ps_lattice_internal.h File Reference

Word graph search implementation. More...

Go to the source code of this file.

Data Structures
struct	latlink_list_s
	Linked list of DAG link pointers. More...
struct	ps_lattice_s
	Word graph structure used in bestpath/nbest search. More...
struct	ps_latlink_s
	Links between DAG nodes. More...
struct	ps_latnode_s
	DAG nodes. More...
struct	dag_seg_s
	Segmentation "iterator" for backpointer table results. More...
struct	ps_latpath_s
	Partial path structure used in N-best (A*) search. More...
struct	ps_astar_s
	A* search structure. More...
struct	astar_seg_s
	Segmentation "iterator" for A* search results. More...

Typedefs
typedef struct latlink_list_s	latlink_list_t
	Linked list of DAG link pointers. More...
typedef struct dag_seg_s	dag_seg_t
	Segmentation "iterator" for backpointer table results.
typedef struct ps_latpath_s	ps_latpath_t
	Partial path structure used in N-best (A*) search. More...
typedef struct ps_astar_s	ps_astar_t
	A* search structure.
typedef struct astar_seg_s	astar_seg_t
	Segmentation "iterator" for A* search results.

Functions
ps_lattice_t *	ps_lattice_init_search (ps_search_t *search, int n_frame)
	Construct an empty word graph with reference to a search structure.
void	ps_lattice_penalize_fillers (ps_lattice_t *dag, int32 silpen, int32 fillpen)
	Insert penalty for fillers.
void	ps_lattice_delete_unreachable (ps_lattice_t *dag)
	Remove nodes marked as unreachable.
void	ps_lattice_pushq (ps_lattice_t *dag, ps_latlink_t *link)
	Add an edge to the traversal queue.
ps_latlink_t *	ps_lattice_popq (ps_lattice_t *dag)
	Remove an edge from the traversal queue.
void	ps_lattice_delq (ps_lattice_t *dag)
	Clear and reset the traversal queue.
latlink_list_t *	latlink_list_new (ps_lattice_t *dag, ps_latlink_t *link, latlink_list_t *next)
	Create a new lattice link element.
char const *	ps_lattice_hyp (ps_lattice_t *dag, ps_latlink_t *link)
	Get hypothesis string after bestpath search.
ps_seg_t *	ps_lattice_seg_iter (ps_lattice_t *dag, ps_latlink_t *link, float32 lwf)
	Get hypothesis segmentation iterator after bestpath search.
ps_astar_t *	ps_astar_start (ps_lattice_t *dag, ngram_model_t *lmset, float32 lwf, int sf, int ef, int w1, int w2)
	Begin N-Gram based A* search on a word graph. More...
ps_latpath_t *	ps_astar_next (ps_astar_t *nbest)
	Find next best hypothesis of A* on a word graph. More...
void	ps_astar_finish (ps_astar_t *nbest)
	Finish N-best search, releasing resources associated with it.
char const *	ps_astar_hyp (ps_astar_t *nbest, ps_latpath_t *path)
	Get hypothesis string from A* search.
ps_seg_t *	ps_astar_seg_iter (ps_astar_t *astar, ps_latpath_t *path, float32 lwf)
	Get hypothesis segmentation from A* search.

Detailed Description

Word graph search implementation.

Definition in file ps_lattice_internal.h.

Typedef Documentation

typedef struct latlink_list_s latlink_list_t

Linked list of DAG link pointers.

Because the same link structure is used for forward and reverse links, as well as for the agenda used in bestpath search, we can't store the list pointer inside latlink_t. We could use glist_t here, but it wastes 4 bytes per entry on 32-bit machines.

typedef struct ps_latpath_s ps_latpath_t

Partial path structure used in N-best (A*) search.

Each partial path (latpath_t) is constructed by extending another partial path–parent–by one node.

Function Documentation

ps_latpath_t* ps_astar_next

(

ps_astar_t *

nbest

)

Find next best hypothesis of A* on a word graph.

Returns

a complete path, or NULL if no more hypotheses exist.

Definition at line 1771 of file ps_lattice.c.

References ps_lattice_s::end, ps_latnode_s::fef, ps_latpath_s::next, ps_latpath_s::node, and ps_latnode_s::sf.

Referenced by ps_nbest_next().

ps_astar_t* ps_astar_start	(	ps_lattice_t *	dag,
		ngram_model_t *	lmset,
		float32	lwf,
		int	sf,
		int	ef,
		int	w1,
		int	w2
	)

Begin N-Gram based A* search on a word graph.

Parameters

sf	Starting frame for N-best search.
ef	Ending frame for N-best search, or -1 for last frame.
w1	First context word, or -1 for none.
w2	Second context word, or -1 for none.

Returns

0 for success, <0 on error.

Definition at line 1712 of file ps_lattice.c.

References ps_latnode_s::basewid, ps_lattice_s::end, ps_latnode_s::exits, ps_astar_s::latpath_alloc, ps_lattice_s::n_frames, ps_latnode_s::next, ps_latpath_s::node, ps_lattice_s::nodes, ps_latpath_s::parent, ps_latnode_s::rem_score, ps_latpath_s::score, SENSCR_SHIFT, ps_latnode_s::sf, and WORST_SCORE.

Referenced by ps_nbest().