D4RValue.h

// -*- mode: c++; c-basic-offset:4 -*-

// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.

// Copyright (c) 2014 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.

#ifndef _D4RValue_h
#define _D4RValue_h

#include <string>
#include <vector>

#include <D4Function.h>
#include <dods-datatypes.h>

namespace libdap {

class BaseType;
class D4RValue;

// Factory class to build RValue objects. User by the parser/ce-evaluator
D4RValue *D4RValueFactory(std::string cpps);

/** @brief Container for parsed DAP4 function/filter rvalues. */
class D4RValueList {
private:
    std::vector<D4RValue *> d_rvalues;

    void m_duplicate(const D4RValueList &src);

public:
    /** @brief Mutable iterator over `D4RValue*` entries. */
    typedef std::vector<D4RValue *>::iterator iter;

    D4RValueList() {}
    /** @brief Copy-constructs an rvalue list. @param src Source list. */
    D4RValueList(const D4RValueList &src) { m_duplicate(src); }
    /** @brief Builds a one-element rvalue list. @param rv Initial rvalue pointer. */
    D4RValueList(D4RValue *rv) { add_rvalue(rv); }

    virtual ~D4RValueList();

    /**
     * @brief Assigns this list from another list.
     * @param rhs Source list.
     * @return This list after assignment.
     */
    D4RValueList &operator=(const D4RValueList &rhs) {
        if (this == &rhs)
            return *this;
        m_duplicate(rhs);
        return *this;
    }

    /**
     * @brief Appends an rvalue pointer.
     * @param rv Rvalue pointer to append.
     */
    void add_rvalue(D4RValue *rv) { d_rvalues.push_back(rv); }

    /**
     * @brief Returns an rvalue by index.
     * @param i Zero-based index.
     * @return Rvalue pointer at index `i`.
     */
    D4RValue *get_rvalue(unsigned int i) { return d_rvalues.at(i); }

    /** @brief Returns an iterator to the first rvalue. */
    iter begin() { return d_rvalues.begin(); }
    /** @brief Returns an iterator one past the last rvalue. */
    iter end() { return d_rvalues.end(); }

    /** @brief Returns the number of rvalues in this list. */
    unsigned int size() const { return d_rvalues.size(); }
};

/**
 * Holds the RValues for the D4 function parser and for the filter
 * expression evaluator.
 */
class D4RValue {
public:
    /** @brief Identifies what source currently provides this rvalue's value. */
    enum value_kind { unknown, basetype, function, constant };

private:
    BaseType *d_variable; // This is a weak pointer; do not delete

    D4Function d_func;    // (weak) pointer to a function returning BaseType *
    D4RValueList *d_args; // pointer to arguments to the function; delete

    BaseType *d_constant; // pointer; delete.

    value_kind d_value_kind;

    /** @brief Clone 'src' to 'this'. */
    void m_duplicate(const D4RValue &src);

    friend class D4RValueList;

public:
    D4RValue() : d_variable(0), d_func(0), d_args(0), d_constant(0), d_value_kind(unknown) {}
    /** @brief Copy-constructs an rvalue. @param src Source rvalue. */
    D4RValue(const D4RValue &src) { m_duplicate(src); }
    /** @brief Builds an rvalue that references a dataset variable. @param btp Variable pointer. */
    D4RValue(BaseType *btp) : d_variable(btp), d_func(0), d_args(0), d_constant(0), d_value_kind(basetype) {}
    /** @brief Builds an rvalue that evaluates a function call.
     * @param f Function pointer.
     * @param args Function argument list.
     */
    D4RValue(D4Function f, D4RValueList *args)
        : d_variable(0), d_func(f), d_args(args), d_constant(0), d_value_kind(function) {}

    /** @brief Builds an unsigned-integer constant rvalue. @param ui Constant value. */
    D4RValue(unsigned long long ui);
    /** @brief Builds a signed-integer constant rvalue. @param i Constant value. */
    D4RValue(long long i);
    /** @brief Builds a floating-point constant rvalue. @param r Constant value. */
    D4RValue(double r);
    /** @brief Builds a string constant rvalue. @param s Constant value. */
    D4RValue(std::string s);
    /** @brief Builds a byte-vector constant rvalue. @param byte_args Constant values. */
    D4RValue(std::vector<dods_byte> &byte_args);
    /** @brief Builds an int8-vector constant rvalue. @param byte_int8 Constant values. */
    D4RValue(std::vector<dods_int8> &byte_int8);
    /** @brief Builds a uint16-vector constant rvalue. @param byte_uint16 Constant values. */
    D4RValue(std::vector<dods_uint16> &byte_uint16);
    /** @brief Builds an int16-vector constant rvalue. @param byte_int16 Constant values. */
    D4RValue(std::vector<dods_int16> &byte_int16);
    /** @brief Builds a uint32-vector constant rvalue. @param byte_uint32 Constant values. */
    D4RValue(std::vector<dods_uint32> &byte_uint32);
    /** @brief Builds an int32-vector constant rvalue. @param byte_int32 Constant values. */
    D4RValue(std::vector<dods_int32> &byte_int32);
    /** @brief Builds a uint64-vector constant rvalue. @param byte_uint64 Constant values. */
    D4RValue(std::vector<dods_uint64> &byte_uint64);
    /** @brief Builds an int64-vector constant rvalue. @param byte_int64 Constant values. */
    D4RValue(std::vector<dods_int64> &byte_int64);
    /** @brief Builds a float32-vector constant rvalue. @param byte_float32 Constant values. */
    D4RValue(std::vector<dods_float32> &byte_float32);
    /** @brief Builds a float64-vector constant rvalue. @param byte_float64 Constant values. */
    D4RValue(std::vector<dods_float64> &byte_float64);

    virtual ~D4RValue();

    /**
     * @brief Assigns this rvalue from another rvalue.
     * @param rhs Source rvalue.
     * @return This rvalue after assignment.
     */
    D4RValue &operator=(D4RValue &rhs) {
        if (this == &rhs)
            return *this;

        m_duplicate(rhs);

        return *this;
    }

    /**
     * @brief What kind of thing holds the value
     * Values in DAP4 constraints are either constants, dataset variables
     * or function results. It might be nice to know the source of a
     * given value in order to optimize the evaluation of certain kinds of
     * expressions.
     * @return The 'value_kind' of this value.
     */
    value_kind get_kind() const { return d_value_kind; }

    // This is the call that will be used to return the value of a function.
    // jhrg 3/10/14
    virtual BaseType *value(DMR &dmr);
    // And this optimizes value() for filters, where functions are not supported.
    virtual BaseType *value();
};

} // namespace libdap
#endif // _RValue_h