Problem 1 - General Container
Much inspiration was had from Chapters 5 and 9, "Containers", of Austern's
"Generic Programming and the STL", and the SGI STL documentation.
A C++ container must:
- contain elements (value semantics rather than pointer semantics)
- provide access to those elements (iterators and keyed lookup)
- supplies functionality necessary for regular types (basic STL concepts)
and classically supported at least assignment and copy construction (I
understand that this requirement is weakened in C++0x?).
A general-purpose container is capable of using all available memory, but
does not do so unless necessary; this will require the variable-size
container model. Our container will thus model the Sequence or
Associative Container concepts. As a Sequence is required to effectively
support the Stack and Queue container adapters, we'll want a well-ordered
underlying container for Problems 2 and 3. Since vector furthermore lacks
pop_front(), list or deque suggest themselves (given Problem 2).
If we are optimizing for LIFO, FIFO or FLIFO behavior, we can use very
simple, very aggressive allocation and management. At most, we will need
to track:
- Allocated regions (one pointer each), since we can't robustly request
gigantic contiguous regions (especially in the absence of VM). This
Sequence will itself need only FLIFO support; a deque would work well.
- Free space in the head and tail regions (1 or 2 unsigned ints).
- The object size, adjusted for padding (if applicable).
As this will provide both a lean solution to Problem 1 and a natural,
efficient base for Problems 2 and 3, I'll likely optimize for this case.
I'll thus essentially be implementing a deque object.
To more effectively support atomic (non-iterated) types, we can use TR1's
type_traits to test for integral types at compile time, specializing on
is_integral<T>::value.
OPTIONAL: To spice up this solution, I can use VMA remapping via
OS-specific functionality such as Linux's mremap().
Problem 2 - General Queue
Queue container adapter atop Problem 1.
Problem 3 - General Stack
Stack container adapter atop Problem 1.