morph::ui::author::Handle< T > Class Template Reference

An expression of a document, typed by the C++ value it evaluates to (spec 5 §11). More...

#include <author.hpp>

Public Types
using	ValueType = T
	The C++ type of the value.

Public Member Functions
	Handle ()=default
	An absent handle.
template<typename L> requires detail::Literal<std::remove_cvref_t<L>> && (detail::assignable<detail::LiteralT<L>, T>())
	Handle (L const &literal)
	A constant.
template<typename U> requires (!std::same_as<U, T>) && (detail::assignable<U, T>())
	Handle (Handle< U > const &other)
	A handle of another value type that can stand for this one.
bool	present () const noexcept
	Whether the handle holds an expression.
Json const &	json () const
	The expression's JSON.
template<typename Class, typename Member> requires std::same_as<T, Any> || std::same_as<detail::UnwrappedT<T>, Class>
Handle< Member >	at (Member Class::*member) const
	A field of the value, by member pointer: a renamed field is a compile error.
Handle< Any >	at (std::string_view field) const
	A field of the value, by name.
Handle	orElse (Handle const &fallback) const
	The value, or a fallback when it is null.

Static Public Member Functions
static Handle	raw (Json json)
	A handle over an expression's JSON, for a form no builder spells.

Detailed Description

template<typename T = Any>
class morph::ui::author::Handle< T >

An expression of a document, typed by the C++ value it evaluates to (spec 5 §11).

A handle is a JSON expression tree. Operators build calls of the expr/1 library: a + b is add, a < b is lt, a && b is and, !a is not; at reads a field by member pointer, and orElse is coalesce. A default-constructed handle is absent: a builder leaves out the key it would fill.

Template Parameters

T	The C++ type of the value, Any when the screen cannot know it.

Definition at line 648 of file author.hpp.

Member Typedef Documentation

ValueType

template<typename T = Any>

using morph::ui::author::Handle< T >::ValueType = T

The C++ type of the value.

Definition at line 651 of file author.hpp.

Constructor & Destructor Documentation

Handle() [1/2]

template<typename T = Any>

template<typename L>
requires detail::Literal<std::remove_cvref_t<L>> && (detail::assignable<detail::LiteralT<L>, T>())

morph::ui::author::Handle< T >::Handle ( L const & literal )

inline

A constant.

Template Parameters

L	The constant's C++ type, which must be able to stand for T.

Parameters

literal

The constant.

Definition at line 661 of file author.hpp.

Handle() [2/2]

template<typename T = Any>

template<typename U>
requires (!std::same_as<U, T>) && (detail::assignable<U, T>())

morph::ui::author::Handle< T >::Handle ( Handle< U > const & other )

inline

A handle of another value type that can stand for this one.

Template Parameters

U	The other value type.

Parameters

other

The handle.

Definition at line 669 of file author.hpp.

Member Function Documentation

raw()

template<typename T = Any>

Handle morph::ui::author::Handle< T >::raw ( Json json )

inlinestaticnodiscard

A handle over an expression's JSON, for a form no builder spells.

Parameters

json	The expression.

Returns

The handle.

Definition at line 675 of file author.hpp.

present()

template<typename T = Any>

bool morph::ui::author::Handle< T >::present ( ) const

inlinenodiscardnoexcept

Whether the handle holds an expression.

Returns

False for a default-constructed handle.

Definition at line 683 of file author.hpp.

json()

template<typename T = Any>

Json const & morph::ui::author::Handle< T >::json ( ) const

inlinenodiscard

The expression's JSON.

Returns

The JSON.

Exceptions

AuthoringError

when the handle is absent.

Definition at line 688 of file author.hpp.

at() [1/2]

template<typename T = Any>

template<typename Class, typename Member>
requires std::same_as<T, Any> || std::same_as<detail::UnwrappedT<T>, Class>

Handle< Member > morph::ui::author::Handle< T >::at ( Member Class::* member ) const

inlinenodiscard

A field of the value, by member pointer: a renamed field is a compile error.

Template Parameters

Class	The class of the member, the value's type.
Member	The member's type.

Parameters

member

The member.

Returns

The field read.

Exceptions

AuthoringError

when the handle is not a named read.

Definition at line 703 of file author.hpp.

at() [2/2]

template<typename T = Any>

Handle< Any > morph::ui::author::Handle< T >::at ( std::string_view field ) const

inlinenodiscard

A field of the value, by name.

Parameters

field

The field, or a dotted path.

Returns

The field read.

Exceptions

AuthoringError

when the handle is not a named read.

Definition at line 711 of file author.hpp.

orElse()

template<typename T = Any>

Handle morph::ui::author::Handle< T >::orElse ( Handle< T > const & fallback ) const

inlinenodiscard

The value, or a fallback when it is null.

Parameters

fallback

The fallback.

Returns

coalesce(this, fallback).

Definition at line 718 of file author.hpp.

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

• morph/ui/author.hpp