83 lines
3.2 KiB
C++
83 lines
3.2 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include "kernel/expr.h"
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namespace lean {
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bool is_lt(expr const & a, expr const & b, bool use_hash) {
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if (is_eqp(a, b)) return false;
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if (!a && b) return true; // the null expression is the smallest one
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if (a && !b) return false;
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if (a.kind() != b.kind()) return a.kind() < b.kind();
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if (use_hash) {
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if (a.hash() < b.hash()) return true;
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if (a.hash() > b.hash()) return false;
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}
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if (a == b) return false;
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if (is_var(a)) return var_idx(a) < var_idx(b);
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switch (a.kind()) {
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case expr_kind::Var:
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lean_unreachable(); // LCOV_EXCL_LINE
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case expr_kind::Constant:
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return const_name(a) < const_name(b);
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case expr_kind::App:
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if (num_args(a) != num_args(b))
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return num_args(a) < num_args(b);
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for (unsigned i = 0; i < num_args(a); i++) {
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if (arg(a, i) != arg(b, i))
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return is_lt(arg(a, i), arg(b, i), use_hash);
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}
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lean_unreachable(); // LCOV_EXCL_LINE
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case expr_kind::Eq:
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if (eq_lhs(a) != eq_lhs(b))
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return is_lt(eq_lhs(a), eq_lhs(b), use_hash);
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else
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return is_lt(eq_rhs(a), eq_rhs(b), use_hash);
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case expr_kind::Lambda: // Remark: we ignore get_abs_name because we want alpha-equivalence
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case expr_kind::Pi:
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if (abst_domain(a) != abst_domain(b))
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return is_lt(abst_domain(a), abst_domain(b), use_hash);
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else
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return is_lt(abst_body(a), abst_body(b), use_hash);
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case expr_kind::Type:
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return ty_level(a) < ty_level(b);
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case expr_kind::Value:
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return to_value(a) < to_value(b);
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case expr_kind::Let:
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if (let_type(a) != let_type(b)) {
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return is_lt(let_type(a), let_type(b), use_hash);
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} else if (let_value(a) != let_value(b)){
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return is_lt(let_value(a), let_value(b), use_hash);
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} else {
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return is_lt(let_body(a), let_body(b), use_hash);
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}
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case expr_kind::MetaVar:
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if (metavar_name(a) != metavar_name(b)) {
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return metavar_name(a) < metavar_name(b);
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} else {
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auto it1 = metavar_lctx(a).begin();
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auto it2 = metavar_lctx(b).begin();
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auto end1 = metavar_lctx(a).end();
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auto end2 = metavar_lctx(b).end();
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for (; it1 != end1 && it2 != end2; ++it1, ++it2) {
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if (it1->kind() != it2->kind()) {
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return it1->kind() < it2->kind();
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} else if (it1->s() != it2->s()) {
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return it1->s() < it2->s();
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} else if (it1->is_inst()) {
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if (it1->v() != it2->v())
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return is_lt(it1->v(), it2->v(), use_hash);
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} else {
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if (it1->n() != it2->n())
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return it1->n() < it2->n();
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}
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}
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return it1 == end1 && it2 != end2;
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}
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}
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lean_unreachable(); // LCOV_EXCL_LINE
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}
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}
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