92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
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/*
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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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#pragma once
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#include <utility>
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#include "util/lazy_list.h"
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#include "util/list.h"
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namespace lean {
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template<typename T>
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lazy_list<T> take(unsigned sz, lazy_list<T> l) {
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if (sz == 0 || !l) {
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return lazy_list<T>();
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} else {
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return lazy_list<T>(head(l), [=]() { return take(sz - 1, tail(l)); });
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}
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}
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template<typename T1, typename T2>
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lazy_list<std::pair<T1, T2>> zip(lazy_list<T1> const & l1, lazy_list<T2> const & l2) {
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if (l1 && l2) {
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return lazy_list<std::pair<T1, T2>>(mk_pair(head(l1), head(l2)), [=]() { return zip(tail(l1), tail(l2)); });
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} else {
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return lazy_list<std::pair<T1, T2>>();
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}
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}
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template<typename T>
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lazy_list<T> to_lazy(list<T> const & l) {
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if (l)
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return lazy_list<T>(head(l), [=]() { return to_lazy(tail(l)); });
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else
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return lazy_list<T>();
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}
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template<typename T>
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lazy_list<T> append(lazy_list<T> const & l1, lazy_list<T> const & l2) {
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if (!l1)
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return l2;
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else if (!l2)
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return l1;
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else
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return lazy_list<T>(head(l1), [=]() { return append(tail(l1), l2); });
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}
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template<typename T, typename F>
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lazy_list<T> map(lazy_list<T> const & l, F && f) {
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if (!l)
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return l;
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else
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return lazy_list<T>(f(head(l)), [=]() { return map(tail(l), f); });
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}
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template<typename T>
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lazy_list<T> interleave(lazy_list<T> const & l1, lazy_list<T> const & l2) {
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if (!l1)
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return l2;
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else if (!l2)
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return l1;
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else
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return lazy_list<T>(head(l1), [=]() { return interleave(l2, tail(l1)); });
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}
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template<typename T, typename P>
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lazy_list<T> filter(lazy_list<T> const & l, P && p) {
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if (!l)
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return l;
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else if (p(head(l)))
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return lazy_list<T>(head(l), [=]() { return filter(tail(l), p); });
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else
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return filter(tail(l), p);
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}
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template<typename T, typename F>
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lazy_list<T> map_append_aux(lazy_list<T> const & h, lazy_list<T> const & l, F && f) {
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if (!l)
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return h;
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else if (h)
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return lazy_list<T>(head(h), [=]() { return map_append_aux(tail(h), l, f); });
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else
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return map_append_aux(f(head(l)), tail(l), f);
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}
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template<typename T, typename F>
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lazy_list<T> map_append(lazy_list<T> const & l, F && f) {
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return map_append_aux(lazy_list<T>(), l, f);
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}
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}
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