On Jun 13, 2017, at 3:09 PM, Belcourt, Kenneth via Boost-users <boost-users@lists.boost.org> wrote:

[ snip …]

Now we’re trying to automate some testing and we test our executable with an input file that has hundreds of lines like this:

--inverse 1 --tolerance 1e-15 --rank 2

--inverse 1 --tolerance 1e-15 --rank 3

--inverse 1 --tolerance 1e-15 --rank 4

where each line is a separate test case that we run with the specified options. I was looking for a program options parser that can parse a string, so I can read one line of input from this file into a string, and run that test case:

[ snip ]

The only program option parsers I see are parse_command_line, parse_config_file, and parse_environment. Is there an easy way (without having to construct an argc/argv data structure) to parse a string of program options?

char dashes[] = "--";

char dash[] = " -";

string::size_type loc;

string buffer;

// open file

ifstream ifp(s);

while (!ifp.eof() && ifp.good()) {

// read a line of input

getline(ifp, buffer);

// replace all occurrences of double-dash with newline

loc = buffer.rfind(dashes);

while (string::npos != loc) {

buffer[loc] = '\n';

buffer[loc+integer::one] = ' ';

loc = buffer.rfind(dashes);

}

// replace all occurrences of space-dash with newline

loc = buffer.rfind(dash);

while (string::npos != loc) {

buffer[loc+integer::one] = '\n';

loc = buffer.rfind(dash);

}

// check if first option has single dash without leading space

if ('-' == buffer[0]) {

// remove leading dash

buffer.erase(integer::zero, integer::one);

}

stringstream ss(buffer);

po::parse_config_file(ss, desc);

}

This still requires modifying our input files to use assignment form so this: