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<HTML><HEAD><TITLE>Using the ACCENT Compiler Compiler</TITLE></HEAD><BODY bgcolor="white"><TABLE cellspacing=20> <TR> <TD valign="top"> <img src="logo.gif"> </TD> <TD valign="bottom" align="left"> <a href="index.html">The Accent Compiler Compiler</a> <h1>Using the ACCENT Compiler Compiler</h1> </TD> </TR> <TR> <TD align="right" valign="top"> <!-- MENU --> <font face="helvetica"> <a href="index.html">Accent</a><br> <a href="overview.html">Overview</a><br> <a href="tutorial.html">Tutorial</a><br> <a href="language.html">Language</a><br> <a href="installation.html">Installation</a><br> Usage<br> <a href="lex.html">Lex</a><br> <a href="algorithms.html">Algorithms</a><br> <a href="distribution.html">Distribution</a><br> </font> </TD> <TD valign="top"> <!--- begin main content --><h3>How To Generate a Language Processor</h3><table><tr><td bgcolor="#e9e9d2"><pre> spec.acc spec.lex auxil.c art.o | | | | | | | | V V | | +------+ +---+ | | |ACCENT| |LEX| | | +------+ +---+ | | | | | | | | | | V V | | yygrammar.h lex.yy.c | | yygrammar.c | | | | | | | +------------+--+------+--------+ | V +--+ |CC| +--+ | | V calculator</pre></td></tr></table><h3>Accent</h3><i>Accent</i> is invoked with the command<pre> accent file</pre>This reads the grammar in <tt>file</tt>and generates the output files<tt>yygrammar.h</tt> and<tt>yygrammar.c</tt>.<p><tt>yygrammar.h</tt> contains definitions of token codesand a definition of the type <tt>YYSTYPE</tt> (which is onlyeffective if there is no previous definition specified by the user).<p><tt>yygrammar.c</tt> contains the grammar encoding and a generatedtree walker that performs the semantic actions specified by the user.<p>Example:<pre> accent spec.acc</pre>The file<a href="spec.acc">spec.acc</a>contains the <i>Accent</i> specification of a simple desk calculator.<h3>Lex</h3>The scanner should be generated with <i>Lex</i>.<i>Lex</i> is invoked by the command<pre> lex file</pre>which reads the specification in <tt>file</tt>,a table of regular expressions and corresponding actions,and generates a file <tt>yy.lex.c</tt>.This file contains the function <tt>yylex()</tt>,the lexical analyzer which is invoked by the parser.<p>Example:<pre> lex spec.lex</pre>The file<a href="spec.lex">spec.lex</a>contains the <i>Lex</i> specificationfor the desk calculator.<h3>Auxiliary Functions</h3>The user has to prepare some auxiliary functions:<p>There should be a <tt>main()</tt> function that invokesthe parser function <tt>yyparse()</tt>.<p><tt>yyerror(char *msg)</tt>is invoked by the parser when an error is detected. It should printthe text <tt>msg</tt> and perhaps the current line number.<p>The scanner needs a function <tt>yywrap()</tt>(it can be used to switch to a further input file).In its simplest form it just returns <tt>1</tt>(indicating no further input file).<p>In our example, the file <a href="auxil.c"><tt>auxil.c</tt></a>defines these functions.<h3>Accent Runtime</h3>To create a functioning parser one also has to supplythe <i>Accent Runtime</i>.This is contained in the file <tt>art.o</tt> in thedirectory <tt>art</tt> of the distribution.<h3>Compiling and Linking</h3>The <i>C</i> compiler is usedto compile the sources and create the object program.<p>Example:<pre>cc -o calculator yygrammar.c lex.yy.c auxil.c $ART</pre>(where <tt>$ART</tt> refers to the Accent runtime).<p>The file<a href="build"><tt>build</tt></a>contains a shell script to produce and run the desk calculator.<p>Invoking the optimizer during compilation increases parser speedby a factor of two.For the GNU C compiler you should specify <tt>-O3</tt> as an optionwhen compiling the Accent runtime and the generated program. <!--- end main content --> <br> <br> <font face="helvetica" size="1"> <a href="http://accent.compilertools.net">accent.compilertools.net</a> </font> </TD> </TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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