457 lines
14 KiB
C++
457 lines
14 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 <utility>
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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/kernel_bindings.h"
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#include "library/locals.h"
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#include "library/match.h"
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namespace lean {
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static name g_tmp_prefix = name::mk_internal_unique_name();
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level mk_idx_meta_univ(unsigned i) {
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return mk_meta_univ(name(g_tmp_prefix, i));
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}
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bool is_idx_meta_univ(level const & l) {
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if (!is_meta(l))
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return false;
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name const & n = meta_id(l);
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return !n.is_atomic() && n.is_numeral() && n.get_prefix() == g_tmp_prefix;
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}
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unsigned to_meta_idx(level const & l) {
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lean_assert(is_idx_meta_univ(l));
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return meta_id(l).get_numeral();
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}
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class match_fn : public match_context {
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buffer<optional<expr>> & m_esubst;
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buffer<optional<level>> & m_lsubst;
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name_generator m_ngen;
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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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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(var_idx(p) < m_esubst.size());
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unsigned vidx = var_idx(p);
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unsigned sz = m_esubst.size();
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unsigned i = sz - vidx - 1;
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m_stack.emplace_back(true, i);
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m_esubst[i] = t;
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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.size());
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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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}
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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 vidx = var_idx(x);
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unsigned sz = m_esubst.size();
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if (vidx >= sz)
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throw_exception();
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return m_esubst[sz - vidx - 1];
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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.size())
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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 m_ngen.next(); }
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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)(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(m_ngen.next(), 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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if (p.kind() == k || t.kind() == k)
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return false;
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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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return match_core(app_fn(p), app_fn(t)) && _match(app_arg(p), app_arg(t));
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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_meta_univ(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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bool match_core(expr const & p, expr const & t) {
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if (p.kind() != t.kind())
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return try_plugin(p, t);
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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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}
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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_var(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 if (has_local(t)) {
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return false;
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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_var(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(buffer<optional<expr>> & esubst, buffer<optional<level>> & lsubst, name_generator const & ngen,
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name_map<name> * name_subst, match_plugin const * plugin):
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m_esubst(esubst), m_lsubst(lsubst), m_ngen(ngen), m_name_subst(name_subst), m_plugin(plugin) {}
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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, buffer<optional<expr>> & esubst, buffer<optional<level>> & lsubst,
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name const * prefix, name_map<name> * name_subst, match_plugin const * plugin) {
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lean_assert(closed(t));
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if (prefix)
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return match_fn(esubst, lsubst, name_generator(*prefix), name_subst, plugin).match(p, t);
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else
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return match_fn(esubst, lsubst, name_generator(g_tmp_prefix), name_subst, plugin).match(p, t);
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}
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match_plugin mk_whnf_match_plugin(std::shared_ptr<type_checker> const & tc) {
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return [=](expr const & p, expr const & t, match_context & ctx) { // NOLINT
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try {
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constraint_seq cs;
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expr p1 = tc->whnf(p, cs);
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expr t1 = 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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static unsigned updt_idx_meta_univ_range(level const & l, unsigned r) {
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for_each(l, [&](level const & l) {
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if (!has_meta(l)) return false;
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if (is_idx_meta_univ(l)) {
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unsigned new_r = to_meta_idx(l) + 1;
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if (new_r > r)
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r = new_r;
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}
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return true;
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});
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return r;
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}
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static unsigned get_idx_meta_univ_range(expr const & e) {
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if (!has_univ_metavar(e))
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return 0;
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unsigned r = 0;
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for_each(e, [&](expr const & e, unsigned) {
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if (!has_univ_metavar(e)) return false;
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if (is_constant(e))
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for (level const & l : const_levels(e))
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r = updt_idx_meta_univ_range(l, r);
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if (is_sort(e))
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r = updt_idx_meta_univ_range(sort_level(e), r);
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return true;
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});
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return r;
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}
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DECL_UDATA(match_plugin)
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static const struct luaL_Reg match_plugin_m[] = {
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{"__gc", match_plugin_gc},
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{0, 0}
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};
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static int mk_whnf_match_plugin(lua_State * L) {
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return push_match_plugin(L, mk_whnf_match_plugin(to_type_checker_ref(L, 1)));
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}
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static int match(lua_State * L) {
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int nargs = lua_gettop(L);
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expr p = to_expr(L, 1);
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expr t = to_expr(L, 2);
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match_plugin * plugin = nullptr;
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if (nargs >= 3)
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plugin = &to_match_plugin(L, 3);
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if (!closed(t))
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throw exception("higher-order pattern matching failure, input term must not contain free variables");
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unsigned r1 = get_free_var_range(p);
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unsigned r2 = get_idx_meta_univ_range(p);
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buffer<optional<expr>> esubst;
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buffer<optional<level>> lsubst;
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esubst.resize(r1); lsubst.resize(r2);
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if (match(p, t, esubst, lsubst, nullptr, nullptr, plugin)) {
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lua_newtable(L);
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int i = 1;
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for (auto s : esubst) {
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if (s)
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push_expr(L, *s);
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else
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lua_pushboolean(L, false);
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lua_rawseti(L, -2, i);
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i = i + 1;
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}
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lua_newtable(L);
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i = 1;
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for (auto s : lsubst) {
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if (s)
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push_level(L, *s);
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else
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lua_pushboolean(L, false);
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lua_rawseti(L, -2, i);
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i = i + 1;
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}
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} else {
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lua_pushnil(L);
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lua_pushnil(L);
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}
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return 2;
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}
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static int mk_idx_meta_univ(lua_State * L) {
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return push_level(L, mk_idx_meta_univ(luaL_checkinteger(L, 1)));
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}
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void open_match(lua_State * L) {
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luaL_newmetatable(L, match_plugin_mt);
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lua_pushvalue(L, -1);
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lua_setfield(L, -2, "__index");
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setfuncs(L, match_plugin_m, 0);
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SET_GLOBAL_FUN(mk_whnf_match_plugin, "whnf_match_plugin");
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SET_GLOBAL_FUN(match_plugin_pred, "is_match_plugin");
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SET_GLOBAL_FUN(mk_idx_meta_univ, "mk_idx_meta_univ");
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SET_GLOBAL_FUN(match, "match");
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}
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}
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