CRuntimeCompiledExpression.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, 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 "expr-precomp.h"  // Precompiled headers

#include <mrpt/expr/CRuntimeCompiledExpression.h>
#include <mrpt/core/exceptions.h>
#include <cmath>  // M_PI

#define exprtk_disable_string_capabilities  // Workaround a bug in Ubuntu
// precise's GCC+libstdc++

// Disable some parts of exprtk to build faster and reduce lib size:
#define exprtk_disable_enhanced_features
#define exprtk_disable_superscalar_unroll
#define exprtk_disable_rtl_vecops
#define exprtk_disable_rtl_io_file
#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::expr;

struct CRuntimeCompiledExpression::Impl
{
    exprtk::expression<double> m_compiled_formula;
    std::string m_original_expr_str;
};

CRuntimeCompiledExpression::CRuntimeCompiledExpression():
    m_impl(mrpt::make_impl<CRuntimeCompiledExpression::Impl>())
{
}

CRuntimeCompiledExpression::~CRuntimeCompiledExpression(){}

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_impl->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();

    m_impl->m_compiled_formula.register_symbol_table(symbol_table);

    // Compile user-given expressions:
    exprtk::parser<double> parser;
    if (!parser.compile(
            expression,
            m_impl->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_impl);
    return m_impl->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);
    }
    m_impl->m_compiled_formula.register_symbol_table(symbol_table);
}

exprtk::expression<double>& CRuntimeCompiledExpression::get_raw_exprtk_expr()
{
    ASSERT_(m_impl);
    return m_impl->m_compiled_formula;
}
const exprtk::expression<double>&
    CRuntimeCompiledExpression::get_raw_exprtk_expr() const
{
    ASSERT_(m_impl);
    return m_impl->m_compiled_formula;
}

bool CRuntimeCompiledExpression::is_compiled() const
{
    ASSERT_(m_impl);
    return m_impl->m_compiled_formula;
}
const std::string& CRuntimeCompiledExpression::get_original_expression() const
{
    return m_impl->m_original_expr_str;
}