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/******************************************************************************
* Top contributors (to current version):
* Dejan Jovanovic, Clark Barrett, 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.
* ****************************************************************************
*
* A substitution mapping for theory simplification.
*/
#include "theory/substitutions.h"
#include "expr/node_algorithm.h"
#include "theory/rewriter.h"
using namespace std;
namespace cvc5 {
namespace theory {
SubstitutionMap::SubstitutionMap(context::Context* context)
: d_context(),
d_substitutions(context ? context : &d_context),
d_substitutionCache(),
d_cacheInvalidated(false),
d_cacheInvalidator(context ? context : &d_context, d_cacheInvalidated)
{
}
struct substitution_stack_element {
TNode d_node;
bool d_children_added;
substitution_stack_element(TNode node) : d_node(node), d_children_added(false)
{
}
};/* struct substitution_stack_element */
Node SubstitutionMap::internalSubstitute(TNode t, NodeCache& cache) {
Debug("substitution::internal") << "SubstitutionMap::internalSubstitute(" << t << ")" << endl;
if (d_substitutions.empty()) {
return t;
}
// Do a topological sort of the subexpressions and substitute them
vector<substitution_stack_element> toVisit;
toVisit.push_back((TNode) t);
while (!toVisit.empty())
{
// The current node we are processing
substitution_stack_element& stackHead = toVisit.back();
TNode current = stackHead.d_node;
Debug("substitution::internal") << "SubstitutionMap::internalSubstitute(" << t << "): processing " << current << endl;
// If node already in the cache we're done, pop from the stack
NodeCache::iterator find = cache.find(current);
if (find != cache.end()) {
toVisit.pop_back();
continue;
}
NodeMap::iterator find2 = d_substitutions.find(current);
if (find2 != d_substitutions.end()) {
Node rhs = (*find2).second;
Assert(rhs != current);
internalSubstitute(rhs, cache);
d_substitutions[current] = cache[rhs];
cache[current] = cache[rhs];
toVisit.pop_back();
continue;
}
// Not yet substituted, so process
if (stackHead.d_children_added)
{
// Children have been processed, so substitute
NodeBuilder builder(current.getKind());
if (current.getMetaKind() == kind::metakind::PARAMETERIZED) {
builder << Node(cache[current.getOperator()]);
}
for (unsigned i = 0; i < current.getNumChildren(); ++ i) {
Assert(cache.find(current[i]) != cache.end());
builder << Node(cache[current[i]]);
}
// Mark the substitution and continue
Node result = builder;
if (result != current) {
find = cache.find(result);
if (find != cache.end()) {
result = find->second;
}
else {
find2 = d_substitutions.find(result);
if (find2 != d_substitutions.end()) {
Node rhs = (*find2).second;
Assert(rhs != result);
internalSubstitute(rhs, cache);
d_substitutions[result] = cache[rhs];
cache[result] = cache[rhs];
result = cache[rhs];
}
}
}
Debug("substitution::internal") << "SubstitutionMap::internalSubstitute(" << t << "): setting " << current << " -> " << result << endl;
cache[current] = result;
toVisit.pop_back();
}
else
{
// Mark that we have added the children if any
if (current.getNumChildren() > 0 || current.getMetaKind() == kind::metakind::PARAMETERIZED) {
stackHead.d_children_added = true;
// We need to add the operator, if any
if(current.getMetaKind() == kind::metakind::PARAMETERIZED) {
TNode opNode = current.getOperator();
NodeCache::iterator opFind = cache.find(opNode);
if (opFind == cache.end()) {
toVisit.push_back(opNode);
}
}
// We need to add the children
for(TNode::iterator child_it = current.begin(); child_it != current.end(); ++ child_it) {
TNode childNode = *child_it;
NodeCache::iterator childFind = cache.find(childNode);
if (childFind == cache.end()) {
toVisit.push_back(childNode);
}
}
} else {
// No children, so we're done
Debug("substitution::internal") << "SubstitutionMap::internalSubstitute(" << t << "): setting " << current << " -> " << current << endl;
cache[current] = current;
toVisit.pop_back();
}
}
}
// Return the substituted version
return cache[t];
}/* SubstitutionMap::internalSubstitute() */
void SubstitutionMap::addSubstitution(TNode x, TNode t, bool invalidateCache)
{
Debug("substitution") << "SubstitutionMap::addSubstitution(" << x << ", " << t << ")" << endl;
Assert(d_substitutions.find(x) == d_substitutions.end());
// this causes a later assert-fail (the rhs != current one, above) anyway
// putting it here is easier to diagnose
Assert(x != t) << "cannot substitute a term for itself";
d_substitutions[x] = t;
// Also invalidate the cache if necessary
if (invalidateCache) {
d_cacheInvalidated = true;
}
else {
d_substitutionCache[x] = d_substitutions[x];
}
}
void SubstitutionMap::addSubstitutions(SubstitutionMap& subMap, bool invalidateCache)
{
SubstitutionMap::NodeMap::const_iterator it = subMap.begin();
SubstitutionMap::NodeMap::const_iterator it_end = subMap.end();
for (; it != it_end; ++ it) {
Assert(d_substitutions.find((*it).first) == d_substitutions.end());
d_substitutions[(*it).first] = (*it).second;
if (!invalidateCache) {
d_substitutionCache[(*it).first] = d_substitutions[(*it).first];
}
}
if (invalidateCache) {
d_cacheInvalidated = true;
}
}
Node SubstitutionMap::apply(TNode t, bool doRewrite) {
Debug("substitution") << "SubstitutionMap::apply(" << t << ")" << endl;
// Setup the cache
if (d_cacheInvalidated) {
d_substitutionCache.clear();
d_cacheInvalidated = false;
Debug("substitution") << "-- reset the cache" << endl;
}
// Perform the substitution
Node result = internalSubstitute(t, d_substitutionCache);
Debug("substitution") << "SubstitutionMap::apply(" << t << ") => " << result << endl;
if (doRewrite)
{
result = Rewriter::rewrite(result);
}
return result;
}
void SubstitutionMap::print(ostream& out) const {
NodeMap::const_iterator it = d_substitutions.begin();
NodeMap::const_iterator it_end = d_substitutions.end();
for (; it != it_end; ++ it) {
out << (*it).first << " -> " << (*it).second << endl;
}
}
void SubstitutionMap::debugPrint() const { print(CVC5Message.getStream()); }
} // namespace theory
std::ostream& operator<<(std::ostream& out, const theory::SubstitutionMap::iterator& i) {
return out << "[CDMap-iterator]";
}
} // namespace cvc5
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