vrtexpression.h

/******************************************************************************
 *
 * Project:  Virtual GDAL Datasets
 * Purpose:  Implementation of MathExpression
 * Author:   Daniel Baston
 *
 ******************************************************************************
 * Copyright (c) 2024, ISciences LLC
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/
 
#pragma once
 
#include "cpl_error.h"
 
#include <string_view>
#include <vector>
 
namespace gdal
{

class MathExpression /* non final */
{
  public:
    virtual ~MathExpression();

    static std::unique_ptr<MathExpression> Create(const char *pszExpression,
                                                  const char *pszDialect);

    virtual void RegisterVariable(std::string_view osVariable,
                                  double *pdfLocation) = 0;

    virtual void RegisterVector(std::string_view osVariable,
                                std::vector<double> *padfLocation) = 0;

    virtual CPLErr Compile() = 0;

    virtual CPLErr Evaluate() = 0;

    virtual const std::vector<double> &Results() const = 0;
};

 
#if GDAL_VRT_ENABLE_EXPRTK

class ExprtkExpression final : public MathExpression
{
  public:
    explicit ExprtkExpression(std::string_view osExpression);
 
    ~ExprtkExpression() override;
 
    void RegisterVariable(std::string_view osVariable,
                          double *pdfLocation) override;
 
    void RegisterVector(std::string_view osVariable,
                        std::vector<double> *padfLocation) override;
 
    CPLErr Compile() override;
 
    CPLErr Evaluate() override;
 
    const std::vector<double> &Results() const override;
 
  private:
    class Impl;
 
    std::unique_ptr<Impl> m_pImpl;
};
 
#endif
 
#if GDAL_VRT_ENABLE_MUPARSER

class MuParserExpression final : public MathExpression
{
  public:
    explicit MuParserExpression(std::string_view osExpression);
 
    ~MuParserExpression() override;
 
    void RegisterVariable(std::string_view osVariable,
                          double *pdfLocation) override;
 
    void RegisterVector(std::string_view osVariable,
                        std::vector<double> *padfLocation) override;
 
    CPLErr Compile() override;
 
    CPLErr Evaluate() override;
 
    const std::vector<double> &Results() const override;
 
  private:
    class Impl;
 
    std::unique_ptr<Impl> m_pImpl;
};
 
#endif
 
inline std::unique_ptr<MathExpression>
MathExpression::Create([[maybe_unused]] const char *pszExpression,
                       const char *pszDialect)
{
    if (EQUAL(pszDialect, "exprtk"))
    {
#if GDAL_VRT_ENABLE_EXPRTK
        return std::make_unique<gdal::ExprtkExpression>(pszExpression);
#else
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "Dialect '%s' is not supported by this GDAL build. A GDAL "
                 "build with ExprTk is needed.",
                 pszDialect);
#endif
    }
    else if (EQUAL(pszDialect, "muparser"))
    {
#if GDAL_VRT_ENABLE_MUPARSER
        return std::make_unique<gdal::MuParserExpression>(pszExpression);
#else
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "Dialect '%s' is not supported by this GDAL build. A GDAL "
                 "build with muparser is needed.",
                 pszDialect);
#endif
    }
    else
    {
        CPLError(CE_Failure, CPLE_IllegalArg, "Unknown expression dialect: %s",
                 pszDialect);
    }
    return nullptr;
}
 
bool MuParserHasDefineFunUserData();

 
}  // namespace gdal