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feat(library/elaborator): do not create trivial constraints of the form 'ctx |- t =:= t'

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-12-16 16:41:20 -08:00
parent 5b29fd8d93
commit 91f4ced83b
1 changed files with 18 additions and 25 deletions
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43
src/library/elaborator/elaborator.cpp
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@ -316,6 +316,8 @@ class elaborator::imp {
*/
void push_new_constraint(cnstr_list & active_cnstrs, bool is_eq,
context const & new_ctx, expr const & new_a, expr const & new_b, justification const & new_jst) {
if (new_a == new_b)
return; // trivial constraint
if (is_eq)
push_front(active_cnstrs, mk_eq_constraint(new_ctx, new_a, new_b, new_jst));
else
@ -349,12 +351,7 @@ class elaborator::imp {
The update is justified by \c new_jst.
*/
void push_updated_constraint(unification_constraint const & c, expr const & new_a, expr const & new_b, justification const & new_jst) {
lean_assert(is_eq(c) || is_convertible(c));
context const & ctx = get_context(c);
if (is_eq(c))
push_active(mk_eq_constraint(ctx, new_a, new_b, new_jst));
else
push_active(mk_convertible_constraint(ctx, new_a, new_b, new_jst));
push_new_constraint(m_state.m_active_cnstrs, is_eq(c), get_context(c), new_a, new_b, new_jst);
}
/**
@ -365,17 +362,16 @@ class elaborator::imp {
*/
void push_updated_constraint(unification_constraint const & c, bool is_lhs, expr const & new_a, justification const & new_jst) {
lean_assert(is_eq(c) || is_convertible(c));
context const & ctx = get_context(c);
if (is_eq(c)) {
if (is_lhs)
push_active(mk_eq_constraint(ctx, new_a, eq_rhs(c), new_jst));
push_updated_constraint(c, new_a, eq_rhs(c), new_jst);
else
push_active(mk_eq_constraint(ctx, eq_lhs(c), new_a, new_jst));
push_updated_constraint(c, eq_lhs(c), new_a, new_jst);
} else {
if (is_lhs)
push_active(mk_convertible_constraint(ctx, new_a, convertible_to(c), new_jst));
push_updated_constraint(c, new_a, convertible_to(c), new_jst);
else
push_active(mk_convertible_constraint(ctx, convertible_from(c), new_a, new_jst));
push_updated_constraint(c, convertible_from(c), new_a, new_jst);
}
}
@ -779,7 +775,7 @@ class elaborator::imp {
expr s = mk_lambda(types, b);
if (!is_lhs)
swap(m, s);
push_active(mk_eq_constraint(ctx, m, s, new_jst));
push_new_eq_constraint(ctx, m, s, new_jst);
return true;
} else {
return false;
@ -1165,7 +1161,7 @@ class elaborator::imp {
// ctx |- a2 == b2
justification new_jst(new destruct_justification(c));
for (unsigned i = 1; i < num_args(a); i++)
push_active(mk_eq_constraint(ctx, arg(a, i), arg(b, i), new_jst));
push_new_eq_constraint(ctx, arg(a, i), arg(b, i), new_jst);
return true;
}
@ -1220,25 +1216,22 @@ class elaborator::imp {
}
case expr_kind::Eq: {
justification new_jst(new destruct_justification(c));
push_active(mk_eq_constraint(ctx, eq_lhs(a), eq_lhs(b), new_jst));
push_active(mk_eq_constraint(ctx, eq_rhs(a), eq_rhs(b), new_jst));
push_new_eq_constraint(ctx, eq_lhs(a), eq_lhs(b), new_jst);
push_new_eq_constraint(ctx, eq_rhs(a), eq_rhs(b), new_jst);
return true;
}
case expr_kind::Pi: {
justification new_jst(new destruct_justification(c));
push_active(mk_eq_constraint(ctx, abst_domain(a), abst_domain(b), new_jst));
push_new_eq_constraint(ctx, abst_domain(a), abst_domain(b), new_jst);
context new_ctx = extend(ctx, abst_name(a), abst_domain(a));
if (eq)
push_active(mk_eq_constraint(new_ctx, abst_body(a), abst_body(b), new_jst));
else
push_active(mk_convertible_constraint(new_ctx, abst_body(a), abst_body(b), new_jst));
push_new_constraint(eq, new_ctx, abst_body(a), abst_body(b), new_jst);
return true;
}
case expr_kind::Lambda: {
justification new_jst(new destruct_justification(c));
push_active(mk_eq_constraint(ctx, abst_domain(a), abst_domain(b), new_jst));
push_new_eq_constraint(ctx, abst_domain(a), abst_domain(b), new_jst);
context new_ctx = extend(ctx, abst_name(a), abst_domain(a));
push_active(mk_eq_constraint(new_ctx, abst_body(a), abst_body(b), new_jst));
push_new_eq_constraint(new_ctx, abst_body(a), abst_body(b), new_jst);
return true;
}
case expr_kind::App:
@ -1246,7 +1239,7 @@ class elaborator::imp {
if (num_args(a) == num_args(b)) {
justification new_jst(new destruct_justification(c));
for (unsigned i = 0; i < num_args(a); i++)
push_active(mk_eq_constraint(ctx, arg(a, i), arg(b, i), new_jst));
push_new_eq_constraint(ctx, arg(a, i), arg(b, i), new_jst);
return true;
} else {
m_conflict = justification(new unification_failure_justification(c));
@ -1336,7 +1329,7 @@ class elaborator::imp {
if (is_type(lhs1) && is_type(lhs2)) {
justification new_jst(new normalize_justification(c));
expr new_lhs = mk_type(max(ty_level(lhs1), ty_level(lhs2)));
push_active(mk_eq_constraint(get_context(c), new_lhs, rhs, new_jst));
push_new_eq_constraint(get_context(c), new_lhs, rhs, new_jst);
return true;
}
if (lhs1 == rhs) {
@ -1402,7 +1395,7 @@ class elaborator::imp {
s.m_idx++;
s.m_curr_assumption = mk_assumption();
m_state = s.m_prev_state;
push_active(mk_eq_constraint(get_context(choice), choice_mvar(choice), choice_ith(choice, idx), s.m_curr_assumption));
push_new_eq_constraint(get_context(choice), choice_mvar(choice), choice_ith(choice, idx), s.m_curr_assumption);
return true;
} else {
m_conflict = justification(new unification_failure_by_cases_justification(choice, s.m_failed_justifications.size(),