public Dictionary <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode> ComputeBottomUpMapping(ISymbolicExpressionTreeNode n1, ISymbolicExpressionTreeNode n2)
{
var comparer = new SymbolicExpressionTreeNodeComparer(); // use a node comparer because it's faster than calling node.ToString() (strings are expensive) and comparing strings
var compactedGraph = Compact(n1, n2);
var forwardMap = new Dictionary <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode>(); // nodes of t1 => nodes of t2
var reverseMap = new Dictionary <ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode>(); // nodes of t2 => nodes of t1
// visit nodes in order of decreasing height to ensure correct mapping
var nodes1 = n1.IterateNodesPrefix().OrderByDescending(x => x.GetDepth()).ToList();
var nodes2 = n2.IterateNodesPrefix().ToList();
for (int i = 0; i < nodes1.Count; ++i)
{
var v = nodes1[i];
if (forwardMap.ContainsKey(v))
{
continue;
}
var kv = compactedGraph[v];
ISymbolicExpressionTreeNode w = null;
for (int j = 0; j < nodes2.Count; ++j)
{
var t = nodes2[j];
if (reverseMap.ContainsKey(t) || compactedGraph[t] != kv)
{
continue;
}
w = t;
break;
}
if (w == null)
{
continue;
}
// at this point we know that v and w are isomorphic, however, the mapping cannot be done directly
// (as in the paper) because the trees are unordered (subtree order might differ). the solution is
// to sort subtrees from under commutative labels (this will work because the subtrees are isomorphic!)
// while iterating over the two subtrees
var vv = IterateBreadthOrdered(v, comparer).ToList();
var ww = IterateBreadthOrdered(w, comparer).ToList();
int len = Math.Min(vv.Count, ww.Count);
for (int j = 0; j < len; ++j)
{
var s = vv[j];
var t = ww[j];
Debug.Assert(!reverseMap.ContainsKey(t));
forwardMap[s] = t;
reverseMap[t] = s;
}
}
return(forwardMap);
}
public void SortSubtrees(ISymbolicExpressionTreeNode node) {
if (node.SubtreeCount == 0) return;
var subtrees = node.Subtrees as List<ISymbolicExpressionTreeNode> ?? node.Subtrees.ToList();
if (IsSymmetric(node.Symbol)) {
var comparer = new SymbolicExpressionTreeNodeComparer();
subtrees.Sort(comparer);
}
foreach (var s in subtrees)
SortSubtrees(s);
}
public void SortSubtrees(ISymbolicExpressionTreeNode node)
{
if (node.SubtreeCount == 0)
{
return;
}
var subtrees = node.Subtrees as List <ISymbolicExpressionTreeNode> ?? node.Subtrees.ToList();
if (IsSymmetric(node.Symbol))
{
var comparer = new SymbolicExpressionTreeNodeComparer();
subtrees.Sort(comparer);
}
foreach (var s in subtrees)
{
SortSubtrees(s);
}
}
public Dictionary<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode> ComputeBottomUpMapping(ISymbolicExpressionTreeNode n1, ISymbolicExpressionTreeNode n2) {
var comparer = new SymbolicExpressionTreeNodeComparer(); // use a node comparer because it's faster than calling node.ToString() (strings are expensive) and comparing strings
var compactedGraph = Compact(n1, n2);
var forwardMap = new Dictionary<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode>(); // nodes of t1 => nodes of t2
var reverseMap = new Dictionary<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode>(); // nodes of t2 => nodes of t1
// visit nodes in order of decreasing height to ensure correct mapping
var nodes1 = n1.IterateNodesPrefix().OrderByDescending(x => x.GetDepth()).ToList();
var nodes2 = n2.IterateNodesPrefix().ToList();
for (int i = 0; i < nodes1.Count; ++i) {
var v = nodes1[i];
if (forwardMap.ContainsKey(v))
continue;
var kv = compactedGraph[v];
ISymbolicExpressionTreeNode w = null;
for (int j = 0; j < nodes2.Count; ++j) {
var t = nodes2[j];
if (reverseMap.ContainsKey(t) || compactedGraph[t] != kv)
continue;
w = t;
break;
}
if (w == null) continue;
// at this point we know that v and w are isomorphic, however, the mapping cannot be done directly
// (as in the paper) because the trees are unordered (subtree order might differ). the solution is
// to sort subtrees from under commutative labels (this will work because the subtrees are isomorphic!)
// while iterating over the two subtrees
var vv = IterateBreadthOrdered(v, comparer).ToList();
var ww = IterateBreadthOrdered(w, comparer).ToList();
int len = Math.Min(vv.Count, ww.Count);
for (int j = 0; j < len; ++j) {
var s = vv[j];
var t = ww[j];
Debug.Assert(!reverseMap.ContainsKey(t));
forwardMap[s] = t;
reverseMap[t] = s;
}
}
return forwardMap;
}
