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feat(library/app_builder): new app_builder on top of type_context

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The new version is more robust, and invokes type class resolution if needed.
This commit is contained in:
Leonardo de Moura 2015-11-01 12:02:49 -08:00
parent 87ec7383dd
commit ee0974650a
6 changed files with 245 additions and 231 deletions
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14
src/frontends/lean/builtin_cmds.cpp
View file

@ -1141,22 +1141,26 @@ static environment relevant_thms_cmd(parser & p) {
static environment app_builder_cmd(parser & p) {
environment const & env = p.env();
type_checker tc(env);
app_builder b(tc);
auto pos = p.pos();
app_builder b(env);
name c = p.check_constant_next("invalid #app_builder command, constant expected");
p.check_token_next(get_lparen_tk(), "invalid #app_builder command, '(' expected");
buffer<expr> args;
while (true) {
args.push_back(p.parse_expr());
expr e; level_param_names ls;
std::tie(e, ls) = parse_local_expr(p);
args.push_back(e);
if (!p.curr_is_token(get_comma_tk()))
break;
p.next();
}
p.check_token_next(get_rparen_tk(), "invalid #app_builder command, ')' expected");
if (auto r = b.mk_app(c, args.size(), args.data())) {
p.regular_stream() << *r << "\n";
type_checker tc(env);
expr t = tc.check_ignore_undefined_universes(*r).first;
p.regular_stream() << *r << " : " << t << "\n";
} else {
p.regular_stream() << "<failed>\n";
throw parser_error(sstream() << "failed to build application for '" << c << "'", pos);
}
return env;
}

