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ImHex/source/helpers/math_evaluator.cpp

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#include "helpers/math_evaluator.hpp"
#include <string>
#include <queue>
#include <stack>
#include <stdexcept>
#include <cmath>
#include <cstdint>
#include <optional>
#include <numbers>
namespace hex {
s16 comparePrecedence(const Operator& a, const Operator& b) {
return (static_cast<s8>(a) & 0x0F0) - (static_cast<s8>(b) & 0x0F0);
}
bool isLeftAssociative(const Operator op) {
return (static_cast<u32>(op) & 0xF00) == 0;
}
std::pair<Operator, size_t> toOperator(std::string input) {
if (input.starts_with("##")) return { Operator::Combine, 2 };
if (input.starts_with("==")) return { Operator::Equals, 2 };
if (input.starts_with("!=")) return { Operator::NotEquals, 2 };
if (input.starts_with(">=")) return { Operator::GreaterThanOrEquals, 2 };
if (input.starts_with("<=")) return { Operator::LessThanOrEquals, 2 };
if (input.starts_with(">>")) return { Operator::ShiftRight, 2 };
if (input.starts_with("<<")) return { Operator::ShiftLeft, 2 };
if (input.starts_with("||")) return { Operator::Or, 2 };
if (input.starts_with("^^")) return { Operator::Xor, 2 };
if (input.starts_with("&&")) return { Operator::And, 2 };
if (input.starts_with("**")) return { Operator::Exponentiation, 2 };
if (input.starts_with(">")) return { Operator::GreaterThan, 1 };
if (input.starts_with("<")) return { Operator::LessThan, 1 };
if (input.starts_with("!")) return { Operator::Not, 1 };
if (input.starts_with("|")) return { Operator::BitwiseOr, 1 };
if (input.starts_with("^")) return { Operator::BitwiseXor, 1 };
if (input.starts_with("&")) return { Operator::BitwiseAnd, 1 };
if (input.starts_with("~")) return { Operator::BitwiseNot, 1 };
if (input.starts_with("+")) return { Operator::Addition, 1 };
if (input.starts_with("-")) return { Operator::Subtraction, 1 };
if (input.starts_with("*")) return { Operator::Multiplication, 1 };
if (input.starts_with("/")) return { Operator::Division, 1 };
if (input.starts_with("%")) return { Operator::Modulus, 1 };
if (input.starts_with("=")) return { Operator::Assign, 1 };
return { Operator::Invalid, 0 };
}
std::queue<Token> MathEvaluator::parseInput(const char *input) {
std::queue<Token> inputQueue;
char *prevPos = const_cast<char*>(input);
for (char *pos = prevPos; *pos != 0x00;) {
if (std::isdigit(*pos) || *pos == '.') {
auto number = std::strtold(pos, &pos);
if (*pos == 'x') {
pos--;
number = std::strtoull(pos, &pos, 0);
}
inputQueue.push(Token{ .type = TokenType::Number, .number = number });
} else if (*pos == '(') {
inputQueue.push(Token{ .type = TokenType::Bracket, .bracketType = BracketType::Left});
pos++;
} else if (*pos == ')') {
inputQueue.push(Token{ .type = TokenType::Bracket, .bracketType = BracketType::Right});
pos++;
} else if (std::isspace(*pos)) {
pos++;
} else {
auto [op, width] = toOperator(pos);
if (op != Operator::Invalid) {
inputQueue.push(Token{ .type = TokenType::Operator, .op = op });
pos += width;
} else {
Token token;
while (std::isalpha(*pos) || *pos == '_') {
token.name += *pos;
pos++;
}
if (*pos == '(') {
pos++;
u32 depth = 1;
std::vector<std::string> expressions;
expressions.emplace_back();
while (*pos != 0x00) {
if (*pos == '(') depth++;
else if (*pos == ')') depth--;
if (depth == 0)
break;
if (depth == 1 && *pos == ',') {
expressions.emplace_back();
pos++;
}
expressions.back() += *pos;
pos++;
}
pos++;
for (const auto &expression : expressions) {
if (expression == "" && expressions.size() > 1)
throw std::invalid_argument("Invalid function call syntax!");
else if (expression == "")
break;
auto inputQueue = parseInput(expression.c_str());
auto postfixTokens = toPostfix(inputQueue);
auto result = evaluate(postfixTokens);
if (!result.has_value())
throw std::invalid_argument("Invalid argument for function!");
token.arguments.push_back(result.value());
}
token.type = TokenType::Function;
inputQueue.push(token);
} else {
