| 1 | // |
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| 2 | // SPDX-License-Identifier: BSD-3-Clause |
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| 3 | // Copyright (c) Contributors to the OpenEXR Project. |
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| 4 | // |
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| 5 | |
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| 6 | #ifndef INCLUDED_IEXNAMESPACE_H |
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| 7 | #define INCLUDED_IEXNAMESPACE_H |
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| 8 | |
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| 9 | // |
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| 10 | // The purpose of this file is to make it possible to specify an |
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| 11 | // IEX_INTERNAL_NAMESPACE as a preprocessor definition and have all of the |
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| 12 | // Iex symbols defined within that namespace rather than the standard |
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| 13 | // Iex namespace. Those symbols are made available to client code through |
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| 14 | // the IEX_NAMESPACE in addition to the IEX_INTERNAL_NAMESPACE. |
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| 15 | // |
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| 16 | // To ensure source code compatibility, the IEX_NAMESPACE defaults to Iex |
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| 17 | // and then "using namespace IEX_INTERNAL_NAMESPACE;" brings all of the |
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| 18 | // declarations from the IEX_INTERNAL_NAMESPACE into the IEX_NAMESPACE. This |
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| 19 | // means that client code can continue to use syntax like Iex::BaseExc, but |
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| 20 | // at link time it will resolve to a mangled symbol based on the |
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| 21 | // IEX_INTERNAL_NAMESPACE. |
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| 22 | // |
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| 23 | // As an example, if one needed to build against a newer version of Iex and |
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| 24 | // have it run alongside an older version in the same application, it is now |
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| 25 | // possible to use an internal namespace to prevent collisions between the |
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| 26 | // older versions of Iex symbols and the newer ones. To do this, the |
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| 27 | // following could be defined at build time: |
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| 28 | // |
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| 29 | // IEX_INTERNAL_NAMESPACE = Iex_v2 |
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| 30 | // |
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| 31 | // This means that declarations inside Iex headers look like this (after the |
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| 32 | // preprocessor has done its work): |
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| 33 | // |
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| 34 | // namespace Iex_v2 { |
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| 35 | // ... |
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| 36 | // class declarations |
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| 37 | // ... |
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| 38 | // } |
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| 39 | // |
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| 40 | // namespace Iex { |
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| 41 | // using namespace Iex_v2; |
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| 42 | // } |
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| 43 | // |
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| 44 | |
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| 45 | // |
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| 46 | // Open Source version of this file pulls in the IexConfig.h file |
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| 47 | // for the configure time options. |
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| 48 | // |
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| 49 | #include "IexConfig.h" |
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| 50 | |
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| 51 | #ifndef IEX_NAMESPACE |
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| 52 | #define IEX_NAMESPACE Iex |
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| 53 | #endif |
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| 54 | |
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| 55 | #ifndef IEX_INTERNAL_NAMESPACE |
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| 56 | #define IEX_INTERNAL_NAMESPACE IEX_NAMESPACE |
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| 57 | #endif |
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| 58 | |
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| 59 | // |
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| 60 | // We need to be sure that we import the internal namespace into the public one. |
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| 61 | // To do this, we use the small bit of code below which initially defines |
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| 62 | // IEX_INTERNAL_NAMESPACE (so it can be referenced) and then defines |
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| 63 | // IEX_NAMESPACE and pulls the internal symbols into the public namespace. |
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| 64 | // |
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| 65 | |
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| 66 | namespace IEX_INTERNAL_NAMESPACE {} |
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| 67 | namespace IEX_NAMESPACE { |
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| 68 | using namespace IEX_INTERNAL_NAMESPACE; |
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| 69 | } |
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| 70 | |
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| 71 | // |
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| 72 | // There are identical pairs of HEADER/SOURCE ENTER/EXIT macros so that |
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| 73 | // future extension to the namespace mechanism is possible without changing |
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| 74 | // project source code. |
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| 75 | // |
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| 76 | |
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| 77 | #define namespace IEX_INTERNAL_NAMESPACE { |
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| 78 | #define } |
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| 79 | |
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| 80 | #define IEX_INTERNAL_NAMESPACE_SOURCE_ENTER namespace IEX_INTERNAL_NAMESPACE { |
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| 81 | #define IEX_INTERNAL_NAMESPACE_SOURCE_EXIT } |
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| 82 | |
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| 83 | #endif // INCLUDED_IEXNAMESPACE_H |
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| 84 | |
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