389
src/library/app_builder.cpp
View file

@ -10,241 +10,212 @@ Author: Leonardo de Moura
#include "library/match.h"
#include "library/app_builder.h"
#include "library/kernel_bindings.h"
#include "library/tmp_type_context.h"
namespace lean {
struct app_builder::imp {
// For each declaration we associate the number of explicit arguments provided to
// it, and which of them are used to infer the implicit arguments.
struct decl_info {
unsigned m_nargs; // total number of explicit arguments
list<unsigned> m_used_idxs; // which ones are used to infer implicit arguments
decl_info(unsigned nargs, list<unsigned> const & used_idxs):
m_nargs(nargs), m_used_idxs(used_idxs) {}
decl_info() {}
tmp_type_context m_ctx;
struct entry {
unsigned m_num_umeta;
unsigned m_num_emeta;
expr m_app;
list<optional<expr>> m_inst_args; // "mask" of implicit instance arguments
list<expr> m_expl_args; // metavars for explicit arguments
/*
IMPORTANT: for m_inst_args we store the arguments in reverse order.
For example, the first element in the list indicates whether the last argument
is an instance implicit argument or not. If it is not none, then the element
is the associated metavariable
m_expl_args are also stored in reverse order
*/
};
struct cache_key {
struct key {
name m_name;
list<expr> m_arg_types;
unsigned m_num_expl;
unsigned m_hash;
cache_key(name const & n, unsigned num_arg_types, expr const * arg_types):
m_name(n), m_arg_types(to_list(arg_types, arg_types + num_arg_types)) {
m_hash = m_name.hash();
for (unsigned i = 0; i < num_arg_types; i++)
m_hash = hash(m_hash, arg_types[i].hash());
}
};
struct cache_key_hash_fn {
unsigned operator()(cache_key const & e) const { return e.m_hash; }
};
struct cache_key_equal_fn {
bool operator()(cache_key const & e1, cache_key const & e2) const {
return
e1.m_name == e2.m_name &&
e1.m_arg_types == e2.m_arg_types;
}
};
// If nil, then the mask is composed of the last m_num_expl arguments.
// If nonnil, then the mask is NOT of the form [false*, true*]
list<bool> m_mask;
// The cache stores a mapping (decl + type of explicit arguments ==> term t).
// If t is closed term, then we obtain the final application by using
// mk_app(t, explicit_args)
// If t contains free variables, then we obtain the final application by using
// instantiate(t, explicit_args)
typedef scoped_map<cache_key, expr, cache_key_hash_fn, cache_key_equal_fn> cache;
type_checker & m_tc;
whnf_match_plugin m_plugin;
name_map<decl_info> m_decl_info;
cache m_cache;
buffer<levels> m_levels;
imp(type_checker & tc):m_tc(tc), m_plugin(tc) {
m_levels.push_back(levels());
}
// Make sure m_levels contains at least nlvls metavariable universe levels
void ensure_levels(unsigned nlvls) {
while (m_levels.size() <= nlvls) {
level new_lvl = mk_idx_metauniv(m_levels.size() - 1);
levels new_lvls = append(m_levels.back(), levels(new_lvl));
m_levels.push_back(new_lvls);
}
}
// We say the given mask is simple if it is of the form (false*, true*).
// That is, a block of false followed by a blocked of true
static bool is_simple_mask(buffer<bool> & explicit_mask) {
static bool is_simple(list<bool> const & mask) {
bool found_true = false;
for (bool const & b : explicit_mask) {
if (b)
for (bool b : mask) {
if (b) {
found_true = true;
else if (found_true)
} else if (found_true) {
// found (true, false)
return false;
}
}
return true;
}
key(name const & c, unsigned n):
m_name(c), m_num_expl(n),
m_hash(::lean::hash(c.hash(), n)) {
}
key(name const & c, list<bool> const & m):
m_name(c), m_num_expl(length(m)) {
m_hash = ::lean::hash(c.hash(), m_num_expl);
if (!is_simple(m)) {
m_mask = m;
for (bool b : m) {
if (b)
m_hash = ::lean::hash(m_hash, 17u);
else
m_hash = ::lean::hash(m_hash, 31u);
}
}
}
bool check_invariant() const {
lean_assert(empty(m_mask) || length(m_mask) == m_num_expl);
lean_assert(empty(m_mask) || !is_simple(m_mask));
return true;
}
unsigned hash() const {
return m_hash;
}
friend bool operator==(key const & k1, key const & k2) {
return k1.m_name == k2.m_name && k1.m_num_expl == k2.m_num_expl && k1.m_mask == k2.m_mask;
}
};
struct key_hash_fn {
unsigned operator()(key const & k) const { return k.hash(); }
};
typedef std::unordered_map<key, entry, key_hash_fn> map;
map m_map;
imp(environment const & env, io_state const & ios, reducible_behavior b):
