Generic type information using either Runtime type information (RTTI) or Compile time type information (CTTI) More...

#include <type_info.hpp>

Collaboration diagram for jau::type_info:

Public Member Functions
	type_info () noexcept
	Constructor for an empty type_info instance, i.e.

	type_info (const char *signature_, bool identity_instance=false, bool identity_signature=false) noexcept
	Constructor using a `const char*` signature with a static storage duration.

	type_info (const std::type_info &info_, bool identity_instance=false) noexcept
	Constructor using an RTTI std::type_info reference, i.e.

constexpr size_t	hash_code () const noexcept
	Returns an unspecified hash code of this instance.

constexpr bool	identInst () const noexcept
	Returns true if this instance has a unique address (for same type_info).

constexpr bool	identName () const noexcept
	Returns true if internal_name() has a unique identity address (for same signature strings).

constexpr const char *	internal_name () const noexcept
	Returns the type name, compiler implementation specific.

std::string	name () const noexcept
	Returns the demangled name of internal_name().

bool	operator!= (const type_info &rhs) const noexcept

constexpr bool	operator== (const type_info &rhs) const noexcept
	Return true if both instances are equal.

std::string	toString () const noexcept

Static Public Member Functions
static void	abort_invalid (const char *signature) noexcept
	Aborts program execution if given signature is nullptr or has a string length == 0.

static constexpr bool	is_valid (const char *signature) noexcept
	Returns true if given signature is not nullptr and has a string length > 0, otherwise false.

Static Public Attributes
static constexpr const bool	limited_lambda_id
	Static constexpr boolean indicating whether resulting type_info uniqueness is limited for lambda function types.

Detailed Description

Generic type information using either Runtime type information (RTTI) or Compile time type information (CTTI)

jau::type_info exposes same properties as RTTI std::type_index, i.e. can be used as index in associative and unordered associative containers and is CopyConstructible and CopyAssignable.

jau::type_info is compatible with std::type_index operations.

jau::type_info can be utilized w/o RTTI using Compile time type information (CTTI) information, i.e. JAU_PRETTY_FUNCTION via jau::ctti_name<R, L, A...>().

Consider using jau::make_ctti<R, L, A...>() for construction, as it removes the RTTI and CTTI code path differences.

RTTI and Compile time type information (CTTI) Natures

If RTTI is being used, see cxx_rtti_available, jau::type_info may be instantiated with a std::type_info reference as returned from typeid(T).

Without RTTI jau::type_info may be instantiated using JAU_PRETTY_FUNCTION. Hence utilizes Compile time type information (CTTI) only.

In both cases, jau::type_info will solely operate on the const char* signature and its hash value, aligning memory footprint and operations.

Use jau::make_ctti<R, L, A...>() for construction, as it removes the RTTI and CTTI code path differences.

Notes about lifecycle and identity

Prologue

We assume block scope and static storage duration (runtime lifecycle) of

(1) [typeid(T)]((https://en.cppreference.com/w/cpp/language/typeid)
- (1.1) The typeid expression is an lvalue expression which refers to an object with static storage duration.
- (1.2) There is no guarantee that the same std::type_info instance will be referred to by all evaluations of the typeid expression on the same type, although they would compare equal.
(2) JAU_PRETTY_FUNCTION, aka PRETTY_FUNCTION with properties of func
- (2.1) This variable has block scope and static storage duration.

Equality Comparison

compare the static name storage references (pointer) and return true if equal (fast path)
due to (1.2), see above, the static name storage strings must be compared
- compare the names' hash value and return false if not matching (fast path)
- compare the static names' string and return the result (slow strcmp() equality)
  - this avoids a potential hash collision.

Limitations

Non unique lambda type names without RTTI using `gcc` or non `clang` compiler

Due to limitations of jau::make_ctti<R, L, A...>(), not using RTTI on gcc or non clang compiler will erroneously mistake different lambda functions defined within one function and using same function prototype R<A...> to be the same.

jau::type_info::limited_lambda_id exposes the potential limitation.

See also: Identity; jau::make_ctti<R, L, A...>

Definition at line 224 of file type_info.hpp.

Constructor & Destructor Documentation

◆ type_info() [1/3]

jau::type_info::type_info ( )

inlinenoexcept

Constructor for an empty type_info instance, i.e.

empty name() signature.

Definition at line 276 of file type_info.hpp.

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◆ type_info() [2/3]

jau::type_info::type_info	(	const std::type_info &	info_,
		bool	identity_instance = false )

inlinenoexcept

Constructor using an RTTI std::type_info reference, i.e.

typeid(T) result.

