1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/ossrv/stdcpp/tsrc/Boost_test/ptr_container/src/tut1.cpp Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,355 @@
1.4 +//
1.5 +// Boost.Pointer Container
1.6 +//
1.7 +// Copyright Thorsten Ottosen 2003-2005. Use, modification and
1.8 +// distribution is subject to the Boost Software License, Version
1.9 +// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
1.10 +// http://www.boost.org/LICENSE_1_0.txt)
1.11 +//
1.12 +// For more information, see http://www.boost.org/libs/ptr_container/
1.13 +//
1.14 +
1.15 +//
1.16 +// This example is intended to get you started.
1.17 +// Notice how the smart container
1.18 +//
1.19 +// 1. takes ownership of objects
1.20 +// 2. transfers ownership
1.21 +// 3. applies indirection to iterators
1.22 +// 4. clones objects from other smart containers
1.23 +//
1.24 +
1.25 +//
1.26 +// First we select which container to use.
1.27 +//
1.28 +#include <boost/ptr_container/ptr_deque.hpp>
1.29 +
1.30 +//
1.31 +// we need these later in the example
1.32 +//
1.33 +#include <boost/assert.hpp>
1.34 +#include <string>
1.35 +#include <exception>
1.36 +
1.37 +
1.38 +//
1.39 +// Then we define a small polymorphic class
1.40 +// hierarchy.
1.41 +//
1.42 +
1.43 +class animal : boost::noncopyable
1.44 +{
1.45 + virtual std::string do_speak() const = 0;
1.46 + std::string name_;
1.47 +
1.48 +protected:
1.49 + //
1.50 + // Animals cannot be copied...
1.51 + //
1.52 + animal( const animal& r ) : name_( r.name_ ) { }
1.53 + void operator=( const animal& );
1.54 +
1.55 +private:
1.56 + //
1.57 + // ...but due to advances in genetics, we can clone them!
1.58 + //
1.59 +
1.60 + virtual animal* do_clone() const = 0;
1.61 +
1.62 +public:
1.63 + animal( const std::string& name ) : name_(name) { }
1.64 + virtual ~animal() throw() { }
1.65 +
1.66 + std::string speak() const
1.67 + {
1.68 + return do_speak();
1.69 + }
1.70 +
1.71 + std::string name() const
1.72 + {
1.73 + return name_;
1.74 + }
1.75 +
1.76 + animal* clone() const
1.77 + {
1.78 + return do_clone();
1.79 + }
1.80 +};
1.81 +
1.82 +//
1.83 +// An animal is still not Clonable. We need this last hook.
1.84 +//
1.85 +// Notice that we pass the animal by const reference
1.86 +// and return by pointer.
1.87 +//
1.88 +
1.89 +animal* new_clone( const animal& a )
1.90 +{
1.91 + return a.clone();
1.92 +}
1.93 +
1.94 +//
1.95 +// We do not need to define 'delete_clone()' since
1.96 +// since the default is to call the default 'operator delete()'.
1.97 +//
1.98 +
1.99 +const std::string muuuh = "Muuuh!";
1.100 +const std::string oiink = "Oiiink";
1.101 +
1.102 +class cow : public animal
1.103 +{
1.104 + virtual std::string do_speak() const
1.105 + {
1.106 + return muuuh;
1.107 + }
1.108 +
1.109 + virtual animal* do_clone() const
1.110 + {
1.111 + return new cow( *this );
1.112 + }
1.113 +
1.114 +public:
1.115 + cow( const std::string& name ) : animal(name) { }
1.116 +};
1.117 +
1.118 +class pig : public animal
1.119 +{
1.120 + virtual std::string do_speak() const
1.121 + {
1.122 + return oiink;
1.123 + }
1.124 +
1.125 + virtual animal* do_clone() const
1.126 + {
1.127 + return new pig( *this );
1.128 + }
1.129 +
1.130 +public:
1.131 + pig( const std::string& name ) : animal(name) { }
1.132 +};
1.133 +
1.134 +//
1.135 +// Then we, of course, need a place to put all
1.136 +// those animals.
