# ifndef CPPAD_CORE_IDENTICAL_HPP
# define CPPAD_CORE_IDENTICAL_HPP
/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-18 Bradley M. Bell

CppAD is distributed under the terms of the
             Eclipse Public License Version 2.0.

This Source Code may also be made available under the following
Secondary License when the conditions for such availability set forth
in the Eclipse Public License, Version 2.0 are satisfied:
      GNU General Public License, Version 2.0 or later.
---------------------------------------------------------------------------- */

# include <cppad/local/define.hpp>

namespace CppAD { // BEGIN_CPPAD_NAMESPACE
/*!
\file identical.hpp
Check if certain properties is true for any possible AD tape play back.
*/

// ---------------------------------------------------------------------------
/*!
Determine if an AD<Base> object is a parameter, and could never have
a different value during any tape playback.

An AD<Base> object x is identically a parameter if and only if
all of the objects in the following chain are parameters:
\code
    x , x.value , x.value.value , ...
\endcode
In such a case, the value of the object will always be the same
no matter what the independent variable values are at any level.

\param x
values that we are checking for identically a pamameter.

\return
returns true iff x is identically a parameter.
*/
template <class Base>
bool IdenticalCon(const AD<Base> &x)
{   return Constant(x) && IdenticalCon(x.value_); }
// Zero ==============================================================
/*!
Determine if an AD<Base> is equal to zero,
and must be equal zero during any tape playback.

\param x
object that we are checking.

\return
returns true if and only if
 x is equals zero and is identically a parameter \ref CppAD::IdenticalCon.
*/
template <class Base>
bool IdenticalZero(const AD<Base> &x)
{   return Constant(x) && IdenticalZero(x.value_); }
// One ==============================================================
/*!
Determine if an AD<Base> is equal to one,
and must be equal one during any tape playback.

\param x
object that we are checking.

\return
returns true if and only if
 x is equals one and is identically a parameter \ref CppAD::IdenticalCon.
*/
template <class Base>
bool IdenticalOne(const AD<Base> &x)
{   return Constant(x) && IdenticalOne(x.value_); }
// Equal ===================================================================
/*!
Determine if two AD<Base> objects are equal,
and must be equal during any tape playback.

\param x
first of two objects we are checking for equal.

\param y
second of two objects we are checking for equal.

\return
returns true if and only if
the arguments are equal and both identically parameters \ref CppAD::IdenticalCon.
*/
template <class Base>
bool IdenticalEqualCon
(const AD<Base> &x, const AD<Base> &y)
{   bool constant;
    constant  = Constant(x) & Constant(y);
    return constant  && IdenticalEqualCon(x.value_, y.value_);
}
// ==========================================================================

} // END_CPPAD_NAMESPACE
# endif
