583 lines
26 KiB
C++
583 lines
26 KiB
C++
/*
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Copyright (c) 2015 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 <vector>
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#include "util/lbool.h"
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#include "util/interrupt.h"
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#include "util/sexpr/option_declarations.h"
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#include "kernel/instantiate.h"
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#include "kernel/metavar.h"
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#include "kernel/abstract.h"
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#include "kernel/for_each_fn.h"
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#include "library/normalize.h"
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#include "library/reducible.h"
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#include "library/class.h"
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#include "library/local_context.h"
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#include "library/generic_exception.h"
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#include "library/io_state_stream.h"
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#include "library/replace_visitor.h"
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#include "library/constants.h"
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#include "library/pp_options.h"
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#include "library/choice_iterator.h"
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#include "library/type_context.h"
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#include "library/class_instance_resolution.h"
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// The following include files are need by the old type class resolution procedure
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#include "util/lazy_list_fn.h"
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#include "library/unifier.h"
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#include "library/metavar_closure.h"
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namespace lean {
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[[ noreturn ]] void throw_class_exception(char const * msg, expr const & m) { throw_generic_exception(msg, m); }
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[[ noreturn ]] void throw_class_exception(expr const & m, pp_fn const & fn) { throw_generic_exception(m, fn); }
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static name * g_class_force_new = nullptr;
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static name * g_prefix = nullptr;
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bool get_class_force_new(options const & o) {
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return o.get_bool(*g_class_force_new, false);
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}
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struct cienv {
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typedef std::unique_ptr<default_type_context> ti_ptr;
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ti_ptr m_ti_ptr;
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void reset(environment const & env, io_state const & ios, list<expr> const & ctx) {
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m_ti_ptr.reset(new default_type_context(env, ios, ctx));
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}
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bool compatible_env(environment const & env) {
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environment const & curr_env = m_ti_ptr->env();
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return env.is_descendant(curr_env) && curr_env.is_descendant(env);
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}
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void ensure_compatible(environment const & env, io_state const & ios, list<expr> const & ctx) {
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if (!m_ti_ptr || !compatible_env(env) || !m_ti_ptr->compatible_local_instances(ctx))
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reset(env, ios, ctx);
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if (!m_ti_ptr->update_options(ios.get_options()))
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m_ti_ptr->clear_cache();
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}
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optional<expr> operator()(environment const & env, io_state const & ios,
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pos_info_provider const * pip, list<expr> const & ctx, expr const & type,
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expr const & pos_ref) {
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ensure_compatible(env, ios, ctx);
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type_context::scope_pos_info scope(*m_ti_ptr, pip, pos_ref);
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return m_ti_ptr->mk_class_instance(type);
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}
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};
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MK_THREAD_LOCAL_GET_DEF(cienv, get_cienv);
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static optional<expr> mk_class_instance(environment const & env, io_state const & ios, list<expr> const & ctx,
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expr const & e, pos_info_provider const * pip, expr const & pos_ref) {
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return get_cienv()(env, ios, pip, ctx, e, pos_ref);
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}
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optional<expr> mk_class_instance(environment const & env, io_state const & ios, list<expr> const & ctx,
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expr const & e, pos_info_provider const * pip) {
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return mk_class_instance(env, ios, ctx, e, pip, e);
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}
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optional<expr> mk_class_instance(environment const & env, list<expr> const & ctx, expr const & e, pos_info_provider const * pip) {
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return mk_class_instance(env, get_dummy_ios(), ctx, e, pip);
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}
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// Auxiliary class for generating a lazy-stream of instances.
