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Commit 70493a10 by Niels
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iterator_wrapper for const objects (#83)

parent 00f9296d
Showing with 431 additions and 56 deletions
README.md
......@@ -398,7 +398,7 @@ $ make
$ ./json_unit "*"
===============================================================================
All tests passed (3341888 assertions in 28 test cases)
All tests passed (3341947 assertions in 28 test cases)
```
For more information, have a look at the file [.travis.yml](https://github.com/nlohmann/json/blob/master/.travis.yml).
src/json.hpp
......@@ -6152,43 +6152,35 @@ class basic_json
}
};
/*!
@brief wrapper to access iterator member functions in range-based for
This class allows to access @ref iterator::key() and @ref iterator::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:
/// proxy class for the iterator_wrapper functions
template<typename IteratorType>
class iteration_proxy
{
private:
/// the container to iterate
typename basic_json::reference container;
/// the type of the iterator to use while iteration
using json_iterator = decltype(std::begin(container));
/// internal iterator wrapper
class iterator_wrapper_internal
/// helper class for iteration
class iteration_proxy_internal
{
private:
/// the iterator
json_iterator anchor;
IteratorType anchor;
/// an index for arrays
size_t array_index = 0;
public:
/// construct wrapper given an iterator
iterator_wrapper_internal(json_iterator i) : anchor(i)
iteration_proxy_internal(IteratorType it)
: anchor(it)
{}
/// dereference operator (needed for range-based for)
iterator_wrapper_internal& operator*()
iteration_proxy_internal& operator*()
{
return *this;
}
/// increment operator (needed for range-based for)
iterator_wrapper_internal& operator++()
iteration_proxy_internal& operator++()
{
++anchor;
++array_index;
......@@ -6197,7 +6189,7 @@ class basic_json
}
/// inequality operator (needed for range-based for)
bool operator!= (const iterator_wrapper_internal& o)
bool operator!= (const iteration_proxy_internal& o)
{
return anchor != o.anchor;
}
......@@ -6228,31 +6220,57 @@ class basic_json
}
/// return value of the iterator
typename json_iterator::reference value() const
typename IteratorType::reference value() const
{
return anchor.value();
}
};
/// the container to iterate
typename IteratorType::reference container;
public:
/// construct iterator wrapper from a container
iterator_wrapper(typename basic_json::reference cont)
/// construct iteration proxy from a container
iteration_proxy(typename IteratorType::reference cont)
: container(cont)
{}
/// return iterator begin (needed for range-based for)
iterator_wrapper_internal begin()
iteration_proxy_internal begin()
{
return iterator_wrapper_internal(container.begin());
return iteration_proxy_internal(container.begin());
}
/// return iterator end (needed for range-based for)
iterator_wrapper_internal end()
iteration_proxy_internal end()
{
return iterator_wrapper_internal(container.end());
return iteration_proxy_internal(container.end());
}
};
public:
/*!
@brief wrapper to access iterator member functions in range-based for
This functuion allows to access @ref iterator::key() and @ref
iterator::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.
*/
static iteration_proxy<iterator> iterator_wrapper(reference cont)
{
return iteration_proxy<iterator>(cont);
}
/*!
@copydoc iterator_wrapper(reference)
*/
static iteration_proxy<const_iterator> iterator_wrapper(const_reference cont)
{
return iteration_proxy<const_iterator>(cont);
}
private:
//////////////////////
// lexer and parser //
......
src/json.hpp.re2c
......@@ -6152,43 +6152,35 @@ class basic_json
}
};
/*!
@brief wrapper to access iterator member functions in range-based for
This class allows to access @ref iterator::key() and @ref iterator::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:
/// proxy class for the iterator_wrapper functions
template<typename IteratorType>
class iteration_proxy
{
private:
/// the container to iterate
typename basic_json::reference container;
/// the type of the iterator to use while iteration
using json_iterator = decltype(std::begin(container));
/// internal iterator wrapper
class iterator_wrapper_internal
/// helper class for iteration
class iteration_proxy_internal
{
private:
/// the iterator
json_iterator anchor;
IteratorType anchor;
/// an index for arrays
size_t array_index = 0;
public:
/// construct wrapper given an iterator
iterator_wrapper_internal(json_iterator i) : anchor(i)
iteration_proxy_internal(IteratorType it)
: anchor(it)
{}
/// dereference operator (needed for range-based for)
iterator_wrapper_internal& operator*()
iteration_proxy_internal& operator*()
{
return *this;
}
/// increment operator (needed for range-based for)
iterator_wrapper_internal& operator++()
iteration_proxy_internal& operator++()
{
++anchor;
++array_index;
......@@ -6197,7 +6189,7 @@ class basic_json
}
/// inequality operator (needed for range-based for)
bool operator!= (const iterator_wrapper_internal& o)
bool operator!= (const iteration_proxy_internal& o)
{
return anchor != o.anchor;
}
......@@ -6228,31 +6220,57 @@ class basic_json
}
/// return value of the iterator
typename json_iterator::reference value() const
typename IteratorType::reference value() const
{
return anchor.value();
}
};
/// the container to iterate
typename IteratorType::reference container;
public:
/// construct iterator wrapper from a container
iterator_wrapper(typename basic_json::reference cont)
/// construct iteration proxy from a container
iteration_proxy(typename IteratorType::reference cont)
: container(cont)
{}
/// return iterator begin (needed for range-based for)
iterator_wrapper_internal begin()
iteration_proxy_internal begin()
{
return iterator_wrapper_internal(container.begin());
return iteration_proxy_internal(container.begin());
}
/// return iterator end (needed for range-based for)
iterator_wrapper_internal end()
iteration_proxy_internal end()
{
return iterator_wrapper_internal(container.end());
return iteration_proxy_internal(container.end());
}
};
public:
/*!
