lean2/src/frontends/lean/builtin_exprs.cpp

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/*
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 "kernel/abstract.h"
#include "library/placeholder.h"
#include "frontends/lean/builtin_exprs.h"
#include "frontends/lean/token_table.h"
#include "frontends/lean/calc.h"
#include "frontends/lean/parser.h"
namespace lean {
namespace notation {
static name g_llevel_curly(".{");
static name g_rcurly("}");
static name g_in("in");
static name g_colon(":");
static name g_assign(":=");
static name g_comma(",");
static name g_from("from");
static name g_using("using");
static name g_by("by");
static expr parse_Type(parser & p, unsigned, expr const *, pos_info const & pos) {
if (p.curr_is_token(g_llevel_curly)) {
p.next();
level l = p.parse_level();
p.check_token_next(g_rcurly, "invalid Type expression, '}' expected");
return p.save_pos(mk_sort(l), pos);
} else {
return p.save_pos(p.mk_Type(), 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(g_comma)) {
p.next();
return parse_let(p, pos);
} else if (p.curr_is_token(g_in)) {
p.next();
return p.parse_expr();
} else {
throw parser_error("invalid let declaration, 'in' or ',' expected", p.pos());
}
}
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 pos = p.pos();
name id = p.check_id_next("invalid let declaration, identifier expected");
expr type, value;
if (p.curr_is_token(g_assign)) {
p.next();
type = p.save_pos(mk_expr_placeholder(), pos);
value = p.parse_expr();
} else if (p.curr_is_token(g_colon)) {
p.next();
type = p.parse_expr();
p.check_token_next(g_assign, "invalid declaration, ':=' expected");
value = p.parse_expr();
} else {
parser::local_scope scope2(p);
buffer<parameter> ps;
auto lenv = p.parse_binders(ps);
if (p.curr_is_token(g_colon)) {
p.next();
type = p.parse_scoped_expr(ps, lenv);
} else {
type = p.save_pos(mk_expr_placeholder(), pos);
}
p.check_token_next(g_assign, "invalid let declaration, ':=' expected");
value = p.parse_scoped_expr(ps, lenv);
type = p.pi_abstract(ps, type);
value = p.lambda_abstract(ps, value);
}
expr l = p.save_pos(mk_local(id, type), pos);
p.add_local(l);
expr body = abstract(parse_let_body(p, pos), l);
return p.save_pos(mk_let(id, type, value, body), 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_expr_placeholder(), pos);
}
static expr parse_by(parser & p, unsigned, expr const *, pos_info const & pos) {
tactic t = p.parse_tactic();
expr r = p.save_pos(mk_expr_placeholder(), pos);
p.save_hint(r, t);
return r;
}
static expr parse_proof(parser & p, expr const & prop) {
if (p.curr_is_token(g_from)) {
// parse: 'from' expr
p.next();
return p.parse_expr();
} else if (p.curr_is_token(g_by)) {
// parse: 'by' tactic
auto pos = p.pos();
p.next();
tactic t = p.parse_tactic();
expr r = p.save_pos(mk_expr_placeholder(some_expr(prop)), pos);
p.save_hint(r, t);
return r;
} else if (p.curr_is_token(g_using)) {
// parse: 'using' locals* ',' proof
auto using_pos = p.pos();
p.next();
parser::local_scope scope(p);
buffer<expr> locals;
while (!p.curr_is_token(g_comma)) {
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(pr(l), using_pos);
}
return pr;
} else {
throw parser_error("invalid expression, 'by', 'using' or 'from' expected", p.pos());
}
}
static expr parse_have(parser & p, unsigned, expr const *, pos_info const & pos) {
auto id_pos = p.pos();
name id = p.check_id_next("invalid 'have' declaration, identifier expected");
expr prop;
if (p.curr_is_token(g_colon)) {
p.next();
prop = p.parse_expr();
} else {
prop = p.save_pos(mk_expr_placeholder(), id_pos);
}
p.check_token_next(g_comma, "invalid 'have' declaration, ',' expected");
expr proof = parse_proof(p, prop);
p.check_token_next(g_comma, "invalid 'have' declaration, ',' expected");
parser::local_scope scope(p);
expr l = p.save_pos(mk_local(id, prop), pos);
binder_info bi = mk_contextual_info(false);
p.add_local(l, bi);
expr body = abstract(p.parse_expr(), l);
// remark: mk_contextual_info(false) informs the elaborator that prop should not occur inside metavariables.
expr r = p.save_pos(mk_lambda(id, prop, body, bi), pos);
return p.save_pos(mk_app(r, proof), pos);
}
static name H_show("H_show");
static expr parse_show(parser & p, unsigned, expr const *, pos_info const & pos) {
expr prop = p.parse_expr();
p.check_token_next(g_comma, "invalid 'show' declaration, ',' expected");
expr proof = parse_proof(p, prop);
return p.save_pos(mk_let(H_show, prop, proof, Var(0)), pos);
}
static expr parse_calc_expr(parser & p, unsigned, expr const *, pos_info const &) {
return parse_calc(p);
}
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(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("(", Expr), transition(")", Skip)}, 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);
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;
}
}
parse_table get_builtin_nud_table() {
static optional<parse_table> r;
if (!r)
r = notation::init_nud_table();
return *r;
}
parse_table get_builtin_led_table() {
static optional<parse_table> r;
if (!r)
r = notation::init_led_table();
return *r;
}
}