28 lines
988 B
C++
28 lines
988 B
C++
/*
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Copyright (c) 2014 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/lazy_list.h"
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#include "kernel/constraint.h"
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namespace lean {
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/** \brief Abstract (helper) class for creating lazy_list<constraints> */
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class choice_iterator {
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bool m_ignore_failure;
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public:
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choice_iterator(bool ignore_failure = false):m_ignore_failure(ignore_failure) {}
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virtual ~choice_iterator() {}
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virtual optional<constraints> next() = 0;
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bool ignore_failure() const { return m_ignore_failure; }
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};
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/** \brief Convert a choice_iterator into a lazy_list<constraints>
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The lazy list is generated by invoking the method \c choice_iterator::next.
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If c->ignore_failure() is true AND \c c does not produce any result,
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then the singleton lazy_list is produced with an empty set of constraints.
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*/
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lazy_list<constraints> choose(std::shared_ptr<choice_iterator> c);
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}
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