diff --git a/src/backends/llk.c b/src/backends/llk.c
index 69fb7efa979152fc1b9eaa0cc84f0be1ae99a9ed..27258e62db9ee53c75a0f19a7b4e0917d3a3f266 100644
--- a/src/backends/llk.c
+++ b/src/backends/llk.c
@@ -81,28 +81,6 @@ void h_llktable_free(HLLkTable *table)
h_free(table);
}
-/* Compute the predict_k set of production "A -> rhs".
- * Always returns a newly-allocated HCFStringMap.
- */
-HCFStringMap *h_predict(size_t k, HCFGrammar *g,
- const HCFChoice *A, const HCFSequence *rhs)
-{
- assert(k==1); // XXX
- HCFStringMap *ret = h_stringmap_new(g->arena);
-
- // predict(A -> rhs) = first(rhs) u follow(A) if "" can be derived from rhs
- // predict(A -> rhs) = first(rhs) otherwise
-
- h_stringmap_update(ret, h_first_seq(k, g, rhs->items));
- if(h_derives_epsilon_seq(g, rhs->items))
- h_stringmap_update(ret, h_follow(k, g, A));
-
- // make sure there are only strings of length _exactly_ k
- ret->epsilon_branch = NULL;
-
- return ret;
-}
-
void *const CONFLICT = (void *)(uintptr_t)(-1);
// helper for stringmap_merge
@@ -113,7 +91,7 @@ static void *combine_entries(HHashSet *workset, void *dst, const void *src)
if(dst == CONFLICT) { // previous conflict
h_hashset_put(workset, src);
- } else if(dst == src) { // new conflict
+ } else if(dst != src) { // new conflict
h_hashset_put(workset, dst);
h_hashset_put(workset, src);
dst = CONFLICT;
@@ -133,6 +111,12 @@ static void stringmap_merge(HHashSet *workset, HCFStringMap *dst, HCFStringMap *
combine_entries(workset, dst->epsilon_branch, src->epsilon_branch);
else
dst->epsilon_branch = src->epsilon_branch;
+ } else {
+ // if there is a non-conflicting value on the left (dst) side, it means
+ // that prediction is already unambiguous. we can drop the right (src)
+ // side we were going to extend with.
+ if(dst->epsilon_branch && dst->epsilon_branch != CONFLICT)
+ return;
}
if(src->end_branch) {
@@ -164,9 +148,6 @@ static void stringmap_merge(HHashSet *workset, HCFStringMap *dst, HCFStringMap *
}
}
-void pprint_sequence(FILE *f, const HCFGrammar *g, const HCFSequence *seq);
-void pprint_symbol(FILE *f, const HCFGrammar *g, const HCFChoice *x);
-
/* Generate entries for the production "A" in the given table row. */
static int fill_table_row(size_t kmax, HCFGrammar *g, HCFStringMap *row,
const HCFChoice *A)
@@ -181,6 +162,8 @@ static int fill_table_row(size_t kmax, HCFGrammar *g, HCFStringMap *row,
// run until workset exhausted or kmax hit
size_t k;
for(k=1; k<=kmax; k++) {
+ printf("k=%lu\n", k); // XXX debug
+
// allocate a fresh workset for the next round
HHashSet *nextset = h_hashset_new(g->arena, h_eq_ptr, h_hash_ptr);
@@ -199,29 +182,30 @@ static int fill_table_row(size_t kmax, HCFGrammar *g, HCFStringMap *row,
HCFStringMap *pred = h_predict(k, g, A, rhs);
h_stringmap_replace(pred, NULL, rhs);
+ // XXX debug
+ printf("predict(");
+ h_pprint_sequence(stdout, g, rhs);
+ printf(") = ");
+ h_pprint_stringset(stdout, pred, 0);
+
// merge predict set into the row
// accumulates conflicts in new workset
stringmap_merge(nextset, row, pred);
-
- // XXX debug
- if(A == g->start) {
- printf("predict(");
- pprint_sequence(stdout, g, rhs);
- printf(" ) = ");
- h_pprint_stringset(stdout, g, pred, 0);
- }
}
}
// XXX debug
- if(A == g->start) {
- printf("row(");
- pprint_symbol(stdout, g, A);
- printf(") = ");
- h_pprint_stringset(stdout, g, row, 0);
+ printf("row(");
+ h_pprint_symbol(stdout, g, A);
+ printf(") = ");
+ h_pprint_stringset(stdout, row, 0);
+ if(h_stringmap_get(row, (uint8_t *)"a", 1, false)) {
+ printf(" a -> ");
