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Greatly optimize the number of states in FSG created from JSGF
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by avoiding new unnecessary nodes. See for details

https://sourceforge.net/p/cmusphinx/bugs/358/

Patch by Steven J. Boswell II



git-svn-id: svn+ssh://svn.code.sf.net/p/cmusphinx/code/trunk/sphinxbase@12042 94700074-3cef-4d97-a70e-9c8c206c02f5
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nshmyrev committed Nov 10, 2013
1 parent bfacd64 commit e59cac4
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Showing 7 changed files with 189 additions and 185 deletions.
176 changes: 125 additions & 51 deletions src/libsphinxbase/lm/jsgf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,8 @@ extern int yyparse (void* scanner, jsgf_t* jsgf);
* into Sphinx finite-state grammars.
**/

static int expand_rule(jsgf_t *grammar, jsgf_rule_t *rule, int rule_entry, int rule_exit);

jsgf_atom_t *
jsgf_atom_new(char *name, float weight)
{
Expand Down Expand Up @@ -299,94 +301,146 @@ importname2rulename(char *importname)
}
}

static int expand_rule(jsgf_t *grammar, jsgf_rule_t *rule);
#define NO_NODE -1
#define RECURSIVE_NODE -2

/**
*
* Expand a right-hand-side of a rule (i.e. a single alternate).
*
* @returns the FSG state at the end of this rule, NO_NODE if there's an
* error, and RECURSIVE_NODE if the right-hand-side ended in right-recursion (i.e.
* a link to an earlier FSG state).
*/
static int
expand_rhs(jsgf_t *grammar, jsgf_rule_t *rule, jsgf_rhs_t *rhs)
expand_rhs(jsgf_t *grammar, jsgf_rule_t *rule, jsgf_rhs_t *rhs,
int rule_entry, int rule_exit)
{
gnode_t *gn;
int lastnode;

/* Last node expanded in this sequence. */
lastnode = rule->entry;
lastnode = rule_entry;

/* Iterate over atoms in rhs and generate links/nodes */
for (gn = rhs->atoms; gn; gn = gnode_next(gn)) {
jsgf_atom_t *atom = gnode_ptr(gn);

if (jsgf_atom_is_rule(atom)) {
jsgf_rule_t *subrule;
char *fullname;
gnode_t *subnode;
void *val;

/* Special case for <NULL> and <VOID> pseudo-rules */
if (0 == strcmp(atom->name, "<NULL>")) {
/* Emit a NULL transition */
jsgf_add_link(grammar, atom,
lastnode, grammar->nstate);
lastnode = grammar->nstate;
++grammar->nstate;
jsgf_rule_stack_t *rule_stack_entry;

/* Special case for <NULL> and <VOID> pseudo-rules
If this is the only atom in the rhs, and it's the
first rhs in the rule, then emit a null transition,
creating an exit state if needed. */
if (0 == strcmp(atom->name, "<NULL>")) {
if (gn == rhs->atoms && gnode_next(gn) == NULL) {
if (rule_exit == NO_NODE) {
jsgf_add_link(grammar, atom,
lastnode, grammar->nstate);
rule_exit = lastnode = grammar->nstate;
++grammar->nstate;
} else {
jsgf_add_link(grammar, atom,
lastnode, rule_exit);
}
}
continue;
}
}
else if (0 == strcmp(atom->name, "<VOID>")) {
/* Make this entire RHS unspeakable */
return -1;
return NO_NODE;
}

fullname = jsgf_fullname_from_rule(rule, atom->name);
if (hash_table_lookup(grammar->rules, fullname, &val) == -1) {
if (hash_table_lookup(grammar->rules, fullname, (void**)&subrule) == -1) {
E_ERROR("Undefined rule in RHS: %s\n", fullname);
ckd_free(fullname);
return -1;
return NO_NODE;
}
ckd_free(fullname);
subrule = val;
/* Look for this in the stack of expanded rules */
for (subnode = grammar->rulestack; subnode; subnode = gnode_next(subnode))
if (gnode_ptr(subnode) == (void *)subrule)

/* Look for this subrule in the stack of expanded rules */
for (subnode = grammar->rulestack; subnode; subnode = gnode_next(subnode)) {
rule_stack_entry = (jsgf_rule_stack_t *)gnode_ptr(subnode);
if (rule_stack_entry->rule == subrule)
break;
}

if (subnode != NULL) {
/* Allow right-recursion only. */
if (gnode_next(gn) != NULL) {
E_ERROR("Only right-recursion is permitted (in %s.%s)\n",
grammar->name, rule->name);
return -1;
return NO_NODE;
}
/* Add a link back to the beginning of this rule instance */
E_INFO("Right recursion %s %d => %d\n", atom->name, lastnode, subrule->entry);
jsgf_add_link(grammar, atom, lastnode, subrule->entry);
E_INFO("Right recursion %s %d => %d\n", atom->name, lastnode, rule_stack_entry->entry);
jsgf_add_link(grammar, atom, lastnode, rule_stack_entry->entry);

