I have been able to parse stuff more complicated than this, but now I am
stuck with something seemingly simpler.
The expression being parsed is the common sequence:
1,2-5,7,8-11
Question 1: Notice my approach. I first match the whole expression, with
"regex_match", to make sure that it is valid (that works great). Next, I
use "regex_iterator" to break down the parts. Is that good practice? Am
I being inefficient/redundant?
Question 2: My code below only extracts "range terms" ("x-y"), for some
reason I cannot extract "number terms".
As a workaround, I can always feed my data like this:
1-1,2-5,7-7,8-11
but, after a lot of tries, would love to learn how to do this properly.
TIA,
-Ramon
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#include <iostream>
#include
using namespace std;
bool
term_callback(const boost::match_resultsstd::string::const_iterator& what)
{
for (unsigned int i = 0; i < what.size(); i++) {
cout << "what[" << i << "]: " << what[i].str() << endl;
cout << "---------" << endl;
}
return true;
}
int
main(int argc, char *argv[])
{
const char hyphen = '-';
const char left_paren = '(';
const char right_paren = ')';
const char bar = '|';
const char comma = ',';
const char star = '*';
const string number = "[0-9]+";
const string range = number + hyphen + number;
const string term = left_paren + number + bar + range +
right_paren;
const string sequence = term + bar + left_paren + term + comma +
right_paren + star + term;
boost::regex expression(sequence);
boost::regex piece(range);
boost::cmatch matches;
char argument[1024];
strcpy(argument, argv[1]);
if (!boost::regex_match(argument, matches, expression)) {
cerr << "There is no match" << endl;
return 1;
}
string text = argument;
boost::sregex_iterator m1(text.begin(), text.end(), piece);
boost::sregex_iterator m2;
for_each(m1, m2, &term_callback);
return 0;
}
