lean2/src/frontends/lean/builtin_exprs.cpp

480 lines
18 KiB
C++

/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "util/sstream.h"
#include "kernel/abstract.h"
#include "library/annotation.h"
#include "library/placeholder.h"
#include "library/explicit.h"
#include "library/aliases.h"
#include "library/scoped_ext.h"
#include "library/tactic/tactic.h"
#include "library/tactic/expr_to_tactic.h"
#include "library/tactic/exact_tactic.h"
#include "library/tactic/util.h"
#include "library/typed_expr.h"
#include "library/choice.h"
#include "library/let.h"
#include "frontends/lean/builtin_exprs.h"
#include "frontends/lean/token_table.h"
#include "frontends/lean/calc.h"
#include "frontends/lean/begin_end_ext.h"
#include "frontends/lean/parser.h"
#include "frontends/lean/extra_info.h"
#include "frontends/lean/util.h"
#include "frontends/lean/tokens.h"
#include "frontends/lean/info_tactic.h"
namespace lean {
namespace notation {
static expr parse_Type(parser & p, unsigned, expr const *, pos_info const & pos) {
if (p.curr_is_token(get_llevel_curly_tk())) {
p.next();
level l = p.parse_level();
p.check_token_next(get_rcurly_tk(), "invalid Type expression, '}' expected");
return p.save_pos(mk_sort(l), pos);
} else {
return p.save_pos(mk_sort(mk_level_placeholder()), pos);
}
}
static expr parse_let(parser & p, pos_info const & pos);
static expr parse_let_body(parser & p, pos_info const & pos) {
if (p.curr_is_token(get_comma_tk())) {
p.next();
return parse_let(p, pos);
} else if (p.curr_is_token(get_in_tk())) {
p.next();
return p.parse_expr();
} else {
throw parser_error("invalid let declaration, 'in' or ',' expected", p.pos());
}
}
static void parse_let_modifiers(parser & p, bool & is_visible) {
while (true) {
if (p.curr_is_token(get_visible_tk())) {
is_visible = true;
p.next();
} else {
break;
}
}
}
static expr parse_let(parser & p, pos_info const & pos) {
parser::local_scope scope1(p);
if (p.parse_local_notation_decl()) {
return parse_let_body(p, pos);
} else {
auto id_pos = p.pos();
name id = p.check_atomic_id_next("invalid let declaration, identifier expected");
bool is_visible = false;
optional<expr> type;
expr value;
parse_let_modifiers(p, is_visible);
if (p.curr_is_token(get_assign_tk())) {
p.next();
value = p.parse_expr();
} else if (p.curr_is_token(get_colon_tk())) {
p.next();
type = p.parse_expr();
p.check_token_next(get_assign_tk(), "invalid declaration, ':=' expected");
value = p.parse_expr();
} else {
parser::local_scope scope2(p);
buffer<expr> ps;
auto lenv = p.parse_binders(ps);
if (p.curr_is_token(get_colon_tk())) {
p.next();
type = p.parse_scoped_expr(ps, lenv);
type = Pi(ps, *type, p);
}
p.check_token_next(get_assign_tk(), "invalid let declaration, ':=' expected");
value = p.parse_scoped_expr(ps, lenv);
value = Fun(ps, value, p);
}
expr v;
if (type)
v = p.save_pos(mk_typed_expr(*type, value), p.pos_of(value));
else
v = value;
v = p.save_pos(mk_let_value(v), id_pos);
p.add_local_expr(id, v);
expr b = parse_let_body(p, pos);
return p.save_pos(mk_let(id, v, b), pos);
}
}
static expr parse_let_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_let(p, pos);
}
static expr parse_placeholder(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.save_pos(mk_explicit_expr_placeholder(), pos);
}
static environment open_tactic_namespace(parser & p) {
if (!is_tactic_namespace_open(p.env())) {
environment env = using_namespace(p.env(), p.ios(), "tactic");
env = add_aliases(env, name("tactic"), name());
return env;
} else {
return p.env();
}
}
static expr parse_by(parser & p, unsigned, expr const *, pos_info const & pos) {
environment env = open_tactic_namespace(p);
parser::undef_id_to_local_scope scope(p);
parser::local_scope scope2(p, env);
parser::undef_id_to_local_scope scope1(p);
p.next();
expr t = p.parse_expr();
