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✨ add contains function for JSON pointers

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This commit is contained in:
Niels Lohmann 2019-06-30 10:03:08 +02:00
parent 39011a1759
commit 258fa798f1
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GPG key ID: 7F3CEA63AE251B69
7 changed files with 338 additions and 23 deletions
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45
doc/examples/contains_json_pointer.cpp Normal file
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@ -0,0 +1,45 @@
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create a JSON value
json j =
{
{"number", 1}, {"string", "foo"}, {"array", {1, 2}}
};
std::cout << std::boolalpha
<< j.contains("/number"_json_pointer) << '\n'
<< j.contains("/string"_json_pointer) << '\n'
<< j.contains("/string"_json_pointer) << '\n'
<< j.contains("/array"_json_pointer) << '\n'
<< j.contains("/array/1"_json_pointer) << '\n'
<< j.contains("/array/-"_json_pointer) << '\n'
<< j.contains("/array/4"_json_pointer) << '\n'
<< j.contains("/baz"_json_pointer) << std::endl;
// out_of_range.106
try
{
// try to use an array index with leading '0'
j.contains("/array/01"_json_pointer);
}
catch (json::parse_error& e)
{
std::cout << e.what() << '\n';
}
// out_of_range.109
try
{
// try to use an array index that is not a number
j.contains("/array/one"_json_pointer);
}
catch (json::parse_error& e)
{
std::cout << e.what() << '\n';
}
}

1
doc/examples/contains_json_pointer.link Normal file
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@ -0,0 +1 @@
<a target="_blank" href="https://wandbox.org/permlink/3TJ79OzHP4vmN1Nb"><b>online</b></a>

10
doc/examples/contains_json_pointer.output Normal file
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@ -0,0 +1,10 @@
true
true
true
true
true
false
false
false
[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'
[json.exception.parse_error.109] parse error: array index 'one' is not a number

90
include/nlohmann/detail/json_pointer.hpp
View file

@ -2,6 +2,7 @@
#include <algorithm> // all_of
#include <cassert> // assert
#include <cctype> // isdigit
#include <numeric> // accumulate
#include <string> // string
#include <utility> // move
@ -369,7 +370,7 @@ class json_pointer
// j which will be overwritten by a primitive value
for (const auto& reference_token : reference_tokens)
{
switch (result->m_type)
switch (result->type())
{
case detail::value_t::null:
{
@ -446,14 +447,14 @@ class json_pointer
for (const auto& reference_token : reference_tokens)
{
// convert null values to arrays or objects before continuing
if (ptr->m_type == detail::value_t::null)
if (ptr->is_null())
{
// check if reference token is a number
const bool nums =
std::all_of(reference_token.begin(), reference_token.end(),
[](const char x)
[](const unsigned char x)
{
return x >= '0' and x <= '9';
return std::isdigit(x);
});
// change value to array for numbers or "-" or to object otherwise
@ -462,7 +463,7 @@ class json_pointer
: detail::value_t::object;
}
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -521,7 +522,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -586,7 +587,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -645,7 +646,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -692,6 +693,77 @@ class json_pointer
return *ptr;
}
/*!
@throw parse_error.106 if an array index begins with '0'
@throw parse_error.109 if an array index was not a number
*/
bool contains(const BasicJsonType* ptr) const
{
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->type())
{
case detail::value_t::object:
{
if (not ptr->contains(reference_token))
{
// we did not find the key in the object
return false;
}
ptr = &ptr->operator[](reference_token);
break;
}
case detail::value_t::array:
{
if (JSON_UNLIKELY(reference_token == "-"))
{
// "-" always fails the range check
return false;
}
// error condition (cf. RFC 6901, Sect. 4)
if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
{
JSON_THROW(detail::parse_error::create(106, 0,
"array index '" + reference_token +
"' must not begin with '0'"));
}
JSON_TRY
{
const auto idx = static_cast<size_type>(array_index(reference_token));
if (idx >= ptr->size())
{
// index out of range
return false;
}
ptr = &ptr->operator[](idx);
break;
}
JSON_CATCH(std::invalid_argument&)
{
JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
}
break;
}
default:
{
// we do not expect primitive values if there is still a
// reference token to process
return false;
}
}
}
// no reference token left means we found a primitive value
return true;
}
/*!
@brief split the string input to reference tokens
@ -813,7 +885,7 @@ class json_pointer
const BasicJsonType& value,
BasicJsonType& result)
{
switch (value.m_type)
switch (value.type())
{
case detail::value_t::array:
{

