jsonv::value_encoder Class Reference

An encoder which builds a value from the tokens it is given: the sink for a document which is produced token by token through a writer but is wanted as a tree. More...

#include <jsonv/encode.hpp>

Inheritance diagram for jsonv::value_encoder:

Collaboration diagram for jsonv::value_encoder:

Public Member Functions
	value_encoder ()
	Create an instance holding nothing.
	value_encoder (const value_encoder &)=delete
value_encoder &	operator= (const value_encoder &)=delete
	value_encoder (value_encoder &&)=delete
value_encoder &	operator= (value_encoder &&)=delete
value	take () &&
	Hand out the document written so far.
Public Member Functions inherited from jsonv::encoder
void	encode (const jsonv::value &source)
	Encode some source value into this encoder, through write_tree.

Protected Member Functions
virtual void	write_null () override
	Write the null value.
virtual void	write_object_begin () override
	Write the opening of an object value.
virtual void	write_object_end () override
	Write the closing of an object value.
virtual void	write_object_key (std::string_view key) override
	Keep key for the member whose value comes next.
virtual void	write_object_delimiter () override
	Does nothing: a tree has no punctuation.
virtual void	write_array_begin () override
	Write the opening of an array value.
virtual void	write_array_end () override
	Write the closing of an array value.
virtual void	write_array_delimiter () override
	Does nothing: a tree has no punctuation.
virtual void	write_string (std::string_view value) override
	The string is copied into the tree as it is, valid UTF-8 or not.
virtual void	write_integer (std::int64_t value) override
	Write an integer value.
virtual void	write_decimal (double value) override
	Kept as given: a value can hold a NaN or an infinity, so nothing is substituted for one.
virtual void	write_boolean (bool value) override
	Write a boolean value.
virtual void	write_tree (jsonv::value &&source) override
	Takes source as it is.
virtual void	write_tree (const jsonv::value &source) override
	Copies source in whole.

Detailed Description

An encoder which builds a value from the tokens it is given: the sink for a document which is produced token by token through a writer but is wanted as a tree.

It is the mirror of reader::from_value, which hands a tree out as tokens.

jsonv::value_encoder sink;
jsonv::writer        to(sink);
to.object_begin()
    .key("a").integer(1)
    .key("b").array_begin().string("x").string("y").array_end()
  .object_end();
jsonv::value built = std::move(sink).take();   // {"a":1,"b":["x","y"]}

An object is built as a value keeps one, so a key which repeats within it keeps the value written last, as parse keeps it by default; a document built from tokens and the same document parsed from text select the same data. The encoder holds one document at a time: a second root value written before take replaces the first, as a repeated key does.

See also

writer

reader::from_value

Definition at line 308 of file encode.hpp.

Member Function Documentation

take()

value jsonv::value_encoder::take

(

)

&&

Hand out the document written so far.

This instance is left holding nothing, as it was constructed, so another document may follow.

Exceptions

std::logic_error

if an object or array is still open, or if nothing has been written at all. A JSON document is never empty, so a writer which has produced nothing has not produced null.

write_array_begin()

virtual void jsonv::value_encoder::write_array_begin ( )

overrideprotectedvirtual

Write the opening of an array value.

[

Implements jsonv::encoder.

write_array_delimiter()

virtual void jsonv::value_encoder::write_array_delimiter ( )

overrideprotectedvirtual

Does nothing: a tree has no punctuation.

Implements jsonv::encoder.

write_array_end()

virtual void jsonv::value_encoder::write_array_end ( )

overrideprotectedvirtual

Write the closing of an array value.

]

Implements jsonv::encoder.

write_boolean()

virtual void jsonv::value_encoder::write_boolean ( bool  value )

overrideprotectedvirtual

Write a boolean value.

true

Implements jsonv::encoder.

write_decimal()

virtual void jsonv::value_encoder::write_decimal ( double  value )

overrideprotectedvirtual

Kept as given: a value can hold a NaN or an infinity, so nothing is substituted for one.

Implements jsonv::encoder.

write_integer()

virtual void jsonv::value_encoder::write_integer ( std::int64_t  value )

overrideprotectedvirtual

Write an integer value.

902

Implements jsonv::encoder.

write_null()

virtual void jsonv::value_encoder::write_null ( )

overrideprotectedvirtual

Write the null value.

null

Implements jsonv::encoder.

write_object_begin()

virtual void jsonv::value_encoder::write_object_begin ( )

overrideprotectedvirtual

Write the opening of an object value.

{

Implements jsonv::encoder.

write_object_delimiter()

virtual void jsonv::value_encoder::write_object_delimiter ( )

overrideprotectedvirtual

Does nothing: a tree has no punctuation.

Implements jsonv::encoder.

write_object_end()

virtual void jsonv::value_encoder::write_object_end ( )

overrideprotectedvirtual

Write the closing of an object value.

}

Implements jsonv::encoder.

write_object_key()

virtual void jsonv::value_encoder::write_object_key ( std::string_view  key )

overrideprotectedvirtual

Keep key for the member whose value comes next.

Implements jsonv::encoder.

write_string()

virtual void jsonv::value_encoder::write_string ( std::string_view  value )

overrideprotectedvirtual

The string is copied into the tree as it is, valid UTF-8 or not.

Implements jsonv::encoder.

write_tree() [1/2]

virtual void jsonv::value_encoder::write_tree ( const jsonv::value &  source )

overrideprotectedvirtual

Copies source in whole.

A tree written as an lvalue – to_json of a value, or of anything holding one – costs what copying it does rather than a rebuild through the hooks above, which inserts each member and grows each array one element at a time.

Reimplemented from jsonv::encoder.

write_tree() [2/2]

virtual void jsonv::value_encoder::write_tree ( jsonv::value &&  source )

overrideprotectedvirtual

Takes source as it is.

A tree handed over whole is placed where the next value goes without being rebuilt, which is what keeps a serializer on the value bridge linear in the depth of what it serializes.

Reimplemented from jsonv::encoder.

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

• jsonv/encode.hpp