/// <summary>The actual insertion function, recursive version.</summary>
/// <remarks>
/// The actual insertion function, recursive version.
/// PLEASE NOTE that the implementation has been adapted to consume less stack memory
/// </remarks>
private char Insert(TernaryTree.TreeInsertionParams @params)
{
char?newBranch = InsertNewBranchIfNeeded(@params);
if (newBranch == null)
{
return(InsertIntoExistingBranch(@params));
}
else
{
return((char)newBranch);
}
}
// PLEASE NOTE that this function is a result of refactoring "insert" method which
// is a modification of the original work
// Returns null if insertion is not needed and the id of the new node if insertion was performed
private char?InsertNewBranchIfNeeded(TernaryTree.TreeInsertionParams @params)
{
char p = @params.p;
char[] key = @params.key;
int start = @params.start;
char val = @params.val;
int len = Strlen(key, start);
if (p == 0)
{
// this means there is no branch, this node will start a new branch.
// Instead of doing that, we store the key somewhere else and create
// only one node with a pointer to the key
p = freenode++;
// holds data
eq[p] = val;
length++;
hi[p] = (char)0;
if (len > 0)
{
// indicates branch is compressed
sc[p] = (char)0xFFFF;
// use 'lo' to hold pointer to key
lo[p] = (char)kv.Alloc(len + 1);
Strcpy(kv.GetArray(), lo[p], key, start);
}
else
{
sc[p] = (char)0;
lo[p] = (char)0;
}
return(p);
}
else
{
return(null);
}
}
// PLEASE NOTE that this function is a result of refactoring "insert" method which
// is a modification of the original work
private char InsertIntoExistingBranch(TernaryTree.TreeInsertionParams @params)
{
char initialP = @params.p;
TernaryTree.TreeInsertionParams paramsToInsertNext = @params;
while (paramsToInsertNext != null)
{
char p = paramsToInsertNext.p;
// We are inserting into an existing branch hence the id must be non-zero
System.Diagnostics.Debug.Assert(p != 0);
char[] key = paramsToInsertNext.key;
int start = paramsToInsertNext.start;
char val = paramsToInsertNext.val;
int len = Strlen(key, start);
paramsToInsertNext = null;
if (sc[p] == 0xFFFF)
{
// branch is compressed: need to decompress
// this will generate garbage in the external key array
// but we can do some garbage collection later
char pp = freenode++;
// previous pointer to key
lo[pp] = lo[p];
// previous pointer to data
eq[pp] = eq[p];
lo[p] = (char)0;
if (len > 0)
{
sc[p] = kv.Get(lo[pp]);
eq[p] = pp;
lo[pp]++;
if (kv.Get(lo[pp]) == 0)
{
// key completly decompressed leaving garbage in key array
lo[pp] = (char)0;
sc[pp] = (char)0;
hi[pp] = (char)0;
}
else
{
// we only got first char of key, rest is still there
sc[pp] = (char)0xFFFF;
}
}
else
{
// In this case we can save a node by swapping the new node
// with the compressed node
sc[pp] = (char)0xFFFF;
hi[p] = pp;
sc[p] = (char)0;
eq[p] = val;
length++;
break;
}
}
char s = key[start];
if (s < sc[p])
{
TernaryTree.TreeInsertionParams branchParams = new TernaryTree.TreeInsertionParams(lo[p], key, start, val);
char?insertNew = InsertNewBranchIfNeeded(branchParams);
if (insertNew == null)
{
paramsToInsertNext = branchParams;
}
else
{
lo[p] = (char)insertNew;
}
}
else
{
if (s == sc[p])
{
if (s != 0)
{
TernaryTree.TreeInsertionParams branchParams = new TernaryTree.TreeInsertionParams(eq[p], key, start + 1,
val);
char?insertNew = InsertNewBranchIfNeeded(branchParams);
if (insertNew == null)
{
paramsToInsertNext = branchParams;
}
else
{
eq[p] = (char)insertNew;
}
}
else
{
// key already in tree, overwrite data
eq[p] = val;
}
}
else
{
TernaryTree.TreeInsertionParams branchParams = new TernaryTree.TreeInsertionParams(hi[p], key, start, val);
char?insertNew = InsertNewBranchIfNeeded(branchParams);
if (insertNew == null)
{
paramsToInsertNext = branchParams;
}
else
{
hi[p] = (char)insertNew;
}
}
}
}
return(initialP);
}