123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159 |
- /*=============================================================================
- Copyright (c) 2001-2003 Daniel Nuffer
- 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)
- =============================================================================*/
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Demonstrates the ASTs. This is discussed in the
- // "Trees" chapter in the Spirit User's Guide.
- //
- ///////////////////////////////////////////////////////////////////////////////
- #define BOOST_SPIRIT_DUMP_PARSETREE_AS_XML
- #include <boost/spirit/include/classic_core.hpp>
- #include <boost/spirit/include/classic_ast.hpp>
- #include <boost/spirit/include/classic_tree_to_xml.hpp>
- #include <boost/assert.hpp>
- #include "tree_calc_grammar.hpp"
- #include <iostream>
- #include <stack>
- #include <functional>
- #include <string>
- #if defined(BOOST_SPIRIT_DUMP_PARSETREE_AS_XML)
- #include <map>
- #endif
- // This example shows how to use an AST.
- ////////////////////////////////////////////////////////////////////////////
- using namespace std;
- using namespace BOOST_SPIRIT_CLASSIC_NS;
- typedef char const* iterator_t;
- typedef tree_match<iterator_t> parse_tree_match_t;
- typedef parse_tree_match_t::tree_iterator iter_t;
- ////////////////////////////////////////////////////////////////////////////
- long evaluate(parse_tree_match_t hit);
- long eval_expression(iter_t const& i);
- long evaluate(tree_parse_info<> info)
- {
- return eval_expression(info.trees.begin());
- }
- long eval_expression(iter_t const& i)
- {
- cout << "In eval_expression. i->value = " <<
- string(i->value.begin(), i->value.end()) <<
- " i->children.size() = " << i->children.size() << endl;
- if (i->value.id() == calculator::integerID)
- {
- BOOST_ASSERT(i->children.size() == 0);
- // extract integer (not always delimited by '\0')
- string integer(i->value.begin(), i->value.end());
- return strtol(integer.c_str(), 0, 10);
- }
- else if (i->value.id() == calculator::factorID)
- {
- // factor can only be unary minus
- BOOST_ASSERT(*i->value.begin() == '-');
- return - eval_expression(i->children.begin());
- }
- else if (i->value.id() == calculator::termID)
- {
- if (*i->value.begin() == '*')
- {
- BOOST_ASSERT(i->children.size() == 2);
- return eval_expression(i->children.begin()) *
- eval_expression(i->children.begin()+1);
- }
- else if (*i->value.begin() == '/')
- {
- BOOST_ASSERT(i->children.size() == 2);
- return eval_expression(i->children.begin()) /
- eval_expression(i->children.begin()+1);
- }
- else
- BOOST_ASSERT(0);
- }
- else if (i->value.id() == calculator::expressionID)
- {
- if (*i->value.begin() == '+')
- {
- BOOST_ASSERT(i->children.size() == 2);
- return eval_expression(i->children.begin()) +
- eval_expression(i->children.begin()+1);
- }
- else if (*i->value.begin() == '-')
- {
- BOOST_ASSERT(i->children.size() == 2);
- return eval_expression(i->children.begin()) -
- eval_expression(i->children.begin()+1);
- }
- else
- BOOST_ASSERT(0);
- }
- else
- {
- BOOST_ASSERT(0); // error
- }
- return 0;
- }
- ////////////////////////////////////////////////////////////////////////////
- int
- main()
- {
- // look in tree_calc_grammar for the definition of calculator
- calculator calc;
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "\t\tThe simplest working calculator...\n\n";
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "Type an expression...or [q or Q] to quit\n\n";
- string str;
- while (getline(cin, str))
- {
- if (str.empty() || str[0] == 'q' || str[0] == 'Q')
- break;
- tree_parse_info<> info = ast_parse(str.c_str(), calc);
- if (info.full)
- {
- #if defined(BOOST_SPIRIT_DUMP_PARSETREE_AS_XML)
- // dump parse tree as XML
- std::map<parser_id, std::string> rule_names;
- rule_names[calculator::integerID] = "integer";
- rule_names[calculator::factorID] = "factor";
- rule_names[calculator::termID] = "term";
- rule_names[calculator::expressionID] = "expression";
- tree_to_xml(cout, info.trees, str.c_str(), rule_names);
- #endif
- // print the result
- cout << "parsing succeeded\n";
- cout << "result = " << evaluate(info) << "\n\n";
- }
- else
- {
- cout << "parsing failed\n";
- }
- }
- cout << "Bye... :-) \n\n";
- return 0;
- }
|