m_ctx(env, ios, b) {
}
levels mk_metavars(declaration const & d, buffer<expr> & mvars, buffer<optional<expr>> & inst_args) {
m_ctx.clear();
unsigned num_univ = d.get_num_univ_params();
buffer<level> lvls_buffer;
for (unsigned i = 0; i < num_univ; i++) {
lvls_buffer.push_back(m_ctx.mk_uvar());
}
levels lvls = to_list(lvls_buffer);
expr type = m_ctx.whnf(instantiate_type_univ_params(d, lvls));
while (is_pi(type)) {
expr mvar = m_ctx.mk_mvar(binding_domain(type));
if (binding_info(type).is_inst_implicit())
inst_args.push_back(some_expr(mvar));
else
inst_args.push_back(none_expr());
mvars.push_back(mvar);
type = m_ctx.whnf(instantiate(binding_body(type), mvar));
}
return lvls;
}
optional<entry> get_entry(name const & c, unsigned nargs) {
key k(c, nargs);
lean_assert(k.check_invariant());
auto it = m_map.find(k);
if (it == m_map.end()) {
if (auto d = m_ctx.env().find(c)) {
buffer<expr> mvars;
buffer<optional<expr>> inst_args;
levels lvls = mk_metavars(*d, mvars, inst_args);
if (nargs > mvars.size())
return optional<entry>(); // insufficient number of arguments
entry e;
e.m_num_umeta = d->get_num_univ_params();
e.m_num_emeta = mvars.size();
e.m_app = ::lean::mk_app(mk_constant(c, lvls), mvars);
e.m_inst_args = reverse_to_list(inst_args.begin(), inst_args.end());
e.m_expl_args = reverse_to_list(mvars.begin() + mvars.size() - nargs, mvars.end());
m_map.insert(mk_pair(k, e));
return optional<entry>(e);
} else {
return optional<entry>(); // unknown decl
}
} else {
return optional<entry>(it->second);
}
}
bool check_all_assigned(entry const & e) {
lean_assert(e.m_num_emeta == length(e.m_inst_args));
// recall that the flags at e.m_inst_args are stored in reverse order.
// For example, the first flag in the list indicates whether the last argument
// is an instance implicit argument or not.
unsigned i = e.m_num_emeta;
for (optional<expr> const & inst_arg : e.m_inst_args) {
lean_assert(i > 0);
--i;
if (inst_arg) {
expr type = m_ctx.instantiate_uvars_mvars(mlocal_type(*inst_arg));
if (auto v = m_ctx.mk_class_instance(type)) {
if (!m_ctx.force_assign(*inst_arg, *v))
return false;
} else {
return false;
}
}
if (!m_ctx.is_mvar_assigned(i))
return false;
}
for (unsigned i = 0; i < e.m_num_umeta; i++) {
if (!m_ctx.is_uvar_assigned(i))
return false;
}
return true;
}
void save_decl_info(declaration const & d, unsigned nargs, buffer<unsigned> const & used_idxs) {
if (!m_decl_info.contains(d.get_name())) {
m_decl_info.insert(d.get_name(), decl_info(nargs, to_list(used_idxs)));
}
}
optional<expr> mk_app_core(declaration const & d, unsigned nargs, expr const * args, bool use_cache) {
unsigned num_univs = d.get_num_univ_params();
ensure_levels(num_univs);
expr type = instantiate_type_univ_params(d, m_levels[num_univs]);
buffer<optional<level>> lsubst;
buffer<optional<expr>> esubst;
lsubst.resize(num_univs, none_level());
constraint_seq cs;
buffer<unsigned> used_idxs;
buffer<expr> used_types;
buffer<bool> explicit_mask;
buffer<expr> domain_types;
unsigned idx = 0;
while (is_pi(type)) {
explicit_mask.push_back(is_explicit(binding_info(type)));
esubst.push_back(none_expr());
domain_types.push_back(binding_domain(type));
// TODO(Leo): perhaps, we should cache the result of this while-loop.
// The result of this computation can be reused in future calls.
expr meta = mk_idx_metavar(idx, binding_domain(type));
idx++;
type = instantiate(binding_body(type), meta);
}
unsigned i = domain_types.size();
unsigned j = nargs;
while (i > 0) {
optional<expr> mk_app(name const & c, unsigned nargs, expr const * args) {
optional<entry> e = get_entry(c, nargs);
if (!e)
return none_expr();
m_ctx.clear();
m_ctx.set_next_uvar_idx(e->m_num_umeta);
m_ctx.set_next_mvar_idx(e->m_num_emeta);
unsigned i = nargs;
for (auto m : e->m_expl_args) {
if (i == 0)
return none_expr();
--i;
if (explicit_mask[i]) {
if (j == 0)
return none_expr();
--j;
expr arg_type = m_tc.infer(args[j], cs);
if (cs)
return none_expr();
bool assigned = false;
if (!match(domain_types[i], arg_type, lsubst, esubst,
nullptr, nullptr, &m_plugin, &assigned))
return none_expr();
if (assigned && use_cache) {
used_idxs.push_back(j);
used_types.push_back(arg_type);
}
esubst[i] = some_expr(args[j]);
} else {
if (!esubst[i])
return none_expr();
expr arg_type = m_tc.infer(*esubst[i], cs);
if (cs)
return none_expr();
