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feat(frontends/lean/placeholder_elaborator): add 'elaborator.unique_class_instances' flag, closes #265

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By default, it is false.
When it is true, class instance resolution generates an error if there
is more than one solution.
This commit is contained in:
Leonardo de Moura 2014-10-30 14:20:34 -07:00
parent 64c3ba7b74
commit 79f73c44dc
3 changed files with 83 additions and 23 deletions
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3
src/frontends/lean/init_module.cpp
View file

@ -24,6 +24,7 @@ Author: Leonardo de Moura
#include "frontends/lean/parse_table.h"
#include "frontends/lean/token_table.h"
#include "frontends/lean/info_tactic.h"
#include "frontends/lean/placeholder_elaborator.h"
#include "frontends/lean/scanner.h"
#include "frontends/lean/pp.h"
#include "frontends/lean/server.h"
@ -52,10 +53,12 @@ void initialize_frontend_lean_module() {
initialize_info_manager();
initialize_info_tactic();
initialize_pp();
initialize_placeholder_elaborator();
initialize_server();
}
void finalize_frontend_lean_module() {
finalize_server();
finalize_placeholder_elaborator();
finalize_pp();
finalize_info_tactic();
finalize_info_manager();

100
src/frontends/lean/placeholder_elaborator.cpp
View file

@ -6,6 +6,7 @@ Author: Leonardo de Moura
*/
#include "util/lazy_list_fn.h"
#include "util/flet.h"
#include "util/sexpr/option_declarations.h"
#include "kernel/instantiate.h"
#include "kernel/for_each_fn.h"
#include "kernel/abstract.h"
@ -18,7 +19,28 @@ Author: Leonardo de Moura
#include "frontends/lean/local_context.h"
#include "frontends/lean/choice_iterator.h"
#ifndef LEAN_DEFAULT_ELABORATOR_UNIQUE_CLASS_INSTANCES
#define LEAN_DEFAULT_ELABORATOR_UNIQUE_CLASS_INSTANCES false
#endif
namespace lean {
static name * g_elaborator_unique_class_instances = nullptr;
void initialize_placeholder_elaborator() {
g_elaborator_unique_class_instances = new name{"elaborator", "unique_class_instances"};
register_bool_option(*g_elaborator_unique_class_instances, LEAN_DEFAULT_ELABORATOR_UNIQUE_CLASS_INSTANCES,
"(elaborator) generate an error if there is more than one solution "
"for a class-instance resolution problem");
}
void finalize_placeholder_elaborator() {
delete g_elaborator_unique_class_instances;
}
bool get_elaborator_unique_class_instances(options const & o) {
return o.get_bool(*g_elaborator_unique_class_instances, LEAN_DEFAULT_ELABORATOR_UNIQUE_CLASS_INSTANCES);
}
/** \brief Context for handling placeholder metavariable choice constraint */
struct placeholder_context {
io_state m_ios;
@ -217,6 +239,7 @@ constraint mk_placeholder_root_cnstr(std::shared_ptr<placeholder_context> const
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 const & ngen) {
if (!is_ext_class(C->tc(), meta_type)) {
@ -230,32 +253,63 @@ constraint mk_placeholder_root_cnstr(std::shared_ptr<placeholder_context> const
unifier_config new_cfg(cfg);
new_cfg.m_discard = false;
new_cfg.m_use_exceptions = false;
auto to_cnstrs_fn = [=](substitution const & subst, constraints const & cnstrs) {
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);
bool relax = C->m_relax;
constraints cs = cls.mk_constraints(new_s, new_j, relax);
return append(cs, postponed);
};
unify_result_seq seq1 = unify(env, 1, &c, 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 solution (modulo universe metavariables)
return !has_expr_metavar_relaxed(result);
});
lazy_list<constraints> seq3 = map2<constraints>(seq2, [=](pair<substitution, constraints> const & p) {
substitution new_s = p.first;
if (get_elaborator_unique_class_instances(C->m_ios.get_options())) {
optional<expr> solution;
substitution subst;
constraints cnstrs;
for_each(seq1, [&](pair<substitution, constraints> const & p) {
subst = p.first;
cnstrs = p.second;
expr next_solution = subst.instantiate(new_meta);
if (solution) {
// TODO(Leo): more informative error message
throw exception("ambiguous class-instance resolution, there is more than one solution");
} else {
solution = next_solution;
}
});
if (!solution) {
if (is_strict)
return lazy_list<constraints>();
else
return lazy_list<constraints>(constraints());
} else {
// some constraints may have been postponed (example: universe level constraints)
constraints postponed = map(p.second,
[&](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);
bool relax = C->m_relax;
constraints cs = cls.mk_constraints(new_s, new_j, relax);
return append(cs, postponed);
});
if (is_strict) {
return seq3;
return lazy_list<constraints>(to_cnstrs_fn(subst, cnstrs));
}
} else {
// make sure it does not fail by appending empty set of constraints
return append(seq3, lazy_list<constraints>(constraints()));
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);
});
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()));
}
}
};
bool owner = false;

3
src/frontends/lean/placeholder_elaborator.h
View file

@ -29,4 +29,7 @@ pair<expr, constraint> mk_placeholder_elaborator(
environment const & env, io_state const & ios, local_context const & ctx,
name const & prefix, optional<name> const & suffix, bool relax_opaque, bool use_local_instances,
bool is_strict, optional<expr> const & type, tag g, unifier_config const & cfg);
void initialize_placeholder_elaborator();
void finalize_placeholder_elaborator();
}