1.137 +//
1.138 +
1.139 +class farm
1.140 +{
1.141 + //
1.142 + // This is where the smart containers are handy
1.143 + //
1.144 + typedef boost::ptr_deque<animal> barn_type;
1.145 + barn_type barn;
1.146 +
1.147 + //
1.148 + // An error type
1.149 + //
1.150 + struct farm_trouble : public std::exception { };
1.151 +
1.152 +public:
1.153 + //
1.154 + // We would like to make it possible to
1.155 + // iterate over the animals in the farm
1.156 + //
1.157 + typedef barn_type::iterator animal_iterator;
1.158 +
1.159 + //
1.160 + // We also need to count the farm's size...
1.161 + //
1.162 + typedef barn_type::size_type size_type;
1.163 +
1.164 + //
1.165 + // And we also want to transfer an animal
1.166 + // safely around. The easiest way to think
1.167 + // about '::auto_type' is to imagine a simplified
1.168 + // 'std::auto_ptr<T>' ... this means you can expect
1.169 + //
1.170 + // T* operator->()
1.171 + // T* release()
1.172 + // deleting destructor
1.173 + //
1.174 + // but not more.
1.175 + //
1.176 + typedef barn_type::auto_type animal_transport;
1.177 +
1.178 + //
1.179 + // Create an empty farm.
1.180 + //
1.181 + farm() { }
1.182 +
1.183 + //
1.184 + // We need a constructor that can make a new
1.185 + // farm by cloning a range of animals.
1.186 + //
1.187 + farm( animal_iterator begin, animal_iterator end )
1.188 + :
1.189 + //
1.190 + // Objects are always cloned before insertion
1.191 + // unless we explicitly add a pointer or
1.192 + // use 'release()'. Therefore we actually
1.193 + // clone all animals in the range
1.194 + //
1.195 + barn( begin, end ) { }
1.196 +
1.197 + //
1.198 + // ... so we need some other function too
1.199 + //
1.200 +
1.201 + animal_iterator begin()
1.202 + {
1.203 + return barn.begin();
1.204 + }
1.205 +
1.206 + animal_iterator end()
1.207 + {
1.208 + return barn.end();
1.209 + }
1.210 +
1.211 + //
1.212 + // Here it is quite ok to have an 'animal*' argument.
1.213 + // The smart container will handle all ownership
1.214 + // issues.
1.215 + //
1.216 + void buy_animal( animal* a )
1.217 + {
1.218 + barn.push_back( a );
1.219 + }
1.220 +
1.221 + //
1.222 + // The farm can also be in economical trouble and
1.223 + // therefore be in the need to sell animals.
1.224 + //
1.225 + animal_transport sell_animal( animal_iterator to_sell )
1.226 + {
1.227 + if( to_sell == end() )
1.228 + throw farm_trouble();
1.229 +
1.230 + //
1.231 + // Here we remove the animal from the barn,
1.232 + // but the animal is not deleted yet...it's
1.233 + // up to the buyer to decide what
1.234 + // to do with it.
1.235 + //
1.236 + return barn.release( to_sell );
1.237 + }
1.238 +
1.239 + //
1.240 + // How big a farm do we have?
