bool EvalQuantifier()

in rapidjson/internal/regex.h [429:466]
33 lines of code
12 McCabe index (conditional complexity)

    bool EvalQuantifier(Stack<Allocator>& operandStack, unsigned n, unsigned m) {
        RAPIDJSON_ASSERT(n <= m);
        RAPIDJSON_ASSERT(operandStack.GetSize() >= sizeof(Frag));

        if (n == 0) {
            if (m == 0)                             // a{0} not support
                return false;
            else if (m == kInfinityQuantifier)
                Eval(operandStack, kZeroOrMore);    // a{0,} -> a*
            else {
                Eval(operandStack, kZeroOrOne);         // a{0,5} -> a?
                for (unsigned i = 0; i < m - 1; i++)
                    CloneTopOperand(operandStack);      // a{0,5} -> a? a? a? a? a?
                for (unsigned i = 0; i < m - 1; i++)
                    Eval(operandStack, kConcatenation); // a{0,5} -> a?a?a?a?a?
            }
            return true;
        }

        for (unsigned i = 0; i < n - 1; i++)        // a{3} -> a a a
            CloneTopOperand(operandStack);

        if (m == kInfinityQuantifier)
            Eval(operandStack, kOneOrMore);         // a{3,} -> a a a+
        else if (m > n) {
            CloneTopOperand(operandStack);          // a{3,5} -> a a a a
            Eval(operandStack, kZeroOrOne);         // a{3,5} -> a a a a?
            for (unsigned i = n; i < m - 1; i++)
                CloneTopOperand(operandStack);      // a{3,5} -> a a a a? a?
            for (unsigned i = n; i < m; i++)
                Eval(operandStack, kConcatenation); // a{3,5} -> a a aa?a?
        }

        for (unsigned i = 0; i < n - 1; i++)
            Eval(operandStack, kConcatenation);     // a{3} -> aaa, a{3,} -> aaa+, a{3.5} -> aaaa?a?

        return true;
    }