return p.mk_by(t, pos);
}
static expr parse_begin_end_core(parser & p, pos_info const & pos) {
if (!p.has_tactic_decls())
throw parser_error("invalid 'begin-end' expression, tactic module has not been imported", pos);
environment env = open_tactic_namespace(p);
parser::local_scope scope2(p, env);
parser::undef_id_to_local_scope scope1(p);
p.next();
optional<expr> pre_tac = get_begin_end_pre_tactic(env);
buffer<expr> tacs;
bool first = true;
while (!p.curr_is_token(get_end_tk())) {
if (first) {
first = false;
} else {
auto pos = p.pos();
p.check_token_next(get_comma_tk(), "invalid 'begin-end' expression, ',' expected");
if (p.collecting_info()) {
expr info_tac = p.save_pos(mk_info_tactic_expr(), pos);
tacs.push_back(mk_begin_end_element_annotation(info_tac));
}
}
if (p.curr_is_token(get_end_tk()))
break;
bool use_exact = (p.curr_is_token(get_have_tk()) || p.curr_is_token(get_show_tk()) ||
p.curr_is_token(get_assume_tk()) || p.curr_is_token(get_take_tk()) ||
p.curr_is_token(get_fun_tk()));
auto pos = p.pos();
expr tac = p.parse_expr();
if (use_exact)
tac = p.mk_app(get_exact_tac_fn(), tac, pos);
if (pre_tac)
tac = p.mk_app({get_and_then_tac_fn(), *pre_tac, tac}, pos);
tac = mk_begin_end_element_annotation(tac);
tacs.push_back(tac);
}
auto end_pos = p.pos();
p.next();
if (tacs.empty()) {
expr tac = get_id_tac_fn();
if (pre_tac)
tac = p.mk_app({get_and_then_tac_fn(), *pre_tac, tac}, end_pos);
tac = mk_begin_end_element_annotation(tac);
tacs.push_back(tac);
}
expr r = tacs[0];
if (tacs.size() == 1) {
// Hack: for having a uniform squiggle placement for unsolved goals.
// That is, the result is always of the form and_then(...).
r = p.mk_app({get_and_then_tac_fn(), r, mk_begin_end_element_annotation(get_id_tac_fn())}, end_pos);
}
for (unsigned i = 1; i < tacs.size(); i++) {
r = p.mk_app({get_and_then_tac_fn(), r, tacs[i]}, end_pos);
}
return p.mk_by(mk_begin_end_annotation(r), end_pos);
}
static expr parse_begin_end(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_begin_end_core(p, pos);
}
static expr parse_proof_qed_core(parser & p, pos_info const & pos) {
expr r = p.save_pos(mk_proof_qed_annotation(p.parse_expr()), pos);
p.check_token_next(get_qed_tk(), "invalid proof-qed, 'qed' expected");
return r;
}
static expr parse_proof(parser & p, expr const & prop) {
if (p.curr_is_token(get_from_tk())) {
// parse: 'from' expr
p.next();
return p.parse_expr();
} else if (p.curr_is_token(get_proof_tk())) {
auto pos = p.pos();
p.next();
return parse_proof_qed_core(p, pos);
} else if (p.curr_is_token(get_begin_tk())) {
auto pos = p.pos();
return parse_begin_end_core(p, pos);
} else if (p.curr_is_token(get_by_tk())) {
// parse: 'by' tactic
auto pos = p.pos();
p.next();
expr t = p.parse_expr();
return p.mk_by(t, pos);
} else if (p.curr_is_token(get_using_tk())) {
// parse: 'using' locals* ',' proof
auto using_pos = p.pos();
p.next();
parser::local_scope scope(p);
buffer<expr> locals;
while (!p.curr_is_token(get_comma_tk())) {
auto id_pos = p.pos();
expr l = p.parse_expr();
if (!is_local(l))
throw parser_error("invalid 'using' declaration for 'have', local expected", id_pos);
p.add_local(l);
locals.push_back(l);
}
p.next(); // consume ','
expr pr = parse_proof(p, prop);
unsigned i = locals.size();
while (i > 0) {
--i;
expr l = locals[i];
pr = p.save_pos(Fun(l, pr), using_pos);
pr = p.save_pos(mk_app(pr, l), using_pos);
}
return pr;
} else {
throw parser_error("invalid expression, 'by', 'using' or 'from' expected", p.pos());
}
}
static expr parse_have_core(parser & p, pos_info const & pos, optional<expr> const & prev_local) {
auto id_pos = p.pos();
bool is_visible = false;
name id;
expr prop;
if (p.curr_is_token(get_visible_tk())) {
p.next();
is_visible = true;
id = p.mk_fresh_name();
prop = p.parse_expr();
} else if (p.curr_is_identifier()) {
