305 lines
8.5 KiB
C++
305 lines
8.5 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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#pragma once
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#include <utility>
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#include <functional>
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#include "util/list.h"
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#include "util/buffer.h"
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#include "util/pair.h"
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namespace lean {
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/** \brief Copy the values in the list \c l to the buffer \c r. */
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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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/** \brief Copy the cells in the list \c l to the buffer \c r. */
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template<typename T>
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void to_buffer(list<T> const & l, buffer<typename list<T>::cell *> & r) {
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typename list<T>::cell * it = l.raw();
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while (it) {
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r.push_back(it);
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it = it->tail().raw();
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}
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}
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/** \brief Create a list using the values in the cells from \c begin to \c end. */
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template<typename T>
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list<T> cells_to_list(typename list<T>::cell * const * begin, typename list<T>::cell * const * end) {
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list<T> r;
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auto it = end;
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while (it != begin) {
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--it;
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r = cons((*it)->head(), r);
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}
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return r;
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}
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/** \brief Create a list using the values in the cells from \c b. */
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template<typename T>
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list<T> buffer_to_list(buffer<typename list<T>::cell*> const & b) {
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return cells_to_list<T>(b.begin(), b.end());
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}
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/** \brief Return the reverse list. */
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template<typename T>
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list<T> reverse(list<T> const & l) {
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if (is_nil(l)) {
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return l;
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} else {
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buffer<typename list<T>::cell *> tmp;
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to_buffer(l, tmp);
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std::reverse(tmp.begin(), tmp.end());
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return buffer_to_list<T>(tmp);
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}
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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<typename list<T>::cell*> 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(cells_to_list<T>(beg, beg + mid),
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cells_to_list<T>(beg + mid, tmp.end()));
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}
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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, reverse(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_reverse_second(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), reverse_to_list(beg+mid, tmp.end()));
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}
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}
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/** \brief Append two lists */
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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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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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buffer<typename list<T>::cell*> tmp;
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list<T> r = l2;
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to_buffer(l1, tmp);
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unsigned i = tmp.size();
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while (i > 0) {
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--i;
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r = cons(tmp[i]->head(), r);
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}
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return r;
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}
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}
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/** \brief Given list <tt>(a_0, ..., a_k)</tt>, return list <tt>(f(a_0), ..., f(a_k))</tt>. */
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template<typename To, typename From, typename F>
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list<To> map2(list<From> const & l, F && f) {
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static_assert(std::is_same<typename std::result_of<F(From const &)>::type, To>::value,
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"map: return type of f is not equal to input type");
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if (is_nil(l)) {
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return list<To>();
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} else {
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buffer<To> new_vs;
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for (auto const & v : l)
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new_vs.push_back(f(v));
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return to_list(new_vs.begin(), new_vs.end());
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}
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}
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/** \brief Given list <tt>(a_0, ..., a_k)</tt>, return list <tt>(f(a_0), ..., f(a_k))</tt>. */
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template<typename T, typename F>
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list<T> map(list<T> const & l, F && f) {
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return map2<T, T, F>(l, std::move(f));
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}
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/**
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\brief Filter/Remove elements from the list
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that do not satisfy the given predicate.
