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refactor(library): monotonic total order on terms

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-02-22 23:09:12 -08:00
parent 8cd78e00f1
commit e0ef6b2e9a
3 changed files with 67 additions and 62 deletions
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6
src/library/CMakeLists.txt
View file

@ -1,6 +1,6 @@
add_library(library deep_copy.cpp)
# kernel_bindings.cpp deep_copy.cpp
# context_to_lambda.cpp placeholder.cpp expr_lt.cpp substitution.cpp
add_library(library deep_copy.cpp expr_lt.cpp)
# kernel_bindings.cpp
# context_to_lambda.cpp placeholder.cpp substitution.cpp
# fo_unify.cpp bin_op.cpp equality.cpp io_state_stream.cpp printer.cpp
# hop_match.cpp)

120
src/library/expr_lt.cpp
View file

@ -5,14 +5,45 @@ Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "kernel/expr.h"
#include "library/expr_lt.h"
namespace lean {
bool is_lt(expr const & a, expr const & b, bool use_hash);
static bool is_lt(optional<expr> const & a, optional<expr> const & b, bool use_hash) {
if (is_eqp(a, b)) return false;
else if (!a && b) return true;
else if (a && !b) return false;
else return is_lt(*a, *b, use_hash);
bool is_lt(level const & a, level const & b, bool use_hash) {
if (is_eqp(a, b)) return false;
if (kind(a) != kind(b)) return kind(a) < kind(b);
if (use_hash) {
if (hash(a) < hash(b)) return true;
if (hash(a) > hash(b)) return false;
}
if (a == b) return false;
switch (kind(a)) {
case level_kind::Zero: return true;
case level_kind::Succ: return is_lt(succ_of(a), succ_of(b), use_hash);
case level_kind::Param: return param_id(a) < param_id(b);
case level_kind::Meta: return meta_id(a) < meta_id(b);
case level_kind::Max:
if (max_lhs(a) != max_lhs(b))
return is_lt(max_lhs(a), max_lhs(b), use_hash);
else
return is_lt(max_lhs(a), max_lhs(b), use_hash);
case level_kind::IMax:
if (imax_lhs(a) != imax_lhs(b))
return is_lt(imax_lhs(a), imax_lhs(b), use_hash);
else
return is_lt(imax_lhs(a), imax_lhs(b), use_hash);
}
lean_unreachable(); // LCOV_EXCL_LINE
}
bool is_lt(levels const & as, levels const & bs, bool use_hash) {
if (is_nil(as))
return !is_nil(bs);
if (is_nil(bs))
return false;
if (car(as) == car(bs))
return is_lt(cdr(as), cdr(bs), use_hash);
else
return is_lt(car(as), car(bs), use_hash);
}
bool is_lt(expr const & a, expr const & b, bool use_hash) {
@ -27,25 +58,19 @@ bool is_lt(expr const & a, expr const & b, bool use_hash) {
if (a.hash() > b.hash()) return false;
}
if (a == b) return false;
if (is_var(a)) return var_idx(a) < var_idx(b);
switch (a.kind()) {
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
return var_idx(a) < var_idx(b);
case expr_kind::Constant:
return const_name(a) < const_name(b);
case expr_kind::App:
if (num_args(a) != num_args(b))
return num_args(a) < num_args(b);
for (unsigned i = 0; i < num_args(a); i++) {
if (arg(a, i) != arg(b, i))
return is_lt(arg(a, i), arg(b, i), use_hash);
}
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::HEq:
if (heq_lhs(a) != heq_lhs(b))
return is_lt(heq_lhs(a), heq_lhs(b), use_hash);
if (const_name(a) != const_name(b))
return const_name(a) < const_name(b);
else
return is_lt(heq_rhs(a), heq_rhs(b), use_hash);
