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feat(frontends/lean/decl_cmds): allow 'empty' set of pattern matching equations

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This commit is contained in:
Leonardo de Moura 2015-03-05 14:34:56 -08:00
parent 8e9ccf8b6f
commit 28487ede3b
3 changed files with 63 additions and 48 deletions
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2
src/emacs/lean-syntax.el
View file

@ -119,7 +119,7 @@
;; modifiers
(,(rx (or "\[persistent\]" "\[notation\]" "\[visible\]" "\[instance\]" "\[class\]" "\[parsing-only\]"
"\[coercion\]" "\[reducible\]" "\[irreducible\]" "\[semireducible\]" "\[quasireducible\]" "\[wf\]"
"\[whnf\]" "\[multiple-instances\]"
"\[whnf\]" "\[multiple-instances\]" "\[none\]"
"\[decls\]" "\[declarations\]" "\[all-transparent\]" "\[coercions\]" "\[classes\]"
"\[notations\]" "\[abbreviations\]" "\[begin-end-hints\]" "\[tactic-hints\]" "\[reduce-hints\]"))
. 'font-lock-doc-face)

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

@ -604,58 +604,64 @@ expr parse_equations(parser & p, name const & n, expr const & type, buffer<name>
}
}
check_eqn_prefix(p);
for (expr const & fn : fns)
p.add_local(fn);
while (true) {
expr lhs;
unsigned prev_num_undef_ids = p.get_num_undef_ids();
buffer<expr> locals;
{
parser::undef_id_to_local_scope scope2(p);
buffer<expr> lhs_args;
auto lhs_pos = p.pos();
if (p.curr_is_token(get_explicit_tk())) {
p.next();
name fn_name = p.check_id_next("invalid recursive equation, identifier expected");
lhs_args.push_back(p.save_pos(mk_explicit(get_equation_fn(fns, fn_name, lhs_pos)), lhs_pos));
} else {
expr first = p.parse_expr(get_max_prec());
expr fn = first;
if (is_explicit(fn))
fn = get_explicit_arg(fn);
if (is_local(fn) && is_equation_fn(fns, local_pp_name(fn))) {
lhs_args.push_back(first);
} else if (fns.size() == 1) {
lhs_args.push_back(p.save_pos(mk_explicit(fns[0]), lhs_pos));
lhs_args.push_back(first);
if (p.curr_is_token(get_none_tk())) {
// no equations have been provided
p.next();
eqns.push_back(Fun(fns, mk_no_equation(), p));
} else {
for (expr const & fn : fns)
p.add_local(fn);
while (true) {
expr lhs;
unsigned prev_num_undef_ids = p.get_num_undef_ids();
buffer<expr> locals;
{
parser::undef_id_to_local_scope scope2(p);
buffer<expr> lhs_args;
auto lhs_pos = p.pos();
if (p.curr_is_token(get_explicit_tk())) {
p.next();
name fn_name = p.check_id_next("invalid recursive equation, identifier expected");
lhs_args.push_back(p.save_pos(mk_explicit(get_equation_fn(fns, fn_name, lhs_pos)), lhs_pos));
} else {
throw parser_error("invalid recursive equation, head symbol in left-hand-side is not a constant",
lhs_pos);
expr first = p.parse_expr(get_max_prec());
expr fn = first;
if (is_explicit(fn))
fn = get_explicit_arg(fn);
if (is_local(fn) && is_equation_fn(fns, local_pp_name(fn))) {
lhs_args.push_back(first);
} else if (fns.size() == 1) {
lhs_args.push_back(p.save_pos(mk_explicit(fns[0]), lhs_pos));
lhs_args.push_back(first);
} else {
throw parser_error("invalid recursive equation, head symbol in left-hand-side is not a constant",
lhs_pos);
}
}
while (!p.curr_is_token(get_assign_tk()))
lhs_args.push_back(p.parse_expr(get_max_prec()));
lhs = p.save_pos(mk_app(lhs_args.size(), lhs_args.data()), lhs_pos);
unsigned num_undef_ids = p.get_num_undef_ids();
for (unsigned i = prev_num_undef_ids; i < num_undef_ids; i++) {
locals.push_back(p.get_undef_id(i));
}
}
while (!p.curr_is_token(get_assign_tk()))
lhs_args.push_back(p.parse_expr(get_max_prec()));
lhs = p.save_pos(mk_app(lhs_args.size(), lhs_args.data()), lhs_pos);
unsigned num_undef_ids = p.get_num_undef_ids();
for (unsigned i = prev_num_undef_ids; i < num_undef_ids; i++) {
locals.push_back(p.get_undef_id(i));
validate_equation_lhs(p, lhs, locals);
lhs = merge_equation_lhs_vars(lhs, locals);
auto assign_pos = p.pos();
p.check_token_next(get_assign_tk(), "invalid declaration, ':=' expected");
{
parser::local_scope scope2(p);
for (expr const & local : locals)
p.add_local(local);
expr rhs = p.parse_expr();
eqns.push_back(Fun(fns, Fun(locals, p.save_pos(mk_equation(lhs, rhs), assign_pos), p)));
}
if (!is_eqn_prefix(p))
break;
p.next();
}
validate_equation_lhs(p, lhs, locals);
lhs = merge_equation_lhs_vars(lhs, locals);
auto assign_pos = p.pos();
p.check_token_next(get_assign_tk(), "invalid declaration, ':=' expected");
{
parser::local_scope scope2(p);
for (expr const & local : locals)
p.add_local(local);
expr rhs = p.parse_expr();
eqns.push_back(Fun(fns, Fun(locals, p.save_pos(mk_equation(lhs, rhs), assign_pos), p)));
}
if (!is_eqn_prefix(p))
break;
p.next();
}
}
if (p.curr_is_token(get_wf_tk())) {

9
tests/lean/run/empty_eq.lean Normal file
View file

@ -0,0 +1,9 @@
import data.fin
open nat
open fin
definition case0 {C : fin zero → Type} : Π (f : fin zero), C f
| [none]
print definition case0