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class class_multi_instance_iterator : public choice_iterator {
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io_state m_ios;
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default_type_context m_ti;
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type_context::scope_pos_info m_scope_pos_info;
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expr m_new_meta;
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justification m_new_j;
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optional<expr> m_first;
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public:
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class_multi_instance_iterator(environment const & env, io_state const & ios, list<expr> const & ctx,
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expr const & e, pos_info_provider const * pip, expr const & pos_ref,
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expr const & new_meta, justification const & new_j,
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bool is_strict):
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choice_iterator(!is_strict),
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m_ios(ios),
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m_ti(env, ios, ctx, true),
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m_scope_pos_info(m_ti, pip, pos_ref),
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m_new_meta(new_meta),
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m_new_j(new_j) {
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m_first = m_ti.mk_class_instance(e);
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}
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virtual ~class_multi_instance_iterator() {}
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virtual optional<constraints> next() {
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optional<expr> r;
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if (m_first) {
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r = m_first;
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m_first = none_expr();
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} else {
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r = m_ti.next_class_instance();
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}
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if (r) {
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constraint c = mk_eq_cnstr(m_new_meta, *r, m_new_j);
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return optional<constraints>(constraints(c));
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} else {
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return optional<constraints>();
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}
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}
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};
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static constraint mk_class_instance_root_cnstr(environment const & env, io_state const & ios, local_context const & _ctx, expr const & m, bool is_strict,
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bool use_local_instances, pos_info_provider const * pip) {
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justification j = mk_failed_to_synthesize_jst(env, m);
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auto choice_fn = [=](expr const & meta, expr const & meta_type, substitution const & s, name_generator &&) {
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local_context ctx;
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if (use_local_instances)
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ctx = _ctx.instantiate(substitution(s));
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cienv & cenv = get_cienv();
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cenv.ensure_compatible(env, ios, ctx.get_data());
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auto cls_name = cenv.m_ti_ptr->is_class(meta_type);
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if (!cls_name) {
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// do nothing, since type is not a class.
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return lazy_list<constraints>(constraints());
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}
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bool multiple_insts = try_multiple_instances(env, *cls_name);
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pair<expr, justification> mj = update_meta(meta, s);
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expr new_meta = mj.first;
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justification new_j = mj.second;
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if (multiple_insts) {
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return choose(std::shared_ptr<choice_iterator>(new class_multi_instance_iterator(env, ios, ctx.get_data(),
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meta_type, pip, meta,
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new_meta, new_j, is_strict)));
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} else {
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if (auto r = mk_class_instance(env, ios, ctx.get_data(), meta_type, pip, meta)) {
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constraint c = mk_eq_cnstr(new_meta, *r, new_j);
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return lazy_list<constraints>(constraints(c));
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} else if (is_strict) {
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return lazy_list<constraints>();
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} else {
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return lazy_list<constraints>(constraints());
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}
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}
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};
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bool owner = false;
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delay_factor factor;
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return mk_choice_cnstr(m, choice_fn, factor, owner, j);
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}
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/** \brief Create a metavariable, and attach choice constraint for generating
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solutions using class-instances
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*/
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pair<expr, constraint> mk_new_class_instance_elaborator(
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environment const & env, io_state const & ios, local_context const & ctx,
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name const & prefix, optional<name> const & suffix, bool use_local_instances,
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bool is_strict, optional<expr> const & type, tag g, pos_info_provider const * pip) {
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name_generator ngen(prefix);
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expr m = ctx.mk_meta(ngen, suffix, type, g);
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constraint c = mk_class_instance_root_cnstr(env, ios, ctx, m, is_strict,
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use_local_instances, pip);
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return mk_pair(m, c);
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}
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optional<expr> mk_class_instance(environment const & env, io_state const & ios, local_context const & ctx, expr const & type, bool use_local_instances) {
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if (use_local_instances)
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return mk_class_instance(env, ios, ctx.get_data(), type, nullptr);
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else
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return mk_class_instance(env, ios, list<expr>(), type, nullptr);
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}
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optional<expr> mk_class_instance(environment const & env, local_context const & ctx, expr const & type) {
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return mk_class_instance(env, ctx.get_data(), type, nullptr);
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}
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optional<expr> mk_hset_instance(type_checker & tc, io_state const & ios, list<expr> const & ctx, expr const & type) {
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level lvl = sort_level(tc.ensure_type(type).first);
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expr is_hset = tc.whnf(mk_app(mk_constant(get_is_trunc_is_hset_name(), {lvl}), type)).first;
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return mk_class_instance(tc.env(), ios, ctx, is_hset);
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}
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optional<expr> mk_subsingleton_instance(environment const & env, io_state const & ios, list<expr> const & ctx, expr const & type) {
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cienv & cenv = get_cienv();
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cenv.ensure_compatible(env, ios, ctx);
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return cenv.m_ti_ptr->mk_subsingleton_instance(type);
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}
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void initialize_class_instance_resolution() {
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g_prefix = new name(name::mk_internal_unique_name());
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g_class_force_new = new name{"class", "force_new"};
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register_bool_option(*g_class_force_new, false,
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"(class) force new type class resolution procedure to be used even in HoTT mode (THIS IS TEMPORARY OPTION)");
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}
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void finalize_class_instance_resolution() {
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delete g_prefix;
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delete g_class_force_new;
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}
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/*
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The rest of this module implements the old more powerful and *expensive* type class
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resolution procedure. We still have it because the HoTT library contains
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type class instances that require full-higher order unification to be solved.
