lean2/src/kernel/context.cpp

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/*
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 <utility>
#include "util/exception.h"
#include "kernel/context.h"
namespace lean {
std::pair<context_entry const &, context> context::lookup_ext(unsigned i) const {
list<context_entry> const * it1 = &m_list;
while (*it1) {
if (i == 0)
return std::pair<context_entry const &, context>(head(*it1), context(tail(*it1)));
--i;
it1 = &tail(*it1);
}
throw exception("unknown free variable");
}
context_entry const & context::lookup(unsigned i) const {
list<context_entry> const * it1 = &m_list;
while (*it1) {
if (i == 0)
return head(*it1);
--i;
it1 = &tail(*it1);
}
throw exception("unknown free variable");
}
optional<context_entry> context::find(unsigned i) const {
list<context_entry> const * it1 = &m_list;
while (*it1) {
if (i == 0)
return some(head(*it1));
--i;
it1 = &tail(*it1);
}
return optional<context_entry>();
}
static list<context_entry> remove_core(list<context_entry> const & l, unsigned s, unsigned n) {
if (l) {
if (s == 0) {
if (n > 0) {
return remove_core(tail(l), 0, n-1);
} else {
return l;
}
} else {
return cons(head(l), remove_core(tail(l), s-1, n));
}
} else {
return l;
}
}
context context::remove(unsigned s, unsigned n) const {
return context(remove_core(m_list, s, n));
}
static list<context_entry> insert_at_core(list<context_entry> const & l, unsigned i, name const & n, expr const & d) {
if (i == 0) {
return cons(context_entry(n, d), l);
} else {
lean_assert(l);
return cons(head(l), insert_at_core(tail(l), i - 1, n, d));
}
}
context context::insert_at(unsigned i, name const & n, expr const & d) const {
return context(insert_at_core(m_list, i, n, d));
}
}