Documented the header file kludge, (in anticipation of buffering Section 1.)

diff --git a/main.c b/main.c
index 28c91b7436eb9b633f6ef6d63a7cb0db45676c00..16a2f886835449df5145cef53125f51f1e0bc8c1 100644 (file)
--- a/main.c
+++ b/main.c
@@ -199,6 +199,7 @@ void check_options()
                use_read = false;
                }
 
+       /* See comments in flexend() for an explanation of this error condition. */
        if ( use_stdout && headerfilename )
            flexerror( _( "Can't specify header option if writing to stdout.") );
 
@@ -477,6 +478,16 @@ int exit_status;
                                skelname );
                }
 
+       /* flex generates the header file by rewinding the output FILE
+        * pointer. However, since we can't rewind stdout, we must disallow
+        * %option header if we are writing to stdout. This is a kludge. 
+        * This kludge can be rewritten when we get around to buffering
+        * Section 1 of the input file, because then we'll have seen all the
+        * %options BEFORE we begin generating the scanner. The lack of
+        * buffering causes other problems, too. For example, it is the
+        * reason we currently can't provide a mechanism to allow the user
+        * to inject arbtrary class members into the generated C++ scanner. - JM
+        */
        if ( headerfilename && exit_status == 0 && outfile_created && !ferror(stdout))
                {
                        /* Copy the file we just wrote to a header file. */