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bison中一个calc的C++版实现，区别于传统的C语言实现，我这边整理了一个可编译的版本用以参考
calc++-driver.h
#ifndef CALCXX_DRIVER_HH
# define CALCXX_DRIVER_HH
# include <string>
# include <map>
# include "calc++-parser.h"// Tell Flex the lexer's prototype ...
# define YY_DECL \yy::calcxx_parser::token_type \yylex (yy::calcxx_parser::semantic_type* yylval, \yy::calcxx_parser::location_type* yylloc, \calcxx_driver& driver)// ... and declare it for the parser's sake.
YY_DECL;// Conducting the whole scanning and parsing of Calc++.
class calcxx_driver
{
public:calcxx_driver ();virtual ~calcxx_driver ();std::map<std::string, int> variables;int result;// Handling the scanner.void scan_begin ();void scan_end ();bool trace_scanning;// Run the parser. Return 0 on success.int parse (const std::string& f);std::string file;bool trace_parsing;// Error handling.void error (const yy::location& l, const std::string& m);void error (const std::string& m);
};
#endif // ! CALCXX_DRIVER_HH
calc++-driver.cpp
#include "calc++-driver.h"
#include "calc++-parser.h"calcxx_driver::calcxx_driver (): trace_scanning (false), trace_parsing (false)
{variables["one"] = 1;variables["two"] = 2;
}calcxx_driver::~calcxx_driver ()
{
}int
calcxx_driver::parse (const std::string &f)
{file = f;scan_begin ();yy::calcxx_parser parser (*this);parser.set_debug_level (trace_parsing);int res = parser.parse ();scan_end ();return res;
}void
calcxx_driver::error (const yy::location& l, const std::string& m)
{std::cerr << l << ": " << m << std::endl;
}void
calcxx_driver::error (const std::string& m)
{std::cerr << m << std::endl;
}
calc++-scanner.l
%{ /* -*- C++ -*- */
# include <cstdlib>
# include <cerrno>
# include <climits>
# include <string>
# include "calc++-driver.h"
# include "calc++-parser.h"/* Work around an incompatibility in flex (at least versions2.5.31 through 2.5.33): it generates code that doesnot conform to C89. See Debian bug 333231<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>. */
# undef yywrap
# define yywrap() 1/* By default yylex returns int, we use token_type.Unfortunately yyterminate by default returns 0, which isnot of token_type. */
#define yyterminate() return token::END
%}%option noyywrap nounput batch debug nounistd never-interactiveid [a-zA-Z][a-zA-Z_0-9]*
int [0-9]+
blank [ \t]%{
# define YY_USER_ACTION yylloc->columns (yyleng);
%}
%%
%{yylloc->step ();
%}
{blank}+ yylloc->step ();
[\n]+ yylloc->lines (yyleng); yylloc->step ();%{typedef yy::calcxx_parser::token token;
%}/* Convert ints to the actual type of tokens. */
[-+*/] return yy::calcxx_parser::token_type (yytext[0]);":=" return token::ASSIGN;{int} {errno = 0;long n = strtol (yytext, NULL, 10);if (! (INT_MIN <= n && n <= INT_MAX && errno != ERANGE))driver.error (*yylloc, "integer is out of range");yylval->ival = n;return token::NUMBER;}{id} {yylval->sval = new std::string (yytext);return token::IDENTIFIER;}. driver.error (*yylloc, "invalid character");
%%
void
calcxx_driver::scan_begin ()
{yy_flex_debug = trace_scanning;if (file.empty () || file == "-")yyin = stdin;else if (!(yyin = fopen (file.c_str (), "r"))){error ("cannot open " + file + ": " + strerror(errno));exit (EXIT_FAILURE);}
}void
calcxx_driver::scan_end ()
{fclose (yyin);
}
calc++-parser.y
%skeleton "lalr1.cc" /* -*- C++ -*- */
//%require "2.7"
%defines
%define parser_class_name "calcxx_parser"%code requires {
# include <string>
class calcxx_driver;
}// The parsing context.
%parse-param { calcxx_driver& driver }
%lex-param { calcxx_driver& driver }%locations
%initial-action
{
// Initialize the initial location.
@$.begin.filename = @$.end.filename = &driver.file;
};%debug
%error-verbose// Symbols.
%union
{int ival;std::string *sval;
};%code {
# include "calc++-driver.h"
}%token END 0 "end of file"
%token ASSIGN ":="
%token <sval> IDENTIFIER "identifier"
%token <ival> NUMBER "number"
%type <ival> exp%printer { std::cout << *$$; } "identifier"
%destructor { delete $$; } "identifier"%printer { std::cout << $$; } <ival>%%
%start unit;
unit: assignments exp { driver.result = $2; };assignments:/* Nothing. */ {}| assignments assignment {};assignment:"identifier" ":=" exp{ driver.variables[*$1] = $3; delete $1; };%left '+' '-';
%left '*' '/';
exp: exp '+' exp { $$ = $1 + $3; }| exp '-' exp { $$ = $1 - $3; }| exp '*' exp { $$ = $1 * $3; }| exp '/' exp { $$ = $1 / $3; }| "identifier" { $$ = driver.variables[*$1]; delete $1; }| "number" { $$ = $1; };
%%void
yy::calcxx_parser::error (const yy::calcxx_parser::location_type& l,const std::string& m)
{driver.error (l, m);
}
main.cpp
#include <iostream>
#include "calc++-driver.h"int
main (int argc, char *argv[])
{calcxx_driver driver;for (int i = 1; i < argc; ++i){if (argv[i] == std::string ("-p"))driver.trace_parsing = true;else if (argv[i] == std::string ("-s"))driver.trace_scanning = true;else if (!driver.parse (argv[i]))std::cout << driver.result << std::endl;}return 0;
}
最后对应的Makefile
all: calc++.execalc++.exe: calc++-driver.o calc++-parser.o calc++-scanner.o main.og++ -o calc++.exe calc++-driver.o calc++-parser.o calc++-scanner.o main.ocalc++-driver.o: calc++-driver.cpp calc++-driver.h calc++-parser.hg++ -c calc++-driver.cppcalc++-parser.o: calc++-parser.cpp calc++-parser.h calc++-driver.hg++ -c calc++-parser.cppcalc++-parser.cpp calc++-parser.h: calc++-parser.ybison --defines=calc++-parser.h -ocalc++-parser.cpp calc++-parser.ycalc++-scanner.o: calc++-scanner.cpp calc++-parser.h calc++-driver.hg++ -c calc++-scanner.cppcalc++-scanner.cpp: calc++-scanner.lflex -ocalc++-scanner.cpp calc++-scanner.lmain.o:.PHONY: clean
clean:-rm *.o calc++-parser.h calc++-parser.cpp calc++-scanner.cpp location.hh position.hh stack.hh calc++.exe
注意：在lexer文件中有这样的选项
%option .. nounistd never-interactive
其目的是避免在VC++中出现的编译错误 Cannot open include file: 'unistd.h'
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