Summary of source format

• The general form of a lex source file is
  
  definitions
  %%
  rules
  %%
  user routines

• The definitions section contains any combination of

  • definitions of abbreviations in the form
    
    name space translation

  • included code in the form
    
    %{
    C code
    %}

  • start conditions in the form

    Start name1 name2 . . .
    

  • changes to internal array sizes in the form

    %x nnn
    

    where nnn is a decimal integer representing an array size and x selects the parameter as follows:

    p	positions
    n	states
    e	tree nodes
    a	transitions
    k	packed character classes
    o	output array size

• Lines in the rules section have the form

  expression action
  

  where the action may be continued on succeeding lines by using braces to delimit it.

• The lex operator characters are

  " \ [] ^ - ? .  | () $ / {} <> +
  

• Important lex variables, functions, and macros are

  yytext[]	array of char
  yyleng	int
  yylex()	function
  yywrap()	function
  yymore()	function
  yyless(n)	function
  REJECT	macro
  ECHO	macro
  input()	macro
  unput(c)	macro
  output(c)	macro