1.241 + //
1.242 + size_type size() const
1.243 + {
1.244 + return barn.size();
1.245 + }
1.246 +
1.247 + //
1.248 + // If things are bad, we might choose to sell all animals :-(
1.249 + //
1.250 + std::auto_ptr<barn_type> sell_farm()
1.251 + {
1.252 + return barn.release();
1.253 + }
1.254 +
1.255 + //
1.256 + // However, if things are good, we might buy somebody
1.257 + // else's farm :-)
1.258 + //
1.259 +
1.260 + void buy_farm( std::auto_ptr<barn_type> other )
1.261 + {
1.262 + //
1.263 + // This line inserts all the animals from 'other'
1.264 + // and is guaranteed either to succeed or to have no
1.265 + // effect
1.266 + //
1.267 + barn.transfer( barn.end(), // insert new animals at the end
1.268 + *other ); // we want to transfer all animals,
1.269 + // so we use the whole container as argument
1.270 + //
1.271 + // You might think you would have to do
1.272 + //
1.273 + // other.release();
1.274 + //
1.275 + // but '*other' is empty and can go out of scope as it wants
1.276 + //
1.277 + BOOST_ASSERT( other->empty() );
1.278 + }
1.279 +
1.280 +}; // class 'farm'.
1.281 +
1.282 +#include <boost/test/included/test_exec_monitor.hpp>
1.283 +int test_main(int,char *[])
1.284 +{
1.285 + //
1.286 + // First we make a farm
1.287 + //
1.288 + farm animal_farm;
1.289 + BOOST_ASSERT( animal_farm.size() == 0u );
1.290 +
1.291 + animal_farm.buy_animal( new pig("Betty") );
1.292 + animal_farm.buy_animal( new pig("Benny") );
1.293 + animal_farm.buy_animal( new pig("Jeltzin") );
1.294 + animal_farm.buy_animal( new cow("Hanz") );
1.295 + animal_farm.buy_animal( new cow("Mary") );
1.296 + animal_farm.buy_animal( new cow("Frederik") );
1.297 + BOOST_ASSERT( animal_farm.size() == 6u );
1.298 +
1.299 + //
1.300 + // Then we make another farm...it will actually contain
1.301 + // a clone of the other farm.
1.302 + //
1.303 + farm new_farm( animal_farm.begin(), animal_farm.end() );
1.304 + BOOST_ASSERT( new_farm.size() == 6u );
1.305 +
1.306 + //
1.307 + // Is it really clones in the new farm?
1.308 + //
1.309 + BOOST_ASSERT( new_farm.begin()->name() == "Betty" );
1.310 +
1.311 + //
1.312 + // Then we search for an animal, Mary (the Crown Princess of Denmark),
1.313 + // because we would like to buy her ...
1.314 + //
1.315 + typedef farm::animal_iterator iterator;
1.316 + iterator to_sell;
1.317 + for( iterator i = animal_farm.begin(),
1.318 + end = animal_farm.end();
1.319 + i != end; ++i )
1.320 + {
1.321 + if( i->name() == "Mary" )
1.322 + {
1.323 + to_sell = i;
1.324 + break;
1.325 + }
1.326 + }
1.327 +
1.328 + farm::animal_transport mary = animal_farm.sell_animal( to_sell );
1.329 +
1.330 +
1.331 + if( mary->speak() == muuuh )
1.332 + //
1.333 + // Great, Mary is a cow, and she may live longer
1.334 + //
1.335 + new_farm.buy_animal( mary.release() );
1.336 + else
1.337 + //
1.338 + // Then the animal would be destroyed (!)
1.339 + // when we go out of scope.
1.340 + //
1.341 + ;
1.342 +
1.343 + //
1.344 + // Now we can observe some changes to the two farms...
1.345 + //
1.346 + BOOST_ASSERT( animal_farm.size() == 5u );
1.347 + BOOST_ASSERT( new_farm.size() == 7u );
1.348 +
1.349 + //
1.350 + // The new farm has however underestimated how much
1.351 + // it cost to feed Mary and its owner is forced to sell the farm...
1.352 + //
1.353 + animal_farm.buy_farm( new_farm.sell_farm() );
1.354 +
1.355 + BOOST_ASSERT( new_farm.size() == 0u );
1.356 + BOOST_ASSERT( animal_farm.size() == 12u );
1.357 + return 0;
1.358 +}