eyacc(1) General Commands Manual eyacc(1)Name
eyacc - modified yacc allowing much improved error recovery
Syntax
eyacc [-v] [grammar]
Description
The command is an old version of which produces tables used by the Pascal system and its error recovery routines. The command fully enu-
merates test actions in its parser when an error token is in the look-ahead set. This prevents the parser from making undesirable reduc-
tions when an error occurs before the error is detected. The table format is different in than it was in the old as minor changes had been
made for efficiency reasons.
See Alsoyacc(1)eyacc(1)
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YACC(1) General Commands Manual 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 algorithm. 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 lexical 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 gener-
ated 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 `yyerror'
SEE ALSO lex(1)
LR Parsing by A. V. Aho and S. C. Johnson, Computing Surveys, 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.
BUGS
Because file names are fixed, at most one yacc process can be active in a given directory at a time.
YACC(1)