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cleanup, test, and diff

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This commit is contained in:
Niels 2016-04-25 23:17:04 +02:00
parent 96cfe7463f
commit 5e0bf75d60
10 changed files with 2068 additions and 716 deletions
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2
README.md
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@ -428,7 +428,7 @@ $ make
$ ./json_unit "*"
===============================================================================
All tests passed (3344416 assertions in 30 test cases)
All tests passed (3344554 assertions in 31 test cases)
```
For more information, have a look at the file [.travis.yml](https://github.com/nlohmann/json/blob/master/.travis.yml).

34
doc/examples/diff.cpp Normal file
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@ -0,0 +1,34 @@
#include <json.hpp>
using json = nlohmann::json;
int main()
{
// the source document
json source = R"(
{
"baz": "qux",
"foo": "bar"
}
)"_json;
// the target document
json target = R"(
{
"baz": "boo",
"hello": [
"world"
]
}
)"_json;
// create the patch
json patch = json::diff(source, target);
// roundtrip
json patched_source = source.patch(patch);
// output patch and roundtrip result
std::cout << std::setw(4) << patch << "\n\n"
<< std::setw(4) << patched_source << std::endl;
}

1
doc/examples/diff.link Normal file
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@ -0,0 +1 @@
<a target="_blank" href="http://melpon.org/wandbox/permlink/hicmeOK39tBxaluM"><b>online</b></a>

25
doc/examples/diff.output Normal file
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@ -0,0 +1,25 @@
[
{
"op": "replace",
"path": "/baz",
"value": "boo"
},
{
"op": "remove",
"path": "/foo"
},
{
"op": "add",
"path": "/hello",
"value": [
"world"
]
}
]
{
"baz": "boo",
"hello": [
"world"
]
}

30
doc/examples/patch.cpp Normal file
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@ -0,0 +1,30 @@
#include <json.hpp>
using json = nlohmann::json;
int main()
{
// the original document
json doc = R"(
{
"baz": "qux",
"foo": "bar"
}
)"_json;
// the patch
json patch = R"(
[
{ "op": "replace", "path": "/baz", "value": "boo" },
{ "op": "add", "path": "/hello", "value": ["world"] },
{ "op": "remove", "path": "/foo"}
]
)"_json;
// apply the patch
json patched_doc = doc.patch(patch);
// output original and patched document
std::cout << std::setw(4) << doc << "\n\n"
<< std::setw(4) << patched_doc << std::endl;
}

1
doc/examples/patch.link Normal file
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@ -0,0 +1 @@
<a target="_blank" href="http://melpon.org/wandbox/permlink/lbczW3AzcUbH1Nbo"><b>online</b></a>

11
doc/examples/patch.output Normal file
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@ -0,0 +1,11 @@
{
"baz": "qux",
"foo": "bar"
}
{
"baz": "boo",
"hello": [
"world"
]
}

679
src/json.hpp
View file

@ -3595,121 +3595,6 @@ class basic_json
}
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. Similar to
@ref operator[](const typename object_t::key_type&), `null` values
are created in arrays and objects if necessary.
In particular:
- If the JSON pointer points to an object key that does not exist, it
is created an filled with a `null` value before a reference to it
is returned.
- If the JSON pointer points to an array index that does not exist, it
is created an filled with a `null` value before a reference to it
is returned. All indices between the current maximum and the given
index are also filled with `null`.
- The special value `-` is treated as a synonym for the index past the
end.
@param[in] ptr a JSON pointer
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer}
@since version 2.0.0
*/
reference operator[](const json_pointer& ptr)
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. The function does not change the JSON
value; no `null` values are created. In particular, the the special value
`-` yields an exception.
@param[in] ptr JSON pointer to the desired element
@return const reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
@since version 2.0.0
*/
const_reference operator[](const json_pointer& ptr) const
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a reference to the element at with specified JSON pointer @a ptr,
with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer}
@since version 2.0.0
*/
reference at(const json_pointer& ptr)
{
return ptr.get_checked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a const reference to the element at with specified JSON pointer
@a ptr, with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer_const}
@since version 2.0.0
*/
const_reference at(const json_pointer& ptr) const
{
return ptr.get_checked(this);
}
/*!
@brief access specified object element with default value
@ -4145,8 +4030,8 @@ class basic_json
@throw std::domain_error when called on a type other than JSON array;
example: `"cannot use erase() with null"`
@throw std::out_of_range when `idx >= size()`; example: `"index out of
range"`
@throw std::out_of_range when `idx >= size()`; example: `"array index 17
is out of range"`
@complexity Linear in distance between @a idx and the end of the container.
