formats::yaml::ValueBuilder Class Reference

#include <userver/formats/yaml/value_builder.hpp>

Detailed Description

Builder for YAML.

Class provides methods for building YAML. For read only access to the existing YAML values use formats::yaml::Value.

Example usage:

    // #include <userver/formats/yaml.hpp>
    formats::yaml::ValueBuilder builder;
    builder["key1"] = 1;
    formats::yaml::ValueBuilder sub_builder;
    sub_builder["key3"] = "val";
    builder["key2"] = sub_builder.ExtractValue();
 
    formats::yaml::Value yaml = builder.ExtractValue();
 
    ASSERT_EQ(yaml["key1"].As<int>(), 1);
    ASSERT_EQ(yaml["key2"]["key3"].As<std::string>(), "val");

Customization example:

namespace my_namespace {
 
struct MyKeyValue {
    std::string field1;
    int field2;
};
 
// The function must be declared in the namespace of your type
formats::json::Value Serialize(const MyKeyValue& data, formats::serialize::To<formats::json::Value>) {
    formats::json::ValueBuilder builder;
    builder["field1"] = data.field1;
    builder["field2"] = data.field2;
 
    return builder.ExtractValue();
}
 
TEST(JsonValueBuilder, ExampleCustomization) {
    MyKeyValue object = {"val", 1};
    formats::json::ValueBuilder builder;
    builder["example"] = object;
    auto json = builder.ExtractValue();
    ASSERT_EQ(json["example"]["field1"].As<std::string>(), "val");
    ASSERT_EQ(json["example"]["field2"].As<int>(), 1);
}
 
TEST(JsonValueBuilder, StringViewRemove) {
    formats::json::ValueBuilder builder;
    const std::string str = "ab";
    builder["a"] = 1;
    builder[str] = 2;
    builder.Remove(std::string_view(str.data(), 1));
 
    EXPECT_EQ(1, builder.GetSize());
 
    const auto value = builder.ExtractValue();
    EXPECT_EQ(2, value[str].As<int>());
}
 
TEST(JsonValueBuilder, StringViewHasMember) {
    formats::json::ValueBuilder main_builder;
    const std::string str = "ab";
    main_builder[str] = 2;
    EXPECT_EQ(false, main_builder.HasMember("a"));
    EXPECT_EQ(false, main_builder.HasMember(std::string_view(str.data(), 1)));
    EXPECT_EQ(true, main_builder.HasMember(std::string_view(str.data(), 2)));
}
 
TEST(JsonValueBuilder, StringViewEmplaceNocheck) {
    formats::json::ValueBuilder main_builder;
    const std::string str = "ab";
    main_builder.EmplaceNocheck(std::string_view(str.data(), 1), 1);
    main_builder.EmplaceNocheck(std::string_view(str.data(), 2), 2);
    main_builder.EmplaceNocheck(std::string_view(std::string(1024, 'a') + 'b'), 1025);
 
    const auto value = main_builder.ExtractValue();
    EXPECT_EQ(1, value["a"].As<int>());
    EXPECT_EQ(2, value["ab"].As<int>());
    EXPECT_EQ(1025, value[std::string(1024, 'a') + 'b'].As<int>());
}
 
}  // namespace my_namespace
 

See also

Formats (JSON, YAML, BSON, ...)

Definition at line 36 of file value_builder.hpp.