/* Let our caller know that this rhs didn't reach an
end state. */
lastnode = RECURSIVE_NODE;
}
else {
/* If this is the last atom in this rhs, link its
expansion to the parent rule's exit state.
Otherwise, create a new exit state for it. */
int subruleexit = NO_NODE;
if (gnode_next(gn) == NULL && rule_exit >= 0)
subruleexit = rule_exit;

/* Expand the subrule */
if (expand_rule(grammar, subrule) == -1)
return -1;
/* Add a link into the subrule. */
jsgf_add_link(grammar, atom,
lastnode, subrule->entry);
lastnode = subrule->exit;
lastnode = expand_rule(grammar, subrule, lastnode, subruleexit);

if (lastnode == NO_NODE)
return NO_NODE;
}
}
else {
/* Add a link for this token and create a new exit node. */
/* An exit-state is created if this isn't the last atom
in the rhs, or if the containing rule doesn't have an
exit state yet.
Otherwise, the rhs's exit state becomes the containing
rule's exit state. */

int exitstate;
if (gnode_next(gn) == NULL && rule_exit >= 0) {
exitstate = rule_exit;
} else {
exitstate = grammar->nstate;
++grammar->nstate;
}

/* Add a link for this token */
jsgf_add_link(grammar, atom,
lastnode, grammar->nstate);
lastnode = grammar->nstate;
++grammar->nstate;
lastnode, exitstate);
lastnode = exitstate;
}
}

return lastnode;
}

static int
expand_rule(jsgf_t *grammar, jsgf_rule_t *rule)
expand_rule(jsgf_t *grammar, jsgf_rule_t *rule, int rule_entry,
int rule_exit)
{
jsgf_rule_stack_t* rule_stack_entry;
jsgf_rhs_t *rhs;
float norm;

/* Push this rule onto the stack */
grammar->rulestack = glist_add_ptr(grammar->rulestack, rule);
rule_stack_entry = (jsgf_rule_stack_t*)ckd_calloc(1, sizeof (jsgf_rule_stack_t));
rule_stack_entry->rule = rule;
rule_stack_entry->entry = rule_entry;
grammar->rulestack = glist_add_ptr(grammar->rulestack,
rule_stack_entry);

/* Normalize weights for all alternatives exiting rule->entry */
/* Normalize weights for all alternatives exiting rule_entry */
norm = 0;
for (rhs = rule->rhs; rhs; rhs = rhs->alt) {
if (rhs->atoms) {
Expand All @@ -395,28 +449,43 @@ expand_rule(jsgf_t *grammar, jsgf_rule_t *rule)
}
}

rule->entry = grammar->nstate++;
rule->exit = grammar->nstate++;
if (norm == 0) norm = 1;
for (rhs = rule->rhs; rhs; rhs = rhs->alt) {
int lastnode;

if (rhs->atoms) {
jsgf_atom_t *atom = gnode_ptr(rhs->atoms);
atom->weight /= norm;
}
lastnode = expand_rhs(grammar, rule, rhs);
if (lastnode == -1) {
return -1;
atom->weight /= norm;
}
else {
jsgf_add_link(grammar, NULL, lastnode, rule->exit);

lastnode = expand_rhs(grammar, rule, rhs,
rule_entry, rule_exit);

if (lastnode == NO_NODE) {
return NO_NODE;
} else if (lastnode == RECURSIVE_NODE) {
/* The rhs ended with right-recursion, i.e. a transition to
an earlier state. Nothing needs to happen at this level. */
;
} else if (rule_exit == NO_NODE) {
/* If this rule doesn't have an exit state yet, use the exit
state of its first right-hand-side.
All other right-hand-sides will use this exit state. */
assert (lastnode >= 0);
rule_exit = lastnode;
}
}

/* If no exit-state was created, use the entry-state. */
if (rule_exit == NO_NODE) {
rule_exit = rule_entry;
}

/* Pop this rule from the rule stack */
ckd_free(gnode_ptr(grammar->rulestack));
grammar->rulestack = gnode_free(grammar->rulestack, NULL);
return rule->exit;

return rule_exit;
}

jsgf_rule_iter_t *
Expand Down Expand Up @@ -454,20 +523,24 @@ jsgf_build_fsg_internal(jsgf_t *grammar, jsgf_rule_t *rule,
fsg_model_t *fsg;
glist_t nulls;
gnode_t *gn;
int rule_entry, rule_exit;

/* Clear previous links */
for (gn = grammar->links; gn; gn = gnode_next(gn)) {
ckd_free(gnode_ptr(gn));
}
glist_free(grammar->links);
grammar->links = NULL;
rule->entry = rule->exit = 0;
grammar->nstate = 0;
expand_rule(grammar, rule);

