Head

GCC Code Coverage Report

Directory:	.		Exec	Total	Coverage
File:	src/theory/builtin/theory_builtin_rewriter.cpp	Lines:	225	250	90.0 %
Date:	2021-05-24	Branches:	655	1541	42.5 %


/******************************************************************************
 * Top contributors (to current version):
 *   Andrew Reynolds, Haniel Barbosa, Morgan Deters
 *
 * This file is part of the cvc5 project.
 *
 * Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 * in the top-level source directory and their institutional affiliations.
 * All rights reserved.  See the file COPYING in the top-level source
 * directory for licensing information.
 * ****************************************************************************
 *
 * [[ Add one-line brief description here ]]
 *
 * [[ Add lengthier description here ]]
 * \todo document this file
 */

#include "theory/builtin/theory_builtin_rewriter.h"

#include "expr/attribute.h"
#include "expr/node_algorithm.h"
#include "theory/rewriter.h"

using namespace std;

namespace cvc5 {
namespace theory {
namespace builtin {

Node TheoryBuiltinRewriter::blastDistinct(TNode in) {
  Assert(in.getKind() == kind::DISTINCT);

  if(in.getNumChildren() == 2) {
    // if this is the case exactly 1 != pair will be generated so the
    // AND is not required
    Node eq = NodeManager::currentNM()->mkNode(kind::EQUAL, in[0], in[1]);
    Node neq = NodeManager::currentNM()->mkNode(kind::NOT, eq);
    return neq;
  }

  // assume that in.getNumChildren() > 2 => diseqs.size() > 1
  vector<Node> diseqs;
  for(TNode::iterator i = in.begin(); i != in.end(); ++i) {
    TNode::iterator j = i;
    while(++j != in.end()) {
      Node eq = NodeManager::currentNM()->mkNode(kind::EQUAL, *i, *j);
      Node neq = NodeManager::currentNM()->mkNode(kind::NOT, eq);
      diseqs.push_back(neq);
    }
  }
  Node out = NodeManager::currentNM()->mkNode(kind::AND, diseqs);
  return out;
}

RewriteResponse TheoryBuiltinRewriter::postRewrite(TNode node) {
  if( node.getKind()==kind::LAMBDA ){
    // The following code ensures that if node is equivalent to a constant
    // lambda, then we return the canonical representation for the lambda, which
    // in turn ensures that two constant lambdas are equivalent if and only
    // if they are the same node.
    // We canonicalize lambdas by turning them into array constants, applying
    // normalization on array constants, and then converting the array constant
    // back to a lambda.
    Trace("builtin-rewrite") << "Rewriting lambda " << node << "..." << std::endl;
    Node anode = getArrayRepresentationForLambda( node );
    // Only rewrite constant array nodes, since these are the only cases
    // where we require canonicalization of lambdas. Moreover, applying the
    // below code is not correct if the arguments to the lambda occur
    // in return values. For example, lambda x. ite( x=1, f(x), c ) would
    // be converted to (store (storeall ... c) 1 f(x)), and then converted
    // to lambda y. ite( y=1, f(x), c), losing the relation between x and y.
    if (!anode.isNull() && anode.isConst())
    {
      Assert(anode.getType().isArray());
      //must get the standard bound variable list
      Node varList = NodeManager::currentNM()->getBoundVarListForFunctionType( node.getType() );
      Node retNode = getLambdaForArrayRepresentation( anode, varList );
      if( !retNode.isNull() && retNode!=node ){
        Trace("builtin-rewrite") << "Rewrote lambda : " << std::endl;
        Trace("builtin-rewrite") << "     input  : " << node << std::endl;
        Trace("builtin-rewrite") << "     output : " << retNode << ", constant = " << retNode.isConst() << std::endl;
        Trace("builtin-rewrite") << "  array rep : " << anode << ", constant = " << anode.isConst() << std::endl;
        Assert(anode.isConst() == retNode.isConst());
        Assert(retNode.getType() == node.getType());
        Assert(expr::hasFreeVar(node) == expr::hasFreeVar(retNode));
        return RewriteResponse(REWRITE_DONE, retNode);
      }
    }
    else
    {
      Trace("builtin-rewrite-debug") << "...failed to get array representation." << std::endl;
    }
    return RewriteResponse(REWRITE_DONE, node);
  }
  // otherwise, do the default call
  return doRewrite(node);
}

RewriteResponse TheoryBuiltinRewriter::doRewrite(TNode node)
{
  switch (node.getKind())
  {
    case kind::WITNESS:
    {
      // it is important to run this rewriting at prerewrite and postrewrite,
      // since e.g. arithmetic rewrites equalities in ways that may make an
      // equality not in solved form syntactically, e.g. (= x (+ 1 a)) rewrites
      // to (= a (- x 1)), where x no longer is in solved form.
      Node rnode = rewriteWitness(node);
      return RewriteResponse(REWRITE_DONE, rnode);
    }
    case kind::DISTINCT:
      return RewriteResponse(REWRITE_DONE, blastDistinct(node));
    default: return RewriteResponse(REWRITE_DONE, node);
  }
}

TypeNode TheoryBuiltinRewriter::getFunctionTypeForArrayType(TypeNode atn,
                                                            Node bvl)
{
  std::vector<TypeNode> children;
  for (unsigned i = 0; i < bvl.getNumChildren(); i++)
  {
    Assert(atn.isArray());
    Assert(bvl[i].getType() == atn.getArrayIndexType());
    children.push_back(atn.getArrayIndexType());
    atn = atn.getArrayConstituentType();
  }
  children.push_back(atn);
  return NodeManager::currentNM()->mkFunctionType(children);
}

