folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType > Class Template Reference

#include <Base-inl.h>

Inheritance diagram for folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >:

Public Member Functions
	Generator (Source source, size_t count, Random rng)
template<class Handler >
bool	apply (Handler &&handler) const
Public Member Functions inherited from folly::gen::GenImpl< StorageType &&, Generator< Value, Source, Rand, StorageType > >
bool	apply (Handler &&handler) const
void	foreach (Body &&body) const
Public Member Functions inherited from folly::gen::FBounded< Self >
const Self &	self () const
Self &	self ()

Static Public Attributes
static constexpr bool	infinite = false
Static Public Attributes inherited from folly::gen::GenImpl< StorageType &&, Generator< Value, Source, Rand, StorageType > >
static constexpr bool	infinite

Private Attributes
Source	source_
size_t	count_
Rand	rng_

Additional Inherited Members
Public Types inherited from folly::gen::GenImpl< StorageType &&, Generator< Value, Source, Rand, StorageType > >
typedef StorageType &&	ValueType
typedef std::decay< StorageType && >::type	StorageType
Protected Member Functions inherited from folly::gen::GenImpl< StorageType &&, Generator< Value, Source, Rand, StorageType > >
	GenImpl ()=default
	GenImpl (GenImpl &&)=default
	GenImpl (const GenImpl &)=default
GenImpl &	operator= (GenImpl &&)=default
GenImpl &	operator= (const GenImpl &)=default

Detailed Description

template<class Random>
template<class Value, class Source, class Rand, class StorageType = typename std::decay<Value>::type>
class folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >

Definition at line 884 of file Base-inl.h.

Constructor & Destructor Documentation

template<class Random>

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

folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::Generator ( Source  source, size_t  count, Random  rng  )

inlineexplicit

Definition at line 897 of file Base-inl.h.

        : source_(std::move(source)), count_(count), rng_(std::move(rng)) {}

Member Function Documentation

template<class Random>

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

template<class Handler >

bool folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::apply ( Handler &&  handler ) const

inline

Definition at line 901 of file Base-inl.h.

References handler(), folly::gen::move, v, val, value, and testing::Value().

                                        {
      if (count_ == 0) {
        return false;
      }
      std::vector<StorageType> v;
      v.reserve(count_);
      // use reservoir sampling to give each source value an equal chance
      // of appearing in our output.
      size_t n = 1;
      source_.foreach([&](Value value) -> void {
        if (v.size() < count_) {
          v.push_back(std::forward<Value>(value));
        } else {
          // alternatively, we could create a std::uniform_int_distribution
          // instead of using modulus, but benchmarks show this has
          // substantial overhead.
          size_t index = rng_() % n;
          if (index < v.size()) {
            v[index] = std::forward<Value>(value);
          }
        }
        ++n;
      });

      // output is unsorted!
      for (auto& val : v) {
        if (!handler(std::move(val))) {
          return false;
        }
      }
      return true;
    }

Member Data Documentation

template<class Random>

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

size_t folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::count_

private

Definition at line 893 of file Base-inl.h.

template<class Random>

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

constexpr bool folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::infinite = false

static

Definition at line 935 of file Base-inl.h.

template<class Random>

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

Rand folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::rng_

mutableprivate

Definition at line 894 of file Base-inl.h.

template<class Random>

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

Source folly::gen::detail::Sample< Random >::Generator< Value, Source, Rand, StorageType >::source_

private

Definition at line 887 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