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Example:
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definition is_equiv_tr [instance] [constructor] {A : Type} (P : A → Type) {x y : A}
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(p : x = y) : (is_equiv (transport P p)) := ...
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*/
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/** \brief Context for handling class-instance metavariable choice constraint */
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struct class_instance_context {
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io_state m_ios;
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name_generator m_ngen;
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type_checker_ptr m_tc;
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expr m_main_meta;
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bool m_use_local_instances;
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bool m_trace_instances;
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bool m_conservative;
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unsigned m_max_depth;
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bool m_trans_instances;
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char const * m_fname;
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optional<pos_info> m_pos;
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class_instance_context(environment const & env, io_state const & ios,
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name const & prefix, bool use_local_instances):
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m_ios(ios),
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m_ngen(prefix),
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m_use_local_instances(use_local_instances) {
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m_fname = nullptr;
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m_trace_instances = get_class_trace_instances(ios.get_options());
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m_max_depth = get_class_instance_max_depth(ios.get_options());
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m_conservative = true; // We removed the option class.conservative
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m_trans_instances = get_class_trans_instances(ios.get_options());
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m_tc = mk_class_type_checker(env, m_ngen.mk_child(), m_conservative);
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options opts = m_ios.get_options();
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opts = opts.update_if_undef(get_pp_purify_metavars_name(), false);
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opts = opts.update_if_undef(get_pp_implicit_name(), true);
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m_ios.set_options(opts);
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}
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environment const & env() const { return m_tc->env(); }
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io_state const & ios() const { return m_ios; }
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bool use_local_instances() const { return m_use_local_instances; }
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type_checker & tc() const { return *m_tc; }
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bool trace_instances() const { return m_trace_instances; }
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void set_main_meta(expr const & meta) { m_main_meta = meta; }
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expr const & get_main_meta() const { return m_main_meta; }
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void set_pos(char const * fname, optional<pos_info> const & pos) {
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m_fname = fname;
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m_pos = pos;
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}
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optional<pos_info> const & get_pos() const { return m_pos; }
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char const * get_file_name() const { return m_fname; }
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unsigned get_max_depth() const { return m_max_depth; }
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bool use_trans_instances() const { return m_trans_instances; }
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};
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static pair<expr, constraint>
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mk_class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
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optional<expr> const & type, tag g, unsigned depth, bool use_globals);
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/** \brief Choice function \c fn for synthesizing class instances.
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The function \c fn produces a stream of alternative solutions for ?m.
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In this case, \c fn will do the following:
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1) if the elaborated type of ?m is a 'class' C, then the stream will start with
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a) all local instances of class C (if elaborator.local_instances == true)
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b) all global instances of class C
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*/
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struct class_instance_elaborator : public choice_iterator {
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std::shared_ptr<class_instance_context> m_C;
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local_context m_ctx;
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expr m_meta;
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// elaborated type of the metavariable
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expr m_meta_type;
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// local instances that should also be included in the
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// class-instance resolution.
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// This information is retrieved from the local context
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list<expr> m_local_instances;
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// global declaration names that are class instances.
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// This information is retrieved using #get_class_instances.