TypeNode TheoryBuiltinRewriter::getArrayTypeForFunctionType(TypeNode ftn)
{
  Assert(ftn.isFunction());
  // construct the curried array type
  unsigned nchildren = ftn.getNumChildren();
  TypeNode ret = ftn[nchildren - 1];
  for (int i = (static_cast<int>(nchildren) - 2); i >= 0; i--)
  {
    ret = NodeManager::currentNM()->mkArrayType(ftn[i], ret);
  }
  return ret;
}

Node TheoryBuiltinRewriter::getLambdaForArrayRepresentationRec(
    TNode a,
    TNode bvl,
    unsigned bvlIndex,
    std::unordered_map<TNode, Node>& visited)
{
  std::unordered_map<TNode, Node>::iterator it = visited.find(a);
  if( it==visited.end() ){
    Node ret;
    if( bvlIndex<bvl.getNumChildren() ){
      Assert(a.getType().isArray());
      if( a.getKind()==kind::STORE ){
        // convert the array recursively
        Node body = getLambdaForArrayRepresentationRec( a[0], bvl, bvlIndex, visited );
        if( !body.isNull() ){
          // convert the value recursively (bounded by the number of arguments in bvl)
          Node val = getLambdaForArrayRepresentationRec( a[2], bvl, bvlIndex+1, visited );
          if( !val.isNull() ){
            Assert(!TypeNode::leastCommonTypeNode(a[1].getType(),
                                                  bvl[bvlIndex].getType())
                        .isNull());
            Assert(!TypeNode::leastCommonTypeNode(val.getType(), body.getType())
                        .isNull());
            Node cond = bvl[bvlIndex].eqNode( a[1] );
            ret = NodeManager::currentNM()->mkNode( kind::ITE, cond, val, body );
          }
        }
      }else if( a.getKind()==kind::STORE_ALL ){
        ArrayStoreAll storeAll = a.getConst<ArrayStoreAll>();
        Node sa = storeAll.getValue();
        // convert the default value recursively (bounded by the number of arguments in bvl)
        ret = getLambdaForArrayRepresentationRec( sa, bvl, bvlIndex+1, visited );
      }
    }else{
      ret = a;
    }
    visited[a] = ret;
    return ret;
  }else{
    return it->second;
  }
}

Node TheoryBuiltinRewriter::getLambdaForArrayRepresentation( TNode a, TNode bvl ){
  Assert(a.getType().isArray());
  std::unordered_map<TNode, Node> visited;
  Trace("builtin-rewrite-debug") << "Get lambda for : " << a << ", with variables " << bvl << std::endl;
  Node body = getLambdaForArrayRepresentationRec( a, bvl, 0, visited );
  if( !body.isNull() ){
    body = Rewriter::rewrite( body );
    Trace("builtin-rewrite-debug") << "...got lambda body " << body << std::endl;
    return NodeManager::currentNM()->mkNode( kind::LAMBDA, bvl, body );
  }else{
    Trace("builtin-rewrite-debug") << "...failed to get lambda body" << std::endl;
    return Node::null();
  }
}

Node TheoryBuiltinRewriter::getArrayRepresentationForLambdaRec(TNode n,
                                                               TypeNode retType)
{
  Assert(n.getKind() == kind::LAMBDA);
  NodeManager* nm = NodeManager::currentNM();
  Trace("builtin-rewrite-debug") << "Get array representation for : " << n << std::endl;

  Node first_arg = n[0][0];
  Node rec_bvl;
  unsigned size = n[0].getNumChildren();
  if (size > 1)
  {
    std::vector< Node > args;
    for (unsigned i = 1; i < size; i++)
    {
      args.push_back( n[0][i] );
    }
    rec_bvl = nm->mkNode(kind::BOUND_VAR_LIST, args);
  }

  Trace("builtin-rewrite-debug2") << "  process body..." << std::endl;
  std::vector< Node > conds;
  std::vector< Node > vals;
  Node curr = n[1];
  Kind ck = curr.getKind();
  while (ck == kind::ITE || ck == kind::OR || ck == kind::AND
         || ck == kind::EQUAL || ck == kind::NOT || ck == kind::BOUND_VARIABLE)
  {
    Node index_eq;
    Node curr_val;
    Node next;
    // Each iteration of this loop infers an entry in the function, e.g. it
    // has a value under some condition.

