The YACC Parser Generator/Exercise 6 - Revision history

Root: /* How to Compile? */

2021-04-21T14:33:31Z

How to Compile?

← Older revision		Revision as of 14:33, 21 April 2021
Line 70:		Line 70:
	The YACC specification is processed as follows (files '''y.tab.h''', needed by the Flex-generated code, and '''y.tab.c'''):		The YACC specification is processed as follows (files '''y.tab.h''', needed by the Flex-generated code, and '''y.tab.c'''):

	~~byacc~~ -dtv maxint.y		bison -dtv maxint.y

	Compiling the C/C++ code (it is C++ simply because we programmed the extra code in that language):		Compiling the C/C++ code (it is C++ simply because we programmed the extra code in that language):

	g++ -std=c++11 -c lex.yy.c		g++ -std=c++17 -c lex.yy.c
	g++ -std=c++11 -c y.tab.c		g++ -std=c++17 -c y.tab.c
	g++ -o maxint y.tab.o lex.yy.o		g++ -o maxint y.tab.o lex.yy.o

	[[category:Compiladores]]		[[category:Compiladores]]
	[[category:Ensino]]		[[category:Ensino]]

Root: /* The Syntactic Analyzer (YACC) Specification */

2021-04-21T14:32:55Z

The Syntactic Analyzer (YACC) Specification

← Older revision		Revision as of 14:32, 21 April 2021
Line 35:		Line 35:
	#include <limits>		#include <limits>
	#include <iostream>		#include <iostream>
			extern int yylex();
	inline void yyerror(const char *msg) { std::cerr << msg << std::endl; }		inline void yyerror(const char *msg) { std::cerr << msg << std::endl; }
	%}		%}
Line 57:		Line 58:

	%%		%%
	~~extern int yylex();~~
	extern int yyparse();		extern int yyparse();
	int main() { return yyparse(); }		int main() { return yyparse(); }

Root: /* How to Compile? */

2020-04-02T14:08:51Z

How to Compile?

← Older revision		Revision as of 14:08, 2 April 2020
Line 80:		Line 80:
	[[category:Compiladores]]		[[category:Compiladores]]
	[[category:Ensino]]		[[category:Ensino]]
	~~[[category:PRIVATE]]~~

Root at 15:24, 27 March 2020

2020-03-27T15:24:10Z

← Older revision		Revision as of 15:24, 27 March 2020
Line 80:		Line 80:
	[[category:Compiladores]]		[[category:Compiladores]]
	[[category:Ensino]]		[[category:Ensino]]
			[[category:PRIVATE]]

Root at 11:22, 12 February 2019

2019-02-12T11:22:01Z

← Older revision		Revision as of 11:22, 12 February 2019
Line 9:		Line 9:

	The lexical analyzer ('''maxint.l''') is very simple and limited to recognizing the indispensable tokens.		The lexical analyzer ('''maxint.l''') is very simple and limited to recognizing the indispensable tokens.
	<text>		<source lang="text">
	%option noyywrap		%option noyywrap
	%{		%{
Line 26:		Line 26:

	%%		%%
	</~~text~~>		</source>

	== The Syntactic Analyzer (YACC) Specification ==		== The Syntactic Analyzer (YACC) Specification ==

	The syntactic analyzer ('''maxint.y''') will be built to immediately compute the maximum values in a syntax-directed fashion (as they occur).		The syntactic analyzer ('''maxint.y''') will be built to immediately compute the maximum values in a syntax-directed fashion (as they occur).
	<text>		<source lang="text">
	%{		%{
	#include <limits>		#include <limits>
Line 60:		Line 60:
	extern int yyparse();		extern int yyparse();
	int main() { return yyparse(); }		int main() { return yyparse(); }
	</~~text~~>		</source>

	== How to Compile? ==		== How to Compile? ==

Root: Created page with "{{TOCright}} == Problema == Considere uma linguagem constituída por uma sequência de intervalos, possivelmente vazia. Os intervalos são definidos por valores reais (os li..."

2016-06-21T18:48:51Z

Created page with "{{TOCright}} == Problema == Considere uma linguagem constituída por uma sequência de intervalos, possivelmente vazia. Os intervalos são definidos por valores reais (os li..."

New page

{{TOCright}}
== Problema ==

Considere uma linguagem constituída por uma sequência de intervalos, possivelmente vazia. Os intervalos são definidos por valores reais (os limites inferior e superior são separados por ''':'''). Os intervalos são separados entre si por vírgulas (''','''). A representação dos números reais é como em C++. Pretende-se determinar a largura do maior intervalo da sequência, ignorando os intervalos inválidos (em que o limite superior é menor que o limite inferior).

Escreva uma especificação YACC para o problema acima. Codifique toda a especificação (incluindo as zonas de declarações e de regras) e todas as funções auxiliares. '''Não utilizar variáveis globais.'''

== The Lexical Analyzer (Flex) Specification ==

The lexical analyzer ('''maxint.l''') is very simple and limited to recognizing the indispensable tokens.
<text>
%option noyywrap
%{
#include <string>
#include "y.tab.h"
%}
%%

[0-9]*\.[0-9]+([Ee][-+]?[0-9]+)? yylval.d = std::stod(yytext); return tDOUBLE;
[0-9]+\.[0-9]*([Ee][-+]?[0-9]+)? yylval.d = std::stod(yytext); return tDOUBLE;
[0-9]+([Ee][-+]?[0-9]+) yylval.d = std::stod(yytext); return tDOUBLE;

[,:] return *yytext;

.|\n ; /* ignore the rest */

%%
</text>

== The Syntactic Analyzer (YACC) Specification ==

The syntactic analyzer ('''maxint.y''') will be built to immediately compute the maximum values in a syntax-directed fashion (as they occur).
<text>
%{
#include <limits>
#include <iostream>
inline void yyerror(const char *msg) { std::cerr << msg << std::endl; }
%}

%union { double d; }

%token <d> tDOUBLE
%type <d> sequence interval

%%

top : sequence { std::cout << "longest interval: " << $1 << std::endl; }
| /* empty */ { std::cout << "empty sequence" << std::endl; }
;

sequence : interval { $$ = $1; }
| sequence ',' interval { $$ = std::max($1, $3); }
;

interval : tDOUBLE ':' tDOUBLE { $$ = $1 > $3 ? -1 : $3 - $1; }
;

%%
extern int yylex();
extern int yyparse();
int main() { return yyparse(); }
</text>

== How to Compile? ==

The Flex specification is processed as follows (the file '''lex.yy.c''' is produced):

flex maxint.l

The YACC specification is processed as follows (files '''y.tab.h''', needed by the Flex-generated code, and '''y.tab.c'''):

byacc -dtv maxint.y

Compiling the C/C++ code (it is C++ simply because we programmed the extra code in that language):

g++ -std=c++11 -c lex.yy.c
g++ -std=c++11 -c y.tab.c
g++ -o maxint y.tab.o lex.yy.o

[[category:Compiladores]]
[[category:Ensino]]