@ -4167,7 +4052,7 @@ class basic_json
{
if (idx >= size())
{
throw std::out_of_range("index out of range");
throw std::out_of_range("array index " + std::to_string(idx) + " is out of range");
}
assert(m_value.array != nullptr);
@ -8969,9 +8854,17 @@ basic_json_parser_63:
: reference_tokens(split(s))
{}
/// test for inequality
bool operator!=(const json_pointer& rhs) const
{
return reference_tokens != rhs.reference_tokens;
}
private:
/// remove and return last reference pointer
std::string pop_back()
{
if (reference_tokens.empty())
if (is_root())
{
throw std::domain_error("JSON pointer has no parent");
}
@ -8981,7 +8874,24 @@ basic_json_parser_63:
return last;
}
private:
/// return whether pointer points to the root document
bool is_root() const
{
return reference_tokens.empty();
}
json_pointer top() const
{
if (is_root())
{
throw std::domain_error("JSON pointer has no parent");
}
json_pointer result = *this;
result.reference_tokens = {reference_tokens[0]};
return result;
}
/*!
@brief create and return a reference to the pointed to value
*/
@ -9020,7 +8930,7 @@ basic_json_parser_63:
case value_t::array:
{
// create an entry in the array
result = &result->operator[](static_cast<size_t>(std::stoi(reference_token)));
result = &result->operator[](static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -9083,7 +8993,7 @@ basic_json_parser_63:
else
{
// convert array index to number; unchecked access
ptr = &ptr->operator[](static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
}
break;
}
@ -9128,7 +9038,7 @@ basic_json_parser_63:
}
// note: at performs range check
ptr = &ptr->at(static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -9180,7 +9090,7 @@ basic_json_parser_63:
}
// use unchecked array access
ptr = &ptr->operator[](static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -9224,7 +9134,7 @@ basic_json_parser_63:
}
// note: at performs range check
ptr = &ptr->at(static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -9291,12 +9201,8 @@ basic_json_parser_63:
}
}
// first transform any occurrence of the sequence '~1' to '/'
replace_substring(reference_token, "~1", "/");
// then transform any occurrence of the sequence '~0' to '~'
replace_substring(reference_token, "~0", "~");
// finally, store the reference token
unescape(reference_token);
result.push_back(reference_token);
}
@ -9332,6 +9238,24 @@ basic_json_parser_63:
);
}
/// escape tilde and slash
static std::string escape(std::string s)
{
// escape "~"" to "~0" and "/" to "~1"
replace_substring(s, "~", "~0");
replace_substring(s, "/", "~1");
return s;
}
/// unescape tilde and slash
static void unescape(std::string& s)
{
// first transform any occurrence of the sequence '~1' to '/'
replace_substring(s, "~1", "/");
// then transform any occurrence of the sequence '~0' to '~'
replace_substring(s, "~0", "~");
}
/*!
@param[in] reference_string the reference string to the current value
@param[in] value the value to consider
@ -9339,7 +9263,7 @@ basic_json_parser_63:
@note Empty objects or arrays are flattened to `null`.
*/
static void flatten(const std::string reference_string,
static void flatten(const std::string& reference_string,
const basic_json& value,
basic_json& result)
{
@ -9376,12 +9300,7 @@ basic_json_parser_63:
// iterate object and use keys as reference string
for (const auto& element : *value.m_value.object)
{
// escape "~"" to "~0" and "/" to "~1"
std::string key(element.first);
replace_substring(key, "~", "~0");
replace_substring(key, "/", "~1");
flatten(reference_string + "/" + key,
flatten(reference_string + "/" + escape(element.first),
element.second, result);
}
}
@ -9435,13 +9354,128 @@ basic_json_parser_63:
std::vector<std::string> reference_tokens {};
};
////////////////////////////
// JSON Pointer functions //
////////////////////////////
//////////////////////////
// JSON Pointer support //
//////////////////////////
/// @name JSON Pointer functions
/// @{
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. Similar to
@ref operator[](const typename object_t::key_type&), `null` values
are created in arrays and objects if necessary.
In particular:
- If the JSON pointer points to an object key that does not exist, it
is created an filled with a `null` value before a reference to it
is returned.
- If the JSON pointer points to an array index that does not exist, it
is created an filled with a `null` value before a reference to it
is returned. All indices between the current maximum and the given
index are also filled with `null`.
- The special value `-` is treated as a synonym for the index past the
end.
@param[in] ptr a JSON pointer
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer}
@since version 2.0.0
*/
reference operator[](const json_pointer& ptr)
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. The function does not change the JSON
value; no `null` values are created. In particular, the the special value
`-` yields an exception.
