| 1 | // A parser for a comma separated list of numbers,
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| 2 | // with positional error reporting
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| 3 |
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| 4 | #include <boost/spirit/include/classic_core.hpp>
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| 5 | #include <boost/spirit/include/classic_position_iterator.hpp>
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| 6 | #include <boost/spirit/include/classic_functor_parser.hpp>
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| 7 | #include "boost/spirit/include/classic_multi_pass.hpp"
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| 8 | #include <iostream>
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| 9 | #include <fstream>
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| 10 | #include <sstream>
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| 11 | #include <vector>
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| 12 |
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| 13 | using namespace std;
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| 14 | using namespace BOOST_SPIRIT_CLASSIC_NS;
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| 15 |
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| 16 | std::ostream & operator<<(std::ostream & out, file_position const & lc) {
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| 17 |
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| 18 | return out << "\nFile:\t" << lc.file
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| 19 | << "\nLine:\t" << lc.line
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| 20 | << "\nCol:\t" << lc.column << endl;
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| 21 | }
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| 22 |
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| 23 | struct error_report_parser {
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| 24 |
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| 25 | char const * eol_msg;
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| 26 | char const * msg;
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| 27 |
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| 28 | error_report_parser(char const * eol_msg_, char const * msg_) :
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| 29 | eol_msg(eol_msg_),
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| 30 | msg (msg_) {
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| 31 | }
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| 32 |
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| 33 | typedef nil_t result_t;
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| 34 |
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| 35 | template <typename ScannerT>
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| 36 | int operator()(ScannerT const& scan, result_t& /*result*/) const {
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| 37 |
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| 38 | if (scan.at_end()) {
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| 39 | if (eol_msg) {
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| 40 | file_position fpos = scan.first.get_position();
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| 41 | cerr << fpos << eol_msg << endl;
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| 42 | }
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| 43 | } else {
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| 44 | if (msg) {
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| 45 | file_position fpos = scan.first.get_position();
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| 46 | cerr << fpos << msg << endl;
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| 47 | }
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| 48 | }
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| 49 |
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| 50 | return -1; // Fail.
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| 51 | }
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| 52 | };
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| 53 |
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| 54 | typedef functor_parser<error_report_parser> error_report_p;
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| 55 |
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| 56 | error_report_p
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| 57 | error_badnumber_or_eol =
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| 58 | error_report_parser(
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| 59 | "Expecting a number, but found the end of the file\n",
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| 60 | "Expecting a number, but found something else\n"
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| 61 | );
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| 62 |
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| 63 | error_report_p
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| 64 | error_badnumber =
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| 65 | error_report_parser(
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| 66 | 0,
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| 67 | "Expecting a number, but found something else\n"
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| 68 | );
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| 69 |
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| 70 | error_report_p
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| 71 | error_comma =
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| 72 | error_report_parser(
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| 73 | 0,
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| 74 | "Expecting a comma, but found something else\n"
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| 75 | );
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| 76 |
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| 77 | bool parse_numbers(istream & istr, vector<double> & v) {
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| 78 |
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| 79 | typedef multi_pass<istreambuf_iterator<char> > multi_pass_stream_iterator;
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| 80 | typedef position_iterator<multi_pass_stream_iterator> position_stream_iterator;
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| 81 |
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| 82 | multi_pass_stream_iterator multi_begin(
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| 83 | make_multi_pass(istreambuf_iterator<char>(istr)));
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| 84 |
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| 85 | multi_pass_stream_iterator multi_end(
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| 86 | make_multi_pass(istreambuf_iterator<char>()));
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| 87 |
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| 88 | position_stream_iterator pos_begin(multi_begin, multi_end, "internal string");
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| 89 | position_stream_iterator pos_end;
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| 90 |
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| 91 | pos_begin.set_tabchars(8);
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| 92 | return parse(pos_begin, pos_end,
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| 93 |
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| 94 | // Begin grammar
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| 95 | (
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| 96 | (real_p[push_back_a(v)] | error_badnumber)
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| 97 | >> *(
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| 98 | (',' | error_comma)
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| 99 | >> (real_p[push_back_a(v)] | error_badnumber_or_eol)
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| 100 | )
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| 101 | )
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| 102 | ,
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| 103 | // End grammar
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| 104 |
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| 105 | space_p).full;
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| 106 | }
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| 107 |
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| 108 | int main(int argc, char **argv) {
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| 109 |
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| 110 | istringstream itest("0, 1, 2");
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| 111 |
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| 112 | vector<double> v;
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| 113 | if (parse_numbers(itest, v)) {
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| 114 |
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| 115 | cout << "Parsing:\n";
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| 116 | cout << itest.str() << "\nParses OK: " << endl;
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| 117 |
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| 118 | for (vector<double>::size_type i = 0; i < v.size(); ++i)
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| 119 | cout << i << ": " << v[i] << endl;
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| 120 |
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| 121 | } else {
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| 122 |
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| 123 | cout << "Parsing failed\n";
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| 124 | }
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| 125 |
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| 126 | return 0;
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| 127 | }
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