A C++ template library for embedded applications
MIT licensed
Designed and
maintained by
John Wellbelove
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circular_buffer

A fixed capacity circular buffer.
STL equivalent: none

etl::circular_buffer<typename T, size_t SIZE>

Inherits from etl::icircular_buffer<T>
etl::icircular_buffer may be used as a size independent pointer or reference type for any etl::circular_buffer
instance.
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External buffer

If the circular buffer size is defined as zero, then the constructor expects pointer and size parameters to the externally
provided buffer. This buffer must not be shared concurrently with any other vector.
When a circular with an external buffer is moved, the data is moved, not the pointer to the buffer.
The external buffer MUST be declared one item larger that the intended capacity of the circular buffer.

A swap on a circular buffer with an external buffer is fast as it will swap buffer pointers rather than copying items.
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Template deduction guides
C++17 and above

template <typename T, typename... Ts>
etl::circular_buffer(T, Ts...)
  -> etl::circular_buffer<etl::enable_if_t<(etl::is_same_v<T, Ts> && ...), T>, 1U + sizeof...(Ts)>;

Example
etl::circular_buffer data{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

Defines data as an circular_buffer of int, of length 10, containing the supplied data.
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Member types

value_type              T
size_type               std::size_t
difference_type         std::ptrdiff_t
reference               value_type&
const_reference         const value_type&
rvalue_reference        value_type&&
pointer                 value_type*
const_pointer           const value_type*
iterator                Random access iterator
const_iterator          Constant random access iterator
reverse_iterator        reverse_iterator<iterator>
const_reverse_iterator  reverse_iterator<const_iterator>
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Static Constants

MAX_SIZE  The maximum size of the circular_buffer.
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Constructor

etl::circular_buffer<typename T, const size_t SIZE>();

etl::circular_buffer<typename T, const size_t SIZE>(const etl::circular_buffer<typename T, const size_t
SIZE>& other);
etl::circular_buffer<typename T, const size_t SIZE>(etl::circular_buffer<typename T, const size_t SIZE>&&
other);
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Element access

reference operator[](size_t i)
const_reference operator[](size_t i) const
Returns a reference or const reference to the indexed element
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reference front()
const_reference front() const
Returns a reference or const reference to the first element.
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reference back()
const_reference back() const
Returns a reference or const reference to the last element.
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Iterators

iterator begin()
const_iterator begin() const
const_iterator cbegin() const

Returns an iterator to the beginning of the circular_buffer.
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iterator end()
const_iterator end() const
const_iterator cend() const

Returns an iterator to the end of the circular_buffer.
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iterator rbegin()
const_reverse_iterator rbegin() const
const_reverse_iterator crbegin() const
Returns a reverse iterator to the beginning of the circular_buffer.
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iterator rend()
const_reverse_iterator rend() const
const_reverse_iterator crend() const
Returns a reverse iterator to the end of the circular_buffer.
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Capacity

bool empty() const

Returns true if the size of the circular_buffer is zero, otherwise false.
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bool full() const
Returns true if the size of the circular_buffer is SIZE, otherwise false.
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size_t size() const
Returns the size of the circular_buffer.
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size_t max_size() const
Returns the maximum possible size of the circular_buffer.
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size_t capacity() const
Returns the maximum possible size of the circular_buffer.
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size_t available() const
Returns the remaining available capacity in the circular_buffer.
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Modifiers

void push(const_reference value)
void push(rvalue_reference value)
Pushes a value to the back of the circular_buffer.
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template <typename TIterator>
void push(TIterator first, const TIterator& last)
Pushes values to the back of the circular_buffer.
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void pop()
Pop a value from the front of the circular_buffer.
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void clear()
Clears the circular_buffer to a size of zero.
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void swap(circular_buffer<T, SIZE> other)
Swaps the circular_buffer with other.
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Non-member functions

==  true if the contents of the vectors are equal, otherwise false.
!=  true if the contents of the vectors are not equal, otherwise false.
swap Swaps two circular buffers. A circular buffer with internal storage copies items while one with an external buffer
will swap pointers.

circular_buffer.h