userver: formats::yaml::Value Class Reference
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formats::yaml::Value Class Referencefinal

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

Detailed Description

Non-mutable YAML value representation.

Class provides non mutable access YAML value. For modification and construction of new YAML values use formats::yaml::ValueBuilder.

Example usage:

// #include <userver/formats/yaml.hpp>
key1: 1
key2:
key3: "val"
)");
const auto key1 = yaml["key1"].As<int>();
ASSERT_EQ(key1, 1);
const auto key3 = yaml["key2"]["key3"].As<std::string>();
ASSERT_EQ(key3, "val");
See also
Formats (JSON, YAML, BSON, ...)
Examples
samples/json2yaml/json2yaml.cpp.

Definition at line 34 of file value.hpp.

Classes

struct  DefaultConstructed
 
struct  IterTraits
 

Public Types

using const_iterator = Iterator<IterTraits>
 
using Exception = formats::yaml::Exception
 
using ParseException = formats::yaml::ParseException
 
using ExceptionWithPath = formats::yaml::ExceptionWithPath
 
using Builder = ValueBuilder
 

Public Member Functions

 Value () noexcept
 Constructs a Value that holds a Null.
 
 Value (Value &&)
 
 Value (const Value &)
 
Valueoperator= (Value &&)
 
Valueoperator= (const Value &)
 
template<class T >
Valueoperator= (T &&) &&
 
 Value (Value &&other, std::string path_prefix)
 Copies other, appending path_prefix to the stored path
 
Value operator[] (std::string_view key) const
 Access member by key for read.
 
Value operator[] (std::size_t index) const
 Access array member by index for read.
 
const_iterator begin () const
 Returns an iterator to the beginning of the held array or map.
 
const_iterator end () const
 Returns an iterator to the end of the held array or map.
 
bool IsEmpty () const
 Returns whether the array or object is empty.
 
std::size_t GetSize () const
 Returns array size or object members count.
 
bool operator== (const Value &other) const
 Compares values.
 
bool operator!= (const Value &other) const
 
bool IsMissing () const
 Returns true if *this holds nothing. When IsMissing() returns true any attempt to get the actual value or iterate over *this will throw MemberMissingException.
 
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 is a map (Type::kObject).
 
template<typename T >
auto As () const
 Returns value of *this converted to the result type of Parse(const Value&, parse::To<T>). Almost always it is T.
 
template<typename T , typename First , typename... Rest>
auto As (First &&default_arg, Rest &&... more_default_args) const
 Returns value of *this converted to T or T(args) if this->IsMissing().
 
template<typename T >
auto As (DefaultConstructed) const
 Returns value of *this converted to T or T() if this->IsMissing().
 
bool HasMember (std::string_view key) const
 Returns true if *this holds a key.
 
std::string GetPath () const
 Returns full path to this value.
 
int GetColumn () const
 Returns 0-based column number of this Value in the original document. Returns -1 if this->IsMissing(). If Value was created using formats::yaml::ValueBuilder, returns 0.
 
int GetLine () const
 Returns 0-based line number of this Value in the original document. Returns -1 if this->IsMissing(). If Value was created using formats::yaml::ValueBuilder, returns 0.
 
Value Clone () const
 Returns new value that is an exact copy if the existing one but references different memory (a deep copy of a *this). The returned value is a root value with path '/'.
 
void CheckNotMissing () const
 
void CheckArray () const
 
void CheckArrayOrNull () const
 
void CheckObjectOrNull () const
 
void CheckObject () const
 
void CheckString () const
 
void CheckObjectOrArrayOrNull () const
 
void CheckInBounds (std::size_t index) const
 
bool IsRoot () const noexcept
 Returns true if *this is a first (root) value.
 
bool DebugIsReferencingSameMemory (const Value &other) const
 Returns true if *this and other reference the value by the same pointer.
 

Member Typedef Documentation

◆ Builder

◆ const_iterator

◆ Exception

◆ ExceptionWithPath

◆ ParseException

Constructor & Destructor Documentation

◆ Value()

formats::yaml::Value::Value ( Value && other,
std::string path_prefix )

Copies other, appending path_prefix to the stored path

Warning
other must have an empty (root) path
Exceptions
`std::logic_error`if other has path other than the root path
See also
GetPath

Member Function Documentation

◆ As() [1/3]

template<typename T >
auto formats::yaml::Value::As ( ) const

Returns value of *this converted to the result type of Parse(const Value&, parse::To<T>). Almost always it is T.

Exceptions
Anythingderived from std::exception.

Example usage:

namespace my_namespace {
struct MyKeyValue {
std::string field1;
int field2;
};
// The function must be declared in the namespace of your type
MyKeyValue Parse(const formats::yaml::Value& yaml,
return MyKeyValue{
yaml["field1"].As<std::string>(""),
yaml["field2"].As<int>(1), // return `1` if "field2" is missing
};
}
TEST(FormatsYaml, ExampleUsageMyStruct) {
my_value:
field1: "one"
field2: 1
)");
auto data = yaml["my_value"].As<MyKeyValue>();
EXPECT_EQ(data.field1, "one");
EXPECT_EQ(data.field2, 1);
}
} // namespace my_namespace
See also
Formats (JSON, YAML, BSON, ...)

