Terminal Expressions

Terminals form the bottom of each grammar: they are compared against the actual input to check for a match.

Special Terminals

nothing: '' or ""

Zero-length literal, always matches at any position. Used to construct optional and any rules, which should be preferred for readability.

anything: .

Match any input of width one. May lead to excessive matches; prefer range or delimited literals.

Literal Terminals

literal: " :: " or ' :: '

Match any input exactly equal to the literal.

“def”

range: literal1 - literal2

Match any input smaller/larger or equal to literal1/literal2.

“a” - “z”

delimited: literal1 :: literal2

Match literal1 followed by the literal2 with arbitrary matches in between. More efficient version of literal1 ( !literal2 . ) literal2.

literal:

‘”’ :: ‘”’

“’” :: “’”