This chapter summarizes the various values available to the user in the rule actions.
holds the text of the current token. It may be modified but not lengthened (you cannot append characters to the end).
If the special directive
%array appears in the first section of
the scanner description, then
yytext is instead declared
char yytext[YYLMAX], where
YYLMAX is a macro definition
that you can redefine in the first section if you don’t like the default
value (generally 8KB). Using
%array results in somewhat slower
scanners, but the value of
yytext becomes immune to calls to
unput(), which potentially destroy its value when
a character pointer. The opposite of
which is the default.
You cannot use
%array when generating C++ scanner classes (the
holds the length of the current token.
is the file which by default
flex reads from. It may be
redefined but doing so only makes sense before scanning begins or after
an EOF has been encountered. Changing it in the midst of scanning will
have unexpected results since
flex buffers its input; use
yyrestart() instead. Once scanning terminates because an
end-of-file has been seen, you can assign yyin at the new input
file and then call the scanner again to continue scanning.
void yyrestart( FILE *new_file )
may be called to point yyin at the new input file. The
switch-over to the new file is immediate (any previously buffered-up
input is lost). Note that calling
yyrestart() with yyin
as an argument thus throws away the current input buffer and continues
scanning the same input file.
is the file to which
ECHO actions are done. It can be reassigned
by the user.
YY_BUFFER_STATE handle to the current buffer.
returns an integer value corresponding to the current start condition.
You can subsequently use this value with
BEGIN to return to that