain the symbol '.'. This determines nested sections.

[section-1.part-1.x]

[section-1.part-1.y]

[section-1.part-2.x]

[section-2.z]

Thus, a section can contain both key-value pairs and other sections. The key and sub-section names cannot match.

[A]
key1 = 1

[A.B]
key2 = 3

[A.B.C]
key3 = 3

Comments

The config file may contain single-line comments. Comments start with the '#' symbol, except when '#' is inside a string value.

key1 = "value1"  # some comment
# another comment