diff --git a/src/backends/llk.c b/src/backends/llk.c
index 1cd95414acfbd1e157b81d47b7e2973190326523..6e8a9836405bdf77fcaad9c4cb766f36ba9508aa 100644
--- a/src/backends/llk.c
+++ b/src/backends/llk.c
@@ -369,12 +369,12 @@ int test_llk(void)
}
h_pprint_grammar(stdout, g, 0);
- printf("generate epsilon: ");
+ printf("derive epsilon: ");
h_pprint_symbolset(stdout, g, g->geneps, 0);
printf("first(A) = ");
- h_pprint_stringset(stdout, g, h_first(1, g, g->start), 0);
+ h_pprint_stringset(stdout, g, h_first(2, g, g->start), 0);
printf("follow(C) = ");
- h_pprint_stringset(stdout, g, h_follow(1, g, h_desugar(&system_allocator, c)), 0);
+ h_pprint_stringset(stdout, g, h_follow(2, g, h_desugar(&system_allocator, c)), 0);
h_compile(p, PB_LLk, NULL);
diff --git a/src/cfgrammar.c b/src/cfgrammar.c
index c965a44ee5b143afa1ce0b30e445a01d0922c2b5..a5a9b1acd59addc4fa5b4563ec028c55fabe7c3d 100644
--- a/src/cfgrammar.c
+++ b/src/cfgrammar.c
@@ -131,8 +131,8 @@ static void ensure_k(HCFGrammar *g, size_t k)
if(g->kmax > 0) {
// we are resizing, copy the old tables over
for(size_t i=0; i<=g->kmax; i++) {
- first[i] = g->first[0];
- follow[i] = g->follow[0];
+ first[i] = g->first[i];
+ follow[i] = g->follow[i];
}
} else {
// we are initializing, allocate the first (in fact, dummy) tables
@@ -151,9 +151,12 @@ static void ensure_k(HCFGrammar *g, size_t k)
g->kmax = k;
}
-
bool h_derives_epsilon(HCFGrammar *g, const HCFChoice *symbol)
{
+ // XXX this can now also be implemented in terms of h_first:
+ // h_stringmap_present_epsilon(h_first(1, g, symbol))
+ // then the geneps structure and associated functions would be unneed
+
assert(g->geneps != NULL);
switch(symbol->type) {
@@ -274,6 +277,11 @@ bool h_stringmap_present(const HCFStringMap *m, const uint8_t *str, size_t n, bo
return (h_stringmap_get(m, str, n, end) != NULL);
}
+bool h_stringmap_present_epsilon(const HCFStringMap *m)
+{
+ return (m->epsilon_branch != NULL);
+}
+
const HCFStringMap *h_first(size_t k, HCFGrammar *g, const HCFChoice *x)
{
@@ -323,11 +331,17 @@ const HCFStringMap *h_first(size_t k, HCFGrammar *g, const HCFChoice *x)
}
// helpers for h_first_seq, definitions below
-static void first_extend(HCFGrammar *g, HCFStringMap *ret,
- size_t k, const HCFStringMap *as, HCFChoice **tail);
static bool is_singleton_epsilon(const HCFStringMap *m);
static bool any_string_shorter(size_t k, const HCFStringMap *m);
+// pointer to functions like h_first_seq
+typedef const HCFStringMap *(*StringSetFun)(size_t, HCFGrammar *, HCFChoice **);
+
+// helper for h_first_seq and h_follow
+static void stringset_extend(HCFGrammar *g, HCFStringMap *ret,
+ size_t k, const HCFStringMap *as,
+ StringSetFun f, HCFChoice **tail);
+
const HCFStringMap *h_first_seq(size_t k, HCFGrammar *g, HCFChoice **s)
{
// shortcut: the first set of the empty sequence, for any k, is {""}
@@ -353,48 +367,11 @@ const HCFStringMap *h_first_seq(size_t k, HCFGrammar *g, HCFChoice **s)
HCFStringMap *ret = h_stringmap_new(g->arena);
// extend the elements of first_k(X) up to length k from tail
- first_extend(g, ret, k, first_x, tail);
+ stringset_extend(g, ret, k, first_x, h_first_seq, tail);
return ret;
}
