109 lines
3.4 KiB
C++
109 lines
3.4 KiB
C++
#include "expression.h"
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#include "./lib/peglib.h"
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#include <QByteArray>
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#include <QString>
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#include <cmath>
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#include <functional>
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peg::parser math(R"(
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EXPRESSION <- P0
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P0 <- P1 (P1_OPERATOR P1)*
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P1 <- P2 (P2_OPERATOR P2)*
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P2 <- P3 (P3_OPERATOR P3)*
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P3 <- NUMBER / FUNCTION / VARIABLE / '(' P0 ')'
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P1_OPERATOR <- < [-+] >
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P2_OPERATOR <- < [/*] >
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P3_OPERATOR <- < '^' >
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NUMBER <- < '-'? [0-9]+ >
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NAME <- < [a-z][a-z0-9]* >
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VARIABLE <- < [x] >
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FUNCTION <- NAME '(' EXPRESSION ( [,\n] EXPRESSION )* ')'
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%whitespace <- [ \t\r]*
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)");
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QMap<QString, std::function<double(double)>> *default_functions = nullptr;
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Expression::Expression(double initial) : value(initial)
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{
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if (default_functions == nullptr) {
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default_functions = new QMap<QString, std::function<double(double)>>();
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default_functions->insert("sin", [](double a) { return sin(a); });
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default_functions->insert("cos", [](double a) { return cos(a); });
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default_functions->insert("tan", [](double a) { return tan(a); });
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default_functions->insert("sqrt", [](double a) { return sqrt(a); });
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default_functions->insert("log", [](double a) { return log(a); });
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default_functions->insert("log10", [](double a) { return log(a); });
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default_functions->insert("trunc", [](double a) { return trunc(a); });
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default_functions->insert("abs", [](double a) { return fabs(a); });
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default_functions->insert("floor", [](double a) { return floor(a); });
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default_functions->insert("ceil", [](double a) { return ceil(a); });
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default_functions->insert("round", [](double a) { return round(a); });
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default_functions->insert("trunc", [](double a) { return trunc(a); });
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}
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fns = QMap<QString, std::function<double(double)>>(*default_functions);
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}
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double Expression::eval(const peg::Ast &ast)
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{
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const auto &nodes = ast.nodes;
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if (ast.name == "NUMBER") {
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return stod(ast.token);
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} else if (ast.name == "FUNCTION") {
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QString name = QString::fromStdString(nodes[0]->token);
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if (!fns.contains(name))
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return 0;
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return fns[name](eval(*nodes[1]));
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} else if (ast.name == "VARIABLE") {
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return value;
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} else if (ast.name[0] == 'P') {
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double result = eval(*nodes[0]);
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for (unsigned int i = 1; i < nodes.size(); i += 2) {
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double arg = eval(*nodes[i + 1]);
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char operation = nodes[i]->token[0];
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switch (operation) {
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case '+':
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result += arg;
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break;
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case '-':
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result -= arg;
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break;
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case '*':
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result *= arg;
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break;
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case '/':
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result /= arg;
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break;
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case '^':
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result = pow(result, arg);
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break;
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default:
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result = 0;
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break;
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}
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}
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return result;
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} else {
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return -1;
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}
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}
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double Expression::parse(const QString &expr)
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{
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QByteArray ba = expr.toUtf8();
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math.enable_ast();
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std::shared_ptr<peg::Ast> ast;
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if (math.parse(ba.data(), ast)) {
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ast = peg::AstOptimizer(true).optimize(ast);
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return eval(*ast);
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}
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return 0;
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}
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