128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
/*
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Copyright (c) 2016 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 "util/list_fn.h"
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#include "kernel/instantiate.h"
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#include "library/trace.h"
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#include "library/locals.h"
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#include "library/type_context.h"
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#include "library/defeq_canonizer.h"
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namespace lean {
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defeq_canonizer::defeq_canonizer(type_context_old & ctx, state & s):
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m_ctx(ctx), m_state(s) {
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}
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optional<name> defeq_canonizer::get_head_symbol(expr type) {
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type = m_ctx.whnf(type);
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expr const & fn = get_app_fn(type);
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if (is_constant(fn)) {
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return optional<name>(const_name(fn));
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} else if (is_pi(type)) {
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type_context_old::tmp_locals locals(m_ctx);
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expr l = locals.push_local_from_binding(type);
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return get_head_symbol(instantiate(binding_body(type), l));
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} else {
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return optional<name>();
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}
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}
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optional<expr> defeq_canonizer::find_defeq(name const & h, expr const & e) {
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list<expr> const * lst = m_state.m_M.find(h);
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if (!lst) return none_expr();
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for (expr const & e1 : *lst) {
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if (locals_subset(e1, e) && m_ctx.is_def_eq(e1, e))
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return some_expr(e1);
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}
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return none_expr();
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}
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void defeq_canonizer::replace_C(expr const & e1, expr const & e2) {
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m_state.m_C.insert(e1, e2);
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if (m_updated)
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*m_updated = true;
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}
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void defeq_canonizer::insert_C(expr const & e1, expr const & e2) {
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m_state.m_C.insert(e1, e2);
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}
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void defeq_canonizer::insert_M(name const & h, expr const & e) {
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list<expr> const * lst = m_state.m_M.find(h);
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if (lst) {
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m_state.m_M.insert(h, cons(e, *lst));
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} else {
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m_state.m_M.insert(h, to_list(e));
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}
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}
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void defeq_canonizer::replace_M(name const & h, expr const & e, expr const & new_e) {
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list<expr> const * lst = m_state.m_M.find(h);
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lean_assert(lst);
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m_state.m_M.insert(h, cons(new_e, remove(*lst, e)));
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}
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expr defeq_canonizer::canonize_core(expr const & e) {
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if (auto it = m_state.m_C.find(e)) {
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expr e1 = *it;
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if (e1 == e)
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return e;
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expr e2 = canonize_core(e1);
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if (e2 != e1) {
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replace_C(e, e2);
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}
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return e2;
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}
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expr e_type = m_ctx.infer(e);
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optional<name> h = get_head_symbol(e_type);
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if (!h) {
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/* canonization is not support for type of e */
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insert_C(e, e);
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return e;
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} else if (optional<expr> new_e = find_defeq(*h, e)) {
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if (get_weight(e) < get_weight(*new_e) && locals_subset(e, *new_e)) {
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replace_C(*new_e, e);
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replace_M(*h, *new_e, e);
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insert_C(e, e);
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return e;
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} else {
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insert_C(e, *new_e);
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return *new_e;
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}
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} else {
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insert_C(e, e);
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insert_M(*h, e);
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return e;
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}
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}
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static void trace(type_context_old & ctx, expr const & e, expr const & r) {
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lean_trace("defeq_canonizer", scope_trace_env _(ctx.env(), ctx); tout() << "\n" << e << "\n==>\n" << r << "\n";);
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}
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expr defeq_canonizer::canonize(expr const & e, bool & updated) {
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type_context_old::transparency_scope scope(m_ctx, transparency_mode::Instances);
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m_updated = &updated;
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expr r = canonize_core(e);
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trace(m_ctx, e, r);
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return r;
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}
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expr defeq_canonizer::canonize(expr const & e) {
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type_context_old::transparency_scope scope(m_ctx, transparency_mode::Instances);
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m_updated = nullptr;
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expr r = canonize_core(e);
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trace(m_ctx, e, r);
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return r;
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}
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void initialize_defeq_canonizer() {
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register_trace_class("defeq_canonizer");
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}
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void finalize_defeq_canonizer() {
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}
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}
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