parser.md

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parser

constructor

parser(grammar<C, T>& g, const options& o = {});

Instantiates a new parser with a given grammar g and options o.

parser parser_with_default_options(g); // g is a grammar created before

parser<>::options o;
o.binarize = true;
parser<> parser_with_binarization(g, o);

methods

parser<C, T>::result parse(..., parse_options po);

Depending on your input source there are several parse methods available:

parser<C, T>::result parse(const C* data, size_t size, parse_options po);

parser<C, T>::result parse(std::basic_istream<C>& is, parse_options po);

parser<C, T>::result parse(const std::string& filename, parse_options po);

parser<C, T>::result parse(int filedescriptor, parse_options po); // WIN32 only

parse accepts an input data pointer with its size, an input stream is, a filename or a windows filedescriptor.

Another argument is parser::parse_options and it's optional.

• size length of the data
• max_length to specify a maximum length of the parsed input or 0 if not limiting (defaults to 0)
• eof, ie end of file character (defaults to std::char_traits<C>::eof())

parse method call returns parse<C, T>::result

parser p(g); // g is a grammar created before

// parse data from a data pointer
auto r1 = p.parse("1+2/1", 5);

// parse up to 5 characters from a file (by provided file descriptor)
auto r2 = p.parse("input.txt");

// parse up to 10 characters from an input stream
// terminating if an end of line reached
auto r3 = p.parse(is, { .max_length = 10, .eof = '\n' });

bool found();

found method returns true if the last parse method call matched a starting literal production rule. This means that the parsed input was parsed fully and successfully and there exists at least one tree with a root being the starting literal. If this method returns false use parser<C, T>::get_error() to obtain more information.

auto f = p.parse("3/3"); // p is a parser created before
if (p.found()) std::out << "input parsed successfuly\n";
else std::cerr << "parse error\n";

parser<C, T>::error get_error();

Returns parser<C, T>::error object containing information about a parsing error if any happened, ie. found() call returned false.

auto f = p.parse("3/"); // p is a parser created before
if (!p.found()) std::cerr << "parse error: " << p.get_error().to_str() << '\n';