5.13. Exercises
| 5-0. | Write a test program that exercises the parts of tiny we've implemented. Try to arrange your program so that it will only compile if the tests succeed. | | 5-1. | Write a metafunction double_first_half that takes a Random Access Sequence of integral constant wrappers of length N as an argument, and returns a copy with the first N/2 elements doubled in value, such that the following is true:
mpl::equal<
double_first_half< mpl::vector_c<int,1,2,3,4> >::type
, mpl::vector_c<int,2,4,3,4>
>::type::value
| | 5-2. | Note that push_back won't compile if its tiny argument already has three elements. How can we get the same guarantees for push_front? | | 5-3. | Drawing on the example of our push_back implementation, implement insert for tiny sequences. Refactor the implementation of push_back so that it shares more code with insert. | | 5-4. | How could we reduce the number of template instantiations required by our implementation of push_back? (Hint: Look at our implementation of end in section 5.11.5 again.) How does that interact with the refactoring in the previous exercise? | | 5-5. | Implement the pop_front, pop_back, and erase algorithms for tiny. | | 5-6. | Write a sequence adapter template called dimensions that, when instantiated on an array type, presents the array's dimensions as a forward, non-extensible sequence:
typedef dimensions<char [10][5][2]> seq;
BOOST_STATIC_ASSERT( mpl::size<seq>::value == 3 );
BOOST_STATIC_ASSERT(( mpl::at_c<seq,0>::type::value == 2 ));
BOOST_STATIC_ASSERT(( mpl::at_c<seq,1>::type::value == 5 ));
BOOST_STATIC_ASSERT(( mpl::at_c<seq,2>::type::value == 10 ));
Consider using the type traits library facilities to simplify the implementation.
| | 5-7. | Modify the dimensions sequence adapter from exercise 5-6 to provide bidirectional iterators and push_back and pop_back operations. | | 5-8. | Write a fibonacci_series class that represents an infinite forward sequence of Fibonacci numbers:
typedef mpl::lower_bound< fibonacci_series, int_<10> >::type n;
BOOST_STATIC_ASSERT( n::value == 8 );
typedef mpl::lower_bound< fibonacci_series, int_<50> >::type m;
BOOST_STATIC_ASSERT( m::value == 34 );
Each element of the Fibonacci series is the sum of the previous two elements. The series begins 0, 1, 1, 2, 3, 5, 8, 13....
| | 5-9. | Modify the fibonacci_series sequence from exercise 5-8 to be limited by a maximum number of elements in the series. Make the sequence's iterators bidirectional:
typedef fibonacci_series<8> seq;
BOOST_STATIC_ASSERT( mpl::size<seq>::value == 8 );
BOOST_STATIC_ASSERT( mpl::back<seq>::type::value == 21 );
| | 5-10*. | Write a tree class template for composing compile-time binary tree data structures:
typedef tree< // double
double // / \
, tree<void*,int,long> // void* char
, char // / \
> tree_seq; // int long
Implement iterators for pre-order, in-order, and post-order traversal of the tree elements:
BOOST_STATIC_ASSERT(( mpl::equal<
preorder_view<tree_seq>
, mpl::vector<double,void*,int,long,char>
, boost::is_same<_1,_2>
>::value ));
BOOST_STATIC_ASSERT(( mpl::equal<
inorder_view<tree_seq>
, mpl::vector<int,void*,long,double,char>
, boost::is_same<_1,_2>
>::value ));
BOOST_STATIC_ASSERT(( mpl::equal<
postorder_view<tree_seq>
, mpl::vector<int,long,void*,char,double>
, boost::is_same<_1,_2>
>::value ));
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