@param[in] ptr JSON pointer to the desired element
@return const reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
@since version 2.0.0
*/
const_reference operator[](const json_pointer& ptr) const
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a reference to the element at with specified JSON pointer @a ptr,
with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer}
@since version 2.0.0
*/
reference at(const json_pointer& ptr)
{
return ptr.get_checked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a const reference to the element at with specified JSON pointer
@a ptr, with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer_const}
@since version 2.0.0
*/
const_reference at(const json_pointer& ptr) const
{
return ptr.get_checked(this);
}
/*!
@brief return flattened JSON value
@ -9505,35 +9539,119 @@ basic_json_parser_63:
/// @}
//////////////////////////
// JSON Patch functions //
//////////////////////////
/// @name JSON Patch functions
/// @{
/*!
@brief applies a JSON patch
[JSON Patch](http://jsonpatch.com) defines a JSON document structure for
expressing a sequence of operations to apply to a JSON) document. With
this funcion, a JSON Patch is applied to the current JSON value by
executing all operations from the patch.
@param[in] patch JSON patch document
@return patched document
@note The original JSON value is not changed; that is, the patch is
applied to a copy of the value.
@note The application of a patch is atomic: Either all operations succeed
and the patched document is returned or an exception is thrown. In
any case, the original value is not changed: the patch is applied
to a copy of the value.
@sa [RFC 6902](https://tools.ietf.org/html/rfc6902)
@throw std::out_of_range if a JSON pointer inside the patch could not
be resolved successfully in the current JSON value; example: `"key baz
not found"`
@throw invalid_argument if the JSON patch is malformed (e.g., mandatory
attributes are missing); example: `"operation add must have member path"`
@complexity Linear in the size of the JSON value and the length of the
JSON patch. As usually only a fraction of the JSON value is affected by
the patch, the complexity can usually be neglected.
@liveexample{The following code shows how a JSON patch is applied to a
value.,patch}
@sa @ref diff -- create a JSON patch by comparing two JSON values
@sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
@sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901)
@since version 2.0.0
*/
basic_json apply_patch(const basic_json& patch) const
basic_json patch(const basic_json& patch) const
{
// make a working copy to apply the patch to
basic_json result = *this;
// the valid JSON Patch operations
enum class patch_operations {add, remove, replace, move, copy, test, invalid};
const auto get_op = [](const std::string op)
{
if (op == "add")
{
return patch_operations::add;
}
if (op == "remove")
{
return patch_operations::remove;
}
if (op == "replace")
{
return patch_operations::replace;
}
if (op == "move")
{
return patch_operations::move;
}
if (op == "copy")
{
return patch_operations::copy;
}
if (op == "test")
{
return patch_operations::test;
}
return patch_operations::invalid;
};
// wrapper for "add" operation; add value at ptr
const auto operation_add = [&result](json_pointer & ptr, basic_json val)
{
// adding to the root of the target document means replacing it
if (ptr.is_root())
{
result = val;
}
else
{
// make sure the top element of the pointer exists
json_pointer top_pointer = ptr.top();
if (top_pointer != ptr)
{
basic_json& x = result.at(top_pointer);
}
// get reference to parent of JSON pointer ptr
const auto last_path = ptr.pop_back();
basic_json& parent = result.at(ptr);
basic_json& parent = result[ptr];
if (parent.is_object())
switch (parent.m_type)
{
case value_t::null:
case value_t::object:
{
// use operator[] to add value
parent[last_path] = val;
break;
}
else if (parent.is_array())
case value_t::array:
{
if (last_path == "-")
{
@ -9541,9 +9659,26 @@ basic_json_parser_63:
parent.push_back(val);
}
else
{
const auto idx = std::stoi(last_path);
if (static_cast<size_type>(idx) > parent.size())
{
// avoid undefined behavior
throw std::out_of_range("array index " + std::to_string(idx) + " is out of range");
}
else
{
// default case: insert add offset
parent.insert(parent.begin() + std::stoi(last_path), val);
parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
}
}
break;
}
