Function opt

quest/src/core/parser.cpp:54–54

captures sub-patterns for later extraction

    string group(string in) { return "(?:" + in + ")"; } // groups sub-patterns to control eval order
    string capt (string in) { return "("   + in + ")"; } // captures sub-patterns for later extraction
    string opt  (string in) { return group(in) + "?"; }  // groups and makes optional a sub-pattern

    // sub-numbers
    string mantissa = "[0-9]+" + opt("[.][0-9]*") + "|[.][0-9]+"; // e.g.  0  0.  .0  0.0