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More LL(k) fixes (Merge branch 'LL' of https://github.com/pesco/hammer)

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This commit is contained in:
Meredith L. Patterson 2013-05-24 06:11:44 -07:00
commit c8dba54bb4
4 changed files with 90 additions and 61 deletions
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78
src/backends/llk.c
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@ -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