default:
{
throw std::domain_error("unexpected parent type " + parent.type_name());
}
}
}
};
@ -9558,11 +9693,21 @@ basic_json_parser_63:
// remove child
if (parent.is_object())
{
parent.erase(parent.find(last_path));
// perform range check
auto it = parent.find(last_path);
if (it != parent.end())
{
parent.erase(it);
}
else
{
throw std::out_of_range("key '" + last_path + "' not found");
}
}
else if (parent.is_array())
{
parent.erase(parent.begin() + std::stoi(last_path));
// note erase performs range check
parent.erase(static_cast<size_type>(std::stoi(last_path)));
}
};
@ -9570,7 +9715,7 @@ basic_json_parser_63:
if (not patch.is_array())
{
// a JSON patch must be an array of objects
throw std::domain_error("JSON patch must be an array of objects");
throw std::invalid_argument("JSON patch must be an array of objects");
}
// iterate and apply th eoperations
@ -9590,13 +9735,13 @@ basic_json_parser_63:
// check if desired value is present
if (it == val.m_value.object->end())
{
throw std::domain_error(error_msg + " must have member '" + member + "'");
throw std::invalid_argument(error_msg + " must have member '" + member + "'");
}
// check if result is of type string
if (string_type and not it->second.is_string())
{
throw std::domain_error(error_msg + " must have string member '" + member + "'");
throw std::invalid_argument(error_msg + " must have string member '" + member + "'");
}
// no error: return value
@ -9606,7 +9751,7 @@ basic_json_parser_63:
// type check
if (not val.is_object())
{
throw std::domain_error("JSON patch must be an array of objects");
throw std::invalid_argument("JSON patch must be an array of objects");
}
// collect mandatory members
@ -9614,51 +9759,251 @@ basic_json_parser_63:
const std::string path = get_value(op, "path", true);
json_pointer ptr(path);
if (op == "add")
switch (get_op(op))
{
case patch_operations::add:
{
operation_add(ptr, get_value("add", "value", false));
break;
}
else if (op == "remove")
case patch_operations::remove:
{
operation_remove(ptr);
break;
}
else if (op == "replace")
case patch_operations::replace:
{
// the "path" location must exist - use at()
result.at(ptr) = get_value("replace", "value", false);
break;
}
else if (op == "move")
case patch_operations::move:
{
const std::string from_path = get_value("move", "from", true);
json_pointer from_ptr(from_path);
basic_json v = result[from_ptr];
// the "from" location must exist - use at()
basic_json v = result.at(from_ptr);
// The move operation is functionally identical to a
// "remove" operation on the "from" location, followed
// immediately by an "add" operation at the target
// location with the value that was just removed.
operation_remove(from_ptr);
operation_add(ptr, v);
break;
}
else if (op == "copy")
case patch_operations::copy:
{
const std::string from_path = get_value("copy", "from", true);;
const json_pointer from_ptr(from_path);
// the "from" location must exist - use at()
result[ptr] = result.at(from_ptr);
break;
}
else if (op == "test")
case patch_operations::test:
{
if (result.at(ptr) != get_value("test", "value", false))
bool success = false;
try
{
// check if "value" matches the one at "path"
// the "path" location must exist - use at()
success = (result.at(ptr) == get_value("test", "value", false));
}
catch (std::out_of_range&)
{
// ignore out of range errors: success remains false
}
// throw an exception if test fails
if (not success)
{
throw std::domain_error("unsuccessful: " + val.dump());
}
break;
}
else
case patch_operations::invalid:
{
// op must be "add", "remove", "replace", "move", "copy", or
// "test"
throw std::domain_error("operation value '" + op + "' is invalid");
throw std::invalid_argument("operation value '" + op + "' is invalid");
}
}
}
return result;
}
/*!
@brief creates a diff as a JSON patch
Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can
be changed into the value @a target by calling @ref patch function.
@invariant For two JSON values @a source and @a target, the following code
yields always `true`:
@code {.cpp}
source.patch(diff(source, target)) == target;
@endcode
@note Currently, only `remove`, `add`, and `replace` operations are
generated.
@param[in] source JSON value to copare from
@param[in] target JSON value to copare against
@param[in] path helper value to create JSON pointers
@return a JSON patch to convert the @a source to @a target
@complexity Linear in the lengths of @a source and @a target.
