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wisent: Wisent Grammar

 
 2 Wisent Grammar
 ****************
 
 In order for Wisent to parse a language, it must be described by a
 “context-free grammar”.  That is a grammar specified as rules that can
 be applied regardless of context.  For more information, see 
 (bison)Language and Grammar, in the Bison manual.
 
    The formal grammar is formulated using “terminal” and “nonterminal”
 items.  Terminals can be Emacs Lisp symbols or characters, and
 nonterminals are symbols only.
 
    Terminals (also known as “tokens”) represent the lexical elements of
 the language like numbers, strings, etc..
 
    For example ‘PLUS’ can represent the operator ‘+’.
 
    Nonterminal symbols are described by rules:
 
      RESULT ≡ COMPONENTS...
 
    ‘RESULT’ is a nonterminal that this rule describes and ‘COMPONENTS’
 are various terminals and nonterminals that are put together by this
 rule.
 
    For example, this rule:
 
      exp ≡ exp PLUS exp
 
    Says that two groupings of type ‘exp’, with a ‘PLUS’ token in
 between, can be combined into a larger grouping of type ‘exp’.
 

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