folly::gen::detail::Reduce< Reducer > Class Template Reference

#include <Base-inl.h>

Inheritance diagram for folly::gen::detail::Reduce< Reducer >:

Public Member Functions
	Reduce ()=default
	Reduce (Reducer reducer)
template<class Source , class Value , class StorageType = typename std::decay<Value>::type>
Optional< StorageType >	compose (const GenImpl< Value, Source > &source) const
Public Member Functions inherited from folly::gen::Operator< Reduce< Reducer > >
ResultGen	compose (const GenImpl< Value, Source > &source) const
Public Member Functions inherited from folly::gen::FBounded< Self >
const Self &	self () const
Self &	self ()

Private Attributes
Reducer	reducer_

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

Detailed Description

template<class Reducer>
class folly::gen::detail::Reduce< Reducer >

Reduce - Functional reduce, for recursively combining values from a source using a reducer function until there is only one item left. Useful for combining values when an empty sequence doesn't make sense.

This type is primarily used through the 'reduce' helper method, like:

sring longest = from(names) | reduce([](string&& best, string& current) { return best.size() >= current.size() ? best : current; });

Definition at line 2099 of file Base-inl.h.

Constructor & Destructor Documentation

template<class Reducer >

folly::gen::detail::Reduce< Reducer >::Reduce ( )

default

template<class Reducer >

folly::gen::detail::Reduce< Reducer >::Reduce ( Reducer  reducer )

inlineexplicit

Definition at line 2104 of file Base-inl.h.

References type, and testing::Value().

: reducer_(std::move(reducer)) {}

Member Function Documentation

template<class Reducer >

template<class Source , class Value , class StorageType = typename std::decay<Value>::type>

Optional<StorageType> folly::gen::detail::Reduce< Reducer >::compose ( const GenImpl< Value, Source > &  source ) const

inline

Definition at line 2110 of file Base-inl.h.

References folly::Optional< Value >::get_pointer(), folly::gen::move, and v.

                                                                            {
    static_assert(!Source::infinite, "Cannot reduce infinite source");
    Optional<StorageType> accum;
    source | [&](Value v) {
      if (auto target = accum.get_pointer()) {
        *target = reducer_(std::move(*target), std::forward<Value>(v));
      } else {
        accum = std::forward<Value>(v);
      }
    };
    return accum;
  }

Member Data Documentation

template<class Reducer >

Reducer folly::gen::detail::Reduce< Reducer >::reducer_

private

Definition at line 2100 of file Base-inl.h.

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

• proxygen/folly/folly/gen/Base-inl.h