@liveexample{The following code shows how a JSON patch is created as a
diff for two JSON values.,diff}
@sa @ref patch -- apply a JSON patch
@sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
@since version 2.0.0
*/
static basic_json diff(const basic_json& source,
const basic_json& target,
std::string path = "") noexcept
{
// the patch
basic_json result(value_t::array);
// if the values are the same, return empty patch
if (source == target)
{
return result;
}
if (source.type() != target.type())
{
// different types: replace value
result.push_back(
{
{"op", "replace"},
{"path", path},
{"value", target}
});
}
else
{
switch (source.type())
{
case value_t::array:
{
// first pass: traverse common elements
size_t i = 0;
while (i < source.size() and i < target.size())
{
// recursive call to compare array values at index i
auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
++i;
}
// i now reached the end of at least one array
// in a second pass, traverse the remaining elements
// remove my remaining elements
while (i < source.size())
{
result.push_back(object(
{
{"op", "remove"},
{"path", path + "/" + std::to_string(i)}
}));
++i;
}
// add other remaining elements
while (i < target.size())
{
result.push_back(
{
{"op", "add"},
{"path", path + "/" + std::to_string(i)},
{"value", target[i]}
});
++i;
}
break;
}
case value_t::object:
{
// first pass: traverse this object's elements
for (auto it = source.begin(); it != source.end(); ++it)
{
// escape the key name to be used in a JSON patch
const auto key = json_pointer::escape(it.key());
if (target.find(it.key()) != target.end())
{
// recursive call to compare object values at key it
auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
}
else
{
// found a key that is not in o -> remove it
result.push_back(object(
{
{"op", "remove"},
{"path", path + "/" + key}
}));
}
}
// second pass: traverse other object's elements
for (auto it = target.begin(); it != target.end(); ++it)
{
if (source.find(it.key()) == source.end())
{
// found a key that is not in this -> add it
const auto key = json_pointer::escape(it.key());
result.push_back(
{
{"op", "add"},
{"path", path + "/" + key},
{"value", it.value()}
});
}
}
break;
}
default:
{
// both primitive type: replace value
result.push_back(
{
{"op", "replace"},
{"path", path},
{"value", target}
});
break;
}
}
}
return result;
}
/// @}
};
@ -9678,9 +10023,9 @@ using json = basic_json<>;
}
/////////////////////////
// nonmember functions //
/////////////////////////
///////////////////////
// nonmember support //
///////////////////////
// specialization of std::swap, and std::hash
namespace std

679
src/json.hpp.re2c
View file

@ -3595,121 +3595,6 @@ class basic_json
}
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. Similar to
@ref operator[](const typename object_t::key_type&), `null` values
are created in arrays and objects if necessary.
In particular:
- If the JSON pointer points to an object key that does not exist, it
is created an filled with a `null` value before a reference to it
is returned.
- If the JSON pointer points to an array index that does not exist, it
is created an filled with a `null` value before a reference to it
is returned. All indices between the current maximum and the given
index are also filled with `null`.
- The special value `-` is treated as a synonym for the index past the
end.
@param[in] ptr a JSON pointer
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer}
@since version 2.0.0
*/
reference operator[](const json_pointer& ptr)
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. The function does not change the JSON
value; no `null` values are created. In particular, the the special value
`-` yields an exception.
@param[in] ptr JSON pointer to the desired element
@return const reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
@since version 2.0.0
*/
const_reference operator[](const json_pointer& ptr) const
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a reference to the element at with specified JSON pointer @a ptr,
with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer}
@since version 2.0.0
*/
reference at(const json_pointer& ptr)
{
return ptr.get_checked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a const reference to the element at with specified JSON pointer
@a ptr, with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer_const}
@since version 2.0.0
*/
const_reference at(const json_pointer& ptr) const
{
return ptr.get_checked(this);
}
/*!
@brief access specified object element with default value
@ -4145,8 +4030,8 @@ class basic_json
@throw std::domain_error when called on a type other than JSON array;
example: `"cannot use erase() with null"`
@throw std::out_of_range when `idx >= size()`; example: `"index out of
range"`
@throw std::out_of_range when `idx >= size()`; example: `"array index 17
is out of range"`
@complexity Linear in distance between @a idx and the end of the container.
@ -4167,7 +4052,7 @@ class basic_json
{
if (idx >= size())
{
throw std::out_of_range("index out of range");
throw std::out_of_range("array index " + std::to_string(idx) + " is out of range");
}
assert(m_value.array != nullptr);
@ -8279,9 +8164,17 @@ class basic_json
: reference_tokens(split(s))
{}
/// test for inequality
bool operator!=(const json_pointer& rhs) const
{
return reference_tokens != rhs.reference_tokens;
}
private:
/// remove and return last reference pointer
std::string pop_back()
{
if (reference_tokens.empty())
if (is_root())
{
throw std::domain_error("JSON pointer has no parent");
}
@ -8291,7 +8184,24 @@ class basic_json
return last;
}
private:
/// return whether pointer points to the root document
bool is_root() const
{
return reference_tokens.empty();
}
json_pointer top() const
{
if (is_root())
{
throw std::domain_error("JSON pointer has no parent");
}
json_pointer result = *this;
result.reference_tokens = {reference_tokens[0]};
return result;
}
/*!