+ h_pprint_sequence(stdout, g, h_stringmap_get(row, (uint8_t *)"a", 1, false));
+ printf("\n");
}
// switch to the updated workset
- h_hashtable_free(workset);
+ h_hashset_free(workset);
workset = nextset;
// if the workset is empty, row is without conflict; we're done
@@ -473,9 +457,9 @@ int test_llk(void)
*/
HParser *X = h_optional(h_ch('x'));
- HParser *Y = h_sequence(h_ch('y'), NULL);
- HParser *A = h_sequence(X, Y, h_ch('a'), NULL);
- HParser *B = h_sequence(Y, h_ch('b'), NULL);
+ //HParser *Y = h_epsilon_p(); //h_sequence(h_ch('y'), NULL);
+ HParser *A = h_sequence(X, h_ch('a'), NULL);
+ HParser *B = h_sequence(h_ch('b'), NULL);
HParser *p = h_choice(A, B, NULL);
HCFGrammar *g = h_cfgrammar(&system_allocator, p);
@@ -489,16 +473,16 @@ int test_llk(void)
printf("derive epsilon: ");
h_pprint_symbolset(stdout, g, g->geneps, 0);
printf("first(A) = ");
- h_pprint_stringset(stdout, g, h_first(3, g, g->start), 0);
+ h_pprint_stringset(stdout, h_first(3, g, g->start), 0);
//printf("follow(C) = ");
- //h_pprint_stringset(stdout, g, h_follow(3, g, h_desugar(&system_allocator, c)), 0);
+ //h_pprint_stringset(stdout, h_follow(3, g, h_desugar(&system_allocator, c)), 0);
- if(h_compile(p, PB_LLk, NULL)) {
+ if(h_compile(p, PB_LLk, (void *)2)) {
fprintf(stderr, "does not compile\n");
return 2;
}
- HParseResult *res = h_parse(p, (uint8_t *)"xa", 2);
+ HParseResult *res = h_parse(p, (uint8_t *)"ab", 2);
if(res)
h_pprint(stdout, res->ast, 0, 2);
else
diff --git a/src/cfgrammar.c b/src/cfgrammar.c
index 1721122e8a3a34496f09949800ca85ff024ef101..d774dd0938d2168b640089c094e17614e40d9380 100644
--- a/src/cfgrammar.c
+++ b/src/cfgrammar.c
@@ -437,7 +437,23 @@ static bool any_string_shorter(size_t k, const HCFStringMap *m)
return false;
}
-const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x);
+// helper for h_predict
+static void remove_all_shorter(size_t k, HCFStringMap *m)
+{
+ if(k==0) return;
+ m->epsilon_branch = NULL;
+ if(k==1) return;
+
+ // iterate over m->char_branches
+ const HHashTable *ht = m->char_branches;
+ for(size_t i=0; i < ht->capacity; i++) {
+ for(HHashTableEntry *hte = &ht->contents[i]; hte; hte = hte->next) {
+ if(hte->key == NULL)
+ continue;
+ remove_all_shorter(k-1, hte->value); // recursion into subtree
+ }
+ }
+}
// h_follow adapted to the signature of StringSetFun
static inline const HCFStringMap *h_follow_(size_t k, HCFGrammar *g, HCFChoice **s)
@@ -507,6 +523,23 @@ const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x)
return ret;
}
+HCFStringMap *h_predict(size_t k, HCFGrammar *g,
+ const HCFChoice *A, const HCFSequence *rhs)
+{
+ HCFStringMap *ret = h_stringmap_new(g->arena);
+
+ // predict_k(A -> rhs) =
+ // { ab | a <- first_k(rhs), b <- follow_k(A), |ab|=k }
+
+ const HCFStringMap *first_rhs = h_first_seq(k, g, rhs->items);
+ stringset_extend(g, ret, k, first_rhs, h_follow_, (HCFChoice **)&A);
+
+ // make sure there are only strings of length _exactly_ k
+ remove_all_shorter(k, ret);
+
+ return ret;
+}
+
// add the set { a b | a <- as, b <- f_l(S), l=k-|a| } to ret
static void stringset_extend(HCFGrammar *g, HCFStringMap *ret,
size_t k, const HCFStringMap *as,
@@ -624,7 +657,7 @@ static HCFChoice **pprint_string(FILE *f, HCFChoice **x)
return x;
}
-void pprint_symbol(FILE *f, const HCFGrammar *g, const HCFChoice *x)
+void h_pprint_symbol(FILE *f, const HCFGrammar *g, const HCFChoice *x)
{
switch(x->type) {
case HCF_CHAR:
@@ -643,32 +676,37 @@ void pprint_symbol(FILE *f, const HCFGrammar *g, const HCFChoice *x)
}
}
-void pprint_sequence(FILE *f, const HCFGrammar *g, const HCFSequence *seq)