    // [1] We infer that the entry has value "curr_val" under condition
    // "index_eq". We set "next" to the node that is the remainder of the
    // function to process.
    if (ck == kind::ITE)
    {
      Trace("builtin-rewrite-debug2")
          << "  process condition : " << curr[0] << std::endl;
      index_eq = curr[0];
      curr_val = curr[1];
      next = curr[2];
    }
    else if (ck == kind::OR || ck == kind::AND)
    {
      Trace("builtin-rewrite-debug2")
          << "  process base : " << curr << std::endl;
      // curr = Rewriter::rewrite(curr);
      // Trace("builtin-rewrite-debug2")
      //     << "  rewriten base : " << curr << std::endl;
      // Complex Boolean return cases, in which
      //  (1) lambda x. (= x v1) v ... becomes
      //      lambda x. (ite (= x v1) true [...])
      //
      //  (2) lambda x. (not (= x v1)) ^ ... becomes
      //      lambda x. (ite (= x v1) false [...])
      //
      // Note the negated cases of the lhs of the OR/AND operators above are
      // handled by pushing the recursion to the then-branch, with the
      // else-branch being the constant value. For example, the negated (1)
      // would be
      //  (1') lambda x. (not (= x v1)) v ... becomes
      //       lambda x. (ite (= x v1) [...] true)
      // thus requiring the rest of the disjunction to be further processed in
      // the then-branch as the current value.
      bool pol = curr[0].getKind() != kind::NOT;
      bool inverted = (pol && ck == kind::AND) || (!pol && ck == kind::OR);
      index_eq = pol ? curr[0] : curr[0][0];
      // processed : the value that is determined by the first child of curr
      // remainder : the remaining children of curr
      Node processed, remainder;
      // the value is the polarity of the first child or its inverse if we are
      // in the inverted case
      processed = nm->mkConst(!inverted? pol : !pol);
      // build an OR/AND with the remaining components
      if (curr.getNumChildren() == 2)
      {
        remainder = curr[1];
      }
      else
      {
        std::vector<Node> remainderNodes{curr.begin() + 1, curr.end()};
        remainder = nm->mkNode(ck, remainderNodes);
      }
      if (inverted)
      {
        curr_val = remainder;
        next = processed;
        // If the lambda contains more variables than the one being currently
        // processed, the current value can be non-constant, since it'll be
        // processed recursively below. Otherwise we fail.
        if (rec_bvl.isNull() && !curr_val.isConst())
        {
          Trace("builtin-rewrite-debug2")
              << "...non-const curr_val " << curr_val << "\n";
          return Node::null();
        }
      }
      else
      {
        curr_val = processed;
        next = remainder;
      }
      Trace("builtin-rewrite-debug2") << "  index_eq : " << index_eq << "\n";
      Trace("builtin-rewrite-debug2") << "  curr_val : " << curr_val << "\n";
      Trace("builtin-rewrite-debug2") << "  next : " << next << std::endl;
    }
    else
    {
      Trace("builtin-rewrite-debug2")
          << "  process base : " << curr << std::endl;
      // Simple Boolean return cases, in which
      //  (1) lambda x. (= x v) becomes lambda x. (ite (= x v) true false)
      //  (2) lambda x. v becomes lambda x. (ite (= x v) true false)
      // Note the negateg cases of the bodies above are also handled.
      bool pol = ck != kind::NOT;
      index_eq = pol ? curr : curr[0];
      curr_val = nm->mkConst(pol);
      next = nm->mkConst(!pol);
    }

    // [2] We ensure that "index_eq" is an equality, if possible.
    if (index_eq.getKind() != kind::EQUAL)
    {
      bool pol = index_eq.getKind() != kind::NOT;
      Node indexEqAtom = pol ? index_eq : index_eq[0];
      if (indexEqAtom.getKind() == kind::BOUND_VARIABLE)
      {
        if (!indexEqAtom.getType().isBoolean())
        {
          // Catches default case of non-Boolean variable, e.g.
          // lambda x : Int. x. In this case, it is not canonical and we fail.
          Trace("builtin-rewrite-debug2")
              << "  ...non-Boolean variable." << std::endl;
          return Node::null();
        }
        // Boolean argument case, e.g. lambda x. ite( x, t, s ) is processed as
        // lambda x. (ite (= x true) t s)
        index_eq = indexEqAtom.eqNode(nm->mkConst(pol));
      }
      else
      {
        // non-equality condition
        Trace("builtin-rewrite-debug2")
            << "  ...non-equality condition." << std::endl;
        return Node::null();
      }
    }
    else if (Rewriter::rewrite(index_eq) != index_eq)
    {
      // equality must be oriented correctly based on rewriter
      Trace("builtin-rewrite-debug2") << "  ...equality not oriented properly." << std::endl;
      return Node::null();
    }

    // [3] We ensure that "index_eq" is an equality that is equivalent to
    // "first_arg" = "curr_index", where curr_index is a constant, and
    // "first_arg" is the current argument we are processing, if possible.
    Node curr_index;
    for( unsigned r=0; r<2; r++ ){
      Node arg = index_eq[r];
      Node val = index_eq[1-r];
      if( arg==first_arg ){
        if (!val.isConst())
        {
          // non-constant value
          Trace("builtin-rewrite-debug2")
              << "  ...non-constant value for argument\n.";
          return Node::null();
        }else{
          curr_index = val;
          Trace("builtin-rewrite-debug2")
              << "  arg " << arg << " -> " << val << std::endl;
          break;
        }
      }
    }
    if (curr_index.isNull())
    {
      Trace("builtin-rewrite-debug2")
          << "  ...could not infer index value." << std::endl;
      return Node::null();
    }

    // [4] Recurse to ensure that "curr_val" has been normalized w.r.t. the
    // remaining arguments (rec_bvl).
    if (!rec_bvl.isNull())
    {
      curr_val = nm->mkNode(kind::LAMBDA, rec_bvl, curr_val);
      Trace("builtin-rewrite-debug") << push;
      Trace("builtin-rewrite-debug2") << push;
      curr_val = getArrayRepresentationForLambdaRec(curr_val, retType);
      Trace("builtin-rewrite-debug") << pop;
      Trace("builtin-rewrite-debug2") << pop;
      if (curr_val.isNull())
      {
        Trace("builtin-rewrite-debug2")
            << "  ...failed to recursively find value." << std::endl;
        return Node::null();
      }
    }
    Trace("builtin-rewrite-debug2")
        << "  ...condition is index " << curr_val << std::endl;

