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feat(frontends/lean): support variables shadowing in patterns

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This commit is contained in:
Sebastian Ullrich 2016-05-29 12:20:18 -04:00 committed by Leonardo de Moura
parent 87c5ba9f52
commit d7789fa58a
4 changed files with 48 additions and 37 deletions
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71
src/frontends/lean/decl_cmds.cpp
View file

@ -542,42 +542,45 @@ static void parse_equations_core(parser & p, buffer<expr> const & fns, buffer<ex
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_decl_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);
} 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()));
lean_assert(lhs_args.size() > 0);
lhs = lhs_args[0];
for (unsigned i = 1; i < lhs_args.size(); i++)
lhs = copy_tag(lhs_args[i], mk_app(lhs, lhs_args[i]));
buffer<expr> lhs_args;
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));
// check if lhs starts with an (explicit) equation function symbol (which is optional for fns.size() == 1)
optional<expr> fn;
auto lhs_pos = p.pos();
if (p.curr_is_token(get_explicit_tk())) {
p.next();
name fn_name = p.check_decl_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 if (p.curr_is_identifier() && (fn = is_equation_fn(fns, p.get_name_val()))) {
p.next();
lhs_args.push_back(p.save_pos(*fn, lhs_pos));
} else {
if (fns.size() == 1) {
lhs_args.push_back(p.save_pos(mk_explicit(fns[0]), lhs_pos));
} else {
throw parser_error("invalid recursive equation, head symbol in left-hand-side is not an equation function",
lhs_pos);
}
}
// parse the remaining left-hand side
{
parser::local_and_undef_id_to_local_scope scope2(p);
while (!p.curr_is_token(get_assign_tk()))
lhs_args.push_back(p.parse_expr(get_max_prec()));
}
lean_assert(lhs_args.size() > 0);
lhs = lhs_args[0];
for (unsigned i = 1; i < lhs_args.size(); i++)
lhs = copy_tag(lhs_args[i], mk_app(lhs, lhs_args[i]));
buffer<expr> locals;
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();
@ -677,7 +680,7 @@ expr parse_match(parser & p, unsigned, expr const *, pos_info const & pos) {
unsigned prev_num_undef_ids = p.get_num_undef_ids();
buffer<expr> locals;
{
parser::undef_id_to_local_scope scope2(p);
parser::local_and_undef_id_to_local_scope scope2(p);
auto lhs_pos = p.pos();
lhs = p.parse_expr();
lhs = p.mk_app(fn, lhs, lhs_pos);

9
src/frontends/lean/parser.cpp
View file

@ -107,6 +107,8 @@ parser::undef_id_to_const_scope::undef_id_to_const_scope(parser & p):
flet<undef_id_behavior>(p.m_undef_id_behavior, undef_id_behavior::AssumeConstant) {}
parser::undef_id_to_local_scope::undef_id_to_local_scope(parser & p):
flet<undef_id_behavior>(p.m_undef_id_behavior, undef_id_behavior::AssumeLocal) {}
parser::local_and_undef_id_to_local_scope::local_and_undef_id_to_local_scope(parser & p):
flet<undef_id_behavior>(p.m_undef_id_behavior, undef_id_behavior::AssumeLocalAndAlsoDefinedLocals) {}
static name * g_tmp_prefix = nullptr;
@ -1474,6 +1476,11 @@ expr parser::id_to_expr(name const & id, pos_info const & p) {
if (ls && m_undef_id_behavior != undef_id_behavior::AssumeConstant)
throw parser_error("invalid use of explicit universe parameter, identifier is a variable, "
"parameter or a constant bound to parameters in a section", p);
if (m_undef_id_behavior == undef_id_behavior::AssumeLocalAndAlsoDefinedLocals) {
expr local = mk_local(id, mk_expr_placeholder());
m_undef_ids.push_back(local);
return save_pos(local, p);
}
auto r = copy_with_new_pos(*it1, p);
save_type_info(r);
save_identifier_info(p, id);
@ -1523,7 +1530,7 @@ expr parser::id_to_expr(name const & id, pos_info const & p) {
if (!r) {
if (m_undef_id_behavior == undef_id_behavior::AssumeConstant) {
r = save_pos(mk_constant(get_namespace(m_env) + id, ls), p);
} else if (m_undef_id_behavior == undef_id_behavior::AssumeLocal) {
} else if (m_undef_id_behavior == undef_id_behavior::AssumeLocal || m_undef_id_behavior == undef_id_behavior::AssumeLocalAndAlsoDefinedLocals) {
expr local = mk_local(id, mk_expr_placeholder());
m_undef_ids.push_back(local);
r = save_pos(local, p);

3
src/frontends/lean/parser.h
View file

@ -83,7 +83,7 @@ typedef std::vector<snapshot> snapshot_vector;
enum class keep_theorem_mode { All, DiscardImported, DiscardAll };
enum class undef_id_behavior { Error, AssumeConstant, AssumeLocal };
enum class undef_id_behavior { Error, AssumeConstant, AssumeLocal, AssumeLocalAndAlsoDefinedLocals };
class parser {
environment m_env;
@ -491,6 +491,7 @@ public:
*/
struct undef_id_to_const_scope : public flet<undef_id_behavior> { undef_id_to_const_scope(parser & p); };
struct undef_id_to_local_scope : public flet<undef_id_behavior> { undef_id_to_local_scope(parser &); };
struct local_and_undef_id_to_local_scope : public flet<undef_id_behavior> { local_and_undef_id_to_local_scope(parser &); };
/** \brief Return the size of the stack of undefined local constants */
unsigned get_num_undef_ids() const { return m_undef_ids.size(); }

2
tests/lean/run/eq23.lean
View file

@ -10,7 +10,7 @@ with tree_list :=
namespace tree_list
definition len {A : Type} : tree_list A → nat
| len (nil A) := 0
| len (nil _) := 0
| len (cons t l) := len l + 1
theorem len_nil {A : Type} : len (nil A) = 0 :=