3c878ecd01
The frontend is still using the old "let-expression macros". We will use the new let-expressions to implement the new tactic framework.
404 lines
13 KiB
C++
404 lines
13 KiB
C++
/*
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Copyright (c) 2013-2014 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 <algorithm>
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#include <utility>
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#include "util/fresh_name.h"
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#include "kernel/abstract.h"
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#include "kernel/instantiate.h"
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#include "kernel/for_each_fn.h"
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#include "kernel/type_checker.h"
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#include "library/locals.h"
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#include "library/match.h"
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#include "library/idx_metavar.h"
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namespace lean {
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class match_fn : public match_context {
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unsigned m_esubst_sz;
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optional<expr> * m_esubst;
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unsigned m_lsubst_sz;
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optional<level> * m_lsubst;
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name_map<name> * m_name_subst;
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match_plugin const * m_plugin;
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buffer<pair<bool, unsigned>> m_stack;
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buffer<unsigned> m_scopes;
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bool * m_assigned; // mark if matcher assigned anything
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void push() {
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m_scopes.push_back(m_stack.size());
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}
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void pop() {
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lean_assert(!m_scopes.empty());
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unsigned old_sz = m_scopes.back();
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while (m_stack.size() > old_sz) {
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auto p = m_stack.back();
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if (p.first)
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m_esubst[p.second] = none_expr();
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else
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m_lsubst[p.second] = none_level();
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m_stack.pop_back();
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}
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m_scopes.pop_back();
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}
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void keep() {
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m_scopes.back() = m_stack.size();
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}
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struct scope {
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match_fn & m;
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scope(match_fn & _m):m(_m) { m.push(); }
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~scope() { m.pop(); }
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void keep() { m.keep(); }
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};
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void _assign(expr const & p, expr const & t) {
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lean_assert(to_meta_idx(p) < m_esubst_sz);
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unsigned i = to_meta_idx(p);
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m_stack.emplace_back(true, i);
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m_esubst[i] = t;
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if (m_assigned)
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*m_assigned = true;
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}
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void _assign(level const & p, level const & l) {
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lean_assert(to_meta_idx(p) < m_lsubst_sz);
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unsigned i = to_meta_idx(p);
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m_stack.emplace_back(false, i);
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m_lsubst[i] = l;
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if (m_assigned)
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*m_assigned = true;
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}
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void throw_exception() const {
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throw exception("ill-formed higher-order matching problem");
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}
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optional<expr> _get_subst(expr const & x) const {
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unsigned i = to_meta_idx(x);
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unsigned sz = m_esubst_sz;
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if (i >= sz)
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throw_exception();
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return m_esubst[i];
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}
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optional<level> _get_subst(level const & x) const {
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unsigned i = to_meta_idx(x);
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if (i >= m_lsubst_sz)
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throw_exception();
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return m_lsubst[i];
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}
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virtual void assign(expr const & p, expr const & t) { return _assign(p, t); }
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virtual void assign(level const & p, level const & t) { return _assign(p, t); }
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virtual optional<expr> get_subst(expr const & x) const { return _get_subst(x); }
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virtual optional<level> get_subst(level const & x) const { return _get_subst(x); }
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virtual name mk_name() { return mk_fresh_name(); }
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bool args_are_distinct_locals(buffer<expr> const & args) {
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for (auto it = args.begin(); it != args.end(); it++) {
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if (!is_local(*it) || contains_local(*it, args.begin(), it))
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return false;
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}
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return true;
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}
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optional<expr> proj(expr const & t, buffer<expr> const & args) {
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expr r = Fun(args, t);
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if (has_local(r))
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return none_expr();
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else
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return some_expr(r);
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}
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bool try_plugin(expr const & p, expr const & t) {
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if (!m_plugin)
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return false;
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return m_plugin->on_failure(p, t, *this);
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}
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bool match_binding_core(expr p, expr t) {
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lean_assert(is_binding(p) && is_binding(t));
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buffer<expr> ls;
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expr_kind k = p.kind();
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while (p.kind() == k && t.kind() == k) {
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if (m_name_subst)
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(*m_name_subst)[binding_name(p)] = binding_name(t);
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expr p_d = instantiate_rev(binding_domain(p), ls.size(), ls.data());