37
include/nlohmann/json.hpp
View file

@ -4001,15 +4001,48 @@ class basic_json
@liveexample{The following code shows an example for `contains()`.,contains}
@sa @ref find(KeyT&&) -- returns an iterator to an object element
@sa @ref contains(const json_pointer&) const -- checks the existence for a JSON pointer
@since version 3.6.0
*/
template<typename KeyT>
bool contains(KeyT&& key) const
template<typename KeyT, typename std::enable_if<
not std::is_same<KeyT, json_pointer>::value, int>::type = 0>
bool contains(KeyT && key) const
{
return is_object() and m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
}
/*!
@brief check the existence of an element in a JSON object given a JSON pointer
Check wehther the given JSON pointer @a ptr can be resolved in the current
JSON value.
@note This method can be executed on any JSON value type.
@param[in] ptr JSON pointer to check its existence.
@return true if the JSON pointer can be resolved to a stored value, false
otherwise.
@post If `j.contains(ptr)` returns true, it is safe to call `j[ptr]`.
@throw parse_error.106 if an array index begins with '0'
@throw parse_error.109 if an array index was not a number
@complexity Logarithmic in the size of the JSON object.
@liveexample{The following code shows an example for `contains()`.,contains_json_pointer}
@sa @ref contains(KeyT &&) const -- checks the existence of a key
@since version 3.7.0
*/
bool contains(const json_pointer& ptr) const
{
return ptr.contains(this);
}
/// @}

127
single_include/nlohmann/json.hpp
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@ -8445,6 +8445,7 @@ class json_reverse_iterator : public std::reverse_iterator<Base>
#include <algorithm> // all_of
#include <cassert> // assert
#include <cctype> // isdigit
#include <numeric> // accumulate
#include <string> // string
#include <utility> // move
@ -8815,7 +8816,7 @@ class json_pointer
// j which will be overwritten by a primitive value
for (const auto& reference_token : reference_tokens)
{
switch (result->m_type)
switch (result->type())
{
case detail::value_t::null:
{
@ -8892,14 +8893,14 @@ class json_pointer
for (const auto& reference_token : reference_tokens)
{
// convert null values to arrays or objects before continuing
if (ptr->m_type == detail::value_t::null)
if (ptr->is_null())
{
// check if reference token is a number
const bool nums =
std::all_of(reference_token.begin(), reference_token.end(),
[](const char x)
[](const unsigned char x)
{
return x >= '0' and x <= '9';
return std::isdigit(x);
});
// change value to array for numbers or "-" or to object otherwise
@ -8908,7 +8909,7 @@ class json_pointer
: detail::value_t::object;
}
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -8967,7 +8968,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -9032,7 +9033,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -9091,7 +9092,7 @@ class json_pointer
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->m_type)
switch (ptr->type())
{
case detail::value_t::object:
{
@ -9138,6 +9139,77 @@ class json_pointer
return *ptr;
}
/*!
@throw parse_error.106 if an array index begins with '0'
@throw parse_error.109 if an array index was not a number
*/
bool contains(const BasicJsonType* ptr) const
{
using size_type = typename BasicJsonType::size_type;
for (const auto& reference_token : reference_tokens)
{
switch (ptr->type())
{
case detail::value_t::object:
{
if (not ptr->contains(reference_token))
{
// we did not find the key in the object
return false;
}
ptr = &ptr->operator[](reference_token);
break;
}
case detail::value_t::array:
{
if (JSON_UNLIKELY(reference_token == "-"))
{
// "-" always fails the range check
return false;
}
// error condition (cf. RFC 6901, Sect. 4)
if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
{
JSON_THROW(detail::parse_error::create(106, 0,
"array index '" + reference_token +
"' must not begin with '0'"));
}
JSON_TRY
{
const auto idx = static_cast<size_type>(array_index(reference_token));
if (idx >= ptr->size())
{
// index out of range
return false;
}
ptr = &ptr->operator[](idx);
break;
}
JSON_CATCH(std::invalid_argument&)
{
JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
}
break;
}
default:
{
// we do not expect primitive values if there is still a
// reference token to process
return false;
}
}
}
// no reference token left means we found a primitive value
return true;
}
/*!
@brief split the string input to reference tokens
@ -9259,7 +9331,7 @@ class json_pointer
const BasicJsonType& value,
BasicJsonType& result)
{
switch (value.m_type)
switch (value.type())
{
case detail::value_t::array:
{
@ -16802,15 +16874,48 @@ class basic_json
@liveexample{The following code shows an example for `contains()`.,contains}
@sa @ref find(KeyT&&) -- returns an iterator to an object element
@sa @ref contains(const json_pointer&) const -- checks the existence for a JSON pointer
@since version 3.6.0
*/
template<typename KeyT>
bool contains(KeyT&& key) const
template<typename KeyT, typename std::enable_if<
not std::is_same<KeyT, json_pointer>::value, int>::type = 0>
bool contains(KeyT && key) const
{
return is_object() and m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
}
/*!
@brief check the existence of an element in a JSON object given a JSON pointer
Check wehther the given JSON pointer @a ptr can be resolved in the current
JSON value.
@note This method can be executed on any JSON value type.
@param[in] ptr JSON pointer to check its existence.
@return true if the JSON pointer can be resolved to a stored value, false
otherwise.
@post If `j.contains(ptr)` returns true, it is safe to call `j[ptr]`.
@throw parse_error.106 if an array index begins with '0'
@throw parse_error.109 if an array index was not a number
@complexity Logarithmic in the size of the JSON object.
@liveexample{The following code shows an example for `contains()`.,contains_json_pointer}
@sa @ref contains(KeyT &&) const -- checks the existence of a key
@since version 3.7.0
*/
bool contains(const json_pointer& ptr) const
{
return ptr.contains(this);
}
/// @}

