Notation

Grammar

The grammar of Par is declared in Lexer and Syntax blocks. It uses the following notation:

• Sequences of capital letters like DIGIT represent lexer tokens

• Italic names in CamelCase like Item represent parser nonterminals

• Character sequences in monospace like type represent literals

• Characters may be represented using escape sequences, like \n

• • x^? means x, zero or once
  • x^* means x, zero or more
  • x⁺ means x, once or more
  • x^a..b means at least a and at most b of x

• x | y means either x or y

• [ and ] group characters together, like [x X] or [a-z]

• character sequences (and groups of them) can be negated by ~, like ~\n

• ( and ) group arbitrary rules for precedence