if (!match(domain_types[i], arg_type, lsubst, esubst,
nullptr, nullptr, &m_plugin))
if (!m_ctx.assign(m, args[i]))
return none_expr();
}
}
bool has_unassigned_lvls = std::find(lsubst.begin(), lsubst.end(), none_level()) != lsubst.end();
if (j > 0 || has_unassigned_lvls)
if (!check_all_assigned(*e))
return none_expr();
if (use_cache)
save_decl_info(d, nargs, used_idxs);
buffer<level> r_lvls;
for (optional<level> const & l : lsubst)
r_lvls.push_back(*l);
buffer<expr> r_args;
for (optional<expr> const & o : esubst)
r_args.push_back(*o);
lean_assert(explicit_mask.size() == r_args.size());
if (!use_cache) {
return some_expr(::lean::mk_app(mk_constant(d.get_name(), to_list(r_lvls)), r_args.size(), r_args.data()));
} else if (is_simple_mask(explicit_mask)) {
expr f = ::lean::mk_app(mk_constant(d.get_name(), to_list(r_lvls)), r_args.size() - nargs, r_args.data());
if (use_cache) {
cache_key k(d.get_name(), used_types.size(), used_types.data());
m_cache.insert(k, f);
}
return some_expr(::lean::mk_app(f, nargs, r_args.end() - nargs));
} else {
buffer<expr> imp_args;
buffer<expr> expl_args;
for (unsigned i = 0; i < explicit_mask.size(); i++) {
if (explicit_mask[i]) {
imp_args.push_back(mk_var(expl_args.size()));
expl_args.push_back(r_args[i]);
} else {
imp_args.push_back(r_args[i]);
}
}
expr f = ::lean::mk_app(mk_constant(d.get_name(), to_list(r_lvls)), imp_args.size(), imp_args.data());
if (use_cache) {
cache_key k(d.get_name(), used_types.size(), used_types.data());
m_cache.insert(k, f);
}
return some_expr(instantiate(f, expl_args.size(), expl_args.data()));
}
return some_expr(m_ctx.instantiate_uvars_mvars(e->m_app));
}
optional<expr> mk_app(declaration const & d, unsigned nargs, expr const * args, bool use_cache) {
if (use_cache) {
if (auto info = m_decl_info.find(d.get_name())) {
if (info->m_nargs != nargs)
optional<expr> mk_app(name const & /* c */, unsigned /* mask_sz */, bool const * /* mask */, expr const * /* args */) {
return none_expr();
buffer<expr> arg_types;
constraint_seq cs;
for (unsigned idx : info->m_used_idxs) {
lean_assert(idx < nargs);
expr t = m_tc.infer(args[idx], cs);
if (cs)
return none_expr(); // constraint was generated
arg_types.push_back(t);
}
cache_key k(d.get_name(), arg_types.size(), arg_types.data());
auto it = m_cache.find(k);
if (it != m_cache.end()) {
if (closed(it->second))
return some_expr(::lean::mk_app(it->second, nargs, args));
else
return some_expr(instantiate(it->second, nargs, args));
} else {
return mk_app_core(d, nargs, args, use_cache);
}
}
}
return mk_app_core(d, nargs, args, use_cache);
}
void push() {
m_cache.push();
}
void pop() {
m_cache.pop();
}
};
app_builder::app_builder(type_checker & tc):m_ptr(new imp(tc)) {}
app_builder::app_builder(environment const & env, io_state const & ios, reducible_behavior b):
m_ptr(new imp(env, ios, b)) {
}
app_builder::app_builder(environment const & env, reducible_behavior b):
app_builder(env, get_dummy_ios(), b) {
}
app_builder::~app_builder() {}
optional<expr> app_builder::mk_app(declaration const & d, unsigned nargs, expr const * args, bool use_cache) {
return m_ptr->mk_app(d, nargs, args, use_cache);
optional<expr> app_builder::mk_app(name const & c, unsigned nargs, expr const * args) {
return m_ptr->mk_app(c, nargs, args);
}
optional<expr> app_builder::mk_app(name const & n, unsigned nargs, expr const * args, bool use_cache) {
declaration const & d = m_ptr->m_tc.env().get(n);
return mk_app(d, nargs, args, use_cache);
optional<expr> app_builder::mk_app(name const & c, unsigned mask_sz, bool const * mask, expr const * args) {
return m_ptr->mk_app(c, mask_sz, mask, args);
}
optional<expr> app_builder::mk_app(name const & n, std::initializer_list<expr> const & args, bool use_cache) {
return mk_app(n, args.size(), args.begin(), use_cache);
}
optional<expr> app_builder::mk_app(name const & n, expr const & a1, bool use_cache) {
return mk_app(n, {a1}, use_cache);
}
optional<expr> app_builder::mk_app(name const & n, expr const & a1, expr const & a2, bool use_cache) {
return mk_app(n, {a1, a2}, use_cache);
}
optional<expr> app_builder::mk_app(name const & n, expr const & a1, expr const & a2, expr const & a3, bool use_cache) {
return mk_app(n, {a1, a2, a3}, use_cache);
}
void app_builder::push() { m_ptr->push(); }
void app_builder::pop() { m_ptr->pop(); }
}