id = p.get_name_val();
p.next();
if (p.curr_is_token(get_visible_tk())) {
p.next();
p.check_token_next(get_colon_tk(), "invalid 'have' declaration, ':' expected");
is_visible = true;
prop = p.parse_expr();
} else if (p.curr_is_token(get_colon_tk())) {
p.next();
prop = p.parse_expr();
} else {
expr left = p.id_to_expr(id, id_pos);
id = p.mk_fresh_name();
prop = p.parse_led(left);
}
} else {
id = p.mk_fresh_name();
prop = p.parse_expr();
}
p.check_token_next(get_comma_tk(), "invalid 'have' declaration, ',' expected");
expr proof;
if (prev_local) {
parser::local_scope scope(p);
p.add_local(*prev_local);
auto proof_pos = p.pos();
proof = parse_proof(p, prop);
proof = p.save_pos(Fun(*prev_local, proof), proof_pos);
proof = p.save_pos(mk_app(proof, *prev_local), proof_pos);
} else {
proof = parse_proof(p, prop);
}
p.check_token_next(get_comma_tk(), "invalid 'have' declaration, ',' expected");
parser::local_scope scope(p);
binder_info bi = mk_contextual_info(is_visible);
expr l = p.save_pos(mk_local(id, prop, bi), pos);
p.add_local(l);
expr body;
if (p.curr_is_token(get_then_tk())) {
auto then_pos = p.pos();
p.next();
p.check_token_next(get_have_tk(), "invalid 'then have' declaration, 'have' expected");
body = parse_have_core(p, then_pos, some_expr(l));
} else {
body = p.parse_expr();
}
// remark: mk_contextual_info(false) informs the elaborator that prop should not occur inside metavariables.
body = abstract(body, l);
expr r = p.save_pos(mk_have_annotation(p.save_pos(mk_lambda(id, prop, body, bi), pos)), pos);
return p.mk_app(r, proof, pos);
}
static expr parse_have(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_have_core(p, pos, none_expr());
}
static name * H_show = nullptr;
static expr parse_show(parser & p, unsigned, expr const *, pos_info const & pos) {
expr prop = p.parse_expr();
p.check_token_next(get_comma_tk(), "invalid 'show' declaration, ',' expected");
expr proof = parse_proof(p, prop);
expr b = p.save_pos(mk_lambda(*H_show, prop, Var(0)), pos);
expr r = p.mk_app(b, proof, pos);
return p.save_pos(mk_show_annotation(r), pos);
}
static name * g_exists_elim = nullptr;
static expr parse_obtain(parser & p, unsigned, expr const *, pos_info const & pos) {
if (!p.env().find(*g_exists_elim))
throw parser_error("invalid use of 'obtain' expression, environment does not contain 'exists_elim' theorem", pos);
// exists_elim {A : Type} {P : A → Prop} {B : Prop} (H1 : ∃ x : A, P x) (H2 : ∀ (a : A) (H : P a), B)
buffer<expr> ps;
auto b_pos = p.pos();
environment env = p.parse_binders(ps);
unsigned num_ps = ps.size();
if (num_ps < 2)
throw parser_error("invalid 'obtain' expression, at least 2 binders expected", b_pos);
bool is_visible = false;
if (p.curr_is_token(get_visible_tk())) {
p.next();
is_visible = true;
}
if (!is_visible) {
expr H = ps[num_ps-1];
ps[num_ps-1] = update_local(H, mlocal_type(H), local_info(H).update_contextual(false));
}
p.check_token_next(get_comma_tk(), "invalid 'obtain' expression, ',' expected");
p.check_token_next(get_from_tk(), "invalid 'obtain' expression, 'from' expected");
expr H1 = p.parse_expr();
p.check_token_next(get_comma_tk(), "invalid 'obtain' expression, ',' expected");
expr b = p.parse_scoped_expr(ps, env);
expr H = ps[num_ps-1];
name H_name = local_pp_name(H);
unsigned i = num_ps-1;
while (i > 1) {
--i;
expr a = ps[i];
expr H_aux = mk_local(p.mk_fresh_name(), H_name.append_after(i), mk_expr_placeholder(), mk_contextual_info(false));
expr H2 = Fun({a, H}, b);
b = mk_app(mk_constant(*g_exists_elim), H_aux, H2);
H = H_aux;
}
expr a = ps[0];
expr H2 = Fun({a, H}, b);
expr r = mk_app(mk_constant(*g_exists_elim), H1, H2);
return p.rec_save_pos(r, pos);
}
static expr parse_calc_expr(parser & p, unsigned, expr const *, pos_info const &) {
return parse_calc(p);
}
