( User Values

Info Catalog ( Misc Macros ( Top ( Yacc
 14 Values Available To the User
 This chapter summarizes the various values available to the user in the
 rule actions.
 `char *yytext'
      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 `yytext' is a
      character pointer.  The opposite of `%array' is `%pointer', which
      is the default.
      You cannot use `%array' when generating C++ scanner classes (the
      `-+' flag).
 `int yyleng'
      holds the length of the current token.
 `FILE *yyin'
      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
 `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.
 `FILE *yyout'
      is the file to which `ECHO' actions are done.  It can be reassigned
      by the user.
      returns a `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 start condition.
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