Classes
struct	IterTraits

Public Types
using	iterator = Iterator<IterTraits>

Public Member Functions
	ValueBuilder ()
	Constructs a valueBuilder that holds kNull.
	ValueBuilder (formats::common::Type type)
	Constructs a valueBuilder that holds default value for provided type.
	ValueBuilder (const ValueBuilder &other)
	ValueBuilder (ValueBuilder &&other)
ValueBuilder &	operator= (const ValueBuilder &other)
ValueBuilder &	operator= (ValueBuilder &&other)
	ValueBuilder (const formats::yaml::Value &other)
	ValueBuilder (formats::yaml::Value &&other)
	ValueBuilder (common::TransferTag, ValueBuilder &&) noexcept
	Transfers the ValueBuilder object.
template<typename T >
	ValueBuilder (const T &t)
	Universal constructor using Serialize.
ValueBuilder	operator[] (const std::string &key)
	Access member by key for modification.
ValueBuilder	operator[] (std::size_t index)
	Access array member by index for modification.
template<typename Tag , utils::StrongTypedefOps Ops, typename Enable = std::enable_if_t<utils::IsStrongTypedefLoggable(Ops)>>
ValueBuilder	operator[] (const utils::StrongTypedef< Tag, std::string, Ops > &key)
	Access member by key for modification.
void	Remove (const std::string &key)
	Remove key from object. If key is missing nothing happens.
iterator	begin ()
iterator	end ()
bool	IsEmpty () const
	Returns whether the array or object is empty.
bool	IsNull () const noexcept
	Returns true if *this holds a Null (Type::kNull).
bool	IsBool () const noexcept
	Returns true if *this is convertible to bool.
bool	IsInt () const noexcept
	Returns true if *this is convertible to int.
bool	IsInt64 () const noexcept
	Returns true if *this is convertible to int64_t.
bool	IsUInt64 () const noexcept
	Returns true if *this is convertible to uint64_t.
bool	IsDouble () const noexcept
	Returns true if *this is convertible to double.
bool	IsString () const noexcept
	Returns true if *this is convertible to std::string.
bool	IsArray () const noexcept
	Returns true if *this is an array (Type::kArray).
bool	IsObject () const noexcept
	Returns true if *this holds a map (Type::kObject).
std::size_t	GetSize () const
	Returns array size or object members count.
bool	HasMember (const char *key) const
	Returns true if value holds a key.
bool	HasMember (const std::string &key) const
	Returns true if value holds a key.
void	Resize (std::size_t size)
	Resize the array value or convert null value into an array of requested size.
void	PushBack (ValueBuilder &&bld)
	Add element into the last position of array.
formats::yaml::Value	ExtractValue ()
	Take out the resulting Value object. After calling this method the object is in unspecified (but valid - possibly null) state.
Concrete type constructors
	ValueBuilder (std::nullptr_t)
	ValueBuilder (bool t)
	ValueBuilder (const char *str)
	ValueBuilder (char *str)
	ValueBuilder (const std::string &str)
	ValueBuilder (std::string_view str)
	ValueBuilder (int t)
	ValueBuilder (unsigned int t)
	ValueBuilder (long t)
	ValueBuilder (unsigned long t)
	ValueBuilder (long long t)
	ValueBuilder (unsigned long long t)
	ValueBuilder (float t)
	ValueBuilder (double t)

Member Typedef Documentation

iterator

using formats::yaml::ValueBuilder::iterator = Iterator<IterTraits>

Definition at line 45 of file value_builder.hpp.

Constructor & Destructor Documentation

ValueBuilder() [1/3]

formats::yaml::ValueBuilder::ValueBuilder ( std::nullptr_t )

inline

Definition at line 65 of file value_builder.hpp.

ValueBuilder() [2/3]

formats::yaml::ValueBuilder::ValueBuilder ( common::TransferTag , ValueBuilder &&  )

noexcept

Transfers the ValueBuilder object.

See also

formats::common::TransferTag for the transfer semantics

ValueBuilder() [3/3]

template<typename T >

formats::yaml::ValueBuilder::ValueBuilder ( const T & t )

inline

Universal constructor using Serialize.

Definition at line 87 of file value_builder.hpp.

Member Function Documentation

ExtractValue()

formats::yaml::Value formats::yaml::ValueBuilder::ExtractValue

(

)

Take out the resulting Value object. After calling this method the object is in unspecified (but valid - possibly null) state.

Exceptions

`YamlException`

if called not from the root builder.

GetSize()

std::size_t formats::yaml::ValueBuilder::GetSize

(

)

const

Returns array size or object members count.

Exceptions

`TypeMismatchException`

if not an array or an object.

IsEmpty()

bool formats::yaml::ValueBuilder::IsEmpty

(

)

const

Returns whether the array or object is empty.

Exceptions

`TypeMismatchException`

if not an array or an object.

operator[]() [1/3]

ValueBuilder formats::yaml::ValueBuilder::operator[]

(

const std::string &

key

)

Access member by key for modification.

Exceptions

`TypeMismatchException`

if not object or null value.

operator[]() [2/3]

template<typename Tag , utils::StrongTypedefOps Ops, typename Enable >

ValueBuilder formats::yaml::ValueBuilder::operator[]

(

const utils::StrongTypedef< Tag, std::string, Ops > &

key

)

Access member by key for modification.

Exceptions

`TypeMismatchException`

if not object or null value.

Definition at line 194 of file value_builder.hpp.

operator[]() [3/3]

ValueBuilder formats::yaml::ValueBuilder::operator[]

(

std::size_t

index

)

Access array member by index for modification.

Exceptions

`TypeMismatchException`	if not an array value.
`OutOfBoundsException`	if index is greater than size.

PushBack()

void formats::yaml::ValueBuilder::PushBack

(

ValueBuilder &&

bld

)

Add element into the last position of array.

Exceptions

`TypeMismatchException`

if not an array or null.

Remove()

void formats::yaml::ValueBuilder::Remove

(

const std::string &

key

)

Remove key from object. If key is missing nothing happens.

Exceptions

`TypeMismatchException`

if value is not an object.

Resize()

void formats::yaml::ValueBuilder::Resize

(

std::size_t

size

)

Resize the array value or convert null value into an array of requested size.

Exceptions

`TypeMismatchException`

if not an array or null.

Friends And Related Symbol Documentation

Iterator< IterTraits >

friend class Iterator< IterTraits >

friend

Definition at line 188 of file value_builder.hpp.

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The documentation for this class was generated from the following file:

• userver/formats/yaml/value_builder.hpp