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expr t_d = instantiate_rev(binding_domain(t), ls.size(), ls.data());
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if (!_match(p_d, t_d))
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return false;
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expr l = mk_local(mk_fresh_name(), binding_name(t), t_d, binding_info(t));
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ls.push_back(l);
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p = binding_body(p);
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t = binding_body(t);
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}
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p = instantiate_rev(p, ls.size(), ls.data());
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t = instantiate_rev(t, ls.size(), ls.data());
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return _match(p, t);
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}
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bool match_binding(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_binding_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_macro_core(expr const & p, expr const & t) {
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if (macro_def(p) == macro_def(t) && macro_num_args(p) == macro_num_args(t)) {
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for (unsigned i = 0; i < macro_num_args(p); i++) {
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if (!_match(macro_arg(p, i), macro_arg(t, i)))
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return false;
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}
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return true;
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}
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return false;
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}
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bool match_macro(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_macro_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_app_core(expr const & p, expr const & t) {
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buffer<expr> p_args;
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buffer<expr> t_args;
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expr const & p_fn = get_app_args(p, p_args);
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expr const & t_fn = get_app_args(t, t_args);
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if (p_args.size() != t_args.size())
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return false;
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if (!match_core(p_fn, t_fn))
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return false;
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for (unsigned i = 0; i < p_args.size(); i++) {
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if (!_match(p_args[i], t_args[i]))
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return false;
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}
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return true;
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}
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bool match_app(expr const & p, expr const & t) {
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{
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scope s(*this);
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if (match_app_core(p, t)) {
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s.keep();
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return true;
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}
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}
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return try_plugin(p, t);
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}
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bool match_level_core(level const & p, level const & l) {
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if (p == l)
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return true;
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if (p.kind() == l.kind()) {
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switch (p.kind()) {
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case level_kind::Zero:
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lean_unreachable(); // LCOV_EXCL_LINE
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case level_kind::Param: case level_kind::Global: case level_kind::Meta:
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return false;
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case level_kind::Succ:
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return match_level(succ_of(p), succ_of(l));
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case level_kind::Max: {
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scope s(*this);
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if (match_level(max_lhs(p), max_lhs(l)) && match_level(max_rhs(p), max_rhs(l))) {
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s.keep();
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return true;
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}
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break;
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}
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case level_kind::IMax: {
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scope s(*this);
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if (match_level(imax_lhs(p), imax_lhs(l)) && match_level(imax_rhs(p), imax_rhs(l))) {
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s.keep();
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return true;
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}
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break;
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}}
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}
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level p1 = normalize(p);
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level l1 = normalize(l);
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if (p1 != p || l1 != l)
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return match_level(p1, l1);
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else
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return false;
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}
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bool match_level(level const & p, level const & l) {
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if (is_idx_metauniv(p)) {
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auto s = _get_subst(p);
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if (s) {
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return match_level_core(*s, l);
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} else {
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_assign(p, l);
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return true;
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}
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}
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return match_level_core(p, l);
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}
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bool match_levels(levels ps, levels ls) {
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while (ps && ls) {
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if (!match_level(head(ps), head(ls)))
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return false;
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ps = tail(ps);
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ls = tail(ls);
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}
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return true;
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}
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bool match_constant(expr const & p, expr const & t) {
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if (const_name(p) == const_name(t))
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return match_levels(const_levels(p), const_levels(t));
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else
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return try_plugin(p, t);
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}
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static expr eta(expr const & e) {
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unsigned num = 0;
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expr it = e;
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while (is_lambda(it)) {
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num++;
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it = binding_body(it);
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}
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if (num == 0)
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return e;