Definition at line 276 of file value.hpp.

◆ As() [2/3]

template<typename T >
auto formats::yaml::Value::As ( Value::DefaultConstructed ) const

Returns value of *this converted to T or T() if this->IsMissing().

Exceptions
Anythingderived from std::exception.
Note
Use as value.As<T>({})

Definition at line 309 of file value.hpp.

◆ As() [3/3]

template<typename T , typename First , typename... Rest>
auto formats::yaml::Value::As ( First && default_arg,
Rest &&... more_default_args ) const

Returns value of *this converted to T or T(args) if this->IsMissing().

Exceptions
Anythingderived from std::exception.

Definition at line 298 of file value.hpp.

◆ begin()

const_iterator formats::yaml::Value::begin ( ) const

Returns an iterator to the beginning of the held array or map.

Exceptions
TypeMismatchExceptionif not an array or an object.

◆ CheckArray()

void formats::yaml::Value::CheckArray ( ) const
Exceptions
MemberMissingExceptionif *this is not an array.

◆ CheckArrayOrNull()

void formats::yaml::Value::CheckArrayOrNull ( ) const
Exceptions
MemberMissingExceptionif *this is not an array or Null.

◆ CheckInBounds()

void formats::yaml::Value::CheckInBounds ( std::size_t index) const
Exceptions
TypeMismatchExceptionif *this is not a map, array or Null; OutOfBoundsException if index >= this->GetSize().

◆ CheckNotMissing()

void formats::yaml::Value::CheckNotMissing ( ) const
Exceptions
MemberMissingExceptionif this->IsMissing().

◆ CheckObject()

void formats::yaml::Value::CheckObject ( ) const
Exceptions
TypeMismatchExceptionif *this is not a map.

◆ CheckObjectOrArrayOrNull()

void formats::yaml::Value::CheckObjectOrArrayOrNull ( ) const
Exceptions
TypeMismatchExceptionif *this is not a map, array or Null.

◆ CheckObjectOrNull()

void formats::yaml::Value::CheckObjectOrNull ( ) const
Exceptions
TypeMismatchExceptionif *this is not a map or Null.

◆ CheckString()

void formats::yaml::Value::CheckString ( ) const
Exceptions
TypeMismatchExceptionif *this is not convertible to std::string.

◆ Clone()

Value formats::yaml::Value::Clone ( ) const

Returns new value that is an exact copy if the existing one but references different memory (a deep copy of a *this). The returned value is a root value with path '/'.

Exceptions
MemberMissingExceptionid this->IsMissing().

◆ end()

const_iterator formats::yaml::Value::end ( ) const

Returns an iterator to the end of the held array or map.

Exceptions
TypeMismatchExceptionif not an array or an object.

◆ GetColumn()

int formats::yaml::Value::GetColumn ( ) const

Returns 0-based column number of this Value in the original document. Returns -1 if this->IsMissing(). If Value was created using formats::yaml::ValueBuilder, returns 0.

Note
This method available only for formats::yaml::Value.

◆ GetLine()

int formats::yaml::Value::GetLine ( ) const

Returns 0-based line number of this Value in the original document. Returns -1 if this->IsMissing(). If Value was created using formats::yaml::ValueBuilder, returns 0.

Note
This method available only for formats::yaml::Value.

◆ GetSize()

std::size_t formats::yaml::Value::GetSize ( ) const

Returns array size or object members count.

Exceptions
TypeMismatchExceptionif not an array or an object.

◆ IsEmpty()

bool formats::yaml::Value::IsEmpty ( ) const

Returns whether the array or object is empty.

Exceptions
TypeMismatchExceptionif not an array or an object.

◆ operator=()

template<class T >
Value & formats::yaml::Value::operator= ( T && ) &&
inline

Definition at line 61 of file value.hpp.

◆ operator==()

Compares values.

Exceptions
MemberMissingExceptionif *this or other is missing.

◆ operator[]() [1/2]

Value formats::yaml::Value::operator[] ( std::size_t index) const

Access array member by index for read.

Exceptions
TypeMismatchExceptionif not an array value.
`OutOfBoundsException`if index is greater or equal than size.

◆ operator[]() [2/2]

Value formats::yaml::Value::operator[] ( std::string_view key) const

Access member by key for read.

Exceptions
TypeMismatchExceptionif not a missing value, an object, or Null.

Friends And Related Symbol Documentation

◆ FromStream

formats::yaml::Value FromStream ( std::istream & )
friend

Parse JSON from stream.

Parse JSON from stream.

◆ FromString

formats::yaml::Value FromString ( const std::string & doc)
friend

Parse YAML from string.

Definition at line 82 of file from_string.hpp.

◆ Iterator< IterTraits >

Definition at line 259 of file value.hpp.

◆ ValueBuilder

Definition at line 262 of file value.hpp.


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