170 lines
7.8 KiB
HTML
170 lines
7.8 KiB
HTML
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<title>yacc(1) - Plan 9 from User Space</title>
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<tr><td width=20><td>
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<tr><td width=20><td><b>YACC(1)</b><td align=right><b>YACC(1)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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yacc – yet another compiler-compiler<br>
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</table>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>yacc</font></tt> [ <i>option ...</i> ] <i>grammar<br>
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</i>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<i>Yacc</i> converts a context-free grammar and translation code into
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a set of tables for an LR(1) parser and translator. The grammar
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may be ambiguous; specified precedence rules are used to break
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ambiguities.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The output file, <tt><font size=+1>y.tab.c</font></tt>, must be compiled by the C compiler to
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produce a program <tt><font size=+1>yyparse</font></tt>. This program must be loaded with a
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lexical analyzer function, <tt><font size=+1>yylex(void)</font></tt> (often generated by <a href="../man1/lex.html"><i>lex</i>(1)</a>),
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with a <tt><font size=+1>main(int argc, char *argv[])</font></tt> program, and with an error
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handling routine,
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<tt><font size=+1>yyerror(char*)</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The options are<br>
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<tt><font size=+1>−o</font></tt> <i>output</i> Direct output to the specified file instead of <tt><font size=+1>y.tab.c</font></tt>.<br>
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<tt><font size=+1>−D</font></tt><i>n</i> Create file <tt><font size=+1>y.debug</font></tt>, containing diagnostic messages. To incorporate
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them in the parser, compile it with preprocessor symbol <tt><font size=+1>yydebug</font></tt>
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defined. The amount of diagnostic output from the parser is regulated
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by value <i>n</i>. The value 0 reports errors; 1 reports reductions;
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higher values (up to 4) include
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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more information about state transitions.<br>
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</table>
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</table>
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<tt><font size=+1>−v</font></tt> Create file <tt><font size=+1>y.output</font></tt>, containing a description of the parsing
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tables and of conflicts arising from ambiguities in the grammar.<br>
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<tt><font size=+1>−d</font></tt> Create file <tt><font size=+1>y.tab.h</font></tt>, containing <tt><font size=+1>#define</font></tt> statements that associate
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<i>yacc</i>-assigned ‘token codes’ with user-declared ‘token names’.
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Include it in source files other than <tt><font size=+1>y.tab.c</font></tt> to give access to
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the token codes.<br>
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<tt><font size=+1>−s</font></tt> <i>stem</i> Change the prefix <tt><font size=+1>y</font></tt> of the file names <tt><font size=+1>y.tab.c</font></tt>, <tt><font size=+1>y.tab.h</font></tt>,
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<tt><font size=+1>y.debug</font></tt>, and <tt><font size=+1>y.output</font></tt> to <i>stem</i>.<br>
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<tt><font size=+1>−S</font></tt> Write a parser that uses Stdio instead of the <tt><font size=+1>print</font></tt> routines
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in libc.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The specification of <i>yacc</i> itself is essentially the same as the
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UNIX version described in the references mentioned below. Besides
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the <tt><font size=+1>−D</font></tt> option, the main relevant differences are:<br>
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The interface to the C environment is by default through <tt><font size=+1><libc.h></font></tt>
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rather than <tt><font size=+1><stdio.h></font></tt>; the <tt><font size=+1>−S</font></tt> option reverses this.<br>
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The parser accepts UTF input text (see <a href="../man7/utf.html"><i>utf</i>(7)</a>), which has a couple
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of effects. First, the return value of <tt><font size=+1>yylex()</font></tt> no longer fits
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in a <tt><font size=+1>short</font></tt>; second, the starting value for non-terminals is now
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0xE000 rather than 257.<br>
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The generated parser can be recursive: actions can call <i>yyparse</i>,
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for example to implement a sort of <tt><font size=+1>#include</font></tt> statement in an interpreter.<br>
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Finally, some undocumented inner workings of the parser have been
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changed, which may affect programs that know too much about its
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structure.<br>
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</table>
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</table>
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<p><font size=+1><b>FILES </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>y.output<br>
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y.tab.c<br>
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y.tab.h<br>
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y.debug<br>
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y.tmp.*</font></tt> temporary file<br>
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<tt><font size=+1>y.acts.*</font></tt> temporary file<br>
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<tt><font size=+1>/usr/local/plan9/lib/yaccpar<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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parser prototype<br>
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</table>
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</table>
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<tt><font size=+1>/usr/local/plan9/lib/yaccpars<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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parser prototype using stdio<br>
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</table>
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</table>
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</table>
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<p><font size=+1><b>SOURCE </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>/usr/local/plan9/src/cmd/yacc.c<br>
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</font></tt>
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</table>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<a href="../man1/lex.html"><i>lex</i>(1)</a><br>
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S. C. Johnson and R. Sethi, “Yacc: A parser generator”, <i>Unix Research
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System Programmer’s Manual,</i> Tenth Edition, Volume 2<br>
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B. W. Kernighan and Rob Pike, <i>The UNIX Programming Environment,</i>
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Prentice Hall, 1984<br>
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</table>
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<p><font size=+1><b>BUGS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The parser may not have full information when it writes to <tt><font size=+1>y.debug</font></tt>
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so that the names of the tokens returned by <tt><font size=+1>yylex</font></tt> may be missing.<br>
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</table>
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<td width=20>
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<tr height=20><td>
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</table>
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<!-- TRAILER -->
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=15><td width=10><td><td width=10>
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<tr><td><td>
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<center>
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<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
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</center>
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</table>
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<!-- TRAILER -->
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</body></html>
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