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generalize grammar analysis to k>1

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This commit is contained in:
Sven M. Hallberg 2013-05-22 20:38:36 +02:00
parent 337cbc2695
commit f5d5c36756
6 changed files with 468 additions and 136 deletions
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36
src/backends/llk.c
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@ -18,12 +18,18 @@ typedef struct HLLkTable_ {
HAllocator *mm__;
} HLLkTable;
// XXX adaptation to LL(1), to be removed
typedef HCharKey HCFToken;
static const HCFToken end_token = 0x200;
#define char_token char_key
/* Interface to look up an entry in the parse table. */
const HCFSequence *h_llk_lookup(const HLLkTable *table, const HCFChoice *x,
HInputStream lookahead)
{
// note the lookahead stream is passed by value, i.e. a copy
// reading bits from it does not consume them from the input
// note the lookahead stream is passed by value, i.e. a copy.
// reading bits from it does not consume them from the real input.
HCFToken tok;
uint8_t c = h_read_bits(&lookahead, 8, false);
if(lookahead.overrun)
@ -71,15 +77,21 @@ HHashSet *h_predict(HCFGrammar *g, const HCFChoice *A, const HCFSequence *rhs)
{
// predict(A -> rhs) = first(rhs) u follow(A) if "" can be derived from rhs
// predict(A -> rhs) = first(rhs) otherwise
HHashSet *first_rhs = h_first_sequence(g, rhs->items);
if(h_sequence_derives_epsilon(g, rhs->items)) {
HHashSet *ret = h_hashset_new(g->arena, h_eq_ptr, h_hash_ptr);
h_hashset_put_all(ret, first_rhs);
h_hashset_put_all(ret, h_follow(g, A));
return ret;
} else {
return first_rhs;
const HCFStringMap *first_rhs = h_first_seq(1, g, rhs->items);
const HCFStringMap *follow_A = h_follow(1, g, A);
HHashSet *ret = h_hashset_new(g->arena, h_eq_ptr, h_hash_ptr);
h_hashset_put_all(ret, first_rhs->char_branches);
if(first_rhs->end_branch)
h_hashset_put(ret, (void *)end_token);
if(h_derives_epsilon_seq(g, rhs->items)) {
h_hashset_put_all(ret, follow_A->char_branches);
if(follow_A->end_branch)
h_hashset_put(ret, (void *)end_token);
}
return ret;
}
/* Generate entries for the production "A -> rhs" in the given table row. */
@ -360,9 +372,9 @@ int test_llk(void)
printf("generate epsilon: ");
h_pprint_symbolset(stdout, g, g->geneps, 0);
printf("first(A) = ");
h_pprint_tokenset(stdout, g, h_first_symbol(g, g->start), 0);
h_pprint_stringset(stdout, g, h_first(1, g, g->start), 0);
printf("follow(C) = ");
h_pprint_tokenset(stdout, g, h_follow(g, h_desugar(&system_allocator, c)), 0);
h_pprint_stringset(stdout, g, h_follow(1, g, h_desugar(&system_allocator, c)), 0);
h_compile(p, PB_LLk, NULL);