/* Create the top-level entry state, and expand the
top-level rule. */
rule_entry = grammar->nstate++;
rule_exit = expand_rule(grammar, rule, rule_entry, NO_NODE);

fsg = fsg_model_init(rule->name, lmath, lw, grammar->nstate);
fsg->start_state = rule->entry;
fsg->final_state = rule->exit;
fsg->start_state = rule_entry;
fsg->final_state = rule_exit;
grammar->links = glist_reverse(grammar->links);
for (gn = grammar->links; gn; gn = gnode_next(gn)) {
jsgf_link_t *link = gnode_ptr(gn);
Expand Down Expand Up @@ -527,7 +600,7 @@ jsgf_read_file(const char *file, logmath_t * lmath, float32 lw)
itor = jsgf_rule_iter_next(itor)) {
rule = jsgf_rule_iter_rule(itor);
if (jsgf_rule_public(rule)) {
jsgf_rule_iter_free(itor);
jsgf_rule_iter_free(itor);
break;
}
}
Expand Down Expand Up @@ -557,6 +630,7 @@ jsgf_write_fsg(jsgf_t *grammar, jsgf_rule_t *rule, FILE *outfh)
logmath_free(lmath);
return -1;
}

jsgf_rule_t *
jsgf_define_rule(jsgf_t *jsgf, char *name, jsgf_rhs_t *rhs, int is_public)
{
Expand Down
10 changes: 7 additions & 3 deletions src/libsphinxbase/lm/jsgf_internal.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ extern "C" {
typedef struct jsgf_rhs_s jsgf_rhs_t;
typedef struct jsgf_atom_s jsgf_atom_t;
typedef struct jsgf_link_s jsgf_link_t;
typedef struct jsgf_rule_stack_s jsgf_rule_stack_t;

struct jsgf_s {
char *version; /**< JSGF version (from header) */
Expand All @@ -82,14 +83,17 @@ struct jsgf_s {
glist_t rulestack; /**< Stack of currently expanded rules. */
};

/* A type to keep track of the stack of rules currently being expanded. */
struct jsgf_rule_stack_s {
jsgf_rule_t *rule; /**< The rule being expanded */
int entry; /**< The entry-state for this expansion */
};

struct jsgf_rule_s {
int refcnt; /**< Reference count. */
char *name; /**< Rule name (NULL for an alternation/grouping) */
int is_public; /**< Is this rule marked 'public'? */
jsgf_rhs_t *rhs; /**< Expansion */

int entry; /**< Entry state for current instance of this rule. */
int exit; /**< Exit state for current instance of this rule. */
};

struct jsgf_rhs_s {
Expand Down
67 changes: 21 additions & 46 deletions test/regression/test.command.fsg
View file
Original file line number Diff line number Diff line change
@@ -1,49 +1,24 @@
FSG_BEGIN <test.command>
NUM_STATES 33
NUM_STATES 10
START_STATE 0
FINAL_STATE 1
TRANSITION 0 2 1.000000
TRANSITION 2 4 1.000000
TRANSITION 3 14 1.000000
TRANSITION 4 7 0.200004 oh
TRANSITION 4 10 0.200004 could
TRANSITION 4 12 0.200004 kindly
TRANSITION 4 13 0.200004 please
TRANSITION 4 6 0.200004
TRANSITION 5 3 1.000000
TRANSITION 6 5 1.000000
TRANSITION 7 8 1.000000 mighty
TRANSITION 8 9 1.000000 computer
TRANSITION 9 5 1.000000
TRANSITION 10 11 1.000000 you
TRANSITION 11 5 1.000000
TRANSITION 12 5 1.000000
TRANSITION 13 5 1.000000
TRANSITION 14 20 0.500041
TRANSITION 14 16 0.500041
TRANSITION 15 24 1.000000
TRANSITION 16 18 0.500041 stop
TRANSITION 16 19 0.500041 stop
TRANSITION 17 15 1.000000
TRANSITION 18 17 1.000000
TRANSITION 19 16 1.000000
TRANSITION 19 17 1.000000
TRANSITION 20 23 0.500041 go
TRANSITION 20 22 0.500041
TRANSITION 21 15 1.000000
TRANSITION 22 21 1.000000
TRANSITION 23 20 1.000000
TRANSITION 23 21 1.000000
TRANSITION 24 26 1.000000
TRANSITION 25 1 1.000000
TRANSITION 26 29 0.250016 thank
TRANSITION 26 31 0.250016 thanks
TRANSITION 26 32 0.250016 please
TRANSITION 26 28 0.250016
TRANSITION 27 25 1.000000
TRANSITION 28 27 1.000000
TRANSITION 29 30 1.000000 you
TRANSITION 30 27 1.000000
TRANSITION 31 27 1.000000
TRANSITION 32 27 1.000000
FINAL_STATE 8
TRANSITION 0 1 0.200004 please
TRANSITION 0 1 0.200004 kindly
TRANSITION 0 2 0.200004 oh
TRANSITION 0 4 0.200004 could
TRANSITION 0 1 0.200004
TRANSITION 1 5 0.500041 stop
TRANSITION 1 6 0.500041 stop
TRANSITION 1 7 0.500041 go
TRANSITION 1 5 0.500041
TRANSITION 2 3 1.000000 mighty
TRANSITION 3 1 1.000000 computer
TRANSITION 4 1 1.000000 you
TRANSITION 5 8 0.250016 please
TRANSITION 5 8 0.250016 thanks
TRANSITION 5 9 0.250016 thank
TRANSITION 5 8 0.250016
TRANSITION 6 1 1.000000
TRANSITION 7 1 1.000000
TRANSITION 9 8 1.000000 you
FSG_END
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