    // [5] Add the entry
    conds.push_back( curr_index );
    vals.push_back( curr_val );

    // we will now process the remainder
    curr = next;
    ck = curr.getKind();
    Trace("builtin-rewrite-debug2")
        << "  process remainder : " << curr << std::endl;
  }
  if( !rec_bvl.isNull() ){
    curr = nm->mkNode(kind::LAMBDA, rec_bvl, curr);
    Trace("builtin-rewrite-debug") << push;
    Trace("builtin-rewrite-debug2") << push;
    curr = getArrayRepresentationForLambdaRec(curr, retType);
    Trace("builtin-rewrite-debug") << pop;
    Trace("builtin-rewrite-debug2") << pop;
  }
  if( !curr.isNull() && curr.isConst() ){
    // compute the return type
    TypeNode array_type = retType;
    for (unsigned i = 0; i < size; i++)
    {
      unsigned index = (size - 1) - i;
      array_type = nm->mkArrayType(n[0][index].getType(), array_type);
    }
    Trace("builtin-rewrite-debug2") << "  make array store all " << curr.getType() << " annotated : " << array_type << std::endl;
    Assert(curr.getType().isSubtypeOf(array_type.getArrayConstituentType()));
    curr = nm->mkConst(ArrayStoreAll(array_type, curr));
    Trace("builtin-rewrite-debug2") << "  build array..." << std::endl;
    // can only build if default value is constant (since array store all must be constant)
    Trace("builtin-rewrite-debug2") << "  got constant base " << curr << std::endl;
    Trace("builtin-rewrite-debug2") << "  conditions " << conds << std::endl;
    Trace("builtin-rewrite-debug2") << "  values " << vals << std::endl;
    // construct store chain
    for (int i = static_cast<int>(conds.size()) - 1; i >= 0; i--)
    {
      Assert(conds[i].getType().isSubtypeOf(first_arg.getType()));
      curr = nm->mkNode(kind::STORE, curr, conds[i], vals[i]);
    }
    Trace("builtin-rewrite-debug") << "...got array " << curr << " for " << n << std::endl;
    return curr;
  }else{
    Trace("builtin-rewrite-debug") << "...failed to get array (cannot get constant default value)" << std::endl;
    return Node::null();
  }
}

Node TheoryBuiltinRewriter::rewriteWitness(TNode node)
{
  Assert(node.getKind() == kind::WITNESS);
  if (node[1].getKind() == kind::EQUAL)
  {
    for (size_t i = 0; i < 2; i++)
    {
      // (witness ((x T)) (= x t)) ---> t
      if (node[1][i] == node[0][0])
      {
        Trace("builtin-rewrite") << "Witness rewrite: " << node << " --> "
                                 << node[1][1 - i] << std::endl;
        // also must be a legal elimination: the other side of the equality
        // cannot contain the variable, and it must be a subtype of the
        // variable
        if (!expr::hasSubterm(node[1][1 - i], node[0][0])
            && node[1][i].getType().isSubtypeOf(node[0][0].getType()))
        {
          return node[1][1 - i];
        }
      }
    }
  }
  else if (node[1] == node[0][0])
  {
    // (witness ((x Bool)) x) ---> true
    return NodeManager::currentNM()->mkConst(true);
  }
  else if (node[1].getKind() == kind::NOT && node[1][0] == node[0][0])
  {
    // (witness ((x Bool)) (not x)) ---> false
    return NodeManager::currentNM()->mkConst(false);
  }
  return node;
}

Node TheoryBuiltinRewriter::getArrayRepresentationForLambda(TNode n)
{
  Assert(n.getKind() == kind::LAMBDA);
  // must carry the overall return type to deal with cases like (lambda ((x Int)
  // (y Int)) (ite (= x _) 0.5 0.0)), where the inner construction for the else
  // case above should be (arraystoreall (Array Int Real) 0.0)
  Node anode = getArrayRepresentationForLambdaRec(n, n[1].getType());
  if (anode.isNull())
  {
    return anode;
  }
  // must rewrite it to make canonical
  return Rewriter::rewrite(anode);
}

}  // namespace builtin
}  // namespace theory
}  // namespace cvc5


Generated by: GCOVR (Version 3.2)

