91 lines
3.0 KiB
C
91 lines
3.0 KiB
C
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//
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// SPDX-License-Identifier: BSD-3-Clause
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// Copyright (c) Contributors to the OpenEXR Project.
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//
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#ifndef INCLUDED_IMFNAMESPACE_H
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#define INCLUDED_IMFNAMESPACE_H
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//
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// The purpose of this file is to have all of the Imath symbols defined within
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// the OPENEXR_IMF_INTERNAL_NAMESPACE namespace rather than the standard Imath
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// namespace. Those symbols are made available to client code through the
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// OPENEXR_IMF_NAMESPACE in addition to the OPENEXR_IMF_INTERNAL_NAMESPACE.
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//
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// To ensure source code compatibility, the OPENEXR_IMF_NAMESPACE defaults to
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// Imath and then "using namespace OPENEXR_IMF_INTERNAL_NAMESPACE;" brings all
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// of the declarations from the OPENEXR_IMF_INTERNAL_NAMESPACE into the
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// OPENEXR_IMF_NAMESPACE.
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// This means that client code can continue to use syntax like
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// Imf::Header, but at link time it will resolve to a
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// mangled symbol based on the OPENEXR_IMF_INTERNAL_NAMESPACE.
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//
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// As an example, if one needed to build against a newer version of Imath and
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// have it run alongside an older version in the same application, it is now
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// possible to use an internal namespace to prevent collisions between the
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// older versions of Imath symbols and the newer ones. To do this, the
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// following could be defined at build time:
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//
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// OPENEXR_IMF_INTERNAL_NAMESPACE = Imf_v2
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//
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// This means that declarations inside Imath headers look like this (after
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// the preprocessor has done its work):
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//
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// namespace Imf_v2 {
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// ...
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// class declarations
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// ...
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// }
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//
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// namespace Imf {
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// using namespace IMF_NAMESPACE_v2;
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// }
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//
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//
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// Open Source version of this file pulls in the OpenEXRConfig.h file
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// for the configure time options.
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//
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#include "OpenEXRConfig.h"
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#ifndef OPENEXR_IMF_NAMESPACE
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# define OPENEXR_IMF_NAMESPACE Imf
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#endif
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#ifndef OPENEXR_IMF_INTERNAL_NAMESPACE
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# define OPENEXR_IMF_INTERNAL_NAMESPACE OPENEXR_IMF_NAMESPACE
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#endif
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//
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// We need to be sure that we import the internal namespace into the public one.
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// To do this, we use the small bit of code below which initially defines
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// OPENEXR_IMF_INTERNAL_NAMESPACE (so it can be referenced) and then defines
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// OPENEXR_IMF_NAMESPACE and pulls the internal symbols into the public
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// namespace.
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//
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namespace OPENEXR_IMF_INTERNAL_NAMESPACE
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{}
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namespace OPENEXR_IMF_NAMESPACE
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{
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using namespace OPENEXR_IMF_INTERNAL_NAMESPACE;
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}
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//
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// There are identical pairs of HEADER/SOURCE ENTER/EXIT macros so that
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// future extension to the namespace mechanism is possible without changing
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// project source code.
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//
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#define OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER \
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namespace OPENEXR_IMF_INTERNAL_NAMESPACE \
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{
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#define OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT }
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#define OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_ENTER \
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namespace OPENEXR_IMF_INTERNAL_NAMESPACE \
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{
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#define OPENEXR_IMF_INTERNAL_NAMESPACE_SOURCE_EXIT }
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#endif /* INCLUDED_IMFNAMESPACE_H */
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