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list<name> m_trans_instances;
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list<name> m_instances;
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justification m_jst;
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unsigned m_depth;
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bool m_displayed_trace_header;
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class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
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expr const & meta, expr const & meta_type,
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list<expr> const & local_insts, list<name> const & trans_insts, list<name> const & instances,
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justification const & j, unsigned depth):
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choice_iterator(), m_C(C), m_ctx(ctx), m_meta(meta), m_meta_type(meta_type),
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m_local_instances(local_insts), m_trans_instances(trans_insts), m_instances(instances), m_jst(j), m_depth(depth) {
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if (m_depth > m_C->get_max_depth()) {
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throw_class_exception("maximum class-instance resolution depth has been reached "
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"(the limit can be increased by setting option 'class.instance_max_depth') "
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"(the class-instance resolution trace can be visualized "
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"by setting option 'class.trace_instances')",
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C->get_main_meta());
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}
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m_displayed_trace_header = false;
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}
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constraints mk_constraints(constraint const & c, buffer<constraint> const & cs) {
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return cons(c, to_list(cs.begin(), cs.end()));
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}
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void trace(expr const & t, expr const & r) {
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if (!m_C->trace_instances())
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return;
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auto out = diagnostic(m_C->env(), m_C->ios());
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if (!m_displayed_trace_header && m_depth == 0) {
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if (auto fname = m_C->get_file_name()) {
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out << fname << ":";
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}
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if (auto pos = m_C->get_pos()) {
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out << pos->first << ":" << pos->second << ":";
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}
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out << " class-instance resolution trace" << endl;
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m_displayed_trace_header = true;
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}
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for (unsigned i = 0; i < m_depth; i++)
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out << " ";
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if (m_depth > 0)
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out << "[" << m_depth << "] ";
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out << m_meta << " : " << t << " := " << r << endl;
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}
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optional<constraints> try_instance(expr const & inst, expr const & inst_type, bool use_globals) {
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type_checker & tc = m_C->tc();
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name_generator & ngen = m_C->m_ngen;
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tag g = inst.get_tag();
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try {
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flet<local_context> scope(m_ctx, m_ctx);
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buffer<expr> locals;
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expr meta_type = m_meta_type;
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while (true) {
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meta_type = tc.whnf(meta_type).first;
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if (!is_pi(meta_type))
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break;
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expr local = mk_local(ngen.next(), binding_name(meta_type),
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binding_domain(meta_type), binding_info(meta_type));
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m_ctx.add_local(local);
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locals.push_back(local);
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meta_type = instantiate(binding_body(meta_type), local);
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}
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expr type = inst_type;
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expr r = inst;
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buffer<constraint> cs;
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while (true) {
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type = tc.whnf(type).first;
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if (!is_pi(type))
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break;
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expr arg;
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if (binding_info(type).is_inst_implicit()) {
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pair<expr, constraint> ac = mk_class_instance_elaborator(m_C, m_ctx, some_expr(binding_domain(type)),
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g, m_depth+1, use_globals);
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arg = ac.first;
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cs.push_back(ac.second);
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} else {
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arg = m_ctx.mk_meta(m_C->m_ngen, some_expr(binding_domain(type)), g);
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}