Line	Exec	Source
1		/******************************************************************************
2		* Top contributors (to current version):
3		* Andrew Reynolds, Haniel Barbosa, Morgan Deters
4		*
5		* This file is part of the cvc5 project.
6		*
7		* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
8		* in the top-level source directory and their institutional affiliations.
9		* All rights reserved. See the file COPYING in the top-level source
10		* directory for licensing information.
11		* ****************************************************************************
12		*
13		* [[ Add one-line brief description here ]]
14		*
15		* [[ Add lengthier description here ]]
16		* \todo document this file
17		*/
18
19		#include "theory/builtin/theory_builtin_rewriter.h"
20
21		#include "expr/attribute.h"
22		#include "expr/node_algorithm.h"
23		#include "theory/rewriter.h"
24
25		using namespace std;
26
27		namespace cvc5 {
28		namespace theory {
29		namespace builtin {
30
31	10798	Node TheoryBuiltinRewriter::blastDistinct(TNode in) {
32	10798	Assert(in.getKind() == kind::DISTINCT);
33
34	10798	if(in.getNumChildren() == 2) {
35		// if this is the case exactly 1 != pair will be generated so the
36		// AND is not required
37	20666	Node eq = NodeManager::currentNM()->mkNode(kind::EQUAL, in[0], in[1]);
38	20666	Node neq = NodeManager::currentNM()->mkNode(kind::NOT, eq);
39	10333	return neq;
40		}
41
42		// assume that in.getNumChildren() > 2 => diseqs.size() > 1
43	930	vector<Node> diseqs;
44	3429	for(TNode::iterator i = in.begin(); i != in.end(); ++i) {
45	2964	TNode::iterator j = i;
46	70608	while(++j != in.end()) {
47	67644	Node eq = NodeManager::currentNM()->mkNode(kind::EQUAL, i, j);
48	67644	Node neq = NodeManager::currentNM()->mkNode(kind::NOT, eq);
49	33822	diseqs.push_back(neq);
50		}
51		}
52	930	Node out = NodeManager::currentNM()->mkNode(kind::AND, diseqs);
53	465	return out;
54		}
55
56	742880	RewriteResponse TheoryBuiltinRewriter::postRewrite(TNode node) {
57	742880	if( node.getKind()==kind::LAMBDA ){
58		// The following code ensures that if node is equivalent to a constant
59		// lambda, then we return the canonical representation for the lambda, which
60		// in turn ensures that two constant lambdas are equivalent if and only
61		// if they are the same node.
62		// We canonicalize lambdas by turning them into array constants, applying
63		// normalization on array constants, and then converting the array constant
64		// back to a lambda.
65	6856	Trace("builtin-rewrite") << "Rewriting lambda " << node << "..." << std::endl;
66	13712	Node anode = getArrayRepresentationForLambda( node );
67		// Only rewrite constant array nodes, since these are the only cases
68		// where we require canonicalization of lambdas. Moreover, applying the
69		// below code is not correct if the arguments to the lambda occur
70		// in return values. For example, lambda x. ite( x=1, f(x), c ) would
71		// be converted to (store (storeall ... c) 1 f(x)), and then converted
72		// to lambda y. ite( y=1, f(x), c), losing the relation between x and y.
73	6856	if (!anode.isNull() && anode.isConst())
74		{
75	2812	Assert(anode.getType().isArray());
76		//must get the standard bound variable list
77	4307	Node varList = NodeManager::currentNM()->getBoundVarListForFunctionType( node.getType() );
78	4307	Node retNode = getLambdaForArrayRepresentation( anode, varList );
79	2812	if( !retNode.isNull() && retNode!=node ){
80	1317	Trace("builtin-rewrite") << "Rewrote lambda : " << std::endl;
81	1317	Trace("builtin-rewrite") << " input : " << node << std::endl;
82	1317	Trace("builtin-rewrite") << " output : " << retNode << ", constant = " << retNode.isConst() << std::endl;
83	1317	Trace("builtin-rewrite") << " array rep : " << anode << ", constant = " << anode.isConst() << std::endl;
84	1317	Assert(anode.isConst() == retNode.isConst());
85	1317	Assert(retNode.getType() == node.getType());
86	1317	Assert(expr::hasFreeVar(node) == expr::hasFreeVar(retNode));
87	1317	return RewriteResponse(REWRITE_DONE, retNode);
88		}
89		}
90		else
91		{
92	4044	Trace("builtin-rewrite-debug") << "...failed to get array representation." << std::endl;
93		}
94	5539	return RewriteResponse(REWRITE_DONE, node);
95		}
96		// otherwise, do the default call
97	736024	return doRewrite(node);
98		}
99
100	1135299	RewriteResponse TheoryBuiltinRewriter::doRewrite(TNode node)
101		{
102	1135299	switch (node.getKind())
103		{
104	2868	case kind::WITNESS:
105		{
106		// it is important to run this rewriting at prerewrite and postrewrite,
107		// since e.g. arithmetic rewrites equalities in ways that may make an
108		// equality not in solved form syntactically, e.g. (= x (+ 1 a)) rewrites
109		// to (= a (- x 1)), where x no longer is in solved form.
110	5736	Node rnode = rewriteWitness(node);
111	2868	return RewriteResponse(REWRITE_DONE, rnode);
112		}
113	10798	case kind::DISTINCT:
114	10798	return RewriteResponse(REWRITE_DONE, blastDistinct(node));
115	1121633	default: return RewriteResponse(REWRITE_DONE, node);
