85 lines
2.9 KiB
C
85 lines
2.9 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 "util/rc.h"
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#include "util/debug.h"
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namespace lean {
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/**
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\brief ML-like lazy lists.
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*/
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template<typename T>
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class lazy_list {
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public:
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class cell {
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MK_LEAN_RC();
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void dealloc() { delete this; }
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T m_head;
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public:
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cell(T const & h):m_rc(0), m_head(h) {}
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virtual ~cell() {}
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T const & head() const { return m_head; }
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virtual lazy_list tail() const { return lazy_list(); }
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};
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private:
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class explicit_cell : public cell {
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lazy_list m_tail;
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public:
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explicit_cell(T const & h, lazy_list const & l):cell(h), m_tail(l) {}
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virtual ~explicit_cell() {}
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virtual lazy_list tail() const { return m_tail; }
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};
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template<typename Tail>
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class lazy_cell : public cell {
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Tail m_tail;
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public:
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lazy_cell(T const & h, Tail const & t):cell(h), m_tail(t) {}
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virtual ~lazy_cell() {}
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virtual lazy_list tail() const { return m_tail(); }
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};
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cell * m_ptr;
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public:
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lazy_list():m_ptr(nullptr) {}
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lazy_list(T const & h):m_ptr(new cell(h)) { m_ptr->inc_ref(); }
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lazy_list(T const & h, lazy_list const & t):m_ptr(new explicit_cell(h, t)) { m_ptr->inc_ref(); }
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template<typename F>
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lazy_list(T const & h, F const & f):m_ptr(new lazy_cell<F>(h, f)) { m_ptr->inc_ref(); }
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lazy_list(lazy_list const & s):m_ptr(s.m_ptr) { if (m_ptr) m_ptr->inc_ref(); }
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lazy_list(lazy_list&& s):m_ptr(s.m_ptr) { s.m_ptr = nullptr; }
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~lazy_list() { if (m_ptr) m_ptr->dec_ref(); }
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lazy_list & operator=(lazy_list const & s) { LEAN_COPY_REF(list, s); }
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lazy_list & operator=(lazy_list && s) { LEAN_MOVE_REF(list, s); }
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operator bool() const { return m_ptr != nullptr; }
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friend T const & head(lazy_list const & l) { lean_assert(l); return l.m_ptr->head(); }
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friend lazy_list tail(lazy_list const & l) { lean_assert(l); return l.m_ptr->tail(); }
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friend lazy_list cons(T const & h, lazy_list const & t) { return lazy_list(h, t); }
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class iterator {
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friend class lazy_list;
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lazy_list m_it;
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iterator(lazy_list const & it):m_it(it) {}
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public:
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iterator(iterator const & s):m_it(s.m_it) {}
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iterator & operator++() { m_it = tail(m_it); return *this; }
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iterator operator++(int) { iterator tmp(*this); operator++(); return tmp; }
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bool operator==(iterator const & s) const { return m_it == s.m_it; }
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bool operator!=(iterator const & s) const { return !operator==(s); }
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T const & operator*() { lean_assert(m_it); return head(m_it); }
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T const * operator->() { lean_assert(m_it); return &(head(m_it)); }
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};
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iterator begin() const { return iterator(*this); }
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iterator end() const { return iterator(lazy_list()); }
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};
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}
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