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feat(library/unifier): add main loop and resolve_conflict

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-06-22 11:57:10 -07:00
parent 644c387cfe
commit 29a00c46d0
2 changed files with 125 additions and 33 deletions
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152
src/library/unifier.cpp
View file

@ -7,6 +7,7 @@ Author: Leonardo de Moura
#include <utility>
#include <memory>
#include <vector>
#include "util/interrupt.h"
#include "util/luaref.h"
#include "util/lazy_list_fn.h"
#include "kernel/for_each_fn.h"
@ -174,7 +175,7 @@ struct unifier_fn {
name_to_cnstrs m_mlvl_occs;
struct case_split {
justification m_curr_assumption; // object used to justify current split
unsigned m_assumption_idx; // idx of the current assumption
justification m_failed_justifications; // justifications for failed branches
// snapshot of the state
substitution m_subst;
@ -191,7 +192,7 @@ struct unifier_fn {
typedef std::vector<std::unique_ptr<case_split>> case_split_stack;
case_split_stack m_case_splits;
justification m_conflict;
optional<justification> m_conflict;
unifier_fn(environment const & env, unsigned num_cs, constraint const * cs,
name_generator const & ngen, substitution const & s, unifier_plugin const & p,
@ -206,7 +207,14 @@ struct unifier_fn {
}
}
bool in_conflict() const { return !m_conflict.is_none(); }
void check_system() {
check_interrupted();
// TODO(Leo): check if exceeded the maximum number of steps
}
bool in_conflict() const { return (bool)m_conflict; } // NOLINT
void set_conflict(justification const & j) { m_conflict = j; }
void reset_conflict() { m_conflict = optional<justification>(); lean_assert(!in_conflict()); }
template<bool MVar>
void add_occ(name const & m, unsigned cidx) {
@ -282,7 +290,7 @@ struct unifier_fn {
}
enum status { Assigned, Failed, Continue };
status process_metavar(expr const & lhs, expr const & rhs, justification const & j) {
status process_metavar_eq(expr const & lhs, expr const & rhs, justification const & j) {
if (!is_meta(lhs))
return Continue;
buffer<expr> locals;
@ -290,7 +298,7 @@ struct unifier_fn {
if (!m || (is_meta(rhs) && get_app_fn(rhs) == *m))
return Continue;
if (!occurs_context_check(rhs, *m, locals)) {
m_conflict = j;
set_conflict(j);
return Failed;
}
lean_assert(!m_subst.is_assigned(*m));
@ -302,6 +310,7 @@ struct unifier_fn {
}
bool process_eq_constraint(constraint const & c) {
lean_assert(is_eq_cnstr(c));
// instantiate
name_set unassigned_lvls, unassigned_exprs;
auto lhs_jst = m_subst.instantiate_metavars(cnstr_lhs_expr(c), &unassigned_lvls, &unassigned_exprs);
@ -314,13 +323,13 @@ struct unifier_fn {
justification new_jst = mk_composite1(mk_composite1(c.get_justification(), lhs_jst.second), rhs_jst.second);
if (!has_metavar(lhs) && !has_metavar(rhs)) {
m_conflict = new_jst;
set_conflict(new_jst);
return false; // trivial failure
}
status st = process_metavar(lhs, rhs, new_jst);
status st = process_metavar_eq(lhs, rhs, new_jst);
if (st != Continue) return st == Assigned;
st = process_metavar(rhs, lhs, new_jst);
st = process_metavar_eq(rhs, lhs, new_jst);
if (st != Continue) return st == Assigned;
if (lhs != cnstr_lhs_expr(c) || rhs != cnstr_rhs_expr(c)) {
@ -328,7 +337,7 @@ struct unifier_fn {
if (m_tc.is_def_eq(lhs, rhs, new_jst)) {
return true;
} else {
m_conflict = new_jst;
set_conflict(new_jst);
return false;
}
}
@ -341,7 +350,7 @@ struct unifier_fn {
return true;
}
status process_meta_lvl(level const & lhs, level const & rhs, justification const & j) {
status process_metavar_eq(level const & lhs, level const & rhs, justification const & j) {
if (!is_meta(lhs))
return Continue;
bool contains = occurs(lhs, rhs);
@ -359,34 +368,49 @@ struct unifier_fn {
}
}
bool process_lvl_constraint(constraint const & c) {
bool process_level_eq_constraint(constraint const & c) {
lean_assert(is_level_eq_cnstr(c));
name_set unassigned_lvls;
auto lhs_jst = m_subst.instantiate_metavars(cnstr_lhs_level(c), &unassigned_lvls);
auto rhs_jst = m_subst.instantiate_metavars(cnstr_rhs_level(c), &unassigned_lvls);
level const & lhs = lhs_jst.first;
level const & rhs = rhs_jst.first;
level lhs = lhs_jst.first;
level rhs = rhs_jst.first;
lhs = normalize(lhs);
rhs = normalize(rhs);
while (is_succ(lhs) && is_succ(rhs)) {
lhs = succ_of(lhs);
rhs = succ_of(rhs);
}
if (lhs == rhs)
return true; // trivial constraint