116		}
117		}
118
119		TypeNode TheoryBuiltinRewriter::getFunctionTypeForArrayType(TypeNode atn,
120		Node bvl)
121		{
122		std::vector<TypeNode> children;
123		for (unsigned i = 0; i < bvl.getNumChildren(); i++)
124		{
125		Assert(atn.isArray());
126		Assert(bvl[i].getType() == atn.getArrayIndexType());
127		children.push_back(atn.getArrayIndexType());
128		atn = atn.getArrayConstituentType();
129		}
130		children.push_back(atn);
131		return NodeManager::currentNM()->mkFunctionType(children);
132		}
133
134		TypeNode TheoryBuiltinRewriter::getArrayTypeForFunctionType(TypeNode ftn)
135		{
136		Assert(ftn.isFunction());
137		// construct the curried array type
138		unsigned nchildren = ftn.getNumChildren();
139		TypeNode ret = ftn[nchildren - 1];
140		for (int i = (static_cast<int>(nchildren) - 2); i >= 0; i--)
141		{
142		ret = NodeManager::currentNM()->mkArrayType(ftn[i], ret);
143		}
144		return ret;
145		}
146
147	17382	Node TheoryBuiltinRewriter::getLambdaForArrayRepresentationRec(
148		TNode a,
149		TNode bvl,
150		unsigned bvlIndex,
151		std::unordered_map<TNode, Node>& visited)
152		{
153	17382	std::unordered_map<TNode, Node>::iterator it = visited.find(a);
154	17382	if( it==visited.end() ){
155	32972	Node ret;
156	16486	if( bvlIndex<bvl.getNumChildren() ){
157	8900	Assert(a.getType().isArray());
158	8900	if( a.getKind()==kind::STORE ){
159		// convert the array recursively
160	11340	Node body = getLambdaForArrayRepresentationRec( a[0], bvl, bvlIndex, visited );
161	5670	if( !body.isNull() ){
162		// convert the value recursively (bounded by the number of arguments in bvl)
163	11340	Node val = getLambdaForArrayRepresentationRec( a[2], bvl, bvlIndex+1, visited );
164	5670	if( !val.isNull() ){
165	5670	Assert(!TypeNode::leastCommonTypeNode(a[1].getType(),
166		bvl[bvlIndex].getType())
167		.isNull());
168	5670	Assert(!TypeNode::leastCommonTypeNode(val.getType(), body.getType())
169		.isNull());
170	11340	Node cond = bvl[bvlIndex].eqNode( a[1] );
171	5670	ret = NodeManager::currentNM()->mkNode( kind::ITE, cond, val, body );
172		}
173		}
174	3230	}else if( a.getKind()==kind::STORE_ALL ){
175	6460	ArrayStoreAll storeAll = a.getConst<ArrayStoreAll>();
176	6460	Node sa = storeAll.getValue();
177		// convert the default value recursively (bounded by the number of arguments in bvl)
178	3230	ret = getLambdaForArrayRepresentationRec( sa, bvl, bvlIndex+1, visited );
179		}
180		}else{
181	7586	ret = a;
182		}
183	16486	visited[a] = ret;
184	16486	return ret;
185		}else{
186	896	return it->second;
187		}
188		}
189
190	2812	Node TheoryBuiltinRewriter::getLambdaForArrayRepresentation( TNode a, TNode bvl ){
191	2812	Assert(a.getType().isArray());
192	5624	std::unordered_map<TNode, Node> visited;
193	2812	Trace("builtin-rewrite-debug") << "Get lambda for : " << a << ", with variables " << bvl << std::endl;
194	5624	Node body = getLambdaForArrayRepresentationRec( a, bvl, 0, visited );
195	2812	if( !body.isNull() ){
196	2812	body = Rewriter::rewrite( body );
197	2812	Trace("builtin-rewrite-debug") << "...got lambda body " << body << std::endl;
198	2812	return NodeManager::currentNM()->mkNode( kind::LAMBDA, bvl, body );
199		}else{
200		Trace("builtin-rewrite-debug") << "...failed to get lambda body" << std::endl;
201		return Node::null();
202		}
203		}
204
205	12622	Node TheoryBuiltinRewriter::getArrayRepresentationForLambdaRec(TNode n,
206		TypeNode retType)
207		{
208	12622	Assert(n.getKind() == kind::LAMBDA);
209	12622	NodeManager* nm = NodeManager::currentNM();
210	12622	Trace("builtin-rewrite-debug") << "Get array representation for : " << n << std::endl;
211
212	25244	Node first_arg = n[0][0];
213	25244	Node rec_bvl;
214	12622	unsigned size = n[0].getNumChildren();
215	12622	if (size > 1)
216		{
217	7276	std::vector< Node > args;
218	7933	for (unsigned i = 1; i < size; i++)
219		{
220	4295	args.push_back( n[0][i] );
221		}
222	3638	rec_bvl = nm->mkNode(kind::BOUND_VAR_LIST, args);
223		}
224
225	12622	Trace("builtin-rewrite-debug2") << " process body..." << std::endl;
226	25244	std::vector< Node > conds;
227	25244	std::vector< Node > vals;
228	25244	Node curr = n[1];
229	12622	Kind ck = curr.getKind();
230	20919	while (ck == kind::ITE \|\| ck == kind::OR \|\| ck == kind::AND
231	32692	\|\| ck == kind::EQUAL \|\| ck == kind::NOT \|\| ck == kind::BOUND_VARIABLE)
232		{
233	18078	Node index_eq;
234	18078	Node curr_val;
235	18078	Node next;
236		// Each iteration of this loop infers an entry in the function, e.g. it
237		// has a value under some condition.
238
239		// [1] We infer that the entry has value "curr_val" under condition
240		// "index_eq". We set "next" to the node that is the remainder of the
241		// function to process.
242	10074	if (ck == kind::ITE)
243		{
244	15422	Trace("builtin-rewrite-debug2")
245	7711	<< " process condition : " << curr[0] << std::endl;
246	7711	index_eq = curr[0];
247	7711	curr_val = curr[1];
248	7711	next = curr[2];
249		}
250	2363	else if (ck == kind::OR \|\| ck == kind::AND)
251		{
