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Improve JSON internal interface.

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This commit is contained in:
Vitaly Baranov 2020-07-20 20:01:58 +03:00
parent 61e43c3ef9
commit 1fb4d9002d
4 changed files with 105 additions and 70 deletions
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20
src/Functions/DummyJSONParser.h
View File

@ -17,6 +17,8 @@ struct DummyJSONParser
class Array;
class Object;
/// References an element in a JSON document, representing a JSON null, boolean, string, number,
/// array or object.
class Element
{
public:
@ -39,6 +41,7 @@ struct DummyJSONParser
Object getObject() const;
};
/// References an array in a JSON document.
class Array
{
public:
@ -58,11 +61,12 @@ struct DummyJSONParser
Element operator[](size_t) const { return {}; }
};
using KeyValuePair = std::pair<std::string_view, Element>;
/// References an object in a JSON document.
class Object
{
public:
using KeyValuePair = std::pair<std::string_view, Element>;
class Iterator
{
public:
@ -76,11 +80,21 @@ struct DummyJSONParser
Iterator begin() const { return {}; }
Iterator end() const { return {}; }
size_t size() const { return 0; }
KeyValuePair operator[](size_t) const { return {}; }
bool find(const std::string_view &, Element &) const { return false; }
#if 0
/// Optional: Provides access to an object's element by index.
KeyValuePair operator[](size_t) const { return {}; }
#endif
};
/// Parses a JSON document, returns the reference to its root element if succeeded.
bool parse(const std::string_view &, Element &) { throw Exception{"Functions JSON* are not supported", ErrorCodes::NOT_IMPLEMENTED}; }
#if 0
/// Optional: Allocates memory to parse JSON documents faster.
void reserve(size_t max_size);
#endif
};
}

28
src/Functions/FunctionsJSON.h
View File

@ -139,6 +139,12 @@ private:
BOOST_TTI_HAS_MEMBER_FUNCTION(reserve)
BOOST_TTI_HAS_MEMBER_FUNCTION(prepare)
template <class T, class = void>
struct has_index_operator : std::false_type {};
template <class T>
struct has_index_operator<T, std::void_t<decltype(std::declval<T>()[0])>> : std::true_type {};
/// Represents a move of a JSON iterator described by a single argument passed to a JSON function.
/// For example, the call JSONExtractInt('{"a": "hello", "b": [-100, 200.0, 300]}', 'b', 1)
/// contains two moves: {MoveType::ConstKey, "b"} and {MoveType::ConstIndex, 1}.
@ -217,38 +223,32 @@ private:
{
auto array = element.getArray();
if (index >= 0)
{
--index;
else
index += array.size();
if (static_cast<size_t>(index) >= array.size())
return false;
element = array[index];
out_key = {};
return true;
}
index += array.size();
if (index < 0)
return false;
element = array[index];
out_key = {};
return true;
}
if constexpr (has_index_operator<typename JSONParser::Object>::value)
{
if (element.isObject())
{
auto object = element.getObject();
if (index >= 0)
{
--index;
else
index += object.size();
if (static_cast<size_t>(index) >= object.size())
return false;
std::tie(out_key, element) = object[index];
return true;
}
index += object.size();
if (index < 0)
return false;
std::tie(out_key, element) = object[index];
return true;
}
return {};

