Skip to content

J
json
Commit 8eb32084 authored by Niels's avatar Niels
Browse files
Options

code for #83 (no tests yet)

parent a26e44d6
Hide whitespace changes
Inline Side-by-side
Showing with 256 additions and 2 deletions
src/json.hpp
View file @ 8eb32084
......@@ -4972,7 +4972,7 @@ class basic_json
/// defines a reference to the type iterated over (value_type)
using reference = typename basic_json::const_reference;
/// the category of the iterator
using iterator_category = std::bidirectional_iterator_tag;
using iterator_category = std::random_access_iterator_tag;
/// default constructor
const_iterator() = default;
......@@ -5689,6 +5689,133 @@ class basic_json
}
};
/*!
@brief wrapper to access iterator member functions in range-based for
This class allows to access @ref key() and @ref value() during range-based
for loops. In these loops, a reference to the JSON values is returned, so
there is no access to the underlying iterator.
*/
class iterator_wrapper
{
private:
/// the container to iterate
basic_json& container;
/// the type of the iterator to use while iteration
using json_iterator = decltype(container.begin());
/// internal iterator wrapper
class iterator_wrapper_internal
{
private:
/// the iterator
json_iterator anchor;
/// an index for arrays
size_t array_index = 0;
size_t container_size = 0;
/// calculate a key for the iterator
std::string calculate_key()
{
switch (anchor.m_object->type())
{
/// use integer array index as key
case (value_t::array):
{
return std::to_string(array_index);
}
/// use key from the object
case (value_t::object):
{
return anchor.key();
}
/// use an empty key for all primitive types
default:
{
return "";
}
}
}
public:
/// construct wrapper given an iterator
iterator_wrapper_internal(json_iterator i, size_t s)
: anchor(i), container_size(s), first(calculate_key()), second(*i)
{}
/// dereference operator (needed for range-based for)
iterator_wrapper_internal operator*()
{
return *this;
}
/// increment operator (needed for range-based for)
iterator_wrapper_internal operator++()
{
++anchor;
++array_index;
first = calculate_key();
if (array_index < container_size)
{
second = *anchor;
}
return *this;
}
/// inequality operator (needed for range-based for)
bool operator!= (const iterator_wrapper_internal& o)
{
return anchor != o.anchor;
}
/// stream operator
friend std::ostream& operator<<(std::ostream& o, const iterator_wrapper_internal& w)
{
return o << w.value();
}
/// return key of the iterator
typename basic_json::string_t key() const
{
return first;
}
/// return value of the iterator
basic_json value() const
{
return second;
}
/// public member to simulate std::map::iterator access
typename basic_json::string_t first;
/// public member to simulate std::map::iterator access
basic_json& second;
};
public:
/// construct iterator wrapper from a container
iterator_wrapper(basic_json& cont)
: container(cont)
{}
/// return iterator begin (needed for range-based for)
iterator_wrapper_internal begin()
{
return iterator_wrapper_internal(container.begin(), container.size());
}
/// return iterator end (needed for range-based for)
iterator_wrapper_internal end()
{
return iterator_wrapper_internal(container.end(), container.size());
}
};
private:
//////////////////////
// lexer and parser //
......
src/json.hpp.re2c
View file @ 8eb32084
......@@ -4972,7 +4972,7 @@ class basic_json
/// defines a reference to the type iterated over (value_type)
using reference = typename basic_json::const_reference;
/// the category of the iterator
using iterator_category = std::bidirectional_iterator_tag;
using iterator_category = std::random_access_iterator_tag;
/// default constructor
const_iterator() = default;
......@@ -5689,6 +5689,133 @@ class basic_json
}
};
/*!
@brief wrapper to access iterator member functions in range-based for
This class allows to access @ref key() and @ref value() during range-based
for loops. In these loops, a reference to the JSON values is returned, so
there is no access to the underlying iterator.
*/
class iterator_wrapper
{
private:
/// the container to iterate
basic_json& container;
/// the type of the iterator to use while iteration
using json_iterator = decltype(container.begin());
/// internal iterator wrapper
class iterator_wrapper_internal
{
private:
/// the iterator
json_iterator anchor;
/// an index for arrays
size_t array_index = 0;
size_t container_size = 0;
/// calculate a key for the iterator
std::string calculate_key()
{
switch (anchor.m_object->type())
{
/// use integer array index as key
case (value_t::array):
{
return std::to_string(array_index);
}
/// use key from the object
case (value_t::object):
{
return anchor.key();
}
/// use an empty key for all primitive types
default:
{
return "";
}
}
}
public:
/// construct wrapper given an iterator
iterator_wrapper_internal(json_iterator i, size_t s)
: anchor(i), container_size(s), first(calculate_key()), second(*i)
{}
/// dereference operator (needed for range-based for)
iterator_wrapper_internal operator*()
{
return *this;
}
/// increment operator (needed for range-based for)
iterator_wrapper_internal operator++()
{
++anchor;
++array_index;
first = calculate_key();
if (array_index < container_size)
{
second = *anchor;
}
return *this;
}
/// inequality operator (needed for range-based for)
bool operator!= (const iterator_wrapper_internal& o)
{
return anchor != o.anchor;
}
/// stream operator
friend std::ostream& operator<<(std::ostream& o, const iterator_wrapper_internal& w)
{
return o << w.value();
}
/// return key of the iterator
typename basic_json::string_t key() const
{
return first;
}
/// return value of the iterator
basic_json value() const
{
return second;
}
/// public member to simulate std::map::iterator access
typename basic_json::string_t first;
/// public member to simulate std::map::iterator access
basic_json& second;
};
public:
/// construct iterator wrapper from a container
iterator_wrapper(basic_json& cont)
: container(cont)
{}
/// return iterator begin (needed for range-based for)
iterator_wrapper_internal begin()
{
return iterator_wrapper_internal(container.begin(), container.size());
}
/// return iterator end (needed for range-based for)
iterator_wrapper_internal end()
{
return iterator_wrapper_internal(container.end(), container.size());
}
};
private:
//////////////////////
// lexer and parser //
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment