lean2/src/library/context_to_lambda.cpp
Leonardo de Moura 3e1fd06903 refactor(kernel/expr): remove 'null' expression, and operator bool for expression
After this commit, a value of type 'expr' cannot be a reference to nullptr.
This commit also fixes several bugs due to the use of 'null' expressions.

TODO: do the same for kernel objects, sexprs, etc.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-07 23:21:10 -08:00

59 lines
1.8 KiB
C++

/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "library/context_to_lambda.h"
namespace lean {
static expr g_fake = Const(name::mk_internal_unique_name());
expr context_to_lambda(context::iterator it, context::iterator const & end, expr const & e) {
if (it == end) {
return e;
} else {
context_entry const & entry = *it;
optional<expr> t;
optional<expr> const & d = entry.get_domain();
optional<expr> const & b = entry.get_body();
lean_assert(b || d);
if (b && d)
t = mk_app(g_fake, *d, *b);
else if (d)
t = mk_app(g_fake, *d, g_fake);
else
t = mk_app(g_fake, g_fake, *b);
lean_assert(t);
return context_to_lambda(++it, end, mk_lambda(entry.get_name(), *t, e));
}
}
expr context_to_lambda(context const & c, expr const & e) {
return context_to_lambda(c.begin(), c.end(), e);
}
bool is_fake_context(expr const & e) {
return is_lambda(e) && is_app(abst_domain(e)) && arg(abst_domain(e), 0) == g_fake;
}
name const & fake_context_name(expr const & e) {
lean_assert(is_fake_context(e));
return abst_name(e);
}
optional<expr> fake_context_domain(expr const & e) {
lean_assert(is_fake_context(e));
expr r = arg(abst_domain(e), 1);
if (!is_eqp(r, g_fake))
return optional<expr>(r);
else
return optional<expr>();
}
optional<expr> fake_context_value(expr const & e) {
lean_assert(is_fake_context(e));
expr r = arg(abst_domain(e), 2);
if (!is_eqp(r, g_fake))
return optional<expr>(r);
else
return optional<expr>();
}
expr const & fake_context_rest(expr const & e) {
return abst_body(e);
}
}