51
test/src/unit-json_pointer.cpp
View file

@ -90,12 +90,18 @@ TEST_CASE("JSON pointers")
// the whole document
CHECK(j[json::json_pointer()] == j);
CHECK(j[json::json_pointer("")] == j);
CHECK(j.contains(json::json_pointer()));
CHECK(j.contains(json::json_pointer("")));
// array access
CHECK(j[json::json_pointer("/foo")] == j["foo"]);
CHECK(j.contains(json::json_pointer("/foo")));
CHECK(j[json::json_pointer("/foo/0")] == j["foo"][0]);
CHECK(j[json::json_pointer("/foo/1")] == j["foo"][1]);
CHECK(j["/foo/1"_json_pointer] == j["foo"][1]);
CHECK(j.contains(json::json_pointer("/foo/0")));
CHECK(j.contains(json::json_pointer("/foo/1")));
CHECK(not j.contains(json::json_pointer("/foo/-")));
// checked array access
CHECK(j.at(json::json_pointer("/foo/0")) == j["foo"][0]);
@ -103,6 +109,8 @@ TEST_CASE("JSON pointers")
// empty string access
CHECK(j[json::json_pointer("/")] == j[""]);
CHECK(j.contains(json::json_pointer("")));
CHECK(j.contains(json::json_pointer("/")));
// other cases
CHECK(j[json::json_pointer("/ ")] == j[" "]);
@ -112,6 +120,14 @@ TEST_CASE("JSON pointers")
CHECK(j[json::json_pointer("/i\\j")] == j["i\\j"]);
CHECK(j[json::json_pointer("/k\"l")] == j["k\"l"]);
// contains
CHECK(j.contains(json::json_pointer("/ ")));
CHECK(j.contains(json::json_pointer("/c%d")));
CHECK(j.contains(json::json_pointer("/e^f")));
CHECK(j.contains(json::json_pointer("/g|h")));
CHECK(j.contains(json::json_pointer("/i\\j")));
CHECK(j.contains(json::json_pointer("/k\"l")));
// checked access
CHECK(j.at(json::json_pointer("/ ")) == j[" "]);
CHECK(j.at(json::json_pointer("/c%d")) == j["c%d"]);
@ -123,14 +139,24 @@ TEST_CASE("JSON pointers")
// escaped access
CHECK(j[json::json_pointer("/a~1b")] == j["a/b"]);
CHECK(j[json::json_pointer("/m~0n")] == j["m~n"]);
CHECK(j.contains(json::json_pointer("/a~1b")));
CHECK(j.contains(json::json_pointer("/m~0n")));
// unescaped access
// access to nonexisting values yield object creation
CHECK(not j.contains(json::json_pointer("/a/b")));
CHECK_NOTHROW(j[json::json_pointer("/a/b")] = 42);
CHECK(j.contains(json::json_pointer("/a/b")));
CHECK(j["a"]["b"] == json(42));
CHECK(not j.contains(json::json_pointer("/a/c/1")));
CHECK_NOTHROW(j[json::json_pointer("/a/c/1")] = 42);
CHECK(j["a"]["c"] == json({nullptr, 42}));
CHECK(j.contains(json::json_pointer("/a/c/1")));
CHECK(not j.contains(json::json_pointer("/a/d/-")));
CHECK_NOTHROW(j[json::json_pointer("/a/d/-")] = 42);
CHECK(not j.contains(json::json_pointer("/a/d/-")));
CHECK(j["a"]["d"] == json::array({42}));
// "/a/b" works for JSON {"a": {"b": 42}}
CHECK(json({{"a", {{"b", 42}}}})[json::json_pointer("/a/b")] == json(42));
@ -143,6 +169,7 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j_primitive.at("/foo"_json_pointer), json::out_of_range&);
CHECK_THROWS_WITH(j_primitive.at("/foo"_json_pointer),
"[json.exception.out_of_range.404] unresolved reference token 'foo'");
CHECK(not j_primitive.contains(json::json_pointer("/foo")));
}
SECTION("const access")
@ -233,11 +260,16 @@ TEST_CASE("JSON pointers")
// the whole document
CHECK(j[""_json_pointer] == j);
CHECK(j.contains(""_json_pointer));
// array access
CHECK(j["/foo"_json_pointer] == j["foo"]);
CHECK(j["/foo/0"_json_pointer] == j["foo"][0]);
CHECK(j["/foo/1"_json_pointer] == j["foo"][1]);
CHECK(j.contains("/foo"_json_pointer));
