96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
/*
|
|
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
|
|
Released under Apache 2.0 license as described in the file LICENSE.
|
|
|
|
Author: Leonardo de Moura
|
|
*/
|
|
#include "util/fresh_name.h"
|
|
#include "kernel/abstract.h"
|
|
#include "library/placeholder.h"
|
|
#include "library/equations_compiler/equations.h"
|
|
#include "frontends/lean/tokens.h"
|
|
#include "frontends/lean/util.h"
|
|
#include "frontends/lean/parser.h"
|
|
#include "frontends/lean/decl_util.h"
|
|
|
|
namespace lean {
|
|
static name * g_match_name = nullptr;
|
|
|
|
bool is_match_binder_name(name const & n) { return n == *g_match_name; }
|
|
|
|
/** \brief Use equations compiler infrastructure to implement match-with */
|
|
expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos) {
|
|
parser::local_scope scope1(p);
|
|
match_definition_scope scope2;
|
|
equations_header header = mk_equations_header(scope2.get_name());
|
|
buffer<expr> eqns;
|
|
buffer<expr> ts;
|
|
try {
|
|
ts.push_back(p.parse_expr());
|
|
while (p.curr_is_token(get_comma_tk())) {
|
|
p.next();
|
|
ts.push_back(p.parse_expr());
|
|
}
|
|
expr fn;
|
|
/* Parse optional type */
|
|
if (p.curr_is_token(get_colon_tk())) {
|
|
p.next();
|
|
expr type = p.parse_expr();
|
|
fn = mk_local(mk_fresh_name(), *g_match_name, type, binder_info());
|
|
} else {
|
|
fn = mk_local(mk_fresh_name(), *g_match_name, mk_expr_placeholder(), binder_info());
|
|
}
|
|
|
|
p.check_token_next(get_with_tk(), "invalid 'match' expression, 'with' expected");
|
|
|
|
if (p.curr_is_token(get_end_tk())) {
|
|
/* Empty match */
|
|
p.next();
|
|
eqns.push_back(Fun(fn, mk_no_equation()));
|
|
expr f = p.save_pos(mk_equations(header, eqns.size(), eqns.data()), pos);
|
|
return p.mk_app(f, ts, pos);
|
|
}
|
|
if (is_eqn_prefix(p))
|
|
p.next(); // optional '|' in the first case
|
|
while (true) {
|
|
auto lhs_pos = p.pos();
|
|
buffer<expr> lhs_args;
|
|
lhs_args.push_back(p.parse_pattern_or_expr());
|
|
while (p.curr_is_token(get_comma_tk())) {
|
|
p.next();
|
|
lhs_args.push_back(p.parse_pattern_or_expr());
|
|
}
|
|
expr lhs = p.mk_app(fn, lhs_args, lhs_pos);
|
|
buffer<expr> locals;
|
|
bool skip_main_fn = true;
|
|
lhs = p.patexpr_to_pattern(lhs, skip_main_fn, locals);
|
|
auto assign_pos = p.pos();
|
|
p.check_token_next(get_assign_tk(), "invalid 'match' expression, ':=' expected");
|
|
{
|
|
parser::local_scope scope2(p);
|
|
for (expr const & local : locals)
|
|
p.add_local(local);
|
|
expr rhs = p.parse_expr();
|
|
eqns.push_back(Fun(fn, Fun(locals, p.save_pos(mk_equation(lhs, rhs), assign_pos), p)));
|
|
}
|
|
if (!is_eqn_prefix(p))
|
|
break;
|
|
p.next();
|
|
}
|
|
} catch (exception & ex) {
|
|
consume_until_end(p);
|
|
ex.rethrow();
|
|
}
|
|
p.check_token_next(get_end_tk(), "invalid 'match' expression, 'end' expected");
|
|
expr f = p.save_pos(mk_equations(header, eqns.size(), eqns.data()), pos);
|
|
return p.mk_app(f, ts, pos);
|
|
}
|
|
|
|
void initialize_match_expr() {
|
|
g_match_name = new name("_match");
|
|
}
|
|
|
|
void finalize_match_expr() {
|
|
delete g_match_name;
|
|
}
|
|
}
|