@brief create and return a reference to the pointed to value
*/
@ -8330,7 +8240,7 @@ class basic_json
case value_t::array:
{
// create an entry in the array
result = &result->operator[](static_cast<size_t>(std::stoi(reference_token)));
result = &result->operator[](static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -8393,7 +8303,7 @@ class basic_json
else
{
// convert array index to number; unchecked access
ptr = &ptr->operator[](static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
}
break;
}
@ -8438,7 +8348,7 @@ class basic_json
}
// note: at performs range check
ptr = &ptr->at(static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -8490,7 +8400,7 @@ class basic_json
}
// use unchecked array access
ptr = &ptr->operator[](static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->operator[](static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -8534,7 +8444,7 @@ class basic_json
}
// note: at performs range check
ptr = &ptr->at(static_cast<size_t>(std::stoi(reference_token)));
ptr = &ptr->at(static_cast<size_type>(std::stoi(reference_token)));
break;
}
@ -8601,12 +8511,8 @@ class basic_json
}
}
// first transform any occurrence of the sequence '~1' to '/'
replace_substring(reference_token, "~1", "/");
// then transform any occurrence of the sequence '~0' to '~'
replace_substring(reference_token, "~0", "~");
// finally, store the reference token
unescape(reference_token);
result.push_back(reference_token);
}
@ -8642,6 +8548,24 @@ class basic_json
);
}
/// escape tilde and slash
static std::string escape(std::string s)
{
// escape "~"" to "~0" and "/" to "~1"
replace_substring(s, "~", "~0");
replace_substring(s, "/", "~1");
return s;
}
/// unescape tilde and slash
static void unescape(std::string& s)
{
// first transform any occurrence of the sequence '~1' to '/'
replace_substring(s, "~1", "/");
// then transform any occurrence of the sequence '~0' to '~'
replace_substring(s, "~0", "~");
}
/*!
@param[in] reference_string the reference string to the current value
@param[in] value the value to consider
@ -8649,7 +8573,7 @@ class basic_json
@note Empty objects or arrays are flattened to `null`.
*/
static void flatten(const std::string reference_string,
static void flatten(const std::string& reference_string,
const basic_json& value,
basic_json& result)
{
@ -8686,12 +8610,7 @@ class basic_json
// iterate object and use keys as reference string
for (const auto& element : *value.m_value.object)
{
// escape "~"" to "~0" and "/" to "~1"
std::string key(element.first);
replace_substring(key, "~", "~0");
replace_substring(key, "/", "~1");
flatten(reference_string + "/" + key,
flatten(reference_string + "/" + escape(element.first),
element.second, result);
}
}
@ -8745,13 +8664,128 @@ class basic_json
std::vector<std::string> reference_tokens {};
};
////////////////////////////
// JSON Pointer functions //
////////////////////////////
//////////////////////////
// JSON Pointer support //
//////////////////////////
/// @name JSON Pointer functions
/// @{
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. Similar to
@ref operator[](const typename object_t::key_type&), `null` values
are created in arrays and objects if necessary.
In particular:
- If the JSON pointer points to an object key that does not exist, it
is created an filled with a `null` value before a reference to it
is returned.
- If the JSON pointer points to an array index that does not exist, it
is created an filled with a `null` value before a reference to it
is returned. All indices between the current maximum and the given
index are also filled with `null`.
- The special value `-` is treated as a synonym for the index past the
end.
@param[in] ptr a JSON pointer
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer}
@since version 2.0.0
*/
reference operator[](const json_pointer& ptr)
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value.
No bound checking is performed. The function does not change the JSON
value; no `null` values are created. In particular, the the special value
`-` yields an exception.
@param[in] ptr JSON pointer to the desired element
@return const reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,operatorjson_pointer_const}
@since version 2.0.0
*/
const_reference operator[](const json_pointer& ptr) const
{
return ptr.get_unchecked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a reference to the element at with specified JSON pointer @a ptr,
with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer}
@since version 2.0.0
*/
reference at(const json_pointer& ptr)
{
return ptr.get_checked(this);
}
/*!
@brief access specified element via JSON Pointer
Returns a const reference to the element at with specified JSON pointer
@a ptr, with bounds checking.
@param[in] ptr JSON pointer to the desired element
@return reference to the element pointed to by @a ptr
@complexity Constant.
@throw std::out_of_range if the JSON pointer can not be resolved
@throw std::domain_error if an array index begins with '0'
@throw std::invalid_argument if an array index was not a number
@liveexample{The behavior is shown in the example.,at_json_pointer_const}
@since version 2.0.0
*/
const_reference at(const json_pointer& ptr) const
{
return ptr.get_checked(this);
}
/*!
@brief return flattened JSON value
@ -8815,35 +8849,119 @@ class basic_json
/// @}
//////////////////////////
// JSON Patch functions //
//////////////////////////
/// @name JSON Patch functions
/// @{
/*!
@brief applies a JSON patch
[JSON Patch](http://jsonpatch.com) defines a JSON document structure for
expressing a sequence of operations to apply to a JSON) document. With
this funcion, a JSON Patch is applied to the current JSON value by
executing all operations from the patch.
@param[in] patch JSON patch document
@return patched document
@note The original JSON value is not changed; that is, the patch is
applied to a copy of the value.
@note The application of a patch is atomic: Either all operations succeed
and the patched document is returned or an exception is thrown. In
any case, the original value is not changed: the patch is applied
to a copy of the value.