252	1698	Trace("builtin-rewrite-debug2")
253	849	<< " process base : " << curr << std::endl;
254		// curr = Rewriter::rewrite(curr);
255		// Trace("builtin-rewrite-debug2")
256		// << " rewriten base : " << curr << std::endl;
257		// Complex Boolean return cases, in which
258		// (1) lambda x. (= x v1) v ... becomes
259		// lambda x. (ite (= x v1) true [...])
260		//
261		// (2) lambda x. (not (= x v1)) ^ ... becomes
262		// lambda x. (ite (= x v1) false [...])
263		//
264		// Note the negated cases of the lhs of the OR/AND operators above are
265		// handled by pushing the recursion to the then-branch, with the
266		// else-branch being the constant value. For example, the negated (1)
267		// would be
268		// (1') lambda x. (not (= x v1)) v ... becomes
269		// lambda x. (ite (= x v1) [...] true)
270		// thus requiring the rest of the disjunction to be further processed in
271		// the then-branch as the current value.
272	849	bool pol = curr[0].getKind() != kind::NOT;
273	849	bool inverted = (pol && ck == kind::AND) \|\| (!pol && ck == kind::OR);
274	849	index_eq = pol ? curr[0] : curr[0][0];
275		// processed : the value that is determined by the first child of curr
276		// remainder : the remaining children of curr
277	1502	Node processed, remainder;
278		// the value is the polarity of the first child or its inverse if we are
279		// in the inverted case
280	849	processed = nm->mkConst(!inverted? pol : !pol);
281		// build an OR/AND with the remaining components
282	849	if (curr.getNumChildren() == 2)
283		{
284	813	remainder = curr[1];
285		}
286		else
287		{
288	72	std::vector<Node> remainderNodes{curr.begin() + 1, curr.end()};
289	36	remainder = nm->mkNode(ck, remainderNodes);
290		}
291	849	if (inverted)
292		{
293	487	curr_val = remainder;
294	487	next = processed;
295		// If the lambda contains more variables than the one being currently
296		// processed, the current value can be non-constant, since it'll be
297		// processed recursively below. Otherwise we fail.
298	487	if (rec_bvl.isNull() && !curr_val.isConst())
299		{
300	392	Trace("builtin-rewrite-debug2")
301	196	<< "...non-const curr_val " << curr_val << "\n";
302	196	return Node::null();
303		}
304		}
305		else
306		{
307	362	curr_val = processed;
308	362	next = remainder;
309		}
310	653	Trace("builtin-rewrite-debug2") << " index_eq : " << index_eq << "\n";
311	653	Trace("builtin-rewrite-debug2") << " curr_val : " << curr_val << "\n";
312	1306	Trace("builtin-rewrite-debug2") << " next : " << next << std::endl;
313		}
314		else
315		{
316	3028	Trace("builtin-rewrite-debug2")
317	1514	<< " process base : " << curr << std::endl;
318		// Simple Boolean return cases, in which
319		// (1) lambda x. (= x v) becomes lambda x. (ite (= x v) true false)
320		// (2) lambda x. v becomes lambda x. (ite (= x v) true false)
321		// Note the negateg cases of the bodies above are also handled.
322	1514	bool pol = ck != kind::NOT;
323	1514	index_eq = pol ? curr : curr[0];
324	1514	curr_val = nm->mkConst(pol);
325	1514	next = nm->mkConst(!pol);
326		}
327
328		// [2] We ensure that "index_eq" is an equality, if possible.
329	9878	if (index_eq.getKind() != kind::EQUAL)
330		{
331	2021	bool pol = index_eq.getKind() != kind::NOT;
332	2758	Node indexEqAtom = pol ? index_eq : index_eq[0];
333	2021	if (indexEqAtom.getKind() == kind::BOUND_VARIABLE)
334		{
335	1069	if (!indexEqAtom.getType().isBoolean())
336		{
337		// Catches default case of non-Boolean variable, e.g.
338		// lambda x : Int. x. In this case, it is not canonical and we fail.
339	664	Trace("builtin-rewrite-debug2")
340	332	<< " ...non-Boolean variable." << std::endl;
341	332	return Node::null();
342		}
343		// Boolean argument case, e.g. lambda x. ite( x, t, s ) is processed as
344		// lambda x. (ite (= x true) t s)
345	737	index_eq = indexEqAtom.eqNode(nm->mkConst(pol));
346		}
347		else
348		{
349		// non-equality condition
350	1904	Trace("builtin-rewrite-debug2")
351	952	<< " ...non-equality condition." << std::endl;
352	952	return Node::null();
353		}
354		}
355	7857	else if (Rewriter::rewrite(index_eq) != index_eq)
356		{
357		// equality must be oriented correctly based on rewriter
358	8	Trace("builtin-rewrite-debug2") << " ...equality not oriented properly." << std::endl;
359	8	return Node::null();
360		}
361
362		// [3] We ensure that "index_eq" is an equality that is equivalent to
363		// "first_arg" = "curr_index", where curr_index is a constant, and
364		// "first_arg" is the current argument we are processing, if possible.
365	16590	Node curr_index;
366	10499	for( unsigned r=0; r<2; r++ ){
367	12230	Node arg = index_eq[r];
368	12230	Node val = index_eq[1-r];
369	10317	if( arg==first_arg ){
370	8404	if (!val.isConst())
371		{
372		// non-constant value
373	402	Trace("builtin-rewrite-debug2")
374	201	<< " ...non-constant value for argument\n.";
375	201	return Node::null();
376		}else{
377	8203	curr_index = val;
378	16406	Trace("builtin-rewrite-debug2")
379	8203	<< " arg " << arg << " -> " << val << std::endl;
380	8203	break;
