CRuntimeCompiledExpression.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#include "base-precomp.h"  // Precompiled headers

#include <mrpt/math/CRuntimeCompiledExpression.h>

#define exprtk_disable_string_capabilities  // Workaround a bug in Ubuntu
// precise's GCC+libstdc++
#include <mrpt/otherlibs/exprtk.hpp>

// We only need this to be on this translation unit, hence the advantage of
// using our MRPT wrapper instead
// of the original exprtk sources.
PIMPL_IMPLEMENT(exprtk::expression<double>)

using namespace mrpt;
using namespace mrpt::math;

CRuntimeCompiledExpression::CRuntimeCompiledExpression()
{
        PIMPL_CONSTRUCT(exprtk::expression<double>, m_compiled_formula);
}

void CRuntimeCompiledExpression::compile(
        /** [in] The expression to be compiled. */
        const std::string& expression,
        /** [in] Map of variables/constants by `name` ->  `value`. The references to
           the values in this map **must** be ensured to be valid thoughout all the
           life of the compiled expression. */
        const std::map<std::string, double>& variables,
        /** A descriptive name of this formula, to be used when generating error
           reports via an  exception, if needed */
        const std::string& expr_name_for_error_reporting)
{
        m_original_expr_str = expression;

        exprtk::symbol_table<double> symbol_table;
        for (const auto& v : variables)
        {
                double& var = const_cast<double&>(v.second);
                symbol_table.add_variable(v.first, var);
        }
        symbol_table.add_constant("M_PI", M_PI);
        symbol_table.add_constants();

        PIMPL_GET_REF(exprtk::expression<double>, m_compiled_formula)
                .register_symbol_table(symbol_table);
        // Compile user-given expressions:
        exprtk::parser<double> parser;
        if (!parser.compile(
                        expression,
                        PIMPL_GET_REF(exprtk::expression<double>, m_compiled_formula)))
                THROW_EXCEPTION_FMT(
                        "Error compiling expression (name=`%s`): `%s`. Error: `%s`",
                        expr_name_for_error_reporting.c_str(), expression.c_str(),
                        parser.error().c_str());
}

double CRuntimeCompiledExpression::eval() const
{
        ASSERT_(m_compiled_formula.ptr.get() != nullptr);
        return PIMPL_GET_CONSTREF(exprtk::expression<double>, m_compiled_formula)
                .value();
}

void CRuntimeCompiledExpression::register_symbol_table(
        /** [in] Map of variables/constants by `name` ->  `value`. The
           references to the values in this map **must** be ensured to be valid
           thoughout all the life of the compiled expression. */
        const std::map<std::string, double*>& variables)
{
        exprtk::symbol_table<double> symbol_table;
        for (const auto& v : variables)
        {
                double* var = const_cast<double*>(v.second);
                symbol_table.add_variable(v.first, *var);
        }
        PIMPL_GET_REF(exprtk::expression<double>, m_compiled_formula)
                .register_symbol_table(symbol_table);
}

exprtk::expression<double>& CRuntimeCompiledExpression::get_raw_exprtk_expr()
{
        ASSERT_(m_compiled_formula.ptr.get() != nullptr);
        return PIMPL_GET_REF(exprtk::expression<double>, m_compiled_formula);
}
const exprtk::expression<double>&
        CRuntimeCompiledExpression::get_raw_exprtk_expr() const
{
        ASSERT_(m_compiled_formula.ptr.get() != nullptr);
        return PIMPL_GET_CONSTREF(exprtk::expression<double>, m_compiled_formula);
}

bool CRuntimeCompiledExpression::is_compiled() const
{
        return m_compiled_formula.ptr.get() != nullptr;
}
const std::string& CRuntimeCompiledExpression::get_original_expression() const
{
        return m_original_expr_str;
}