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*/
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template<typename T, typename P>
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list<T> filter(list<T> const & l, P && p) {
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if (is_nil(l)) {
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return l;
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} else {
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buffer<typename list<T>::cell*> tmp;
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to_buffer(l, tmp);
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unsigned i = tmp.size();
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while (i > 0) {
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--i;
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if (!p(tmp[i]->head())) {
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list<T> r = tmp[i]->tail();
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while (i > 0) {
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--i;
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if (p(tmp[i]->head()))
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r = cons(tmp[i]->head(), r);
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}
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return r;
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}
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}
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return l; // not element was removed
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}
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}
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/** \brief Remove all occurrences of \c a from \c l */
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template<typename T>
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list<T> remove(list<T> const & l, T const & a) {
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return filter(l, [&](T const & v) { return a != v; });
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}
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/** \brief Remove the last element that satisfies \c p. */
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template<typename T, typename P>
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list<T> remove_last(list<T> const & l, P && p) {
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if (!is_nil(l)) {
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buffer<typename list<T>::cell*> tmp;
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to_buffer(l, tmp);
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unsigned i = tmp.size();
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while (i > 0) {
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--i;
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if (p(tmp[i]->head())) {
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list<T> r = tmp[i]->tail();
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while (i > 0) {
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--i;
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r = cons(tmp[i]->head(), r);
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}
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return r;
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}
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}
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}
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return l;
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}
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/**
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\brief Similar to \c map but \c f has signature
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<tt>bool f(T const & in, T & out)</tt>
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If \c out becomes part of the result iff \c f returns true.
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*/
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template<typename T, typename F>
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list<T> map_filter(list<T> const & l, F && f) {
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if (is_nil(l)) {
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return l;
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} else {
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buffer<typename list<T>::cell*> tmp;
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to_buffer(l, tmp);
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unsigned i = tmp.size();
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list<T> r;
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while (i > 0) {
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--i;
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T out;
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if (f(tmp[i]->head(), out))
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r = cons(out, r);
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}
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return r;
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}
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}
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template<typename T, typename F>
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list<T> map_append(list<T> const & l, F && f) {
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if (is_nil(l)) {
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return l;
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} else {
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buffer<T> tmp;
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for (auto const & v : l)
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to_buffer(f(v), tmp);
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return to_list(tmp.begin(), tmp.end());
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}
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}
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/**
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\brief Semantically equivalent to \c map, but it tries to reuse
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list cells. The elements are compared using the predicate \c eq.
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*/
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template<typename T, typename F, typename Eq = std::equal_to<T>>
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list<T> map_reuse(list<T> const & l, F && f, Eq const & eq = Eq()) {
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if (is_nil(l)) {
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return l;
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} else {
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buffer<typename list<T>::cell*> tmp;
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to_buffer(l, tmp);
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auto it = tmp.end();
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auto begin = tmp.begin();
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while (it != begin) {
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--it;
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auto curr = *it;
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auto new_v = f(curr->head());
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if (!eq(new_v, curr->head())) {
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list<T> r(new_v, curr->tail());
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while (it != begin) {
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--it;
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auto curr = *it;
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r = cons(f(curr->head()), r);
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}
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return r;
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}
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}
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return l;
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}
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}
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/** \brief Given list <tt>(a_0, ..., a_k)</tt>, exec f(a_0); f(a_1); ... f(a_k)</tt>. */
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template<typename T, typename F>
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void for_each(list<T> const & l, F && f) {
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static_assert(std::is_same<typename std::result_of<F(T const &)>::type, void>::value,
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"for_each: return type of f is not void");
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typedef typename list<T>::cell cell;
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cell * it = l.raw();
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while (it) {
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f(it->head());
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it = it->tail().raw();
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}
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}
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/** \brief Compare two lists using the binary predicate p. */
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template<typename T, typename P>
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bool compare(list<T> const & l1, list<T> const & l2, P && p) {
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static_assert(std::is_same<typename std::result_of<P(T const &, T const &)>::type, bool>::value,
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"compare: return type of f is not bool");
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auto it1 = l1.begin();
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auto it2 = l2.begin();
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auto end1 = l1.end();
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auto end2 = l2.end();
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for (; it1 != end1 && it2 != end2; ++it1, ++it2) {
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if (!p(*it1, *it2))
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return false;
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}
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return it1 == end1 && it2 == end2;
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}
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/** \brief Return the i-th element of the list */
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template<typename T>
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T const & get_ith(list<T> const & l, unsigned idx) {
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return idx == 0 ? head(l) : get_ith(tail(l), idx - 1);
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}
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}
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