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.

Changes to internal array sizes could be represented as follows:

Table 2-3 Internal Array Sizes

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 can be continued on succeeding lines by using braces to mark it.

The lex operator characters are:

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

Important lex variables, functions, and macros are:

Table 2-4 lex Variables, Functions, and Macros

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