[#bsl-Deque_Base]
= xref:bsl.adoc[bsl]::Deque_Base
:relfileprefix: ../
:mrdocs:

This class describes the basic layout for a deque class. It is important that this class has the same layout as the deque class implementation. It is parameterized by `VALUE_TYPE` only and implements the portion of `bsl::deque` that does not need to know about its (template parameter) type `ALLOCATOR` (in order to generate shorter debug strings). Note that this class must have the same layout as `Deque_Imp` (see implementation file).

== Synopsis

Declared in `<bslstl_deque.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class VALUE_TYPE>
class Deque_Base;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/Deque_Base/const_iterator.adoc[`const_iterator`] 
| This `typedef` is an alias for `const_iterator`.
| xref:bsl/Deque_Base/const_reference.adoc[`const_reference`] 
| This `typedef` is an alias for `const_reference`.
| xref:bsl/Deque_Base/const_reverse_iterator.adoc[`const_reverse_iterator`] 
| This `typedef` is an alias to `bsl::reverse_iterator<const_iterator>`.
| xref:bsl/Deque_Base/difference_type.adoc[`difference_type`] 
| This `typedef` is an alias for `difference_type`.
| xref:bsl/Deque_Base/iterator-03.adoc[`iterator`] 
| This `typedef` is an alias for `iterator`.
| xref:bsl/Deque_Base/reference.adoc[`reference`] 
| This `typedef` is an alias for `reference`.
| xref:bsl/Deque_Base/reverse_iterator.adoc[`reverse_iterator`] 
| This `typedef` is an alias to `bsl::reverse_iterator<iterator>`.
| xref:bsl/Deque_Base/size_type.adoc[`size_type`] 
| This `typedef` is an alias for `size_type`.
| xref:bsl/Deque_Base/value_type.adoc[`value_type`] 
| This `typedef` is an alias for `value_type`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/Deque_Base/at-04.adoc[`at`] 
| `at` overloads
| xref:bsl/Deque_Base/back-06.adoc[`back`] 
| `back` overloads
| xref:bsl/Deque_Base/begin-0fd.adoc[`begin`] 
| `begin` overloads
| xref:bsl/Deque_Base/capacity.adoc[`capacity`] 
| Return the sum of the current size of this deque plus the minimum number of `push_front` or `push_back` operations needed to invalidate iterators in this deque. Note that this method is not part of the C++ standard.
| xref:bsl/Deque_Base/cbegin.adoc[`cbegin`] 
| Return an iterator providing non‐modifiable access to the first element in this deque, and the past‐the‐end iterator if this deque is empty.
| xref:bsl/Deque_Base/cend.adoc[`cend`] 
| Return the past‐the‐end (forward) iterator providing non‐modifiable access to this deque.
| xref:bsl/Deque_Base/crbegin.adoc[`crbegin`] 
| Return a reverse iterator providing non‐modifiable access to the last element in this deque, and the past‐the‐end reverse iterator if this deque is empty.
| xref:bsl/Deque_Base/crend.adoc[`crend`] 
| Return the past‐the‐end reverse iterator providing non‐modifiable access to this deque.
| xref:bsl/Deque_Base/empty.adoc[`empty`] 
| Return `true` if this deque contains no elements, and `false` otherwise.
| xref:bsl/Deque_Base/end-01.adoc[`end`] 
| `end` overloads
| xref:bsl/Deque_Base/front-04.adoc[`front`] 
| `front` overloads
| xref:bsl/Deque_Base/operator_subs-09.adoc[`operator[]`] 
| Subscript operators
| xref:bsl/Deque_Base/rbegin-09.adoc[`rbegin`] 
| `rbegin` overloads
| xref:bsl/Deque_Base/rend-02.adoc[`rend`] 
| `rend` overloads
| xref:bsl/Deque_Base/size.adoc[`size`] 
| Return the number of elements contained by this deque.
|===


== Protected Data Members

[cols="1,4"]
|===
| Name| Description
| xref:bsl/Deque_Base/d_blocksLength.adoc[`d_blocksLength`] 
| Length of the `d_blocks_p` array.
| xref:bsl/Deque_Base/d_blocks_p.adoc[`d_blocks_p`] 
| Array of pointers to blocks (owned).
| xref:bsl/Deque_Base/d_finish.adoc[`d_finish`] 
| The `d_finish` data member.
| xref:bsl/Deque_Base/d_start.adoc[`d_start`] 
| The `d_start` data member.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:bsl/deque-0c.adoc[`deque`] 
| This class template provides an STL‐compliant `deque` that conforms to the `bslma::Allocator` model. For the requirements of a deque class, consult the C++11 standard. In particular, this implementation offers the general rules that: 1. A call to any method that would result in a deque having a size greater than the value returned by `max_size` triggers a call to `bslstl::StdExceptUtil::throwLengthError`. 2. A call to an `at` method that attempts to access a position outside of the valid range of a deque triggers a call to `bslstl::StdExceptUtil::throwOutOfRange`.
|===


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