#include <variant.hpp>

Inheritance diagram for fable::schema::Variant:

Collaboration diagram for fable::schema::Variant:

Public Member Functions
	Variant (std::initializer_list< Box > vec)

	Variant (std::string desc, std::initializer_list< Box > vec)

	Variant (std::vector< Box > &&vec)

	Variant (std::string desc, std::vector< Box > &&vec)

std::unique_ptr< Interface >	clone () const override

	operator Box () const

JsonType	type () const override

std::string	type_string () const override

bool	is_variant () const override

Json	usage () const override

bool	is_required () const override

Variant	require () &&

Variant	required (bool value) &&

bool	has_description () const

void	set_description (std::string s) override

const std::string &	description () const override

Variant	description (std::string desc) &&

Variant	unique_match (bool value) &&

Variant	reset_pointer () &&

Json	json_schema () const override

bool	validate (const Conf &c, std::optional< SchemaError > &err) const override

void	to_json (Json &j) const override

void	from_conf (const Conf &c) override

void	reset_ptr () override

virtual Json	to_json () const

virtual void	to_json (Json &) const=0

Public Member Functions inherited from fable::schema::Interface
virtual void	validate_or_throw (const Conf &c) const final

virtual std::optional< SchemaError >	fail (const Conf &c) const final

virtual bool	is_valid (const Conf &c) const final

virtual Json	to_json () const

Additional Inherited Members
Protected Member Functions inherited from fable::schema::Interface
	Interface (const Interface &)=default

	Interface (Interface &&) noexcept=default

Interface &	operator= (const Interface &)=default

Interface &	operator= (Interface &&) noexcept=default

Detailed Description

Variant deserializes JSON data into one of multiple variants.

Whenever the JSON input can come in different forms but is more or less destined for the same variable (or set of variables), we need to be able to deal with variants. For example, an enumeration is a variant of constants.

Deciding which variant to use for deserializing JSON is not always unambiguous. This class will simply use the first valid schema. For this reason it is strongly recommended to pay attention to making all schemas that are part of a variant distinct from one another. One way to do this is to introduce a required constant (such as a value from an enumeration) into the schema.

Serialization uses the very first schema in the variant list for output. For this reason, the very first schema in the list should contain the schema of the desired output.

Member Function Documentation

◆ clone()

std::unique_ptr<Interface> fable::schema::Variant::clone ( ) const

inlineoverridevirtual

Return a new instance of the object.

This is implemented by Base and allows us to wrap implementors of Interface with Schema.

Implements fable::schema::Interface.

◆ description()

const std::string& fable::schema::Variant::description ( ) const

inlineoverridevirtual

Return human-readable description.

Implements fable::schema::Interface.

◆ from_conf()

void fable::schema::Variant::from_conf ( const Conf & )

inlineoverridevirtual

Apply the input JSON configuration.

This does not validate the input.

Implements fable::schema::Interface.

◆ is_required()

bool fable::schema::Variant::is_required ( ) const

inlineoverridevirtual

Return whether this interface needs to be set.

Implements fable::schema::Interface.

◆ is_variant()

bool fable::schema::Variant::is_variant ( ) const

inlineoverridevirtual

Return whether the accepted input type is a variant.

A variant type is one that is composed of other types, such as the special types: any-of, one-of, and all-of.

Reimplemented from fable::schema::Interface.

◆ json_schema()

Json fable::schema::Variant::json_schema ( ) const

overridevirtual

Return the JSON schema.

Example output:

{ "$schema": "http://json-schema.org/draft-07/schema#", "description": "stand-in no-operation simulator", "properties": { "vehicles": { "description": "list of vehicle names to make available", "items": { "type": "string" }, "type": "array" } }, "title": "nop", "additionalProperties": false, "type": "object" }

See the following links for the specification:

Implements fable::schema::Interface.

◆ reset_ptr()

void fable::schema::Variant::reset_ptr ( )

overridevirtual

Reset the internal pointer to nullptr, protecting against invalid access.

This should be used when a schema is used after the backing data has been deleted.

Implements fable::schema::Interface.

◆ set_description()

void fable::schema::Variant::set_description ( std::string s )

inlineoverridevirtual

Set human-readable description.

Implements fable::schema::Interface.

◆ to_json() [1/3]

virtual Json fable::schema::Interface::to_json

inline

Return the current value of the destination.

Warning: This is NOT an efficient operation, but it can be useful for cases where speed is not important.

◆ to_json() [2/3]

virtual void fable::schema::Interface::to_json

Return the current value of the destination.

Warning: This is NOT an efficient operation, but it can be useful for cases where speed is not important.

◆ to_json() [3/3]

void fable::schema::Variant::to_json ( Json & ) const

inlineoverridevirtual

Return the current value of the destination.

Warning: This is NOT an efficient operation, but it can be useful for cases where speed is not important.

Implements fable::schema::Interface.

◆ type()

JsonType fable::schema::Variant::type ( ) const

inlineoverridevirtual

Return the JSON type.

If this is a variant type of differing types, then null should be returned. Otherwise, the type remains unique and can be returned. A type that is null is almost always a variant type of some sort, if even only an optional type.

Implements fable::schema::Interface.

◆ type_string()

std::string fable::schema::Variant::type_string ( ) const

inlineoverridevirtual

Return the type as a string.

The format of the string is:

"[array of] TYPE"

where TYPE is one of: null, object, boolean, float, integer, unsigned, string, and unknown.

Example output:

"object"
"array of boolean"
"array of object"

Implements fable::schema::Interface.

◆ usage()

Json fable::schema::Variant::usage ( ) const

overridevirtual

Return a compact JSON description of the schema. This is useful for human-readable error output.

Example output:

{ "field1": "boolean! :: lorem ipsum dolor sit amet", "field2": { "field2.1": "integer :: lorem ipsum dolor sit amet" "field2.2": "boolean :: lorem ipsum dolor sit amet" }, "field3": "array of integer :: lorem ipsum dolor sit amet", "field4": [{ "field4.1": "string :: lorem ipsum dolor sit amet" "field4.2": "boolean :: lorem ipsum dolor sit amet" }] }

When describing the schema of a primitive array, we can represent that as a single string. But when the array contains an object, we wrap a single object in an array. This isn't awfully consistent, but it's the best we can do.

Implements fable::schema::Interface.

◆ validate()

bool fable::schema::Variant::validate	(	const Conf &	c,
		std::optional< SchemaError > &	error
	)		const

inlineoverridevirtual

Validate the input JSON configuration for correctness.

This method should only set error if there is an error. This method should not reset error if there is no error. Therefore, the content of error is only valid if the method returns false. This allows you to chain validates and check at the end if there was an error.
This method should not throw if there is a schema error!

Parameters

c	JSON to check
error	reference to store error if occurred

Returns: true if valid

Implements fable::schema::Interface.

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

/home/docs/checkouts/readthedocs.org/user_builds/cloe/checkouts/develop/fable/include/fable/schema/variant.hpp
/home/docs/checkouts/readthedocs.org/user_builds/cloe/checkouts/develop/fable/src/fable/schema/variant.cpp

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ clone()

◆ description()

◆ from_conf()

◆ is_required()

◆ is_variant()

◆ json_schema()

◆ reset_ptr()

◆ set_description()

◆ to_json() [1/3]

◆ to_json() [2/3]

◆ to_json() [3/3]

◆ type()

◆ type_string()

◆ usage()

◆ validate()