Hi, >> On Mon, 14 Apr 2003 22:56:06 -0400, >> Joey Hess <[EMAIL PROTECTED]> said:
Joey, I am going to be presumtuous and assume you would not mind this response going to a public list; I have condensed your questions down to the technical details, and you did imply that you considered filing a bug, so the email was not really personal and private. The reason is that there were a number of questions on IRC about similar topics. > But before the code for the provided C functions is put in the C > file, flex now includes a line that undefs yytext_ptr. Yes, part of cleaning up after itself. > I can work around it easily enough, by either moving the functions > to the top code block, or by making them explicitly call yyunput > instead of the unput macro. Putting it in the top code block won't work, since the yyunput function is first implicitly declared, and then explicitly declared static. yyunput is not an published asset; so may go away at any time. In other words, there are macros and stuff available only in the rules section, for use in actions. The `flex' input file consists of three sections, separated by a line containing only `%%'. definitions %% rules %% user code Flex sets up a number of things that are available in the rules section, and now cleans it all up before polluting the user namespace. Now, actions can be any C statement, but using functions that in turn use flex macros is going to be a problem since declaring the function is going to be problematic. Some of these changes were driven by the need to make flex scanners reentrant, others by hte requirements for having multiple scanners, perhaps with different options, in the same program. > Oh and why do I need an expliciy main() and yyweap() function now? > This code always worked before with flex generating stub functions > automatically. The real code is in the filters package, in > cockney.l, jive.l, and others. With multiple scanners now possible in the same program, flex would not know where to put main, obviously, it shoulkd not generate stubs in all the scanners generated. What is yyweap? manoj
%{ /* code block */ %} /* Definitions Section */ BW [ \t\n] SP [ \t]+ EW [ \t.,;!\?$] %% /* Rules Section */ foo /* after regex */ {unput(yytext[yyleng-1]);}; /* after code block */ /* Rules Section (indented) */ %% /* User Code Section */ int main(void) { yylex(); } int yywrap() { return 1; }
ps. An important potential problem when using `unput()' is that if you are using `%pointer' (the default), a call to `unput()' _destroys_ the contents of `yytext', starting with its rightmost character and devouring one character to the left with each call. If you need the value of `yytext' preserved after a call to `unput()' (as in the above example), you must either first copy it elsewhere, or build your scanner using `%array' instead. Also, `yytext' presently does _not_ dynamically grow if a call to `unput()' results in too much text being pushed back; instead, a run-time error results. This unput behaviour is not POSIX or lex compliant. Also, The `unput()' routine is not redefinable. -- The bomb will never go off. I speak as an expert in explosives. Admiral William Leahy, U.S. Atomic Bomb Project Manoj Srivastava <[EMAIL PROTECTED]> <http://www.debian.org/%7Esrivasta/> 1024R/C7261095 print CB D9 F4 12 68 07 E4 05 CC 2D 27 12 1D F5 E8 6E 1024D/BF24424C print 4966 F272 D093 B493 410B 924B 21BA DABB BF24 424C