folly::gen::detail::IsEmpty< emptyResult > Class Template Reference

#include <Base-inl.h>

Inheritance diagram for folly::gen::detail::IsEmpty< emptyResult >:

Public Member Functions
	IsEmpty ()=default
template<class Source , class Value >
bool	compose (const GenImpl< Value, Source > &source) const
Public Member Functions inherited from folly::gen::Operator< IsEmpty< emptyResult > >
ResultGen	compose (const GenImpl< Value, Source > &source) const
Public Member Functions inherited from folly::gen::FBounded< Self >
const Self &	self () const
Self &	self ()

Additional Inherited Members
Protected Member Functions inherited from folly::gen::Operator< IsEmpty< emptyResult > >
	Operator ()=default
	Operator (Operator &&) noexcept=default
	Operator (const Operator &)=default
Operator &	operator= (Operator &&) noexcept=default
Operator &	operator= (const Operator &)=default

Detailed Description

template<bool emptyResult>
class folly::gen::detail::IsEmpty< emptyResult >

IsEmpty - a helper class for isEmpty and notEmpty

Essentially returns 'result' if the source is empty. Note that this cannot be called on an infinite source, because then there is only one possible return value.

Used primarily through 'isEmpty' and 'notEmpty' static values

bool hasPrimes = g | filter(prime) | notEmpty; bool lacksEvens = g | filter(even) | isEmpty;

Also used in the implementation of 'any' and 'all'

Definition at line 2065 of file Base-inl.h.

Constructor & Destructor Documentation

template<bool emptyResult>

folly::gen::detail::IsEmpty< emptyResult >::IsEmpty ( )

default

Member Function Documentation

template<bool emptyResult>

template<class Source , class Value >

bool folly::gen::detail::IsEmpty< emptyResult >::compose ( const GenImpl< Value, Source > &  source ) const

inline

Definition at line 2070 of file Base-inl.h.

References testing::Value().

                                                           {
    static_assert(
        !Source::infinite,
        "Cannot call 'all', 'any', 'isEmpty', or 'notEmpty' on "
        "infinite source. 'all' and 'isEmpty' will either return "
        "false or hang. 'any' or 'notEmpty' will either return true "
        "or hang.");
    bool ans = emptyResult;
    source | [&](Value /* v */) -> bool {
      ans = !emptyResult;
      return false;
    };
    return ans;
  }

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

• proxygen/folly/folly/gen/Base-inl.h