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(automake.info)Yacc and Lex

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Yacc and Lex support
====================

   Automake has somewhat idiosyncratic support for Yacc and Lex.

   Automake assumes that the `.c' file generated by `yacc' (or `lex')
should be named using the basename of the input file.  That is, for a
yacc source file `foo.y', Automake will cause the intermediate file to
be named `foo.c' (as opposed to `y.tab.c', which is more traditional).

   The extension of a yacc source file is used to determine the
extension of the resulting `C' or `C++' file.  Files with the extension
`.y' will be turned into `.c' files; likewise, `.yy' will become `.cc';
`.y++', `c++'; and `.yxx', `.cxx'.

   Likewise, lex source files can be used to generate `C' or `C++'; the
extensions `.l', `.ll', `.l++', and `.lxx' are recognized.

   You should never explicitly mention the intermediate (`C' or `C++')
file in any `SOURCES' variable; only list the source file.

   The intermediate files generated by `yacc' (or `lex') will be
included in any distribution that is made.  That way the user doesn't
need to have `yacc' or `lex'.

   If a `yacc' source file is seen, then your `configure.in' must
define the variable `YACC'.  This is most easily done by invoking the
macro `AC_PROG_YACC' (*note Particular Program Checks:
(autoconf)Particular Programs.).

   Similarly, if a `lex' source file is seen, then your `configure.in'
must define the variable `LEX'.  You can use `AC_PROG_LEX' to do this
(Note: Particular Program Checks.).
Automake's `lex' support also requires that you use the `AC_DECL_YYTEXT'
macro--automake needs to know the value of `LEX_OUTPUT_ROOT'.  This is
all handled for you if you use the `AM_PROG_LEX' macro (Note: Macros).

   Automake makes it possible to include multiple `yacc' (or `lex')
source files in a single program.  Automake uses a small program called
`ylwrap' to run `yacc' (or `lex') in a subdirectory.  This is necessary
because yacc's output filename is fixed, and a parallel make could
conceivably invoke more than one instance of `yacc' simultaneously.
The `ylwrap' program is distributed with Automake.  It should appear in
the directory specified by `AC_CONFIG_AUX_DIR' (Note: Finding
`configure' Input.), or the current directory if that
macro is not used in `configure.in'.

   For `yacc', simply managing locking is insufficient.  The output of
`yacc' always uses the same symbol names internally, so it isn't
possible to link two `yacc' parsers into the same executable.

   We recommend using the following renaming hack used in `gdb':
     #define	yymaxdepth c_maxdepth
     #define	yyparse	c_parse
     #define	yylex	c_lex
     #define	yyerror	c_error
     #define	yylval	c_lval
     #define	yychar	c_char
     #define	yydebug	c_debug
     #define	yypact	c_pact
     #define	yyr1	c_r1
     #define	yyr2	c_r2
     #define	yydef	c_def
     #define	yychk	c_chk
     #define	yypgo	c_pgo
     #define	yyact	c_act
     #define	yyexca	c_exca
     #define yyerrflag c_errflag
     #define yynerrs	c_nerrs
     #define	yyps	c_ps
     #define	yypv	c_pv
     #define	yys	c_s
     #define	yy_yys	c_yys
     #define	yystate	c_state
     #define	yytmp	c_tmp
     #define	yyv	c_v
     #define	yy_yyv	c_yyv
     #define	yyval	c_val
     #define	yylloc	c_lloc
     #define yyreds	c_reds
     #define yytoks	c_toks
     #define yylhs	c_yylhs
     #define yylen	c_yylen
     #define yydefred c_yydefred
     #define yydgoto	c_yydgoto
     #define yysindex c_yysindex
     #define yyrindex c_yyrindex
     #define yygindex c_yygindex
     #define yytable	 c_yytable
     #define yycheck	 c_yycheck
     #define yyname   c_yyname
     #define yyrule   c_yyrule

   For each define, replace the `c_' prefix with whatever you like.
These defines work for `bison', `byacc', and traditional `yacc's.  If
you find a parser generator that uses a symbol not covered here, please
report the new name so it can be added to the list.