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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Kshitij Bansal, Mudathir Mohamed |
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* |
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* This file is part of the cvc5 project. |
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* |
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* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS |
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* in the top-level source directory and their institutional affiliations. |
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* All rights reserved. See the file COPYING in the top-level source |
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* directory for licensing information. |
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* **************************************************************************** |
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* |
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* Normal form for set constants. |
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*/ |
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#include "cvc5_private.h" |
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#ifndef CVC5__THEORY__SETS__NORMAL_FORM_H |
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#define CVC5__THEORY__SETS__NORMAL_FORM_H |
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#include "expr/emptyset.h" |
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namespace cvc5 { |
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namespace theory { |
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namespace sets { |
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class NormalForm { |
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public: |
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/** |
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* Constructs a set of the form: |
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* (union (singleton c1) ... (union (singleton c_{n-1}) (singleton c_n)))) |
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* from the set { c1 ... cn }, also handles empty set case, which is why |
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* setType is passed to this method. |
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*/ |
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template <bool ref_count> |
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static Node elementsToSet(const std::set<NodeTemplate<ref_count> >& elements, |
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TypeNode setType) |
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{ |
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typedef typename std::set<NodeTemplate<ref_count> >::const_iterator |
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ElementsIterator; |
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NodeManager* nm = NodeManager::currentNM(); |
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if (elements.size() == 0) |
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{ |
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return nm->mkConst(EmptySet(setType)); |
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} |
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else |
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{ |
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TypeNode elementType = setType.getSetElementType(); |
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ElementsIterator it = elements.begin(); |
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Node cur = nm->mkSingleton(elementType, *it); |
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while (++it != elements.end()) |
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{ |
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Node singleton = nm->mkSingleton(elementType, *it); |
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cur = nm->mkNode(kind::UNION, singleton, cur); |
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} |
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return cur; |
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} |
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} |
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/** |
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* Returns true if n is considered a to be a (canonical) constant set value. |
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* A canonical set value is one whose AST is: |
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* (union (singleton c1) ... (union (singleton c_{n-1}) (singleton c_n)))) |
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* where c1 ... cn are constants and the node identifier of these constants |
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* are such that: |
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* c1 > ... > cn. |
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* Also handles the corner cases of empty set and singleton set. |
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*/ |
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static bool checkNormalConstant(TNode n) { |
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Debug("sets-checknormal") << "[sets-checknormal] checkNormal " << n << " :" |
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<< std::endl; |
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if (n.getKind() == kind::EMPTYSET) { |
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return true; |
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} else if (n.getKind() == kind::SINGLETON) { |
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return n[0].isConst(); |
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} else if (n.getKind() == kind::UNION) { |
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// assuming (union {SmallestNodeID} ... (union {BiggerNodeId} ... |
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Node orig = n; |
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TNode prvs; |
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// check intermediate nodes |
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while (n.getKind() == kind::UNION) |
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{ |
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if (n[0].getKind() != kind::SINGLETON || !n[0][0].isConst()) |
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{ |
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// not a constant |
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Trace("sets-isconst") << "sets::isConst: " << orig << " not due to " |
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<< n[0] << std::endl; |
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return false; |
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} |
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Debug("sets-checknormal") |
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<< "[sets-checknormal] element = " << n[0][0] << " " |
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<< n[0][0].getId() << std::endl; |
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if (!prvs.isNull() && n[0][0] >= prvs) |
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{ |
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Trace("sets-isconst") |
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<< "sets::isConst: " << orig << " not due to compare " << n[0][0] |
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<< std::endl; |
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return false; |
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} |
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prvs = n[0][0]; |
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n = n[1]; |
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} |
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// check SmallestNodeID is smallest |
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if (n.getKind() != kind::SINGLETON || !n[0].isConst()) |
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{ |
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Trace("sets-isconst") << "sets::isConst: " << orig |
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<< " not due to final " << n << std::endl; |
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return false; |
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} |
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Debug("sets-checknormal") |
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<< "[sets-checknormal] lst element = " << n[0] << " " |
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<< n[0].getId() << std::endl; |
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// compare last ID |
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if (n[0] < prvs) |
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{ |
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return true; |
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} |
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Trace("sets-isconst") |
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<< "sets::isConst: " << orig << " not due to compare final " << n[0] |
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<< std::endl; |
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} |
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return false; |
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} |
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/** |
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* Converts a set term to a std::set of its elements. This expects a set of |
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* the form: |
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* (union (singleton c1) ... (union (singleton c_{n-1}) (singleton c_n)))) |
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* Also handles the corner cases of empty set and singleton set. |
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*/ |
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static std::set<Node> getElementsFromNormalConstant(TNode n) { |
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Assert(n.isConst()); |
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std::set<Node> ret; |
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if (n.getKind() == kind::EMPTYSET) { |
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return ret; |
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} |
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while (n.getKind() == kind::UNION) { |
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Assert(n[0].getKind() == kind::SINGLETON); |
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ret.insert(ret.begin(), n[0][0]); |
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n = n[1]; |
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} |
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Assert(n.getKind() == kind::SINGLETON); |
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ret.insert(n[0]); |
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return ret; |
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} |
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static Node mkBop( Kind k, std::vector< Node >& els, TypeNode tn, unsigned index = 0 ){ |
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if( index>=els.size() ){ |
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return NodeManager::currentNM()->mkConst(EmptySet(tn)); |
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}else if( index==els.size()-1 ){ |
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return els[index]; |
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}else{ |
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return NodeManager::currentNM()->mkNode( k, els[index], mkBop( k, els, tn, index+1 ) ); |
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} |
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} |
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}; |
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} |
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} |
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} // namespace cvc5 |
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#endif |