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If conflict resolution makes states unreachable, remove those states,

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report rules that are then unused, and don't report conflicts in those
states.
* src/conflicts.c, src/conflicts.h (conflicts_update_state_numbers):
New global function.
* src/lalr.c, src/lalr.h (lalr_update_state_numbers): New global
function.
* src/main.c (main): After conflict resolution, remove the unreachable
states and update all data structures that reference states by number.
* src/state.c (state_new): Initialize each state's reachable member to
false.
(state_mark_reachable_states): New static function.
(state_remove_unreachable_states): New global function.
* src/state.h (struct state): Add member bool reachable.
(state_remove_unreachable_states): Prototype.
* tests/conflicts.at (Unreachable States After Conflict Resolution):
New test case.
* tests/existing.at (GNU pic Grammar): Update test case output now that
an unused rule is discovered.
This commit is contained in:
Joel E. Denny
2007-05-07 02:56:56 +00:00
parent b09f4f4851
commit 5967f0cf59
10 changed files with 347 additions and 1 deletions
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31
src/lalr.c
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@@ -453,6 +453,37 @@ lalr (void)
}
void
lalr_update_state_numbers (state_number old_to_new[], state_number nstates_old)
{
goto_number ngotos_reachable = 0;
symbol_number nonterminal = 0;
aver (nsyms == nvars + ntokens);
for (goto_number i = 0; i < ngotos; ++i)
{
while (i == goto_map[nonterminal])
goto_map[nonterminal++] = ngotos_reachable;
/* If old_to_new[from_state[i]] = nstates_old, remove this goto
entry. */
if (old_to_new[from_state[i]] != nstates_old)
{
/* from_state[i] is not removed, so it and thus to_state[i] are
reachable, so to_state[i] != nstates_old. */
aver (old_to_new[to_state[i]] != nstates_old);
from_state[ngotos_reachable] = old_to_new[from_state[i]];
to_state[ngotos_reachable] = old_to_new[to_state[i]];
++ngotos_reachable;
}
}
while (nonterminal <= nvars)
{
aver (ngotos == goto_map[nonterminal]);
goto_map[nonterminal++] = ngotos_reachable;
}
ngotos = ngotos_reachable;
}
void
lalr_free (void)
{