[#BloombergLP-bslma-SequentialAllocator-2constructor-04]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslma.adoc[bslma]::xref:BloombergLP/bslma/SequentialAllocator.adoc[SequentialAllocator]::SequentialAllocator
:relfileprefix: ../../../
:mrdocs:

Create a sequential allocator using the specified external `buffer` with a maximum buffer size.

== Synopsis

Declared in `<bslma_sequentialallocator.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
SequentialAllocator(
    char* buffer,
    int bufferSize,
    int maxBufferSize,
    xref:BloombergLP/bslma/Allocator.adoc[Allocator]* basicAllocator = 0);
----

== Description

Create a sequential allocator for allocating memory blocks initially from the specified `buffer` the size (in bytes) of which is indicated by the absolute value of the specified `bufferSize`. The specified `maxBufferSize` indicates the maximum size (in bytes) allowed for internally allocated buffers. Optionally specify an alignment `strategy` used to align allocated memory blocks. If `strategy` is not specified, _Natural Alignment_ is used. Optionally specify a `basicAllocator` used to supply memory. If `basicAllocator` is 0, the currently installed default allocator is used. If an `allocate` or `reserveCapacity` request cannot be satisfied from the current buffer, a new buffer is allocated, the size of which is determined by a buffer growth strategy implied by `bufferSize`. If `bufferSize` is negative, the buffer growth strategy used is _Geometric Growth_; otherwise it is *Constant Growth*. (See the component level documentation for further details.) In either case, the new buffer will have sufficient capacity to satisfy the request. If _Geometric Growth_ is in effect, the geometric progression of buffer sizes is capped at `maxBufferSize`. The behavior is undefined unless `0 < maxBufferSize`, and `|bufferSize| <= maxBufferSize`. Note that `maxBufferSize` is ignored if `bufferSize > 0`. Also note that `maxBufferSize` may be overridden by a sufficiently large value passed to `allocate` or `reserveCapacity`.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *buffer*
| The external buffer used for initial allocations.
| *bufferSize*
| The size (in bytes) of `buffer`.
| *maxBufferSize*
| The maximum internal buffer size (in bytes).
| *basicAllocator*
| The allocator used to supply memory.
|===


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