-// add the set { a b | a <- as, b <- first_l(tail), l=k-|a| } to ret
-static void first_extend(HCFGrammar *g, HCFStringMap *ret,
- size_t k, const HCFStringMap *as, HCFChoice **tail)
-{
- if(as->epsilon_branch) {
- // for a="", add first_k(tail) to ret
- h_stringmap_update(ret, h_first_seq(k, g, tail));
- }
-
- if(as->end_branch) {
- // for a="$", nothing can follow; just add "$" to ret
- // NB: formally, "$" is considered to be of length k
- h_stringmap_put_end(ret, INSET);
- }
-
- // iterate over as->char_branches
- const HHashTable *ht = as->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;
- uint8_t c = key_char((HCharKey)hte->key);
-
- // follow the branch to find the set { a' | t a' <- as }
- HCFStringMap *as_ = (HCFStringMap *)hte->value;
-
- // now the elements of ret that begin with t are given by
- // t { a b | a <- as_, b <- first_l(tail), l=k-|a|-1 }
- // so we can use recursion over k
- HCFStringMap *ret_ = h_stringmap_new(g->arena);
- h_stringmap_put_char(ret, c, ret_);
-
- first_extend(g, ret_, k-1, as_, tail);
- }
- }
-}
-
static bool is_singleton_epsilon(const HCFStringMap *m)
{
return ( m->epsilon_branch
@@ -429,15 +406,8 @@ static bool any_string_shorter(size_t k, const HCFStringMap *m)
const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x);
-// pointer to functions like h_first_seq
-typedef const HCFStringMap *(*StringSetFun)(size_t, HCFGrammar *, HCFChoice const* const*);
-
-static void stringset_extend(HCFGrammar *g, HCFStringMap *ret,
- size_t k, const HCFStringMap *as,
- StringSetFun f, HCFChoice const * const *tail);
-
// h_follow adapted to the signature of StringSetFun
-static inline const HCFStringMap *h_follow_(size_t k, HCFGrammar *g, HCFChoice const* const*s)
+static inline const HCFStringMap *h_follow_(size_t k, HCFGrammar *g, HCFChoice **s)
{
return h_follow(k, g, *s);
}
@@ -479,7 +449,7 @@ const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x)
for(hte = &g->nts->contents[i]; hte; hte = hte->next) {
if(hte->key == NULL)
continue;
- HCFChoice const * const a = hte->key; // production's left-hand symbol
+ HCFChoice *a = (void *)hte->key; // production's left-hand symbol
assert(a->type == HCF_CHOICE);
// iterate over the productions for A
@@ -509,7 +479,7 @@ const HCFStringMap *h_follow(size_t k, HCFGrammar *g, const HCFChoice *x)
// 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,
- StringSetFun f, HCFChoice const * const *tail)
+ StringSetFun f, HCFChoice **tail)
{
if(as->epsilon_branch) {
// for a="", add f_k(tail) to ret
diff --git a/src/cfgrammar.h b/src/cfgrammar.h
index f9768c854698c31e81df74f5df12b8aed46aa7b1..cec5d6e9b4b7ea011fe896b7f6d433826ebefcc9 100644
--- a/src/cfgrammar.h
+++ b/src/cfgrammar.h
@@ -46,6 +46,7 @@ void h_stringmap_put_char(HCFStringMap *m, uint8_t c, void *v);
void h_stringmap_update(HCFStringMap *m, const HCFStringMap *n);
void *h_stringmap_get(const HCFStringMap *m, const uint8_t *str, size_t n, bool end);
bool h_stringmap_present(const HCFStringMap *m, const uint8_t *str, size_t n, bool end);
+bool h_stringmap_present_epsilon(const HCFStringMap *m);
/* Convert 'parser' into CFG representation by desugaring and compiling the set