Incomplete last line won't match

Greetings,


Using Flex 2.5.4 and Berkeley Yacc, I have finished a fairly complete
program for analyzing the syntax and logic of a user's source file.
Unfortunately, my program has one glaring flaw. If a user provides a
source file whose last line does not have a newline character at the
end, the parser will fail to recognize all of the rules that it should
and the last line ends up getting echoed to my output file. All of my
other rules and grammar will be fulfilled, but for the last line only
the initial condition rule (.*\n?) will be matched and then no other.
If I simply add a newline to the last line of the file, the code then
works, but I can't seem to get this to work in my program using unput
without getting a buffer error. Any suggestions are most appreciated.


For example, imagine these are the last 3 lines of the source file
where the last line does not have a newline character after the last
letter (testing on the UNIX):


V BL24C 10 A 24 0082-0091
Q BLANK FIELD
C ++++++++++ = INAPPLICABLE, ALWAYS BLANK


The simplified applicable rules should be:


.*\n? {
                                BEGIN COED;
                                yyless(0);
                                }


<COED>^V{ws} {
                                BEGIN V;
                                return VSYM;
                                }


<V>{ident}{ws}{vstat} {
                                BEGIN 0;
                                return VSTAT;
                                }


<COED>^Q{ws} {
                                BEGIN Q;
                                return QSYM;
                                }


<Q>.+\n? {
                                BEGIN 0;
                                return QSTAT;
                                }


<COED>^C{ws} {
                                BEGIN C;
                                return CSYM;
                                }


<C>(\*{1,20}{ws})?{cval}{1,99}({ws}?-{ws}?{cval}{1,99})?{ws}={ws}.+\n? {
                                BEGIN 0;
                                return CSTAT;
                                }


which should close out these simplified grammar statements:


Vgroup : Vstatement Qgroup Cgroup
                                ;


Vstatement : VSYM VSTAT
                                ;


Qgroup : /* empty */
                                | Qstatement
                                ;


Qstatement : QSYM QSTAT
                                ;


Cgroup : /* empty */
                                | Cgroup Cstatement
                                | Cstatement
                                ;


Cstatement : CSYM CSTAT
                                ;
[I'd define my own YY_INPUT that forces a newline at the end of the last
line. -John]

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