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