[3408] | 1 | #ifndef CONSTRAINED_VALUE_HPP___ |
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| 2 | #define CONSTRAINED_VALUE_HPP___ |
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| 3 | |
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| 4 | /* Copyright (c) 2002,2003 CrystalClear Software, Inc. |
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| 5 | * Use, modification and distribution is subject to the |
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| 6 | * Boost Software License, Version 1.0. (See accompanying |
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| 7 | * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
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| 8 | * Author: Jeff Garland |
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| 9 | * $Date: 2008-11-12 14:37:53 -0500 (Wed, 12 Nov 2008) $ |
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| 10 | */ |
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| 11 | |
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| 12 | #include <exception> |
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| 13 | #include <stdexcept> |
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| 14 | #include <boost/config.hpp> |
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| 15 | #include <boost/throw_exception.hpp> |
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| 16 | #include <boost/mpl/if.hpp> |
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| 17 | #include <boost/type_traits/is_base_of.hpp> |
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| 18 | |
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| 19 | namespace boost { |
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| 20 | |
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| 21 | //! Namespace containing constrained_value template and types |
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| 22 | namespace CV { |
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| 23 | //! Represent a min or max violation type |
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| 24 | enum violation_enum {min_violation, max_violation}; |
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| 25 | |
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| 26 | //! A template to specify a constrained basic value type |
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| 27 | /*! This template provides a quick way to generate |
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| 28 | * an integer type with a constrained range. The type |
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| 29 | * provides for the ability to specify the min, max, and |
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| 30 | * and error handling policy. |
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| 31 | * |
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| 32 | * <b>value policies</b> |
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| 33 | * A class that provides the range limits via the min and |
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| 34 | * max functions as well as a function on_error that |
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| 35 | * determines how errors are handled. A common strategy |
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| 36 | * would be to assert or throw and exception. The on_error |
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| 37 | * is passed both the current value and the new value that |
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| 38 | * is in error. |
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| 39 | * |
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| 40 | */ |
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| 41 | template<class value_policies> |
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| 42 | class constrained_value { |
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| 43 | public: |
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| 44 | typedef typename value_policies::value_type value_type; |
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| 45 | // typedef except_type exception_type; |
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| 46 | constrained_value(value_type value) : value_((min)()) |
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| 47 | { |
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| 48 | assign(value); |
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| 49 | } |
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| 50 | constrained_value& operator=(value_type v) |
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| 51 | { |
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| 52 | assign(v); |
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| 53 | return *this; |
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| 54 | } |
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| 55 | //! Return the max allowed value (traits method) |
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| 56 | static value_type max BOOST_PREVENT_MACRO_SUBSTITUTION () {return (value_policies::max)();} |
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| 57 | //! Return the min allowed value (traits method) |
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| 58 | static value_type min BOOST_PREVENT_MACRO_SUBSTITUTION () {return (value_policies::min)();} |
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| 59 | //! Coerce into the representation type |
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| 60 | operator value_type() const {return value_;} |
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| 61 | protected: |
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| 62 | value_type value_; |
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| 63 | private: |
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| 64 | void assign(value_type value) |
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| 65 | { |
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| 66 | //adding 1 below gets rid of a compiler warning which occurs when the |
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| 67 | //min_value is 0 and the type is unsigned.... |
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| 68 | if (value+1 < (min)()+1) { |
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| 69 | value_policies::on_error(value_, value, min_violation); |
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| 70 | return; |
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| 71 | } |
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| 72 | if (value > (max)()) { |
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| 73 | value_policies::on_error(value_, value, max_violation); |
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| 74 | return; |
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| 75 | } |
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| 76 | value_ = value; |
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| 77 | } |
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| 78 | }; |
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| 79 | |
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| 80 | //! Template to shortcut the constrained_value policy creation process |
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| 81 | template<typename rep_type, rep_type min_value, |
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| 82 | rep_type max_value, class exception_type> |
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| 83 | class simple_exception_policy |
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| 84 | { |
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| 85 | struct exception_wrapper : public exception_type |
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| 86 | { |
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| 87 | // In order to support throw_exception mechanism in the BOOST_NO_EXCEPTIONS mode, |
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| 88 | // we'll have to provide a way to acquire std::exception from the exception being thrown. |
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| 89 | // However, we cannot derive from it, since it would make it interceptable by this class, |
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| 90 | // which might not be what the user wanted. |
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| 91 | operator std::out_of_range () const |
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| 92 | { |
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| 93 | // TODO: Make the message more descriptive by using arguments to on_error |
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| 94 | return std::out_of_range("constrained value boundary has been violated"); |
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| 95 | } |
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| 96 | }; |
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| 97 | |
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| 98 | typedef typename mpl::if_< |
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| 99 | is_base_of< std::exception, exception_type >, |
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| 100 | exception_type, |
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| 101 | exception_wrapper |
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| 102 | >::type actual_exception_type; |
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| 103 | |
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| 104 | public: |
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| 105 | typedef rep_type value_type; |
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| 106 | static rep_type min BOOST_PREVENT_MACRO_SUBSTITUTION () { return min_value; } |
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| 107 | static rep_type max BOOST_PREVENT_MACRO_SUBSTITUTION () { return max_value; } |
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| 108 | static void on_error(rep_type, rep_type, violation_enum) |
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| 109 | { |
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| 110 | boost::throw_exception(actual_exception_type()); |
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| 111 | } |
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| 112 | }; |
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| 113 | |
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| 114 | |
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| 115 | |
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| 116 | } } //namespace CV |
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| 117 | |
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| 118 | |
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| 119 | |
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| 120 | |
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| 121 | #endif |
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