justification new_jst = mk_composite1(mk_composite1(c.get_justification(), lhs_jst.second), rhs_jst.second);
if (!has_meta(lhs) && !has_meta(rhs)) {
m_conflict = new_jst;
set_conflict(new_jst);
return false; // trivial failure
}
status st = process_meta_lvl(lhs, rhs, new_jst);
status st = process_metavar_eq(lhs, rhs, new_jst);
if (st != Continue) return st == Assigned;
st = process_meta_lvl(rhs, lhs, new_jst);
st = process_metavar_eq(rhs, lhs, new_jst);
if (st != Continue) return st == Assigned;
if (lhs != cnstr_lhs_level(c) || rhs != cnstr_rhs_level(c)) {
constraint new_c = mk_level_eq_cnstr(lhs, rhs, new_jst);
add_delayed(new_c, &unassigned_lvls, nullptr);
} else {
add_delayed(c, &unassigned_lvls, nullptr);
}
return true;
}
bool process_constraint(constraint const & c) {
if (in_conflict())
return false;
check_system();
switch (c.kind()) {
case constraint_kind::Choice:
add_active(c, nullptr, nullptr);
@ -394,7 +418,7 @@ struct unifier_fn {
case constraint_kind::Eq:
return process_eq_constraint(c);
case constraint_kind::LevelEq:
return process_lvl_constraint(c);
return process_level_eq_constraint(c);
}
lean_unreachable(); // LCOV_EXCL_LINE
}
@ -417,21 +441,90 @@ struct unifier_fn {
return true;
}
optional<substitution> next() {
// TODO(Leo): if m_use_exception == true, then throw exception instead of returning none.
if (in_conflict())
return optional<substitution>();
if (!m_first) {
if (m_case_splits.empty())
return optional<substitution>();
// TODO(Leo): force backtrack
bool resolve_conflict() {
lean_assert(in_conflict());
while (!m_case_splits.empty()) {
std::unique_ptr<case_split> & d = m_case_splits.back();
if (depends_on(*m_conflict, d->m_assumption_idx)) {
d->m_failed_justifications = mk_composite1(d->m_failed_justifications, *m_conflict);
if (d->next(*this)) {
reset_conflict();
return true;
}
m_first = false;
if (m_active.empty() || m_delayed.empty())
return optional<substitution>(m_subst);
// TODO(Leo): search
}
m_case_splits.pop_back();
}
return false;
}
optional<substitution> failure() {
// TODO(Leo): if m_use_exception == true, then throw exception instead of returning none.
return optional<substitution>();
}
bool process_choice_constraint(constraint const & c) {
lean_assert(is_choice_cnstr(c));
// TODO(Leo)
return true;
}
bool process_plugin_constraint(constraint const & c) {
lean_assert(!is_choice_cnstr(c));
lazy_list<constraints> alts = m_plugin(c, m_ngen.mk_child());
auto r = alts.pull();
if (!r)
return false;
// TODO(Leo): create backtracking point
return true;
}
bool process_next_active() {
lean_assert(!m_active.empty());
constraint c = m_active.min()->first;
m_active.erase_min();
if (is_choice_cnstr(c))
return process_choice_constraint(c);
else
return process_plugin_constraint(c);
}
bool process_next_delayed() {
// TODO(Leo)
return true;
}
optional<substitution> next() {
if (in_conflict())
return failure();
if (!m_case_splits.empty()) {
justification all_assumptions;
for (auto const & cs : m_case_splits)
all_assumptions = mk_composite1(all_assumptions, mk_assumption_justification(cs->m_assumption_idx));
set_conflict(all_assumptions);
if (!resolve_conflict())
return failure();
} else if (m_first) {
m_first = false;
} else {
// This is not the first run, and there are no case-splits.
// We don't throw an exception since there are no more solutions.
return optional<substitution>();
}
while (!m_active.empty() || !m_delayed.empty()) {
check_system();
lean_assert(!in_conflict());
bool ok = true;
if (!m_active.empty())
ok = process_next_active();
else
ok = process_next_delayed();
if (!ok && !resolve_conflict())
return failure();
}
lean_assert(!in_conflict())
lean_assert(m_active.empty() && m_delayed.empty());
return optional<substitution>(m_subst);
}
};
lazy_list<substitution> unify(std::shared_ptr<unifier_fn> const & u) {
@ -460,7 +553,6 @@ lazy_list<substitution> unify(environment const & env, expr const & lhs, expr co
name_generator new_ngen(ngen);
bool failed = false;
type_checker tc(env, new_ngen.mk_child(), [&](constraint const & c) {
std::cout << "cnstr: " << c << "\n";
if (!failed) {
auto r = unify_simple(s, c);
switch (r.first) {

2
tests/lua/unify2.lua
View file

@ -29,4 +29,4 @@ local l3 = mk_local("l3", "z", N)
local m = mk_metavar("m", mk_arrow(N, N, N))
test_unify(env, m(l1, l2), f(f(a, l1), l1), 1)
test_unify(env, f(m(l1, l2), l1), f(f(a, l1), l1), 1)
-- test_unify(env, f(m(l1, l2), a), f(f(a, l1), l1), 0)
test_unify(env, f(m(l1, l2), a), f(f(a, l1), l1), 0)