static expr parse_overwrite_notation(parser & p, unsigned, expr const *, pos_info const &) {
name n = p.check_id_next("invalid '#' local notation, identifier expected");
environment env = overwrite_notation(p.env(), n);
return p.parse_scoped_expr(0, nullptr, env);
}
static expr parse_explicit_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr(get_max_prec());
if (is_choice(e)) {
buffer<expr> new_choices;
for (unsigned i = 0; i < get_num_choices(e); i++)
new_choices.push_back(p.save_pos(mk_explicit(get_choice(e, i)), pos));
return p.save_pos(mk_choice(new_choices.size(), new_choices.data()), pos);
} else {
return p.save_pos(mk_explicit(e), pos);
}
}
static expr parse_consume_args_expr(parser & p, unsigned, expr const *, pos_info const & pos) {
expr e = p.parse_expr(get_max_prec());
if (is_choice(e)) {
buffer<expr> new_choices;
for (unsigned i = 0; i < get_num_choices(e); i++)
new_choices.push_back(p.save_pos(mk_consume_args(get_choice(e, i)), pos));
return p.save_pos(mk_choice(new_choices.size(), new_choices.data()), pos);
} else {
return p.save_pos(mk_consume_args(e), pos);
}
}
static expr parse_sorry(parser & p, unsigned, expr const *, pos_info const & pos) {
return p.mk_sorry(pos);
}
static expr parse_rparen(parser & p, unsigned, expr const * args, pos_info const & pos) {
if (p.collecting_info())
return p.save_pos(mk_extra_info(args[0], nulltag), pos);
else
return args[0];
}
static expr parse_proof_qed(parser & p, unsigned, expr const *, pos_info const & pos) {
return parse_proof_qed_core(p, pos);
}
parse_table init_nud_table() {
action Expr(mk_expr_action());
action Skip(mk_skip_action());
action Binders(mk_binders_action());
expr x0 = mk_var(0);
parse_table r;
r = r.add({transition("_", mk_ext_action(parse_placeholder))}, x0);
r = r.add({transition("by", mk_ext_action_core(parse_by))}, x0);
r = r.add({transition("have", mk_ext_action(parse_have))}, x0);
r = r.add({transition("show", mk_ext_action(parse_show))}, x0);
r = r.add({transition("obtain", mk_ext_action(parse_obtain))}, x0);
r = r.add({transition("(", Expr), transition(")", mk_ext_action(parse_rparen))}, x0);
r = r.add({transition("fun", Binders), transition(",", mk_scoped_expr_action(x0))}, x0);
r = r.add({transition("Pi", Binders), transition(",", mk_scoped_expr_action(x0, 0, false))}, x0);
r = r.add({transition("Type", mk_ext_action(parse_Type))}, x0);
r = r.add({transition("let", mk_ext_action(parse_let_expr))}, x0);
r = r.add({transition("calc", mk_ext_action(parse_calc_expr))}, x0);
r = r.add({transition("#", mk_ext_action(parse_overwrite_notation))}, x0);
r = r.add({transition("@", mk_ext_action(parse_explicit_expr))}, x0);
r = r.add({transition("!", mk_ext_action(parse_consume_args_expr))}, x0);
r = r.add({transition("begin", mk_ext_action_core(parse_begin_end))}, x0);
r = r.add({transition("proof", mk_ext_action(parse_proof_qed))}, x0);
r = r.add({transition("sorry", mk_ext_action(parse_sorry))}, x0);
return r;
}
parse_table init_led_table() {
parse_table r(false);
r = r.add({transition("->", mk_expr_action(get_arrow_prec()-1))}, mk_arrow(Var(1), Var(1)));
return r;
}
}
bool is_show_aux_name(name const & n) { return n == *notation::H_show; }
static parse_table * g_nud_table = nullptr;
static parse_table * g_led_table = nullptr;
parse_table get_builtin_nud_table() {
return *g_nud_table;
}
parse_table get_builtin_led_table() {
return *g_led_table;
}
void initialize_builtin_exprs() {
notation::H_show = new name("H_show");
notation::g_exists_elim = new name("exists_elim");
g_nud_table = new parse_table();
*g_nud_table = notation::init_nud_table();
g_led_table = new parse_table();
*g_led_table = notation::init_led_table();
}
void finalize_builtin_exprs() {
delete g_led_table;
delete g_nud_table;
delete notation::H_show;
delete notation::g_exists_elim;
}
}