token.type = TokenType::Variable;
inputQueue.push(token);
}
}
}
if (prevPos == pos)
throw std::invalid_argument("Invalid syntax!");
prevPos = pos;
}
return inputQueue;
}
std::queue<Token> MathEvaluator::toPostfix(std::queue<Token> inputQueue) {
std::queue<Token> outputQueue;
std::stack<Token> operatorStack;
while (!inputQueue.empty()) {
Token currToken = inputQueue.front();
inputQueue.pop();
if (currToken.type == TokenType::Number || currToken.type == TokenType::Variable || currToken.type == TokenType::Function)
outputQueue.push(currToken);
else if (currToken.type == TokenType::Operator) {
while ((!operatorStack.empty())
&& (operatorStack.top().type == TokenType::Operator && currToken.type == TokenType::Operator && (comparePrecedence(operatorStack.top().op, currToken.op) > 0) || (comparePrecedence(operatorStack.top().op, currToken.op) == 0 && isLeftAssociative(currToken.op)))
&& operatorStack.top().type != TokenType::Bracket) {
outputQueue.push(operatorStack.top());
operatorStack.pop();
}
operatorStack.push(currToken);
} else if (currToken.type == TokenType::Bracket) {
if (currToken.bracketType == BracketType::Left)
operatorStack.push(currToken);
else {
if (operatorStack.empty())
throw std::invalid_argument("Mismatching parenthesis!");
while (operatorStack.top().type != TokenType::Bracket || (operatorStack.top().type == TokenType::Bracket && operatorStack.top().bracketType != BracketType::Left)) {
if (operatorStack.empty())
throw std::invalid_argument("Mismatching parenthesis!");
outputQueue.push(operatorStack.top());
operatorStack.pop();
}
operatorStack.pop();
}
}
}
while (!operatorStack.empty()) {
auto top = operatorStack.top();
if (top.type == TokenType::Bracket)
throw std::invalid_argument("Mismatching parenthesis!");
outputQueue.push(top);
operatorStack.pop();
}
return outputQueue;
}
std::optional<long double> MathEvaluator::evaluate(std::queue<Token> postfixTokens) {
std::stack<long double> evaluationStack;
while (!postfixTokens.empty()) {
auto front = postfixTokens.front();
postfixTokens.pop();
if (front.type == TokenType::Number)
evaluationStack.push(front.number);
else if (front.type == TokenType::Operator) {
long double rightOperand, leftOperand;
if (evaluationStack.size() < 2) {
if ((front.op == Operator::Addition || front.op == Operator::Subtraction || front.op == Operator::Not || front.op == Operator::BitwiseNot) && evaluationStack.size() == 1) {
rightOperand = evaluationStack.top(); evaluationStack.pop();
leftOperand = 0;
}
else throw std::invalid_argument("Not enough operands for operator!");
} else {
rightOperand = evaluationStack.top(); evaluationStack.pop();
leftOperand = evaluationStack.top(); evaluationStack.pop();
}
long double result = std::numeric_limits<long double>::quiet_NaN();
switch (front.op) {
default:
case Operator::Invalid:
throw std::invalid_argument("Invalid operator!");
case Operator::And:
result = static_cast<s64>(leftOperand) && static_cast<s64>(rightOperand);
break;
case Operator::Or:
result = static_cast<s64>(leftOperand) && static_cast<s64>(rightOperand);
break;
case Operator::Xor:
result = (static_cast<s64>(leftOperand) ^ static_cast<s64>(rightOperand)) > 0;
break;
case Operator::GreaterThan:
result = leftOperand > rightOperand;
break;
case Operator::LessThan:
result = leftOperand < rightOperand;
break;
case Operator::GreaterThanOrEquals:
result = leftOperand >= rightOperand;
break;
case Operator::LessThanOrEquals:
result = leftOperand <= rightOperand;
break;
case Operator::Equals:
result = leftOperand == rightOperand;
break;
case Operator::NotEquals:
result = leftOperand != rightOperand;
break;
case Operator::Not:
result = !static_cast<s64>(rightOperand);
break;
case Operator::BitwiseOr:
result = static_cast<s64>(leftOperand) | static_cast<s64>(rightOperand);
break;
case Operator::BitwiseXor:
result = static_cast<s64>(leftOperand) ^ static_cast<s64>(rightOperand);
break;
case Operator::BitwiseAnd:
result = static_cast<s64>(leftOperand) & static_cast<s64>(rightOperand);