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r = mk_app(r, arg, g);
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type = instantiate(binding_body(type), arg);
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}
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r = Fun(locals, r);
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trace(meta_type, r);
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constraint c = mk_eq_cnstr(m_meta, r, m_jst);
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return optional<constraints>(mk_constraints(c, cs));
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} catch (exception &) {
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return optional<constraints>();
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}
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}
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optional<constraints> try_instance(name const & inst, bool use_globals) {
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environment const & env = m_C->env();
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if (auto decl = env.find(inst)) {
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name_generator & ngen = m_C->m_ngen;
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buffer<level> ls_buffer;
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unsigned num_univ_ps = decl->get_num_univ_params();
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for (unsigned i = 0; i < num_univ_ps; i++)
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ls_buffer.push_back(mk_meta_univ(ngen.next()));
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levels ls = to_list(ls_buffer.begin(), ls_buffer.end());
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expr inst_cnst = copy_tag(m_meta, mk_constant(inst, ls));
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expr inst_type = instantiate_type_univ_params(*decl, ls);
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return try_instance(inst_cnst, inst_type, use_globals);
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} else {
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return optional<constraints>();
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}
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}
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virtual optional<constraints> next() {
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while (!empty(m_local_instances)) {
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expr inst = head(m_local_instances);
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m_local_instances = tail(m_local_instances);
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if (!is_local(inst))
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continue;
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bool use_globals = true;
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if (auto r = try_instance(inst, mlocal_type(inst), use_globals))
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return r;
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}
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while (!empty(m_trans_instances)) {
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bool use_globals = false;
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name inst = head(m_trans_instances);
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m_trans_instances = tail(m_trans_instances);
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if (auto cs = try_instance(inst, use_globals))
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return cs;
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}
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while (!empty(m_instances)) {
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bool use_globals = true;
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|
name inst = head(m_instances);
|
|
m_instances = tail(m_instances);
|
|
if (auto cs = try_instance(inst, use_globals))
|
|
return cs;
|
|
}
|
|
return optional<constraints>();
|
|
}
|
|
};
|
|
|
|
// Remarks:
|
|
// - we only use get_class_instances and get_class_derived_trans_instances when use_globals is true
|
|
static constraint mk_class_instance_cnstr(std::shared_ptr<class_instance_context> const & C,
|
|
local_context const & ctx, expr const & m, unsigned depth, bool use_globals) {
|
|
environment const & env = C->env();
|
|
justification j = mk_failed_to_synthesize_jst(env, m);
|
|
auto choice_fn = [=](expr const & meta, expr const & meta_type, substitution const &, name_generator const &) {
|
|
if (auto cls_name_it = is_ext_class(C->tc(), meta_type)) {
|
|
name cls_name = *cls_name_it;
|
|
list<expr> const & ctx_lst = ctx.get_data();
|
|
list<expr> local_insts;
|
|
if (C->use_local_instances())
|
|
local_insts = get_local_instances(C->tc(), ctx_lst, cls_name);
|
|
list<name> trans_insts, insts;
|
|
if (use_globals) {
|
|
if (depth == 0 && C->use_trans_instances())
|
|
trans_insts = get_class_derived_trans_instances(env, cls_name);
|
|
insts = get_class_instances(env, cls_name);
|
|
}
|
|
if (empty(local_insts) && empty(insts))
|
|
return lazy_list<constraints>(); // nothing to be done
|
|
// we are always strict with placeholders associated with classes
|
|
return choose(std::make_shared<class_instance_elaborator>(C, ctx, meta, meta_type, local_insts, trans_insts, insts, j, depth));
|
|
} else {
|
|
// do nothing, type is not a class...
|
|
return lazy_list<constraints>(constraints());
|
|
}
|
|
};
|
|
bool owner = false;
|
|
return mk_choice_cnstr(m, choice_fn, to_delay_factor(cnstr_group::Basic), owner, j);
|
|
}
|
|
|
|
static pair<expr, constraint> mk_class_instance_elaborator(std::shared_ptr<class_instance_context> const & C, local_context const & ctx,
|
|
optional<expr> const & type, tag g, unsigned depth, bool use_globals) {
|
|
expr m = ctx.mk_meta(C->m_ngen, type, g);
|
|
constraint c = mk_class_instance_cnstr(C, ctx, m, depth, use_globals);
|
|
return mk_pair(m, c);
|
|
}
|
|
|
|
static constraint mk_class_instance_root_cnstr(std::shared_ptr<class_instance_context> const & C, local_context const & _ctx,
|
|
expr const & m, bool is_strict, unifier_config const & cfg, delay_factor const & factor) {
|
|
environment const & env = C->env();
|
|
justification j = mk_failed_to_synthesize_jst(env, m);
|
|
|
|
auto choice_fn = [=](expr const & meta, expr const & meta_type, substitution const & s,
|
|
name_generator && ngen) {
|
|
environment const & env = C->env();
|
|
auto cls_name_it = is_ext_class(C->tc(), meta_type);
|
|
if (!cls_name_it) {
|
|
// do nothing, since type is not a class.
