Summary of Source Format.

The general form of a Lex source file is:

{definitions}
%%
{rules}
%%
{user subroutines}

1) Definitions, in the form ``name space translation''.

2) Included code, in the form ``space code''.

3) Included code, in the form

%{
code
%}

4) Start conditions, given in the form

%S name1 name2 ...

5) Character set tables, in the form

%T
number space character-string
...
%T

6) Changes to internal array sizes, in the form

%x  nnn

Letter	Parameter
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.

Regular expressions in Lex use the following operators:

x	the character "x"
"x"	an "x", even if x is an operator.
\x	an "x", even if x is an operator.
[xy]	the character x or y.
[x-z]	the characters x, y or z.
[^x]	any character but x.
.	any character but newline.
^x	an x at the beginning of a line.
<y>x	an x when Lex is in start condition y.
x$	an x at the end of a line.
x?	an optional x.
x*	0,1,2, ... instances of x.
x+	1,2,3, ... instances of x.
x|y	an x or a y.
(x)	an x.
x/y	an x but only if followed by y.
{xx}	the translation of xx from the definitions section.
x{m,n}	m through n occurrences of x