C++14 and later CRTP templates for defining iterators, views, and containers
An updated C++20-friendly version of the iterator_facade
and
iterator_adaptor
parts of Boost.Iterator (now called iterator_interface
);
a pre-C++20 version of C++20's view_interface
; and a new template called
container_interface
, meant to aid the creation of new containers; all
targeting standardization. This library requires at least C++14.
For the iterator portion -- if you need to write an iterator, iterator_interface
turns this:
struct repeated_chars_iterator
{
using value_type = char;
using difference_type = std::ptrdiff_t;
using pointer = char const *;
using reference = char const;
using iterator_category = std::random_access_iterator_tag;
constexpr repeated_chars_iterator() noexcept :
first_(nullptr),
size_(0),
n_(0)
{}
constexpr repeated_chars_iterator(
char const * first,
difference_type size,
difference_type n) noexcept :
first_(first),
size_(size),
n_(n)
{}
constexpr reference operator*() const noexcept
{
return first_[n_ % size_];
}
constexpr value_type operator[](difference_type n) const noexcept
{
return first_[(n_ + n) % size_];
}
constexpr repeated_chars_iterator & operator++() noexcept
{
++n_;
return *this;
}
constexpr repeated_chars_iterator operator++(int)noexcept
{
repeated_chars_iterator retval = *this;
++*this;
return retval;
}
constexpr repeated_chars_iterator & operator+=(difference_type n) noexcept
{
n_ += n;
return *this;
}
constexpr repeated_chars_iterator & operator--() noexcept
{
--n_;
return *this;
}
constexpr repeated_chars_iterator operator--(int)noexcept
{
repeated_chars_iterator retval = *this;
--*this;
return retval;
}
constexpr repeated_chars_iterator & operator-=(difference_type n) noexcept
{
n_ -= n;
return *this;
}
friend constexpr bool operator==(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return lhs.first_ == rhs.first_ && lhs.n_ == rhs.n_;
}
friend constexpr bool operator!=(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return !(lhs == rhs);
}
friend constexpr bool operator<(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return lhs.first_ == rhs.first_ && lhs.n_ < rhs.n_;
}
friend constexpr bool operator<=(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return lhs == rhs || lhs < rhs;
}
friend constexpr bool operator>(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return rhs < lhs;
}
friend constexpr bool operator>=(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return rhs <= lhs;
}
friend constexpr repeated_chars_iterator
operator+(repeated_chars_iterator lhs, difference_type rhs) noexcept
{
return lhs += rhs;
}
friend constexpr repeated_chars_iterator
operator+(difference_type lhs, repeated_chars_iterator rhs) noexcept
{
return rhs += lhs;
}
friend constexpr repeated_chars_iterator
operator-(repeated_chars_iterator lhs, difference_type rhs) noexcept
{
return lhs -= rhs;
}
friend constexpr difference_type operator-(
repeated_chars_iterator lhs, repeated_chars_iterator rhs) noexcept
{
return lhs.n_ - rhs.n_;
}
private:
char const * first_;
difference_type size_;
difference_type n_;
};
into this:
struct repeated_chars_iterator : boost::stl_interfaces::iterator_interface<
repeated_chars_iterator,
std::random_access_iterator_tag,
char,
char>
{
constexpr repeated_chars_iterator() noexcept :
first_(nullptr),
size_(0),
n_(0)
{}
constexpr repeated_chars_iterator(
char const * first, difference_type size, difference_type n) noexcept :
first_(first),
size_(size),
n_(n)
{}
constexpr char operator*() const noexcept { return first_[n_ % size_]; }
constexpr repeated_chars_iterator & operator+=(std::ptrdiff_t i) noexcept
{
n_ += i;
return *this;
}
constexpr auto operator-(repeated_chars_iterator other) const noexcept
{
return n_ - other.n_;
}
private:
char const * first_;
difference_type size_;
difference_type n_;
};
The code size savings are even more dramatic for view_interface
and
container_interface
! If you don't ever write iterators, views, containers,
or view adaptors, this is not for you.
This library includes both C++20 concept constrained and SFINAE-constrained versions.
license | BSL-1.0 |
---|---|
project | boost |
url | github.com/boostorg/stl_interfaces |
doc-url | www.boost.org/doc/libs/1_85_0/libs/stl_interfaces |
boost-users@lists.boost.orgMailing list | |
topics | C++Boost |
5 Versions
version | 1.78.0 |
---|---|
repository | https://pkg.cppget.org/1/legacy |
depends | 2; libboost-assert, libboost-config |
reviews | +1 |
version | 1.77.0+1 |
---|---|
repository | https://pkg.cppget.org/1/legacy |
depends | 2; libboost-assert, libboost-config |
reviews | +1 |
version | 1.85.0 |
---|---|
repository | https://pkg.cppget.org/1/testing |
depends | 3; libboost-assert, libboost-config, libboost-type-traits |
reviews | +1 |
version | 1.83.0 |
---|---|
repository | https://pkg.cppget.org/1/stable |
depends | 3; libboost-assert, libboost-config, libboost-type-traits |
reviews | +1 |
version | 1.81.0+1 |
---|---|
repository | https://pkg.cppget.org/1/stable |
depends | 3; libboost-assert, libboost-config, libboost-type-traits |
reviews | +1 |