@sa [RFC 6902](https://tools.ietf.org/html/rfc6902)
@throw std::out_of_range if a JSON pointer inside the patch could not
be resolved successfully in the current JSON value; example: `"key baz
not found"`
@throw invalid_argument if the JSON patch is malformed (e.g., mandatory
attributes are missing); example: `"operation add must have member path"`
@complexity Linear in the size of the JSON value and the length of the
JSON patch. As usually only a fraction of the JSON value is affected by
the patch, the complexity can usually be neglected.
@liveexample{The following code shows how a JSON patch is applied to a
value.,patch}
@sa @ref diff -- create a JSON patch by comparing two JSON values
@sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
@sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901)
@since version 2.0.0
*/
basic_json apply_patch(const basic_json& patch) const
basic_json patch(const basic_json& patch) const
{
// make a working copy to apply the patch to
basic_json result = *this;
// the valid JSON Patch operations
enum class patch_operations {add, remove, replace, move, copy, test, invalid};
const auto get_op = [](const std::string op)
{
if (op == "add")
{
return patch_operations::add;
}
if (op == "remove")
{
return patch_operations::remove;
}
if (op == "replace")
{
return patch_operations::replace;
}
if (op == "move")
{
return patch_operations::move;
}
if (op == "copy")
{
return patch_operations::copy;
}
if (op == "test")
{
return patch_operations::test;
}
return patch_operations::invalid;
};
// wrapper for "add" operation; add value at ptr
const auto operation_add = [&result](json_pointer & ptr, basic_json val)
{
// adding to the root of the target document means replacing it
if (ptr.is_root())
{
result = val;
}
else
{
// make sure the top element of the pointer exists
json_pointer top_pointer = ptr.top();
if (top_pointer != ptr)
{
basic_json& x = result.at(top_pointer);
}
// get reference to parent of JSON pointer ptr
const auto last_path = ptr.pop_back();
basic_json& parent = result.at(ptr);
basic_json& parent = result[ptr];
if (parent.is_object())
switch (parent.m_type)
{
case value_t::null:
case value_t::object:
{
// use operator[] to add value
parent[last_path] = val;
break;
}
else if (parent.is_array())
case value_t::array:
{
if (last_path == "-")
{
@ -8851,9 +8969,26 @@ class basic_json
parent.push_back(val);
}
else
{
const auto idx = std::stoi(last_path);
if (static_cast<size_type>(idx) > parent.size())
{
// avoid undefined behavior
throw std::out_of_range("array index " + std::to_string(idx) + " is out of range");
}
else
{
// default case: insert add offset
parent.insert(parent.begin() + std::stoi(last_path), val);
parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
}
}
break;
}
default:
{
throw std::domain_error("unexpected parent type " + parent.type_name());
}
}
}
};
@ -8868,11 +9003,21 @@ class basic_json
// remove child
if (parent.is_object())
{
parent.erase(parent.find(last_path));
// perform range check
auto it = parent.find(last_path);
if (it != parent.end())
{
parent.erase(it);
}
else
{
throw std::out_of_range("key '" + last_path + "' not found");
}
}
else if (parent.is_array())
{
parent.erase(parent.begin() + std::stoi(last_path));
// note erase performs range check
parent.erase(static_cast<size_type>(std::stoi(last_path)));
}
};
@ -8880,7 +9025,7 @@ class basic_json
if (not patch.is_array())
{
// a JSON patch must be an array of objects
throw std::domain_error("JSON patch must be an array of objects");
throw std::invalid_argument("JSON patch must be an array of objects");
}
// iterate and apply th eoperations
@ -8900,13 +9045,13 @@ class basic_json
// check if desired value is present
if (it == val.m_value.object->end())
{
throw std::domain_error(error_msg + " must have member '" + member + "'");
throw std::invalid_argument(error_msg + " must have member '" + member + "'");
}
// check if result is of type string
if (string_type and not it->second.is_string())
{
throw std::domain_error(error_msg + " must have string member '" + member + "'");
throw std::invalid_argument(error_msg + " must have string member '" + member + "'");
}
// no error: return value
@ -8916,7 +9061,7 @@ class basic_json
// type check
if (not val.is_object())
{
throw std::domain_error("JSON patch must be an array of objects");
throw std::invalid_argument("JSON patch must be an array of objects");
}
// collect mandatory members
@ -8924,51 +9069,251 @@ class basic_json
const std::string path = get_value(op, "path", true);
json_pointer ptr(path);
if (op == "add")
switch (get_op(op))
{
case patch_operations::add:
{
operation_add(ptr, get_value("add", "value", false));
break;
}
else if (op == "remove")
case patch_operations::remove:
{
operation_remove(ptr);
break;
}
else if (op == "replace")
case patch_operations::replace:
{
// the "path" location must exist - use at()
result.at(ptr) = get_value("replace", "value", false);
break;
}
else if (op == "move")
case patch_operations::move:
{
const std::string from_path = get_value("move", "from", true);
json_pointer from_ptr(from_path);
basic_json v = result[from_ptr];
// the "from" location must exist - use at()
basic_json v = result.at(from_ptr);
// The move operation is functionally identical to a
// "remove" operation on the "from" location, followed
// immediately by an "add" operation at the target
// location with the value that was just removed.