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for (unsigned i = 0; i < num; i++) {
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if (!is_app(it))
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return e;
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if (!is_var(app_arg(it), i)) {
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return e;
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}
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it = app_fn(it);
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}
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if (!closed(it))
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return e;
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return it;
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}
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bool match_core(expr const & p, expr const & t) {
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if (p.kind() != t.kind()) {
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if (is_lambda(p) != is_lambda(t)) {
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expr new_p = eta(p);
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expr new_t = eta(t);
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if (is_lambda(new_p) == is_lambda(new_t))
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return _match(new_p, new_t);
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}
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return try_plugin(p, t);
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}
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if (m_plugin) {
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switch (m_plugin->pre(p, t, *this)) {
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case l_true: return true;
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case l_false: return false;
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case l_undef: break;
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}
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}
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switch (p.kind()) {
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case expr_kind::Local: case expr_kind::Meta:
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return mlocal_name(p) == mlocal_name(t);
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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 match_constant(p, t);
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case expr_kind::Sort:
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return match_level(sort_level(p), sort_level(t));
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case expr_kind::Lambda: case expr_kind::Pi:
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return match_binding(p, t);
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case expr_kind::Macro:
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return match_macro(p, t);
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case expr_kind::App:
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return match_app(p, t);
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case expr_kind::Let:
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// TODO(Leo): this module will be deleted in the future.
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lean_unreachable();
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}
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lean_unreachable(); // LCOV_EXCL_LINE
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}
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bool _match(expr const & p, expr const & t) {
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if (is_idx_metavar(p)) {
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auto s = _get_subst(p);
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if (s) {
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return match_core(*s, t);
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} else {
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_assign(p, t);
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return true;
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}
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} else if (is_app(p)) {
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buffer<expr> args;
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expr const & f = get_app_rev_args(p, args);
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if (is_idx_metavar(f)) {
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// higher-order pattern case
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auto s = _get_subst(f);
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if (s) {
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expr new_p = apply_beta(*s, args.size(), args.data());
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return match_core(new_p, t);
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}
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if (args_are_distinct_locals(args)) {
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optional<expr> new_t = proj(t, args);
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if (new_t) {
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_assign(f, *new_t);
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return true;
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}
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}
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}
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// fallback to the first-order case
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}
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return match_core(p, t);
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}
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public:
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match_fn(unsigned lsubst_sz, optional<level> * lsubst,
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unsigned esubst_sz, optional<expr> * esubst,
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name_map<name> * name_subst, match_plugin const * plugin, bool * assigned):
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m_esubst_sz(esubst_sz), m_esubst(esubst),
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m_lsubst_sz(lsubst_sz), m_lsubst(lsubst),
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m_name_subst(name_subst), m_plugin(plugin),
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m_assigned(assigned) {}
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virtual bool match(expr const & p, expr const & t) { return _match(p, t); }
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};
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bool match(expr const & p, expr const & t,
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unsigned lsubst_sz, optional<level> * lsubst,
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unsigned esubst_sz, optional<expr> * esubst,
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name_map<name> * name_subst, match_plugin const * plugin, bool * assigned) {
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lean_assert(closed(t));
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lean_assert(closed(p));
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return match_fn(lsubst_sz, lsubst, esubst_sz, esubst,
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name_subst, plugin, assigned).match(p, t);
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}
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bool match(expr const & p, expr const & t, buffer<optional<level>> & lsubst, buffer<optional<expr>> & esubst,
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name_map<name> * name_subst, match_plugin const * plugin, bool * assigned) {
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return match(p, t, lsubst.size(), lsubst.data(), esubst.size(), esubst.data(),
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name_subst, plugin, assigned);
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}
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bool whnf_match_plugin::on_failure(expr const & p, expr const & t, match_context & ctx) const {
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try {
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constraint_seq cs;
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expr p1 = m_tc.whnf(p, cs);
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expr t1 = m_tc.whnf(t, cs);
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return !cs && (p1 != p || t1 != t) && ctx.match(p1, t1);
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} catch (exception&) {
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return false;
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}
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}
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}
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