CHECK(j.contains("/foo/0"_json_pointer));
CHECK(j.contains("/foo/1"_json_pointer));
CHECK(not j.contains("/foo/-"_json_pointer));
}
}
@ -278,6 +310,12 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j_const.at("/01"_json_pointer), json::parse_error&);
CHECK_THROWS_WITH(j_const.at("/01"_json_pointer),
"[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'");
CHECK_THROWS_AS(j.contains("/01"_json_pointer), json::parse_error&);
CHECK_THROWS_WITH(j.contains("/01"_json_pointer),
"[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'");
CHECK_THROWS_AS(j_const.contains("/01"_json_pointer), json::parse_error&);
CHECK_THROWS_WITH(j_const.contains("/01"_json_pointer),
"[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'");
// error with incorrect numbers
CHECK_THROWS_AS(j["/one"_json_pointer] = 1, json::parse_error&);
@ -294,6 +332,13 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_WITH(j_const.at("/one"_json_pointer) == 1,
"[json.exception.parse_error.109] parse error: array index 'one' is not a number");
CHECK_THROWS_AS(j.contains("/one"_json_pointer), json::parse_error&);
CHECK_THROWS_WITH(j.contains("/one"_json_pointer),
"[json.exception.parse_error.109] parse error: array index 'one' is not a number");
CHECK_THROWS_AS(j_const.contains("/one"_json_pointer), json::parse_error&);
CHECK_THROWS_WITH(j_const.contains("/one"_json_pointer),
"[json.exception.parse_error.109] parse error: array index 'one' is not a number");
CHECK_THROWS_AS(json({{"/list/0", 1}, {"/list/1", 2}, {"/list/three", 3}}).unflatten(), json::parse_error&);
CHECK_THROWS_WITH(json({{"/list/0", 1}, {"/list/1", 2}, {"/list/three", 3}}).unflatten(),
"[json.exception.parse_error.109] parse error: array index 'three' is not a number");
@ -306,6 +351,7 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j_const["/-"_json_pointer], json::out_of_range&);
CHECK_THROWS_WITH(j_const["/-"_json_pointer],
"[json.exception.out_of_range.402] array index '-' (3) is out of range");
CHECK(not j_const.contains("/-"_json_pointer));
// error when using "-" with at
CHECK_THROWS_AS(j.at("/-"_json_pointer), json::out_of_range&);
@ -314,6 +360,7 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j_const.at("/-"_json_pointer), json::out_of_range&);
CHECK_THROWS_WITH(j_const.at("/-"_json_pointer),
"[json.exception.out_of_range.402] array index '-' (3) is out of range");
CHECK(not j_const.contains("/-"_json_pointer));
}
SECTION("const access")
@ -329,11 +376,13 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j.at("/3"_json_pointer), json::out_of_range&);
CHECK_THROWS_WITH(j.at("/3"_json_pointer),
"[json.exception.out_of_range.401] array index 3 is out of range");
CHECK(not j.contains("/3"_json_pointer));
// assign to nonexisting index (with gap)
CHECK_THROWS_AS(j.at("/5"_json_pointer), json::out_of_range&);
CHECK_THROWS_WITH(j.at("/5"_json_pointer),
"[json.exception.out_of_range.401] array index 5 is out of range");
CHECK(not j.contains("/5"_json_pointer));
// assign to "-"
CHECK_THROWS_AS(j["/-"_json_pointer], json::out_of_range&);
@ -342,8 +391,8 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_AS(j.at("/-"_json_pointer), json::out_of_range&);
CHECK_THROWS_WITH(j.at("/-"_json_pointer),
"[json.exception.out_of_range.402] array index '-' (3) is out of range");
CHECK(not j.contains("/-"_json_pointer));
}
}
SECTION("flatten")