@brief wrapper to access iterator member functions in range-based for
This functuion allows to access @ref iterator::key() and @ref
iterator::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.
*/
static iteration_proxy<iterator> iterator_wrapper(reference cont)
{
return iteration_proxy<iterator>(cont);
}
/*!
@copydoc iterator_wrapper(reference)
*/
static iteration_proxy<const_iterator> iterator_wrapper(const_reference cont)
{
return iteration_proxy<const_iterator>(cont);
}
private:
//////////////////////
// lexer and parser //
......
test/unit.cpp
......@@ -9653,6 +9653,141 @@ TEST_CASE("iterator_wrapper")
}
}
SECTION("const object")
{
SECTION("value")
{
const json j = {{"A", 1}, {"B", 2}};
int counter = 1;
for (auto i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "A");
CHECK(i.value() == json(1));
break;
}
case 2:
{
CHECK(i.key() == "B");
CHECK(i.value() == json(2));
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("reference")
{
const json j = {{"A", 1}, {"B", 2}};
int counter = 1;
for (auto& i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "A");
CHECK(i.value() == json(1));
break;
}
case 2:
{
CHECK(i.key() == "B");
CHECK(i.value() == json(2));
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("const value")
{
const json j = {{"A", 1}, {"B", 2}};
int counter = 1;
for (const auto i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "A");
CHECK(i.value() == json(1));
break;
}
case 2:
{
CHECK(i.key() == "B");
CHECK(i.value() == json(2));
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("const reference")
{
const json j = {{"A", 1}, {"B", 2}};
int counter = 1;
for (const auto& i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "A");
CHECK(i.value() == json(1));
break;
}
case 2:
{
CHECK(i.key() == "B");
CHECK(i.value() == json(2));
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
}
SECTION("array")
{
SECTION("value")
......@@ -9799,6 +9934,141 @@ TEST_CASE("iterator_wrapper")
}
}
SECTION("const array")
{
SECTION("value")
{
const json j = {"A", "B"};
int counter = 1;
for (auto i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "0");
CHECK(i.value() == "A");
break;
}
case 2:
{
CHECK(i.key() == "1");
CHECK(i.value() == "B");
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("reference")
{
const json j = {"A", "B"};
int counter = 1;
for (auto& i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "0");
CHECK(i.value() == "A");
break;
}
case 2:
{
CHECK(i.key() == "1");
CHECK(i.value() == "B");
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("const value")
{
const json j = {"A", "B"};
int counter = 1;
for (const auto i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "0");
CHECK(i.value() == "A");
break;
}
case 2:
{
CHECK(i.key() == "1");
CHECK(i.value() == "B");
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
SECTION("const reference")
{
const json j = {"A", "B"};
int counter = 1;
for (const auto& i : json::iterator_wrapper(j))
{
switch (counter++)
{
case 1:
{
CHECK(i.key() == "0");
CHECK(i.value() == "A");
break;
}
case 2:
{
CHECK(i.key() == "1");
CHECK(i.value() == "B");
break;
}
default:
{
break;
}
}
}
CHECK(counter == 3);
}
}
SECTION("primitive")
{
SECTION("value")
......@@ -9826,9 +10096,15 @@ TEST_CASE("iterator_wrapper")
++counter;
CHECK(i.key() == "");
CHECK(i.value() == json(1));
// change value
i.value() = json(2);
}
CHECK(counter == 2);
// check if value has changed
CHECK(j == json(2));
}
SECTION("const value")
......@@ -9846,7 +10122,7 @@ TEST_CASE("iterator_wrapper")
CHECK(counter == 2);
}
SECTION("reference")
SECTION("const reference")
{
json j = 1;
int counter = 1;
......@@ -9861,6 +10137,69 @@ TEST_CASE("iterator_wrapper")
CHECK(counter == 2);
}
}
SECTION("const primitive")
{
SECTION("value")
{
const json j = 1;
int counter = 1;
for (auto i : json::iterator_wrapper(j))
{
++counter;
CHECK(i.key() == "");
CHECK(i.value() == json(1));
}
CHECK(counter == 2);
}
SECTION("reference")
{
const json j = 1;
int counter = 1;
for (auto& i : json::iterator_wrapper(j))
{
++counter;
CHECK(i.key() == "");
CHECK(i.value() == json(1));
}
CHECK(counter == 2);
}
SECTION("const value")
{
const json j = 1;
int counter = 1;
for (const auto i : json::iterator_wrapper(j))
{
++counter;
CHECK(i.key() == "");
CHECK(i.value() == json(1));
}
CHECK(counter == 2);
}
SECTION("const reference")
{
const json j = 1;
int counter = 1;
for (const auto& i : json::iterator_wrapper(j))
{
++counter;
CHECK(i.key() == "");
CHECK(i.value() == json(1));
}
CHECK(counter == 2);
}
}
}
TEST_CASE("compliance tests from json.org")
......
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