yacc - yet another compiler-compiler
yacc [-vVdlt] [-Q[y|n]] [-p sym_prefix] [-b file_prefix]
[-P parser] file
The yacc command converts a context-free grammar into a set of tables for
a simple automaton that executes an LALR(1) parsing algorithm. The
grammar may be ambiguous; specified precedence rules are used to break
ambiguities. yacc processes supplementary code set characters in program
comments and strings, and single-byte supplementary code set characters
in tokens, according to the locale specified in the LC_CTYPE environment
variable [see LANG on environ(5)].
The output file, y.tab.c, must be compiled by the C compiler to produce a
program yyparse. This program must be loaded with the lexical analyzer
program, yylex, as well as main and yyerror, an error handling routine.
These routines may be supplied by the user; the lex(1) command is useful
for creating lexical analyzers usable by yacc. A simple main and yyerror
are available in liby. The yyerror routine in liby.a has the following
signature: int yyerror(const char *). If a user wishes to have a
yyerror with a different signature, they must define the symbol
__my_yyerror at the top of their .y file.
-v Prepares the file y.output, which contains a description of the
parsing tables and a report on conflicts generated by
ambiguities in the grammar.
Use file_prefix instead of y as the prefix for all output
Use sym_prefix instead of yy as the prefix for all external
names produced by yacc. For X/Open compliance, when the
environment variable _XPG is set, then the -p option will work
as described in the previous sentence. If the environment
variable _XPG is not set, then the -p option will work as
described below in the -P option.
-P file Location of the common parser; the code contained here is
emitted verbatim by yacc in the generated code. This provides
compatibility with the old -p flag in AT&T yacc.
-d Generates the file y.tab.h with the #define statements that
associate the yacc-assigned ``token codes'' with the userdeclared
``token names.'' This association allows source files
other than y.tab.c to access the token codes.
-l Specifies that the code produced in y.tab.c will not contain
any #line constructs. This option should only be used after
the grammar and the associated actions are fully debugged.
-Q[y|n] The -Qy option puts the version stamping information in
y.tab.c. This allows you to know what version of yacc built
the file. The -Qn option (the default) writes no version
-t Compiles runtime debugging code by default. Runtime debugging
code is always generated in y.tab.c under conditional
compilation control. By default, this code is not included
when y.tab.c is compiled. Whether or not the -t option is
used, the runtime debugging code is under the control of
YYDEBUG, a preprocessor symbol. If YYDEBUG has a non-zero
value, then the debugging code is included. If its value is
zero, then the code will not be included. The size and
execution time of a program produced without the runtime
debugging code will be smaller and slightly faster.
-V Prints on the standard error output the version information for
defines for token names
yacc.tmp, yacc.debug, yacc.acts
temporary files; these names are used only if the TMPDIR environment
variable is not set. If TMPDIR is set, then these temporary files
are stored in that directory, using unique names.
parser prototype for C programs
The number of reduce-reduce and shift-reduce conflicts is reported on the
standard error output; a more detailed report is found in the y.output
file. Similarly, if some rules are not reachable from the start symbol,
this instance is also reported.
Because file names are fixed, at most one yacc process can be active in a
given directory at a given time.
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