34
src/Functions/RapidJSONParser.h
View File

@ -20,6 +20,8 @@ struct RapidJSONParser
class Array;
class Object;
/// References an element in a JSON document, representing a JSON null, boolean, string, number,
/// array or object.
class Element
{
public:
@ -47,6 +49,7 @@ struct RapidJSONParser
const rapidjson::Value * ptr = nullptr;
};
/// References an array in a JSON document.
class Array
{
public:
@ -67,17 +70,18 @@ struct RapidJSONParser
ALWAYS_INLINE Iterator begin() const { return ptr->Begin(); }
ALWAYS_INLINE Iterator end() const { return ptr->End(); }
ALWAYS_INLINE size_t size() const { return ptr->Size(); }
ALWAYS_INLINE Element operator[](size_t index) const { return *(ptr->Begin() + index); }
ALWAYS_INLINE Element operator[](size_t index) const { assert(index < size()); return *(ptr->Begin() + index); }
private:
const rapidjson::Value * ptr = nullptr;
};
using KeyValuePair = std::pair<std::string_view, Element>;
/// References an object in a JSON document.
class Object
{
public:
using KeyValuePair = std::pair<std::string_view, Element>;
class Iterator
{
public:
@ -96,14 +100,7 @@ struct RapidJSONParser
ALWAYS_INLINE Iterator end() const { return ptr->MemberEnd(); }
ALWAYS_INLINE size_t size() const { return ptr->MemberCount(); }
ALWAYS_INLINE KeyValuePair operator[](size_t index) const
{
auto it = ptr->MemberBegin() + index;
std::string_view key{it->name.GetString(), it->name.GetStringLength()};
return KeyValuePair{key, it->value};
}
ALWAYS_INLINE bool find(const std::string_view & key, Element & result) const
bool find(const std::string_view & key, Element & result) const
{
auto it = ptr->FindMember(rapidjson::StringRef(key.data(), key.length()));
if (it == ptr->MemberEnd())
@ -113,10 +110,20 @@ struct RapidJSONParser
return true;
}
/// Optional: Provides access to an object's element by index.
ALWAYS_INLINE KeyValuePair operator[](size_t index) const
{
assert (index < size());
auto it = ptr->MemberBegin() + index;
std::string_view key{it->name.GetString(), it->name.GetStringLength()};
return {key, it->value};
}
private:
const rapidjson::Value * ptr = nullptr;
};
/// Parses a JSON document, returns the reference to its root element if succeeded.
bool parse(const std::string_view & json, Element & result)
{
rapidjson::MemoryStream ms(json.data(), json.size());
@ -128,6 +135,11 @@ struct RapidJSONParser
return true;
}
#if 0
/// Optional: Allocates memory to parse JSON documents faster.
void reserve(size_t max_size);
#endif
private:
rapidjson::Document document;
};

47
src/Functions/SimdJSONParser.h
View File

@ -25,6 +25,8 @@ struct SimdJSONParser
class Array;
class Object;
/// References an element in a JSON document, representing a JSON null, boolean, string, number,
/// array or object.
class Element
{
public:
@ -52,6 +54,7 @@ struct SimdJSONParser
simdjson::dom::element element;
};
/// References an array in a JSON document.
class Array
{
public:
@ -72,17 +75,18 @@ struct SimdJSONParser
ALWAYS_INLINE Iterator begin() const { return array.begin(); }
ALWAYS_INLINE Iterator end() const { return array.end(); }
ALWAYS_INLINE size_t size() const { return array.size(); }
ALWAYS_INLINE Element operator[](size_t index) const { return array.at(index).first; }
ALWAYS_INLINE Element operator[](size_t index) const { assert(index < size()); return array.at(index).first; }
private:
simdjson::dom::array array;
};
using KeyValuePair = std::pair<std::string_view, Element>;
/// References an object in a JSON document.
class Object
{
public:
using KeyValuePair = std::pair<std::string_view, Element>;
class Iterator
{
public:
@ -101,15 +105,7 @@ struct SimdJSONParser
ALWAYS_INLINE Iterator end() const { return object.end(); }
ALWAYS_INLINE size_t size() const { return object.size(); }
KeyValuePair operator [](size_t index) const
{
Iterator it = begin();
while (index--)
++it;
return *it;
}
ALWAYS_INLINE bool find(const std::string_view & key, Element & result) const
bool find(const std::string_view & key, Element & result) const
{
auto x = object.at_key(key);
if (x.error())
@ -119,17 +115,22 @@ struct SimdJSONParser
return true;
}
/// Optional: Provides access to an object's element by index.
KeyValuePair operator[](size_t index) const
{
assert(index < size());
auto it = object.begin();
while (index--)
++it;
const auto & res = *it;
return {res.key, res.value};
}
private:
simdjson::dom::object object;
};
void reserve(size_t max_size)
{
if (parser.allocate(max_size) != simdjson::error_code::SUCCESS)
throw Exception{"Couldn't allocate " + std::to_string(max_size) + " bytes when parsing JSON",
ErrorCodes::CANNOT_ALLOCATE_MEMORY};
}
/// Parses a JSON document, returns the reference to its root element if succeeded.
bool parse(const std::string_view & json, Element & result)
{
auto document = parser.parse(json.data(), json.size());
@ -140,6 +141,14 @@ struct SimdJSONParser
return true;
}
/// Optional: Allocates memory to parse JSON documents faster.
void reserve(size_t max_size)
{
if (parser.allocate(max_size) != simdjson::error_code::SUCCESS)
throw Exception{"Couldn't allocate " + std::to_string(max_size) + " bytes when parsing JSON",
ErrorCodes::CANNOT_ALLOCATE_MEMORY};
}
private:
simdjson::dom::parser parser;
};