49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include <utility>
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#include "util/exception.h"
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#include "kernel/context.h"
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namespace lean {
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std::pair<context_entry const &, context> context::lookup_ext(unsigned i) const {
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list<context_entry> const * it1 = &m_list;
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while (*it1) {
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if (i == 0)
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return std::pair<context_entry const &, context>(head(*it1), context(tail(*it1)));
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--i;
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it1 = &tail(*it1);
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}
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throw exception("unknown free variable");
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}
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context_entry const & context::lookup(unsigned i) const {
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list<context_entry> const * it1 = &m_list;
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while (*it1) {
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if (i == 0)
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return head(*it1);
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--i;
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it1 = &tail(*it1);
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}
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throw exception("unknown free variable");
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}
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static list<context_entry> remove_core(list<context_entry> const & l, unsigned s, unsigned n) {
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if (s == 0) {
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if (n > 0) {
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return remove_core(tail(l), 0, n-1);
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} else {
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return l;
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}
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} else {
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return cons(head(l), remove_core(tail(l), s-1, n));
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}
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}
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context context::remove(unsigned s, unsigned n) const {
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return context(remove_core(m_list, s, n));
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}
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}
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