libs/spirit/classic/example/fundamental/position_iterator/position_iterator.cpp
/*=============================================================================
Copyright (c) 2002 Juan Carlos Arevalo-Baeza
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)
=============================================================================*/
///////////////////////////////////////////////////////////////////////////////
//
// A parser for a comma separated list of numbers,
// with positional error reporting
// See the "Position Iterator" chapter in the User's Guide.
//
// [ JCAB 9/28/2002 ]
//
///////////////////////////////////////////////////////////////////////////////
#include <boost/spirit/include/classic_core.hpp>
#include <boost/spirit/include/classic_position_iterator.hpp>
#include <boost/spirit/include/classic_functor_parser.hpp>
#include <iostream>
#include <fstream>
#include <vector>
///////////////////////////////////////////////////////////////////////////////
using namespace std;
using namespace BOOST_SPIRIT_CLASSIC_NS;
///////////////////////////////////////////////////////////////////////////////
//
// Our error reporting parsers
//
///////////////////////////////////////////////////////////////////////////////
std::ostream& operator<<(std::ostream& out, file_position const& lc)
{
return out <<
"\nFile:\t" << lc.file <<
"\nLine:\t" << lc.line <<
"\nCol:\t" << lc.column << endl;
}
struct error_report_parser {
char const* eol_msg;
char const* msg;
error_report_parser(char const* eol_msg_, char const* msg_):
eol_msg(eol_msg_),
msg (msg_)
{}
typedef nil_t result_t;
template <typename ScannerT>
int
operator()(ScannerT const& scan, result_t& /*result*/) const
{
if (scan.at_end()) {
if (eol_msg) {
file_position fpos = scan.first.get_position();
cerr << fpos << eol_msg << endl;
}
} else {
if (msg) {
file_position fpos = scan.first.get_position();
cerr << fpos << msg << endl;
}
}
return -1; // Fail.
}
};
typedef functor_parser<error_report_parser> error_report_p;
error_report_p
error_badnumber_or_eol =
error_report_parser(
"Expecting a number, but found the end of the file\n",
"Expecting a number, but found something else\n"
);
error_report_p
error_badnumber =
error_report_parser(
0,
"Expecting a number, but found something else\n"
);
error_report_p
error_comma =
error_report_parser(
0,
"Expecting a comma, but found something else\n"
);
///////////////////////////////////////////////////////////////////////////////
//
// Our comma separated list parser
//
///////////////////////////////////////////////////////////////////////////////
bool
parse_numbers(char const* filename, char const* str, vector<double>& v)
{
typedef position_iterator<char const*> iterator_t;
iterator_t begin(str, str + strlen(str), filename);
iterator_t end;
begin.set_tabchars(8);
return parse(begin, end,
// Begin grammar
(
(real_p[push_back_a(v)] | error_badnumber)
>> *(
(',' | error_comma)
>> (real_p[push_back_a(v)] | error_badnumber_or_eol)
)
)
,
// End grammar
space_p).full;
}
////////////////////////////////////////////////////////////////////////////
//
// Main program
//
////////////////////////////////////////////////////////////////////////////
int
main(int argc, char **argv)
{
cout << "/////////////////////////////////////////////////////////\n\n";
cout << "\tAn error-reporting parser for Spirit...\n\n";
cout << "Parses a comma separated list of numbers from a file.\n";
cout << "The numbers will be inserted in a vector of numbers\n\n";
cout << "/////////////////////////////////////////////////////////\n\n";
char str[65536];
char const* filename;
if (argc > 1) {
filename = argv[1];
ifstream file(filename);
file.get(str, sizeof(str), '\0');
} else {
filename = "<cin>";
cin.get(str, sizeof(str), '\0');
}
vector<double> v;
if (parse_numbers(filename, str, v))
{
cout << "-------------------------\n";
cout << "Parsing succeeded\n";
cout << str << " Parses OK: " << endl;
for (vector<double>::size_type i = 0; i < v.size(); ++i)
cout << i << ": " << v[i] << endl;
cout << "-------------------------\n";
}
else
{
cout << "-------------------------\n";
cout << "Parsing failed\n";
cout << "-------------------------\n";
}
cout << "Bye... :-) \n\n";
return 0;
}