40
src/library/app_builder.h
View file

@ -6,7 +6,9 @@ Author: Leonardo de Moura
*/
#pragma once
#include <memory>
#include "kernel/type_checker.h"
#include "kernel/environment.h"
#include "library/io_state.h"
#include "library/reducible.h"
namespace lean {
/** \brief Helper for creating simple applications where some arguments are inferred using
@ -27,7 +29,8 @@ class app_builder {
struct imp;
std::unique_ptr<imp> m_ptr;
public:
app_builder(type_checker & tc);
app_builder(environment const & env, io_state const & ios, reducible_behavior b = UnfoldReducible);
app_builder(environment const & env, reducible_behavior b = UnfoldReducible);
~app_builder();
/** \brief Create an application (d.{_ ... _} _ ... _ args[0] ... args[nargs-1]).
The missing arguments and universes levels are inferred using type inference.
@ -38,21 +41,24 @@ public:
\remark This methods uses just higher-order pattern matching.
*/
optional<expr> mk_app(declaration const & d, unsigned nargs, expr const * args, bool use_cache = true);
optional<expr> mk_app(name const & n, unsigned nargs, expr const * args, bool use_cache = true);
optional<expr> mk_app(name const & n, std::initializer_list<expr> const & args, bool use_cache = true);
optional<expr> mk_app(name const & n, expr const & a1, bool use_cache = true);
optional<expr> mk_app(name const & n, expr const & a1, expr const & a2, bool use_cache = true);
optional<expr> mk_app(name const & n, expr const & a1, expr const & a2, expr const & a3, bool use_cache = true);
/** \brief Create a backtracking point for cached information.
\remark This method does not invoke tc->push()
*/
void push();
/** \brief Restore backtracking point, values cached between this push and the corresponding pop
are removed from the cache.
optional<expr> mk_app(name const & c, unsigned nargs, expr const * args);
\remark This method does not invoke tc->pop()
*/
void pop();
optional<expr> mk_app(name const & c, std::initializer_list<expr> const & args) {
return mk_app(c, args.size(), args.begin());
}
optional<expr> mk_app(name const & c, expr const & a1) {
return mk_app(c, {a1});
}
optional<expr> mk_app(name const & c, expr const & a1, expr const & a2) {
return mk_app(c, {a1, a2});
}
optional<expr> mk_app(name const & c, expr const & a1, expr const & a2, expr const & a3) {
return mk_app(c, {a1, a2, a3});
}
optional<expr> mk_app(name const & c, unsigned mask_sz, bool const * mask, expr const * args);
};
}

13
src/library/type_context.cpp
View file

@ -722,6 +722,19 @@ bool type_context::process_assignment(expr const & ma, expr const & v) {
}
}
bool type_context::assign(expr const & ma, expr const & v) {
expr const & f = get_app_fn(ma);
if (is_assigned(f)) {
return is_def_eq(ma, v);
} else {
return process_assignment(ma, v);
}
}
bool type_context::force_assign(expr const & ma, expr const & v) {
return process_assignment(ma, v);
}
/** \brief This is an auxiliary method for is_def_eq. It handles the "easy cases". */
lbool type_context::quick_is_def_eq(expr const & e1, expr const & e2) {
if (e1 == e2)

14
src/library/type_context.h
View file

@ -334,6 +334,20 @@ public:
optional<expr> mk_class_instance(expr const & type);
optional<expr> next_class_instance();
/** \brief Given \c ma of the form <tt>?m t_1 ... t_n</tt>, (try to) assign
?m to (an abstraction of) v. Return true if success and false otherwise.
\remark If ?m is already assigned, we just check if ma and v are definitionally
equal. */
bool assign(expr const & ma, expr const & v);
/** \brief Similar to \c assign, but it replaces the existing assignment
if the metavariable is already assigned.
Application: for implicit instance arguments, we want the term to be the one
generated by type class resolution even when it can be inferred by type inference. */
bool force_assign(expr const & ma, expr const & v);
/** \brief Clear internal caches used to speedup computation */
void clear_cache();

12
tests/lean/run/app_builder.lean
View file

@ -9,10 +9,16 @@ set_option pp.all true
#app_builder eq.trans (H1, H2)
#app_builder eq.symm (H1)
open algebra
variables A : Type
variables [s : comm_ring A]
open algebra nat
universe l
constant A : Type.{l}
constant s : comm_ring A
attribute s [instance]
variables x y : A
#app_builder eq.refl (s)
#app_builder eq.refl (x)
#app_builder add (x, y)
#app_builder add (a, b)
#app_builder mul (a, b)
#app_builder sub (x, y)