Reducing cyclomatic complexity of function

[jmpc92]

Hey there, I'm in need of some help here. Any good ideas on how to break this one function into separate functions in order to avoid having so many nested loops? Any input will be appreciated. Thanks!

Relation* RelationalDatabase::select(string relation, vector<string> values) {
	Relation* operand = this->getRelation(relation);
	if (operand == NULL) return NULL;

	Relation* result = new Relation("query", operand->scheme);
	// loop over relation rows
	for (set<vector<string>>::iterator i = operand->rows.begin(); i != operand->rows.end(); i++) {
		bool add_row = true;
		vector<string> row = *i;
		for (unsigned int j = 0; j < values.size(); j++) {
			if (values[j].find("'") != string::npos && values[j] != row[j]) {
				add_row = false;
			}


			// make sure matching IDs also match value
			if (values[j].find("'") == string::npos) {
				for (unsigned int k = j + 1; k < values.size(); k++) {
					if (values[j] == values[k] && row[j] != row[k]) {
						add_row = false;
						break;
					}
				}
			}

			if (!add_row) break;
		}

		if (add_row) {
			result->addRow(row);
		}
	}

	return result;
}.

[kbw]

Do you realize that you're copying vectors?