break;
case Operator::BitwiseNot:
result = ~static_cast<s64>(rightOperand);
break;
case Operator::ShiftLeft:
result = static_cast<s64>(leftOperand) << static_cast<s64>(rightOperand);
break;
case Operator::ShiftRight:
result = static_cast<s64>(leftOperand) >> static_cast<s64>(rightOperand);
break;
case Operator::Addition:
result = leftOperand + rightOperand;
break;
case Operator::Subtraction:
result = leftOperand - rightOperand;
break;
case Operator::Multiplication:
result = leftOperand * rightOperand;
break;
case Operator::Division:
result = leftOperand / rightOperand;
break;
case Operator::Modulus:
result = std::fmod(leftOperand, rightOperand);
break;
case Operator::Exponentiation:
result = std::pow(leftOperand, rightOperand);
break;
case Operator::Combine:
result = (static_cast<u64>(leftOperand) << (64 - __builtin_clzll(static_cast<u64>(rightOperand)))) | static_cast<u64>(rightOperand);
break;
}
evaluationStack.push(result);
} else if (front.type == TokenType::Variable) {
if (this->m_variables.contains(front.name))
evaluationStack.push(this->m_variables.at(front.name));
else
throw std::invalid_argument("Unknown variable!");
} else if (front.type == TokenType::Function) {
if (!this->m_functions[front.name])
throw std::invalid_argument("Unknown function called!");
auto result = this->m_functions[front.name](front.arguments);
if (result.has_value())
evaluationStack.push(result.value());
} else
throw std::invalid_argument("Parenthesis in postfix expression!");
}
if (evaluationStack.empty())
return { };
else if (evaluationStack.size() > 1)
throw std::invalid_argument("Undigested input left!");
else
return evaluationStack.top();
}
std::optional<long double> MathEvaluator::evaluate(std::string input) {
auto inputQueue = parseInput(input.c_str());
std::string resultVariable = "ans";
{
std::queue<Token> queueCopy = inputQueue;
if (queueCopy.front().type == TokenType::Variable) {
resultVariable = queueCopy.front().name;
queueCopy.pop();
if (queueCopy.front().type != TokenType::Operator || queueCopy.front().op != Operator::Assign)
resultVariable = "ans";
else {
inputQueue.pop();
inputQueue.pop();
}
}
}
auto postfixTokens = toPostfix(inputQueue);
auto result = evaluate(postfixTokens);
if (result.has_value()) {
this->setVariable(resultVariable, result.value());
}
return result;
}
void MathEvaluator::setVariable(std::string name, long double value) {
this->m_variables[name] = value;
}
void MathEvaluator::setFunction(std::string name, std::function<std::optional<long double>(std::vector<long double>)> function, size_t minNumArgs, size_t maxNumArgs) {
this->m_functions[name] = [minNumArgs, maxNumArgs, function](auto args) {
if (args.size() < minNumArgs || args.size() > maxNumArgs)
throw std::invalid_argument("Invalid number of function arguments!");
return function(args);
};
}
void MathEvaluator::registerStandardVariables() {
this->setVariable("ans", 0);
}
void MathEvaluator::registerStandardFunctions() {
this->setFunction("sin", [](auto args){ return std::sin(args[0]); }, 1, 1);
this->setFunction("cos", [](auto args){ return std::cos(args[0]); }, 1, 1);
this->setFunction("tan", [](auto args){ return std::tan(args[0]); }, 1, 1);
this->setFunction("sqrt", [](auto args){ return std::sqrt(args[0]); }, 1, 1);
this->setFunction("ceil", [](auto args){ return std::ceil(args[0]); }, 1, 1);
this->setFunction("floor", [](auto args){ return std::floor(args[0]); }, 1, 1);
this->setFunction("sign", [](auto args){ return (args[0] > 0) ? 1 : (args[0] == 0) ? 0 : -1; }, 1, 1);
this->setFunction("abs", [](auto args){ return std::abs(args[0]); }, 1, 1);
this->setFunction("ln", [](auto args){ return std::log(args[0]); }, 1, 1);
this->setFunction("lb", [](auto args){ return std::log2(args[0]); }, 1, 1);
this->setFunction("log", [](auto args){ return args.size() == 1 ? std::log10(args[0]) : std::log(args[1]) / std::log(args[0]); }, 1, 2);
}
}
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