#include <deterministic-fst.h>

Inheritance diagram for CacheDeterministicOnDemandFst< Arc >:

Collaboration diagram for CacheDeterministicOnDemandFst< Arc >:

Public Types
typedef Arc::StateId	StateId

typedef Arc::Weight	Weight

typedef Arc::Label	Label

Public Types inherited from DeterministicOnDemandFst< Arc >
typedef Arc::StateId	StateId

typedef Arc::Weight	Weight

typedef Arc::Label	Label

Public Member Functions
	CacheDeterministicOnDemandFst (DeterministicOnDemandFst< Arc > *fst, StateId num_cached_arcs=100000)
	We don't take ownership of this pointer. The argument is "really" const. More...

virtual StateId	Start ()

virtual Weight	Final (StateId s)
	We don't bother caching the final-probs, just the arcs. More...

virtual bool	GetArc (StateId s, Label ilabel, Arc *oarc)
	Note: ilabel must not be epsilon. More...

Public Member Functions inherited from DeterministicOnDemandFst< Arc >
virtual	~DeterministicOnDemandFst ()

Private Member Functions
size_t	GetIndex (StateId src_state, Label ilabel)

Private Attributes
DeterministicOnDemandFst< Arc > *	fst_

StateId	num_cached_arcs_

std::vector< std::pair< StateId, Arc > >	cached_arcs_

Detailed Description

template<class Arc>
class fst::CacheDeterministicOnDemandFst< Arc >

Definition at line 230 of file deterministic-fst.h.

Member Typedef Documentation

◆ Label

typedef Arc::Label Label

Definition at line 234 of file deterministic-fst.h.

◆ StateId

typedef Arc::StateId StateId

Definition at line 232 of file deterministic-fst.h.

◆ Weight

typedef Arc::Weight Weight

Definition at line 233 of file deterministic-fst.h.

Constructor & Destructor Documentation

◆ CacheDeterministicOnDemandFst()

CacheDeterministicOnDemandFst	(	DeterministicOnDemandFst< Arc > *	fst,
		StateId	num_cached_arcs = `100000`
	)

We don't take ownership of this pointer. The argument is "really" const.

Definition at line 223 of file deterministic-fst-inl.h.

References CacheDeterministicOnDemandFst< Arc >::cached_arcs_, rnnlm::i, and KALDI_ASSERT.

                             : fst_(fst),
                               num_cached_arcs_(num_cached_arcs),
                               cached_arcs_(num_cached_arcs) {
   KALDI_ASSERT(num_cached_arcs > 0);
   for (StateId i = 0; i < num_cached_arcs; i++)
     cached_arcs_[i].first = kNoStateId; // Invalidate all elements of the cache.
 }

Member Function Documentation

◆ Final()

virtual Weight Final ( StateId s )

inlinevirtual

We don't bother caching the final-probs, just the arcs.

Implements DeterministicOnDemandFst< Arc >.

Definition at line 243 of file deterministic-fst.h.

References DeterministicOnDemandFst< Arc >::GetArc().

Referenced by fst::TestBackoffAndCache().

243 { return fst_->Final(s); }

fst::CacheDeterministicOnDemandFst::fst_

DeterministicOnDemandFst< Arc > * fst_

Definition: deterministic-fst.h:251

◆ GetArc()

bool GetArc	(	StateId	s,
		Label	ilabel,
		Arc *	oarc
	)

virtual

Note: ilabel must not be epsilon.

Implements DeterministicOnDemandFst< Arc >.

Definition at line 234 of file deterministic-fst-inl.h.

References CacheDeterministicOnDemandFst< Arc >::cached_arcs_, CacheDeterministicOnDemandFst< Arc >::fst_, CacheDeterministicOnDemandFst< Arc >::GetIndex(), and KALDI_ASSERT.

Referenced by fst::TestBackoffAndCache().

                                                            {
   // Note: we don't cache anything in case a requested arc does not exist.
   // In the uses that we imagine this will be put to, essentially all the
   // requested arcs will exist.  This only affects efficiency.
   KALDI_ASSERT(s >= 0 && ilabel != 0);
   size_t index = this->GetIndex(s, ilabel);
   if (cached_arcs_[index].first == s &&
       cached_arcs_[index].second.ilabel == ilabel) {
     *oarc = cached_arcs_[index].second;
     return true;
   } else {
     Arc arc;
     if (fst_->GetArc(s, ilabel, &arc)) {
       cached_arcs_[index].first = s;
       cached_arcs_[index].second = arc;
       *oarc = arc;
       return true;
     } else {
       return false;
     }
   }
 }

◆ GetIndex()

size_t GetIndex	(	StateId	src_state,
		Label	ilabel
	)

inlineprivate

Definition at line 210 of file deterministic-fst-inl.h.

Referenced by CacheDeterministicOnDemandFst< Arc >::GetArc().

                                      {
   const StateId p1 = 26597, p2 = 50329; // these are two
   // values that I drew at random from a table of primes.
   // note: num_cached_arcs_ > 0.
 
   // We cast to size_t before the modulus, to ensure the
   // result is positive.
   return static_cast<size_t>(src_state * p1 + ilabel * p2) %
       static_cast<size_t>(num_cached_arcs_);
 }