+void h_pprint_sequence(FILE *f, const HCFGrammar *g, const HCFSequence *seq)
{
HCFChoice **x = seq->items;
if(*x == NULL) { // the empty sequence
- fputs(" \"\"", f);
+ fputs("\"\"", f);
} else {
while(*x) {
- fputc(' ', f); // separator
+ if(x != seq->items) fputc(' ', f); // internal separator
if((*x)->type == HCF_CHAR) {
// condense character strings
x = pprint_string(f, x);
} else {
- pprint_symbol(f, g, *x);
+ h_pprint_symbol(f, g, *x);
x++;
}
}
}
+}
+// adds some separators expected below
+static void pprint_sequence(FILE *f, const HCFGrammar *g, const HCFSequence *seq)
+{
+ fputc(' ', f);
+ h_pprint_sequence(f, g, seq);
fputc('\n', f);
}
-static
-void pprint_ntrules(FILE *f, const HCFGrammar *g, const HCFChoice *nt,
- int indent, int len)
+static void pprint_ntrules(FILE *f, const HCFGrammar *g, const HCFChoice *nt,
+ int indent, int len)
{
int i;
int column = indent + len;
@@ -738,7 +776,7 @@ void h_pprint_symbolset(FILE *file, const HCFGrammar *g, const HHashSet *set, in
a = hte->key; // production's left-hand symbol
- pprint_symbol(file, g, a);
+ h_pprint_symbol(file, g, a);
}
}
@@ -801,7 +839,7 @@ pprint_stringset_elems(FILE *file, bool first, char *prefix, size_t n,
return first;
}
-void h_pprint_stringset(FILE *file, const HCFGrammar *g, const HCFStringMap *set, int indent)
+void h_pprint_stringset(FILE *file, const HCFStringMap *set, int indent)
{
int j;
for(j=0; j<indent; j++) fputc(' ', file);
diff --git a/src/cfgrammar.h b/src/cfgrammar.h
index 8dc4449ac91d2f98a3a4fbabb38a8b18e9e446bd..d2270ff08dbe296cf9d5d6d0152ccd307e77a019 100644
--- a/src/cfgrammar.h
+++ b/src/cfgrammar.h
@@ -50,7 +50,7 @@ void *h_stringmap_get(const HCFStringMap *m, const uint8_t *str, size_t n, bool
bool h_stringmap_present(const HCFStringMap *m, const uint8_t *str, size_t n, bool end);
bool h_stringmap_present_epsilon(const HCFStringMap *m);
-static inline void *h_stringmap_get_char(const HCFStringMap *m, const uint8_t c)
+static inline HCFStringMap *h_stringmap_get_char(const HCFStringMap *m, const uint8_t c)
{ return h_hashtable_get(m->char_branches, (void *)char_key(c)); }
@@ -80,8 +80,16 @@ const HCFStringMap *h_first_seq(size_t k, HCFGrammar *g, HCFChoice **s);
/* Compute follow_k set of symbol x. Memoized. */
const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x);
+/* Compute the predict_k set of production "A -> rhs".
+ * Always returns a newly-allocated HCFStringMap.
+ */
+HCFStringMap *h_predict(size_t k, HCFGrammar *g,
+ const HCFChoice *A, const HCFSequence *rhs);
+
/* Pretty-printers for grammars and associated data. */
void h_pprint_grammar(FILE *file, const HCFGrammar *g, int indent);
+void h_pprint_sequence(FILE *f, const HCFGrammar *g, const HCFSequence *seq);
+void h_pprint_symbol(FILE *f, const HCFGrammar *g, const HCFChoice *x);
void h_pprint_symbolset(FILE *file, const HCFGrammar *g, const HHashSet *set, int indent);
-void h_pprint_stringset(FILE *file, const HCFGrammar *g, const HCFStringMap *set, int indent);
+void h_pprint_stringset(FILE *file, const HCFStringMap *set, int indent);
diff --git a/src/parsers/optional.c b/src/parsers/optional.c
index 6cb5331adb3cfd0a36390528c42cfda82ca3c74a..87ba541b91310bae7bd20b30fe2b9387501c0045 100644
--- a/src/parsers/optional.c
+++ b/src/parsers/optional.c
@@ -25,7 +25,6 @@ static bool opt_isValidCF(void *env) {
static HParsedToken* reshape_optional(const HParseResult *p) {
assert(p->ast);
assert(p->ast->token_type == TT_SEQUENCE);
- assert(p->ast->seq->used > 0);
HParsedToken *res = p->ast->seq->elements[0];
if(res)