74 lines
1.6 KiB
C
74 lines
1.6 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 "list.h"
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#include "buffer.h"
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#include "pair.h"
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namespace lean {
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/**
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\brief Copy the values in the list \c l to the buffer \c r.
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*/
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template<typename T>
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void to_buffer(list<T> const & l, buffer<T> & r) {
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for (T const & v : l) {
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r.push_back(v);
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}
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}
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/**
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\brief Auxiliary function for reverse function.
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*/
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template<typename T>
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list<T> reverse_aux(list<T> const & l, list<T> const & r) {
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if (is_nil(l))
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return r;
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else
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return reverse_aux(cdr(l), cons(car(l), r));
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}
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/**
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\brief Return the reverse list.
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*/
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template<typename T>
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list<T> reverse(list<T> const & l) {
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return reverse_aux(l, list<T>());
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}
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/**
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\brief Return two lists \c l1 and \c l2 of approximately the same size s.t.
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<tt>append(l1, l2) == l</tt>
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*/
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template<typename T>
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std::pair<list<T>, list<T>> split(list<T> const & l) {
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if (is_nil(l)) {
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return mk_pair(l, l);
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} else if (is_nil(cdr(l))) {
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return mk_pair(l, list<T>());
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} else {
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buffer<T> tmp;
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to_buffer(l, tmp);
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unsigned mid = tmp.size() / 2;
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auto beg = tmp.begin();
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lean_assert(beg + mid <= tmp.end());
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return mk_pair(to_list(beg, beg + mid),
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to_list(beg + mid, tmp.end()));
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}
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}
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/**
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\brief Append two lists
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*/
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template<typename T>
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list<T> append(list<T> const & l1, list<T> const & l2) {
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buffer<T> tmp;
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to_buffer(l1, tmp);
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to_buffer(l2, tmp);
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return to_list(tmp.begin(), tmp.end());
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}
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}
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