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/*
**************************************************************
* C++ Mathematical Expression Toolkit Library *
* *
* Simple Example 08 *
* Author: Arash Partow (1999-2024) *
* URL: https://www.partow.net/programming/exprtk/index.html *
* *
* Copyright notice: *
* Free use of the Mathematical Expression Toolkit Library is *
* permitted under the guidelines and in accordance with the *
* most current version of the MIT License. *
* https://www.opensource.org/licenses/MIT *
* SPDX-License-Identifier: MIT *
* *
**************************************************************
*/
#include <cstdio>
#include <string>
#include "exprtk.hpp"
template <typename T>
void composite()
{
typedef exprtk::symbol_table<T> symbol_table_t;
typedef exprtk::expression<T> expression_t;
typedef exprtk::parser<T> parser_t;
typedef exprtk::parser_error::type err_t;
typedef exprtk::function_compositor<T> compositor_t;
typedef typename compositor_t::function function_t;
T x = T(1);
T y = T(2);
compositor_t compositor;
symbol_table_t& symbol_table = compositor.symbol_table();
symbol_table.add_constants();
symbol_table.add_variable("x",x);
symbol_table.add_variable("y",y);
compositor.add(
function_t("f") // f(x) = sin(x / pi)
.var("x")
.expression( "sin(x / pi)" ));
compositor.add(
function_t("g") // g(x,y) = 3[f(x) + f(y)]
.vars("x", "y")
.expression( "3*[f(x) + f(y)]" ));
std::string expression_string = "g(1 + f(x), f(y) / 2)";
expression_t expression;
expression.register_symbol_table(symbol_table);
parser_t parser;
if (!parser.compile(expression_string,expression))
{
printf("Error: %s\tExpression: %s\n",
parser.error().c_str(),
expression_string.c_str());
for (std::size_t i = 0; i < parser.error_count(); ++i)
{
const err_t error = parser.get_error(i);
printf("Error: %02d Position: %02d Type: [%14s] Msg: %s\tExpression: %s\n",
static_cast<unsigned int>(i),
static_cast<unsigned int>(error.token.position),
exprtk::parser_error::to_str(error.mode).c_str(),
error.diagnostic.c_str(),
expression_string.c_str());
}
return;
}
const T result = expression.value();
printf("%s = %e\n", expression_string.c_str(), result);
}
int main()
{
composite<double>();
return 0;
}
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