KCV

Key Colon Value 0.1.0

KCV is a plain-text data format, influenced by JSON and TOML. The goal is to reduce the syntax and semantics to a viable minimum. Therefore, KCV represents a one-dimensional dictionary, where each key maps to a list of atomic values. Nothing more.

KCV is released under the terms of the Creative Commons CC0.

Example

singleValue: 42
threeValues: "Hello" 3.14 yes
spaceGalore:
   1  23   4
  56   7  89
newline:no problem:no

Encoding

KCV must be a valid UTF-8 encoded document.

Whitespace characters are: space (U+0020), tab (U+0009), line feed (U+000A), and carriage return (U+000D).

Items

A KCV document contains an unordered set of zero or more items. Each item starts with a key, followed by an ordered list of zero or more values, until the next key or the end of the document.

Keys are marked with a suffixed colon (U+003A).

Key names start with an ASCII letter, followed by zero or more ASCII letters, ASCII digits, hyphens (U+002D), periods (U+002E), and underscores (U+005F). Key names are case-sensitive and must be unique per document.

Values can be Booleans, numbers, or strings.

Each value must be separated from a subsequent key or value by at least one whitespace character. Otherwise, whitespace is ignored around keys and values.

Booleans

Boolean constants are lowercase yes and no.

Numbers

Numbers can be decimal or hexadecimal.

Decimal numbers start with an integer, followed by an optional fraction, followed by an optional exponent.

An integer consists of one or more decimal digits. Redundant leading zeroes are ignored. A negative integer is prefixed with a hyphen-minus (U+002D).

A fraction starts with a period (U+002E), followed by one or more decimal digits.

An exponent starts with a case-insensitive E (U+0045 or U+0065), followed by an integer.

positive: 42
negative: -42
fraction: 3.14
exponent: 314e-2

Hexadecimal numbers start with a lowercase 0x, followed by one or more case-insensitive hexadecimal digits.

hexadecimal: 0xFFdd55

The range, precision, or implementation of numbers is not dictated by KCV.

Strings

Strings are enclosed in double quotes (U+0022).

foo: "This is a string."

In a string, the backslash (U+005C) begins an escape sequence. The following sequences are replaced with single characters:

\" = U+0022 (double quote)
\\ = U+005C (backslash)
\t = U+0009 (tab)
\n = U+000A (line feed)
\r = U+000D (carriage return)

Any Unicode scalar value can be included with a hexadecimal escape sequence. The format is either \uXXXX or \UXXXXXXXX, where X is a case-insensitive hex digit:

\u1E9E     = U+1E9E  (sharp S)
\U0001f603 = U+1F603 (smiling face)

Any other escape sequence is invalid. Except for escape sequences, all correctly encoded characters must be preserved verbatim. Incorrectly encoded characters must not be propagated.