Consider using jau::make_ctti<R, L, A...>() for construction, as it removes the RTTI and CTTI code path differences.

Parameters

info_ RTTI std::type_info reference

See also: jau::make_ctti<R, L, A...>

Definition at line 291 of file type_info.hpp.

◆ type_info() [3/3]

jau::type_info::type_info	(	const char *	signature_,
		bool	identity_instance = false,
		bool	identity_signature = false )

inlinenoexcept

Constructor using a const char* signature with a static storage duration.

Aborts program execution if given signature is nullptr or has a string length == 0.

Parameters

signature_ valid string signature of type with length > 0 with static storage duration.

See also: jau::make_ctti<R, L, A...>

Definition at line 305 of file type_info.hpp.

Member Function Documentation

◆ is_valid()

static constexpr bool jau::type_info::is_valid ( const char * signature )

inlinestaticconstexprnoexcept

Returns true if given signature is not nullptr and has a string length > 0, otherwise false.

Examples: test_functional.hpp.

Definition at line 258 of file type_info.hpp.

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◆ abort_invalid()

static void jau::type_info::abort_invalid ( const char * signature )

inlinestaticnoexcept

Aborts program execution if given signature is nullptr or has a string length == 0.

Definition at line 263 of file type_info.hpp.

◆ operator==()

bool jau::type_info::operator== ( const type_info & rhs ) const

inlineconstexprnoexcept

Return true if both instances are equal.

Parameters

rhs

Returns

See also: Identity

Definition at line 322 of file type_info.hpp.

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◆ operator!=()

bool jau::type_info::operator!= ( const type_info & rhs ) const

inlinenoexcept

Definition at line 336 of file type_info.hpp.

◆ hash_code()

size_t jau::type_info::hash_code ( ) const

inlineconstexprnoexcept

Returns an unspecified hash code of this instance.

Properties

for all type_info objects referring to the same type, their hash code is the same.
type_info objects referring to different types may have the same hash code, i.e. due to hash collision.

Compatible with std::type_info definition.

Returns: Unspecified hash code of this instance.

See also: Identity

Definition at line 352 of file type_info.hpp.

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◆ identInst()

bool jau::type_info::identInst ( ) const

inlineconstexprnoexcept

Returns true if this instance has a unique address (for same type_info).

Definition at line 355 of file type_info.hpp.

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◆ identName()

bool jau::type_info::identName ( ) const

inlineconstexprnoexcept

Returns true if internal_name() has a unique identity address (for same signature strings).

Definition at line 358 of file type_info.hpp.

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◆ internal_name()

const char * jau::type_info::internal_name ( ) const

inlineconstexprnoexcept

Returns the type name, compiler implementation specific.

Examples: test_functional.hpp.

Definition at line 361 of file type_info.hpp.

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◆ name()

std::string jau::type_info::name ( ) const

inlinenoexcept

Returns the demangled name of internal_name().

Definition at line 365 of file type_info.hpp.

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◆ toString()

std::string jau::type_info::toString ( ) const

noexcept

Definition at line 919 of file basic_types.cpp.

Member Data Documentation

◆ limited_lambda_id

const bool jau::type_info::limited_lambda_id

staticconstexpr

Initial value:

=
 
                        true

Static constexpr boolean indicating whether resulting type_info uniqueness is limited for lambda function types.

Always is false if rtti_available == true, i.e. lambda function types are always unique using RTTI.

May return true if:

no RTTI and using gcc
no RTTI and not using clang

See also: CTTI lambda name limitations

Examples: test_functional.hpp, and test_functional_perf.hpp.

Definition at line 244 of file type_info.hpp.

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

include/jau/type_info.hpp
src/basic_types.cpp

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

RTTI and Compile time type information (CTTI) Natures

Notes about lifecycle and identity

Prologue

Equality Comparison

Limitations

Non unique lambda type names without RTTI using gcc or non clang compiler

Constructor & Destructor Documentation

◆ type_info() [1/3]

◆ type_info() [2/3]

◆ type_info() [3/3]

Member Function Documentation

◆ is_valid()

◆ abort_invalid()

◆ operator==()

◆ operator!=()

◆ hash_code()

◆ identInst()

◆ identName()

◆ internal_name()

◆ name()

◆ toString()

Member Data Documentation

◆ limited_lambda_id

Non unique lambda type names without RTTI using `gcc` or non `clang` compiler