Prokee Syntax Notation

The Prokee Syntax Notation is a notation for syntax rules used by some prokee modules.

Characteristics of the syntax notation:

• Terminal symbols are written without quotation marks.
• There is no concatenation operator. Successive symbols are written one after the other (without a comma or space).
• There is no termination symbol ';' (or. '.'). The syntax rules are usually specified individually as separate string literals, which means that no termination symbol is necessary.
• For optional repetitions, "{ }" is omitted. Instead, three dots "..." are used to indicate optional continuation. Since repetition is always optional, the three points are always enclosed in square brackets (see examples below).
• Any Unicode characters can be used as terminal symbols. (Preferred encoding is UTF-8.)
• Spaces are not treated differently than other terminal symbols.
• If non-terminal symbols are to be used as terminal symbols, then a backslash can be prefixed to this symbol.
• As in EBNF, grouping is done with "( )" and optional parts are written within brackets "[ ]". And '|' is used for alternatives.
• Within angle brackets "<>", additional syntax specifications can be specified depending on the application.

	EBNF	Prokee Notation	Remarks
Terminal symbols	'a'	a	No single or double quotes
Termination symbol	'a';	a	No termination symbol
Concatenation	'a', 'b', 'c'	abc	No spaces, no concatenation operator
Alternatives with '|'	'a', 'b' | 'c'	ab|c
Grouping	'a', ( 'b' | 'c' )	a(b|c)
Optional parts	'a', [ 'b' ] , 'c'	a[b]c
Optional repetition, example 1	'a', { 'b' }, 'c'	a[b[...]]c	Optional repetition of the element left of [...]
Optional repetition, example 2	'a', 'b', { 'b' }, 'c'	ab[...]c
Optional repetition, example 3	'a', 'b', { 'a', 'b' }, 'c'	(ab)[...]c
Optional repetition (with separator)	'x', { ',', 'x' }	x[,...]	equal to x[(,x)[...]]