Boost Pointer Container Library

# Pointer Container Library

# Class `ptr_array`

A `ptr_array<T,size>` is a pointer container that uses an underlying `boost::array<void*,size>` to store the pointers. The class is useful when there is no requirement of dynamic expansion and when absolute no overhead is tolerable.

See also:

- reversible_ptr_container
- ptr_sequence_adapter
- ptr_vector

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Synopsis:

    namespace boost
    {

        template
        <
            class T,
            size_t N,
            CloneAllocator = heap_clone_allocator
        >
        class ptr_array : public implementation-defined
        {
        public: // construct/copy/destroy
            ptr_array();
            ptr_array( std::auto_ptr<ptr_array>& r );

        public: // iterators

        public: // capacity

        public: // element access
            T&        front();
            const T&  front() const;
            T&        back();
            const T&  back() const;

            template< size_t idx >
            T&        at();
            template< size_t idx >
            const T&  at() const;
            T&        at( size_t );
            const T&  at( size_t );

            T&        operator[]( size_t );
            const T&  operator[]( size_t ) const;

        public: // modifiers
            void  swap( ptr_array& r );

            template< size_t idx >
            auto_type replace( T* r );
            auto_type replace( size_t idx, T* r );

        public: // pointer container requirements
            std::auto_ptr<ptr_array>  clone() const;
            std::auto_ptr<ptr_array>  release();
            template< size_t idx >
            bool                      is_null() const;
            bool                      is_null( size_t idx ) const;

        }; //  class 'ptr_sequence_adapter'

    } // namespace 'boost'

# Semantics

## Semantics: construct/copy/destroy

- `ptr_array();`

  > - Effects: construct array where each element is null

- `ptr_array( std::auto_ptr<ptr_array>& r );`

  > - Effects: take ownership of the supplied pointers

## Semantics: element access

- `T& front();`

- `const T& front() const;`

  > - Requirements: `not empty();`
  > - Effects: `return *begin();`
  > - Throws: `bad_ptr_container_operation` if `empty() == true`

- `T& back();`

- `const T& back() const;`

  > - Requirements: `not empty();`
  > - Effects: `return *--end();`
  > - Throws: `bad_ptr_container_operation` if `empty() == true`

- `template< size_t idx > T& at( size_type n );`

- `template< size_t idx > const T& at( size_type n ) const;`

  > - Requirements: `idx < size()` (compile-time enforced)
  > - Effects: Returns a reference to the `n`'th element
  > - Throws: nothing

- `T& at( size_type n );`

- `const T& at( size_type n ) const;`

  > - Requirements: `n < size()`
  > - Effects: Returns a reference to the `n`'th element
  > - Throws: `bad_index` if `n >=size()`

- `T& operator[]( size_type n );`

- `const T& operator[]( size_type n ) const;`

  > - Requirements: `n < size()`
  > - Effects: Returns a reference to the `n`'th element
  > - Throws: Nothing

## Semantics: modifiers

- `void swap( ptr_array& r );`

  > - Effects: swaps the two arrays
  > - Complexity: Linear
  > - Throws: nothing

- `template< size_t idx > auto_type replace( T* r );`

  > - Requirements:

  >   > - `idx < size()` (compile-time enforced)
  >   > - `r != 0`

  > - Effects: returns the object indexed by `idx` and replaces it with `r`.

  > - Throws: `bad_pointer` if `x == 0`.

  > - Exception safety: Strong guarantee

- `auto_type replace( size_t idx, T* r );`

  > - Requirements: `` x != 0 and idx < size()``
  > - Effects: returns the object indexed by `idx` and replaces it with `x`.
  > - Throws: `bad_index` if `idx >= size()` and `bad_pointer` if `x == 0`.
  > - Exception safety: Strong guarantee

## Semantics: pointer container requirements

- `std::auto_ptr<ptr_array> clone() const;`

  > - Effects: Returns a deep copy of the container
  > - Throws: `std::bad_alloc` if there is not enough memory to make a clone of the container
  > - Complexity: Linear

- `std::auto_ptr<ptr_array> release();`

  > - Effects: Releases ownership of the container. This is a useful way of returning a container from a function.
  > - Postconditions: `empty() == true` and all pointers are null
  > - Throws: `std::bad_alloc` if the return value cannot be allocated
  > - Exception safety: Strong guarantee

- `template< size_t idx > bool is_null() const;`

  > - Requirements: `idx < size()` (compile-time enforced)
  > - Effects: returns whether the pointer at index `idx` is null
  > - Exception safety: Nothrow guarantee

- `bool is_null( size_type idx ) const;`

  > - Requirements: `idx < size()`
  > - Effects: returns whether the pointer at index `idx` is null
  > - Exception safety: Nothrow guarantee

copyright: | Thorsten Ottosen 2004-2005.