forked from bartvdbraak/blender
6fb6a08bf8
Even tho it's currently only used by Libmv we might use it for something else in the future. Plus, it's actually where it logically belongs to.
109 lines
4.5 KiB
C++
109 lines
4.5 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2015 Google Inc. All rights reserved.
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// http://ceres-solver.org/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: keir@google.com (Keir Mierle)
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#ifndef CERES_INTERNAL_CASTS_H_
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#define CERES_INTERNAL_CASTS_H_
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#include <cassert>
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#include <cstddef> // For NULL.
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namespace ceres {
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// Identity metafunction.
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template <class T>
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struct identity_ {
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typedef T type;
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};
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// Use implicit_cast as a safe version of static_cast or const_cast
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// for implicit conversions. For example:
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// - Upcasting in a type hierarchy.
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// - Performing arithmetic conversions (int32 to int64, int to double, etc.).
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// - Adding const or volatile qualifiers.
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//
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// In general, implicit_cast can be used to convert this code
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// To to = from;
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// DoSomething(to);
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// to this
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// DoSomething(implicit_cast<To>(from));
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//
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// base::identity_ is used to make a non-deduced context, which
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// forces all callers to explicitly specify the template argument.
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template<typename To>
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inline To implicit_cast(typename identity_<To>::type to) {
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return to;
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}
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// This version of implicit_cast is used when two template arguments
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// are specified. It's obsolete and should not be used.
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template<typename To, typename From>
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inline To implicit_cast(typename identity_<From>::type const &f) {
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return f;
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}
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// When you upcast (that is, cast a pointer from type Foo to type
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// SuperclassOfFoo), it's fine to use implicit_cast<>, since upcasts
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// always succeed. When you downcast (that is, cast a pointer from
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// type Foo to type SubclassOfFoo), static_cast<> isn't safe, because
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// how do you know the pointer is really of type SubclassOfFoo? It
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// could be a bare Foo, or of type DifferentSubclassOfFoo. Thus,
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// when you downcast, you should use this macro. In debug mode, we
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// use dynamic_cast<> to double-check the downcast is legal (we die
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// if it's not). In normal mode, we do the efficient static_cast<>
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// instead. Thus, it's important to test in debug mode to make sure
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// the cast is legal!
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// This is the only place in the code we should use dynamic_cast<>.
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// In particular, you SHOULDN'T be using dynamic_cast<> in order to
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// do RTTI (eg code like this:
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// if (dynamic_cast<Subclass1>(foo)) HandleASubclass1Object(foo);
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// if (dynamic_cast<Subclass2>(foo)) HandleASubclass2Object(foo);
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// You should design the code some other way not to need this.
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template<typename To, typename From> // use like this: down_cast<T*>(foo);
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inline To down_cast(From* f) { // so we only accept pointers
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// Ensures that To is a sub-type of From *. This test is here only
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// for compile-time type checking, and has no overhead in an
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// optimized build at run-time, as it will be optimized away
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// completely.
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// TODO(csilvers): This should use COMPILE_ASSERT.
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if (false) {
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implicit_cast<From*, To>(NULL);
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}
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// uses RTTI in dbg and fastbuild. asserts are disabled in opt builds.
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assert(f == NULL || dynamic_cast<To>(f) != NULL); // NOLINT
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return static_cast<To>(f);
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}
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} // namespace ceres
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#endif // CERES_INTERNAL_CASTS_H_
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