The Concepts of Bison
*********************

   This chapter introduces many of the basic concepts without which the
details of Bison will not make sense.  If you do not already know how to
use Bison or Yacc, we suggest you start by reading this chapter
carefully.

* Menu:

* Language and Grammar   Languages and context-free grammars,
                            as mathematical ideas.
* Grammar in Bison   How we represent grammars for Bison's sake.
* Semantic Values    Each token or syntactic grouping can have
                        a semantic value (the value of an integer,
                        the name of an identifier, etc.).
* Semantic Actions   Each rule can have an action containing C code.
* Bison Parser       What are Bison's input and output,
                        how is the output used?
* Stages             Stages in writing and running Bison grammars.
* Grammar Layout     Overall structure of a Bison grammar file.