YACC(1) YACC(1)
NAME
yacc - yet another compiler-compiler
SYNOPSIS
yacc [ -vd ] grammar
DESCRIPTION
Yacc converts a context-free grammar into a set of tables
for a simple automaton which executes an LR(1) parsing algo-
rithm. The grammar may be ambiguous; specified precedence
rules are used to break ambiguities.
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 must
be supplied by the user; Lex(1) is useful for creating lexi-
cal analyzers usable by yacc.
If the -v flag is given, the file y.output is prepared,
which contains a description of the parsing tables and a
report on conflicts generated by ambiguities in the grammar.
If the -d flag is used, the file y.tab.h is generated with
the define statements that associate the yacc-assigned
`token codes' with the user-declared `token names'. This
allows source files other than y.tab.c to access the token
codes.
FILES
y.output
y.tab.c
y.tab.h defines for token names
yacc.tmp, yacc.acts temporary files
/usr/lib/yaccpar parser prototype for C programs
/lib/liby.a library with default `main' and `yyer-
ror'
SEE ALSO
lex(1)
LR Parsing by A. V. Aho and S. C. Johnson, Computing Sur-
veys, June, 1974.
YACC - Yet Another Compiler Compiler by S. C. Johnson.
DIAGNOSTICS
The number of reduce-reduce and shift-reduce conflicts is
reported on the standard output; a more detailed report is
found in the y.output file. Similarly, if some rules are
not reachable from the start symbol, this is also reported.
YACC(1) YACC(1)
BUGS
Because file names are fixed, at most one yacc process can
be active in a given directory at a time.