/** * I got the idea to make a boolean function maker * from the Nand2Tetris course. * * In fact, for those of you who don't know it, * you can create a boolean function by checking * the so called "Truth Table" and picking * up the rows in which the value of the * function is 1. At this point * you should create a unique condition * for which the row is true only in * that particular case. You can also * concatenate more expression by using * the "OR" boolean function. * * For example, if we check the Truth Table of the * XOR boolean expression, what we get is: * * a b Xor * 0 0 0 * 0 1 1 * 1 0 1 * 1 1 0 * * So, XOR gets 1 when: * * a and NOT b * b and NOT a * * @author: Maz */ #include #include #include #include #include class BooleanExpression { public: /** * This constructor initialize the "bits" vector * with pseudo-random N values [0, 1] * * @name BooleanExpression::BooleanExpression() * @param N */ BooleanExpression(int N) { for (int i = 0; i < N; i++) this->bits.push_back(rand()%2); this->vectorSize = this->bits.size(); }; /** * This method takes a lambda function as * parameter in order to cut the string * BooleanExpression::booleanExpression. * * I do this because when i'll build this * string in the BooleanExpression::makeBooleanExpression * method, i will basically leave an extra "OR " * at the end of the string. * * @param cutStr - The lambda function. * @return - The formatted boolean expression. */ template std::string get_booleanExpression(T cutStr) { return cutStr(this->booleanExpression); } /** * Simple getter for the "bits" vector. * I won't use it, tho. * * @return - The "bits" vector. * @see BooleanExpression::makeBooleanExpression */ std::vector get_bits() { return this->bits; } /** * What this method does is simply print all * the bits of the "bits" vector. * * The output will look like: * x y f * 0 0 0 * 1 1 1 * 1 0 1 * 0 0 0 * * @return */ void printBits() { /* * I used "printf()" 'cause IMHO is much more cleaner * in case you want to nicely format the console * output. */ printf("%s %s %s\n", "x", "y", "f"); for (int i = 0; i < this->vectorSize; i++) { printf("%d ", this->bits[i]); if(i!=0 && (i+1)%3==0) printf("\n"); } } /** * This method prepares the * BooleanExpression::booleanExpression string. * * @return */ void makeBooleanExpression() { /* * This two values are going to store * the value of the "x" and the "y" bit. */ int x = 0, y = 0; for (int i = 0; i < this->vectorSize; i++) { // If the "f" bit is equal to 1... if((i+1)%3==0 && bits[i] == 1) { x = bits[i-2]; // x bit y = bits[i-1]; // y bit // Build the expression if(x == 0 && y == 0) this->booleanExpression.append("NOT X and NOT Y OR "); else if(x == 0 && y == 1) this->booleanExpression.append("NOT X and Y OR "); else if(x == 1 && y == 0) this->booleanExpression.append("X and NOT Y OR "); else if(x == 1 && y == 1) this->booleanExpression.append("X and Y OR "); } } } private: std::string booleanExpression = ""; std::vector bits = {}; int vectorSize = this->bits.size(); // For debugging purposes only void _debugPrintBits() { if(this->vectorSize > 0) { std::cout << "[ "; std::for_each(this->bits.begin(), this->bits.end(), [](int el) -> void { std::cout << el << " "; }); std::cout << "]" << std::endl; } else { std::cout << "[ empty ]"; } } }; int main(void) { srand(time(0)); /** * Make a std::unique_ptr to BooleanExpression. * * There's no particular reason to use a pointer, * i just wanted to practice with the STL library. */ std::unique_ptr bool_exp{new BooleanExpression(12)}; bool_exp->printBits(); bool_exp->makeBooleanExpression(); /** * Print the result of the getter * BooleanExpression::get_booleanExpression. * * What the lambda does is basically to cut * the last three characters from the string passed * as an argument. * * This way i can delete the extra "OR " * i used when i built this string. */ std::cout << bool_exp->get_booleanExpression([](std::string s) -> std::string { return std::string("\nf(x, y) = " + s.substr(0, s.length()-3)); }); return 0; }

Boolean Function Maker