|
|
return lazy_list<constraints>(constraints());
|
|
}
|
|
local_context ctx = _ctx.instantiate(substitution(s));
|
|
pair<expr, justification> mj = update_meta(meta, s);
|
|
expr new_meta = mj.first;
|
|
justification new_j = mj.second;
|
|
unsigned depth = 0;
|
|
bool use_globals = true;
|
|
constraint c = mk_class_instance_cnstr(C, ctx, new_meta, depth, use_globals);
|
|
unifier_config new_cfg(cfg);
|
|
new_cfg.m_discard = false;
|
|
new_cfg.m_use_exceptions = false;
|
|
new_cfg.m_pattern = true;
|
|
new_cfg.m_kind = C->m_conservative ? unifier_kind::VeryConservative : unifier_kind::Liberal;
|
|
|
|
auto to_cnstrs_fn = [=](substitution const & subst, constraints const & cnstrs) -> constraints {
|
|
substitution new_s = subst;
|
|
// some constraints may have been postponed (example: universe level constraints)
|
|
constraints postponed = map(cnstrs,
|
|
[&](constraint const & c) {
|
|
// we erase internal justifications
|
|
return update_justification(c, mk_composite1(j, new_j));
|
|
});
|
|
metavar_closure cls(new_meta);
|
|
cls.add(meta_type);
|
|
constraints cs = cls.mk_constraints(new_s, new_j);
|
|
return append(cs, postponed);
|
|
};
|
|
|
|
auto no_solution_fn = [=]() {
|
|
if (is_strict)
|
|
return lazy_list<constraints>();
|
|
else
|
|
return lazy_list<constraints>(constraints());
|
|
};
|
|
|
|
unify_result_seq seq1 = unify(env, 1, &c, std::move(ngen), substitution(), new_cfg);
|
|
unify_result_seq seq2 = filter(seq1, [=](pair<substitution, constraints> const & p) {
|
|
substitution new_s = p.first;
|
|
expr result = new_s.instantiate(new_meta);
|
|
// We only keep complete solutions (modulo universe metavariables)
|
|
return !has_expr_metavar_relaxed(result);
|
|
});
|
|
|
|
if (try_multiple_instances(env, *cls_name_it)) {
|
|
lazy_list<constraints> seq3 = map2<constraints>(seq2, [=](pair<substitution, constraints> const & p) {
|
|
return to_cnstrs_fn(p.first, p.second);
|
|
});
|
|
if (is_strict) {
|
|
return seq3;
|
|
} else {
|
|
// make sure it does not fail by appending empty set of constraints
|
|
return append(seq3, lazy_list<constraints>(constraints()));
|
|
}
|
|
} else {
|
|
auto p = seq2.pull();
|
|
if (!p)
|
|
return no_solution_fn();
|
|
else
|
|
return lazy_list<constraints>(to_cnstrs_fn(p->first.first, p->first.second));
|
|
}
|
|
};
|
|
bool owner = false;
|
|
return mk_choice_cnstr(m, choice_fn, factor, owner, j);
|
|
}
|
|
|
|
/** \brief Create a metavariable, and attach choice constraint for generating
|
|
solutions using class-instances
|
|
*/
|
|
pair<expr, constraint> mk_old_class_instance_elaborator(
|
|
environment const & env, io_state const & ios, local_context const & ctx,
|
|
name const & prefix, optional<name> const & suffix, bool use_local_instances,
|
|
bool is_strict, optional<expr> const & type, tag g, unifier_config const & cfg,
|
|
pos_info_provider const * pip) {
|
|
auto C = std::make_shared<class_instance_context>(env, ios, prefix, use_local_instances);
|
|
expr m = ctx.mk_meta(C->m_ngen, suffix, type, g);
|
|
C->set_main_meta(m);
|
|
if (pip)
|
|
C->set_pos(pip->get_file_name(), pip->get_pos_info(m));
|
|
constraint c = mk_class_instance_root_cnstr(C, ctx, m, is_strict, cfg, delay_factor());
|
|
return mk_pair(m, c);
|
|
}
|
|
|
|
pair<expr, constraint> mk_class_instance_elaborator(
|
|
environment const & env, io_state const & ios, local_context const & ctx,
|
|
name const & prefix, optional<name> const & suffix, bool use_local_instances,
|
|
bool is_strict, optional<expr> const & type, tag g,
|
|
pos_info_provider const * pip) {
|
|
if (is_standard(env) || get_class_force_new(ios.get_options())) {
|
|
return mk_new_class_instance_elaborator(env, ios, ctx, prefix, suffix, use_local_instances,
|
|
is_strict, type, g, pip);
|
|
} else {
|
|
unifier_config cfg(ios.get_options(), true /* use exceptions */, true /* discard */);
|
|
return mk_old_class_instance_elaborator(env, ios, ctx, prefix, suffix, use_local_instances,
|
|
is_strict, type, g, cfg, pip);
|
|
}
|
|
}
|
|
}
|