return is_lt(const_level_params(a), const_level_params(b), use_hash);
case expr_kind::App:
if (app_fn(a) != app_fn(b))
return is_lt(app_fn(a), app_fn(b), use_hash);
else
return is_lt(app_arg(a), app_arg(b), use_hash);
case expr_kind::Pair:
if (pair_first(a) != pair_first(b))
return is_lt(pair_first(a), pair_first(b), use_hash);
@ -53,22 +78,15 @@ bool is_lt(expr const & a, expr const & b, bool use_hash) {
return is_lt(pair_second(a), pair_second(b), use_hash);
else
return is_lt(pair_type(a), pair_type(b), use_hash);
case expr_kind::Proj:
if (proj_first(a) != proj_first(b))
return proj_first(a) && !proj_first(b); // first projection is smaller than the second one.
case expr_kind::Fst: case expr_kind::Snd:
return is_lt(proj_arg(a), proj_arg(b), use_hash);
case expr_kind::Sigma: case expr_kind::Lambda: case expr_kind::Pi:
if (binder_domain(a) != binder_domain(b))
return is_lt(binder_domain(a), binder_domain(b), use_hash);
else
return is_lt(proj_arg(a), proj_arg(b), use_hash);
case expr_kind::Sigma:
case expr_kind::Lambda:
case expr_kind::Pi: // Remark: we ignore get_abs_name because we want alpha-equivalence
if (abst_domain(a) != abst_domain(b))
return is_lt(abst_domain(a), abst_domain(b), use_hash);
else
return is_lt(abst_body(a), abst_body(b), use_hash);
case expr_kind::Type:
return ty_level(a) < ty_level(b);
case expr_kind::Value:
return to_value(a) < to_value(b);
return is_lt(binder_body(a), binder_body(b), use_hash);
case expr_kind::Sort:
return is_lt(sort_level(a), sort_level(b), use_hash);
case expr_kind::Let:
if (let_type(a) != let_type(b)) {
return is_lt(let_type(a), let_type(b), use_hash);
@ -77,29 +95,13 @@ bool is_lt(expr const & a, expr const & b, bool use_hash) {
} else {
return is_lt(let_body(a), let_body(b), use_hash);
}
case expr_kind::MetaVar:
if (metavar_name(a) != metavar_name(b)) {
return metavar_name(a) < metavar_name(b);
} else {
auto it1 = metavar_lctx(a).begin();
auto it2 = metavar_lctx(b).begin();
auto end1 = metavar_lctx(a).end();
auto end2 = metavar_lctx(b).end();
for (; it1 != end1 && it2 != end2; ++it1, ++it2) {
if (it1->kind() != it2->kind()) {
return it1->kind() < it2->kind();
} else if (it1->s() != it2->s()) {
return it1->s() < it2->s();
} else if (it1->is_inst()) {
if (it1->v() != it2->v())
return is_lt(it1->v(), it2->v(), use_hash);
} else {
if (it1->n() != it2->n())
return it1->n() < it2->n();
}
}
return it1 == end1 && it2 != end2;
}
case expr_kind::Local: case expr_kind::Meta:
if (mlocal_name(a) != mlocal_name(b))
return mlocal_name(a) < mlocal_name(b);
else
return is_lt(mlocal_type(a), mlocal_type(b), use_hash);
case expr_kind::Macro:
return to_macro(a) < to_macro(b);
}
lean_unreachable(); // LCOV_EXCL_LINE
}

3
src/library/expr_lt.h
View file

@ -19,4 +19,7 @@ inline bool operator<(expr const & a, expr const & b) { return is_lt(a, b, true
inline bool operator>(expr const & a, expr const & b) { return is_lt(b, a, true); }
inline bool operator<=(expr const & a, expr const & b) { return !is_lt(b, a, true); }
inline bool operator>=(expr const & a, expr const & b) { return !is_lt(a, b, true); }
bool is_lt(level const & a, level const & b, bool use_hash);
bool is_lt(levels const & as, levels const & bs, bool use_hash);
}