operation_remove(from_ptr);
operation_add(ptr, v);
break;
}
else if (op == "copy")
case patch_operations::copy:
{
const std::string from_path = get_value("copy", "from", true);;
const json_pointer from_ptr(from_path);
// the "from" location must exist - use at()
result[ptr] = result.at(from_ptr);
break;
}
else if (op == "test")
case patch_operations::test:
{
if (result.at(ptr) != get_value("test", "value", false))
bool success = false;
try
{
// check if "value" matches the one at "path"
// the "path" location must exist - use at()
success = (result.at(ptr) == get_value("test", "value", false));
}
catch (std::out_of_range&)
{
// ignore out of range errors: success remains false
}
// throw an exception if test fails
if (not success)
{
throw std::domain_error("unsuccessful: " + val.dump());
}
break;
}
else
case patch_operations::invalid:
{
// op must be "add", "remove", "replace", "move", "copy", or
// "test"
throw std::domain_error("operation value '" + op + "' is invalid");
throw std::invalid_argument("operation value '" + op + "' is invalid");
}
}
}
return result;
}
/*!
@brief creates a diff as a JSON patch
Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can
be changed into the value @a target by calling @ref patch function.
@invariant For two JSON values @a source and @a target, the following code
yields always `true`:
@code {.cpp}
source.patch(diff(source, target)) == target;
@endcode
@note Currently, only `remove`, `add`, and `replace` operations are
generated.
@param[in] source JSON value to copare from
@param[in] target JSON value to copare against
@param[in] path helper value to create JSON pointers
@return a JSON patch to convert the @a source to @a target
@complexity Linear in the lengths of @a source and @a target.
@liveexample{The following code shows how a JSON patch is created as a
diff for two JSON values.,diff}
@sa @ref patch -- apply a JSON patch
@sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
@since version 2.0.0
*/
static basic_json diff(const basic_json& source,
const basic_json& target,
std::string path = "") noexcept
{
// the patch
basic_json result(value_t::array);
// if the values are the same, return empty patch
if (source == target)
{
return result;
}
if (source.type() != target.type())
{
// different types: replace value
result.push_back(
{
{"op", "replace"},
{"path", path},
{"value", target}
});
}
else
{
switch (source.type())
{
case value_t::array:
{
// first pass: traverse common elements
size_t i = 0;
while (i < source.size() and i < target.size())
{
// recursive call to compare array values at index i
auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i));
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
++i;
}
// i now reached the end of at least one array
// in a second pass, traverse the remaining elements
// remove my remaining elements
while (i < source.size())
{
result.push_back(object(
{
{"op", "remove"},
{"path", path + "/" + std::to_string(i)}
}));
++i;
}
// add other remaining elements
while (i < target.size())
{
result.push_back(
{
{"op", "add"},
{"path", path + "/" + std::to_string(i)},
{"value", target[i]}
});
++i;
}
break;
}
case value_t::object:
{
// first pass: traverse this object's elements
for (auto it = source.begin(); it != source.end(); ++it)
{
// escape the key name to be used in a JSON patch
const auto key = json_pointer::escape(it.key());
if (target.find(it.key()) != target.end())
{
// recursive call to compare object values at key it
auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
}
else
{
// found a key that is not in o -> remove it
result.push_back(object(
{
{"op", "remove"},
{"path", path + "/" + key}
}));
}
}
// second pass: traverse other object's elements
for (auto it = target.begin(); it != target.end(); ++it)
{
if (source.find(it.key()) == source.end())
{
// found a key that is not in this -> add it
const auto key = json_pointer::escape(it.key());
result.push_back(
{
{"op", "add"},
{"path", path + "/" + key},
{"value", it.value()}
});
}
}
break;
}
default:
{
// both primitive type: replace value
result.push_back(
{
{"op", "replace"},
{"path", path},
{"value", target}
});
break;
}
}
}
return result;
}
/// @}
};
@ -8988,9 +9333,9 @@ using json = basic_json<>;
}
/////////////////////////
// nonmember functions //
/////////////////////////
///////////////////////
// nonmember support //
///////////////////////
// specialization of std::swap, and std::hash
namespace std

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