123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261 |
- /*=============================================================================
- Copyright (c) 2001-2003 Dan Nuffer
- Copyright (c) 2001-2003 Joel de Guzman
- http://spirit.sourceforge.net/
- Use, modification and distribution is subject to the Boost Software
- License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- http://www.boost.org/LICENSE_1_0.txt)
- =============================================================================*/
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Full calculator example with variables
- // [ JDG 9/18/2002 ]
- //
- ///////////////////////////////////////////////////////////////////////////////
- #include <boost/spirit/include/classic_core.hpp>
- #include <boost/spirit/include/classic_symbols.hpp>
- #include <iostream>
- #include <stack>
- #include <functional>
- #include <string>
- using namespace std;
- using namespace BOOST_SPIRIT_CLASSIC_NS;
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Semantic actions
- //
- ///////////////////////////////////////////////////////////////////////////////
- struct push_num
- {
- push_num(stack<double>& eval_)
- : eval(eval_) {}
- void operator()(double n) const
- {
- eval.push(n);
- cout << "push\t" << n << endl;
- }
- stack<double>& eval;
- };
- template <typename op>
- struct do_op
- {
- do_op(op const& the_op, stack<double>& eval_)
- : m_op(the_op), eval(eval_) {}
- void operator()(char const*, char const*) const
- {
- double rhs = eval.top();
- eval.pop();
- double lhs = eval.top();
- eval.pop();
- cout << "popped " << lhs << " and " << rhs << " from the stack. ";
- cout << "pushing " << m_op(lhs, rhs) << " onto the stack.\n";
- eval.push(m_op(lhs, rhs));
- }
- op m_op;
- stack<double>& eval;
- };
- template <class op>
- do_op<op>
- make_op(op const& the_op, stack<double>& eval)
- {
- return do_op<op>(the_op, eval);
- }
- struct do_negate
- {
- do_negate(stack<double>& eval_)
- : eval(eval_) {}
- void operator()(char const*, char const*) const
- {
- double lhs = eval.top();
- eval.pop();
- cout << "popped " << lhs << " from the stack. ";
- cout << "pushing " << -lhs << " onto the stack.\n";
- eval.push(-lhs);
- }
- stack<double>& eval;
- };
- struct get_var
- {
- get_var(stack<double>& eval_)
- : eval(eval_) {}
- void operator()(double n) const
- {
- eval.push(n);
- cout << "push\t" << n << endl;
- }
- stack<double>& eval;
- };
- struct set_var
- {
- set_var(double*& var_)
- : var(var_) {}
- void operator()(double& n) const
- {
- var = &n;
- }
- double*& var;
- };
- struct redecl_var
- {
- void operator()(double& /*n*/) const
- {
- cout << "Warning. You are attempting to re-declare a var.\n";
- }
- };
- struct do_assign
- {
- do_assign(double*& var_, stack<double>& eval_)
- : var(var_), eval(eval_) {}
- void operator()(char const*, char const*) const
- {
- if (var != 0)
- {
- *var = eval.top();
- cout << "assigning\n";
- }
- }
- double*& var;
- stack<double>& eval;
- };
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Our calculator grammar
- //
- ///////////////////////////////////////////////////////////////////////////////
- struct calculator : public grammar<calculator>
- {
- calculator(stack<double>& eval_)
- : eval(eval_) {}
- template <typename ScannerT>
- struct definition
- {
- definition(calculator const& self)
- {
- factor =
- real_p[push_num(self.eval)]
- | vars[get_var(self.eval)]
- | '(' >> expression >> ')'
- | ('-' >> factor)[do_negate(self.eval)]
- ;
- term =
- factor
- >> *( ('*' >> factor)[make_op(multiplies<double>(), self.eval)]
- | ('/' >> factor)[make_op(divides<double>(), self.eval)]
- )
- ;
- expression =
- term
- >> *( ('+' >> term)[make_op(plus<double>(), self.eval)]
- | ('-' >> term)[make_op(minus<double>(), self.eval)]
- )
- ;
- assignment =
- vars[set_var(self.var)]
- >> '=' >> expression[do_assign(self.var, self.eval)]
- ;
- var_decl =
- lexeme_d
- [
- ((alpha_p >> *(alnum_p | '_'))
- - vars[redecl_var()])[vars.add]
- ]
- ;
- declaration =
- lexeme_d["var" >> space_p] >> var_decl >> *(',' >> var_decl)
- ;
- statement =
- declaration | assignment | '?' >> expression
- ;
- }
- symbols<double> vars;
- rule<ScannerT> statement, declaration, var_decl,
- assignment, expression, term, factor;
- rule<ScannerT> const&
- start() const { return statement; }
- };
- mutable double* var;
- stack<double>& eval;
- };
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Main program
- //
- ///////////////////////////////////////////////////////////////////////////////
- int
- main()
- {
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "\t\tThe calculator with variables...\n\n";
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "Type a statement...or [q or Q] to quit\n\n";
- cout << "Variables may be declared:\t\tExample: var i, j, k\n";
- cout << "Assigning to a variable:\t\tExample: i = 10 * j\n";
- cout << "To evaluate an expression:\t\tExample: ? i * 3.33E-3\n\n";
- stack<double> eval;
- calculator calc(eval); // Our parser
- string str;
- while (getline(cin, str))
- {
- if (str.empty() || str[0] == 'q' || str[0] == 'Q')
- break;
- parse_info<> info = parse(str.c_str(), calc, space_p);
- if (info.full)
- {
- cout << "-------------------------\n";
- cout << "Parsing succeeded\n";
- cout << "-------------------------\n";
- }
- else
- {
- cout << "-------------------------\n";
- cout << "Parsing failed\n";
- cout << "stopped at: \": " << info.stop << "\"\n";
- cout << "-------------------------\n";
- }
- }
- cout << "Bye... :-) \n\n";
- return 0;
- }
|