381		}
382		}
383		}
384	8385	if (curr_index.isNull())
385		{
386	364	Trace("builtin-rewrite-debug2")
387	182	<< " ...could not infer index value." << std::endl;
388	182	return Node::null();
389		}
390
391		// [4] Recurse to ensure that "curr_val" has been normalized w.r.t. the
392		// remaining arguments (rec_bvl).
393	8203	if (!rec_bvl.isNull())
394		{
395	1452	curr_val = nm->mkNode(kind::LAMBDA, rec_bvl, curr_val);
396	1452	Trace("builtin-rewrite-debug") << push;
397	1452	Trace("builtin-rewrite-debug2") << push;
398	1452	curr_val = getArrayRepresentationForLambdaRec(curr_val, retType);
399	1452	Trace("builtin-rewrite-debug") << pop;
400	1452	Trace("builtin-rewrite-debug2") << pop;
401	1452	if (curr_val.isNull())
402		{
403	398	Trace("builtin-rewrite-debug2")
404	199	<< " ...failed to recursively find value." << std::endl;
405	199	return Node::null();
406		}
407		}
408	16008	Trace("builtin-rewrite-debug2")
409	8004	<< " ...condition is index " << curr_val << std::endl;
410
411		// [5] Add the entry
412	8004	conds.push_back( curr_index );
413	8004	vals.push_back( curr_val );
414
415		// we will now process the remainder
416	8004	curr = next;
417	8004	ck = curr.getKind();
418	16008	Trace("builtin-rewrite-debug2")
419	8004	<< " process remainder : " << curr << std::endl;
420		}
421	10552	if( !rec_bvl.isNull() ){
422	2585	curr = nm->mkNode(kind::LAMBDA, rec_bvl, curr);
423	2585	Trace("builtin-rewrite-debug") << push;
424	2585	Trace("builtin-rewrite-debug2") << push;
425	2585	curr = getArrayRepresentationForLambdaRec(curr, retType);
426	2585	Trace("builtin-rewrite-debug") << pop;
427	2585	Trace("builtin-rewrite-debug2") << pop;
428		}
429	10552	if( !curr.isNull() && curr.isConst() ){
430		// compute the return type
431	10634	TypeNode array_type = retType;
432	11451	for (unsigned i = 0; i < size; i++)
433		{
434	6134	unsigned index = (size - 1) - i;
435	6134	array_type = nm->mkArrayType(n[0][index].getType(), array_type);
436		}
437	5317	Trace("builtin-rewrite-debug2") << " make array store all " << curr.getType() << " annotated : " << array_type << std::endl;
438	5317	Assert(curr.getType().isSubtypeOf(array_type.getArrayConstituentType()));
439	5317	curr = nm->mkConst(ArrayStoreAll(array_type, curr));
440	5317	Trace("builtin-rewrite-debug2") << " build array..." << std::endl;
441		// can only build if default value is constant (since array store all must be constant)
442	5317	Trace("builtin-rewrite-debug2") << " got constant base " << curr << std::endl;
443	5317	Trace("builtin-rewrite-debug2") << " conditions " << conds << std::endl;
444	5317	Trace("builtin-rewrite-debug2") << " values " << vals << std::endl;
445		// construct store chain
446	13090	for (int i = static_cast<int>(conds.size()) - 1; i >= 0; i--)
447		{
448	7773	Assert(conds[i].getType().isSubtypeOf(first_arg.getType()));
449	7773	curr = nm->mkNode(kind::STORE, curr, conds[i], vals[i]);
450		}
451	5317	Trace("builtin-rewrite-debug") << "...got array " << curr << " for " << n << std::endl;
452	5317	return curr;
453		}else{
454	5235	Trace("builtin-rewrite-debug") << "...failed to get array (cannot get constant default value)" << std::endl;
455	5235	return Node::null();
456		}
457		}
458
459	2868	Node TheoryBuiltinRewriter::rewriteWitness(TNode node)
460		{
461	2868	Assert(node.getKind() == kind::WITNESS);
462	2868	if (node[1].getKind() == kind::EQUAL)
463		{
464	291	for (size_t i = 0; i < 2; i++)
465		{
466		// (witness ((x T)) (= x t)) ---> t
467	194	if (node[1][i] == node[0][0])
468		{
469		Trace("builtin-rewrite") << "Witness rewrite: " << node << " --> "
470		<< node[1][1 - i] << std::endl;
471		// also must be a legal elimination: the other side of the equality
472		// cannot contain the variable, and it must be a subtype of the
473		// variable
474		if (!expr::hasSubterm(node[1][1 - i], node[0][0])
475		&& node[1][i].getType().isSubtypeOf(node[0][0].getType()))
476		{
477		return node[1][1 - i];
478		}
479		}
480		}
481		}
482	2771	else if (node[1] == node[0][0])
483		{
484		// (witness ((x Bool)) x) ---> true
485		return NodeManager::currentNM()->mkConst(true);
486		}
487	2771	else if (node[1].getKind() == kind::NOT && node[1][0] == node[0][0])
488		{
489		// (witness ((x Bool)) (not x)) ---> false
490		return NodeManager::currentNM()->mkConst(false);
491		}
492	2868	return node;
493		}
494
495	8585	Node TheoryBuiltinRewriter::getArrayRepresentationForLambda(TNode n)
496		{
497	8585	Assert(n.getKind() == kind::LAMBDA);
498		// must carry the overall return type to deal with cases like (lambda ((x Int)
499		// (y Int)) (ite (= x _) 0.5 0.0)), where the inner construction for the else
500		// case above should be (arraystoreall (Array Int Real) 0.0)
501	17170	Node anode = getArrayRepresentationForLambdaRec(n, n[1].getType());
502	8585	if (anode.isNull())
503		{
504	5253	return anode;
505		}
506		// must rewrite it to make canonical
507	3332	return Rewriter::rewrite(anode);
508		}
509
510		} // namespace builtin
511		} // namespace theory
512	28191	} // namespace cvc5