public Transformation getTransformation(TreeDefinition aTree, TreeDefinition bTree)
{
Transformation transform = new Transformation();
Transformation t1 = findDistance(aTree, bTree);
transform.totalCost = distance[aTree.getNodeCount(), bTree.getNodeCount()];
Transformation t2 = findDistance(bTree, aTree);
transform.editScriptAtoB = t1.editScriptAtoB;
transform.editScriptBtoA = t2.editScriptAtoB;
transform.pdlA = t1.pdlA;
transform.pdlB = t1.pdlB;
transform.pdlMappingTreeB = t1.pdlMappingTreeB;
transform.pdlMappingTreeA = t1.pdlMappingTreeA;
return transform;
}
//Computes tree edits distance betwee aTree and bTree
public Transformation findDistance(TreeDefinition aTree, TreeDefinition bTree)
{
distance = new double[aTree.getNodeCount() + 1, bTree.getNodeCount() + 1];
distScript = new TreeEditScript[aTree.getNodeCount() + 1, bTree.getNodeCount() + 1];
//Preliminaries
//1. Find left-most leaf and key roots
Dictionary<int, int> aLeftLeaf = new Dictionary<int, int>();
Dictionary<int, int> bLeftLeaf = new Dictionary<int, int>();
List<int> aTreeKeyRoots = new List<int>();
List<int> bTreeKeyRoots = new List<int>();
findHelperTables(aTree, aLeftLeaf, aTreeKeyRoots, aTree.getRootID());
findHelperTables(bTree, bLeftLeaf, bTreeKeyRoots, bTree.getRootID());
var a = bTree.getRootID();
//Comparison
foreach (int aKeyroot in aTreeKeyRoots)
{
foreach (int bKeyroot in bTreeKeyRoots)
{
//Re-initialise forest distance tables
Dictionary<int, Dictionary<int, Double>> fD =
new Dictionary<int, Dictionary<int, Double>>();
//Re-initialise forest edit script distance tables
Dictionary<int, Dictionary<int, TreeEditScript>> fESD =
new Dictionary<int, Dictionary<int, TreeEditScript>>();
setForestDistance(aLeftLeaf[aKeyroot], bLeftLeaf[bKeyroot], 0.0d, fD);
//script is automatically null
//for all descendents of aKeyroot: i
for (int i = aLeftLeaf[aKeyroot]; i <= aKeyroot; i++)
{
var edit = new Delete(i,aTree);
setForestDistance(i,
bLeftLeaf[bKeyroot] - 1,
getForestDistance(i - 1, bLeftLeaf[bKeyroot] - 1, fD) +
edit.getCost(),
fD);
var scriptSuffix = new TreeEditScript(getForestScript(i - 1, bLeftLeaf[bKeyroot] - 1, fESD));
scriptSuffix.Insert(edit);
setForestScript(i, bLeftLeaf[bKeyroot] - 1, scriptSuffix, fESD);
}
//for all descendents of bKeyroot: j
for (int j = bLeftLeaf[bKeyroot]; j <= bKeyroot; j++)
{
var edit = new Insert(j, bTree);
setForestDistance(aLeftLeaf[aKeyroot] - 1, j,
getForestDistance(aLeftLeaf[aKeyroot] - 1, j - 1, fD) +
edit.getCost(),
fD);
var scriptSuffix = new TreeEditScript(getForestScript(aLeftLeaf[aKeyroot] - 1, j - 1, fESD));
scriptSuffix.Insert(edit);
setForestScript(aLeftLeaf[aKeyroot] - 1, j, scriptSuffix, fESD);
}
for (int i = aLeftLeaf[aKeyroot]; i <= aKeyroot; i++)
{
for (int j = bLeftLeaf[bKeyroot]; j <= bKeyroot; j++)
{
TreeEditScript tempScript = null;
EditOperation delEdit = new Delete(i, aTree); ;
EditOperation insEdit = new Insert(j, bTree);
double min;
double delCost = getForestDistance(i - 1, j, fD) + delEdit.getCost();
double insCost = getForestDistance(i, j - 1, fD) + insEdit.getCost();
//This min compares del vs ins
if (delCost <= insCost)
{
//Option 1: Delete node from aTree
tempScript = new TreeEditScript(getForestScript(i - 1, j, fESD));
tempScript.Insert(delEdit);
min = delCost;
}
else
{
//Option 2: Insert node into bTree
tempScript = new TreeEditScript(getForestScript(i, j - 1, fESD));
tempScript.Insert(insEdit);
min = insCost;
}
if (aLeftLeaf[i] == aLeftLeaf[aKeyroot] && bLeftLeaf[j] == bLeftLeaf[bKeyroot])
{
var renEdit = new Rename(i, j, aTree, bTree);
var dist = getForestDistance(i - 1, j - 1, fD) + renEdit.getCost();
distance[i, j] = Math.Min(min, dist);
if (min <= dist)
{
tempScript = new TreeEditScript(tempScript);
distScript[i, j] = tempScript;
}
else
{
tempScript = new TreeEditScript(getForestScript(i - 1, j - 1, fESD));
tempScript.Insert(renEdit);
distScript[i, j] = tempScript;
}
setForestDistance(i, j, distance[i, j], fD);
setForestScript(i, j, new TreeEditScript(distScript[i, j]), fESD);
}
else
{
var value = getForestDistance(aLeftLeaf[i] - 1, bLeftLeaf[j] - 1, fD) + distance[i, j];
setForestDistance(i, j, Math.Min(min, value), fD);
if (min <= value)
setForestScript(i, j, new TreeEditScript(tempScript), fESD);
else
{
var tempList = getForestScript(aLeftLeaf[i] - 1, bLeftLeaf[j] - 1, fESD).script;
tempList = distScript[i, j].script.Concat(tempList).ToList();
setForestScript(i, j, new TreeEditScript(tempList), fESD);
}
setForestDistance(i, j, Math.Min(min, value), fD);
}
}
}
}
}
Transformation transform = new Transformation();
transform.totalCost = distance[aTree.getNodeCount(), bTree.getNodeCount()];
transform.editScriptAtoB = distScript[aTree.getNodeCount(), bTree.getNodeCount()];
transform.pdlA = aTree.pdl;
transform.pdlB = bTree.pdl;
transform.pdlMappingTreeB = bTree.pdlNodeMapping;
transform.pdlMappingTreeA = aTree.pdlNodeMapping;
return transform;
}