/// <summary>
/// Loads an ERC from the ERCBank given the value in the genome.
/// If there is no such ERC, then one is created and randomized, then added to the bank.
/// The point of this mechanism is to enable ERCs to appear in multiple places in a GPTree.
/// </summary>
public GPNode ObtainERC(IEvolutionState state, int genomeVal, int threadnum,
GPNode node, IDictionary <int, GPNode> ercMapsForFancyPrint)
{
// TODO: BRS: Questionable key here because of Java -> C# conversion (hash codes)
var ercList = (IList <GPNode>)ERCBank[genomeVal];
if (ercList == null)
{
ercList = new List <GPNode>();
ERCBank[genomeVal] = ercList;
}
GPNode dummy;
// search array list for an ERC of the same type we want
for (var i = 0; i < ercList.Count; i++)
{
dummy = ercList[i];
// ERC was found inside the list
if (dummy.NodeEquivalentTo(node))
{
if (ercMapsForFancyPrint != null)
{
ercMapsForFancyPrint[genomeVal] = dummy;
}
return(dummy.LightClone());
}
}
// erc was not found in the array list lets make one
node = node.LightClone();
node.ResetNode(state, threadnum);
ercList.Add(node);
if (ercMapsForFancyPrint != null)
{
ercMapsForFancyPrint[genomeVal] = node;
}
return(node);
}
GPNode MakeSubtree(IList <int> index, IList <int> genome,
IEvolutionState es, GPFunctionSet gpfs, GrammarRuleNode rule,
int treeNum, int threadNum, IDictionary <int, GPNode> ercMapsForFancyPrint, IGPNodeParent parent, byte argPosition)
{
//have we exceeded the length of the genome? No point in going further.
if (index[0] >= genome.Count)
{
throw new BigTreeException();
}
//expand the rule with the chromosome to get a body element
int i;
//non existant rule got passed in
if (rule == null)
{
es.Output.Fatal("An undefined rule exists within the grammar.");
}
//more than one rule to consider, pick one based off the genome, and consume the current gene
// avoid mod operation as much as possible
if (rule.GetNumChoices() > 1)
{
i = (genome[index[0]] - (int)GetMinGene(index[0])) % rule.GetNumChoices();
}
else
{
i = 0;
}
index[0]++;
GrammarNode choice = rule.GetChoice(i);
// if body is another rule head
//look up rule
if (choice is GrammarRuleNode)
{
var nextrule = (GrammarRuleNode)choice;
return(MakeSubtree(index, genome, es, gpfs, nextrule,
treeNum, threadNum, ercMapsForFancyPrint, parent, argPosition));
}
else //handle functions
{
GrammarFunctionNode funcgrammarnode = (GrammarFunctionNode)choice;
GPNode validNode = funcgrammarnode.GetGPNodePrototype();
int numChildren = validNode.Children.Length;
//index 0 is the node itself
int numChildrenInGrammar = funcgrammarnode.GetNumArguments();
//does the grammar contain the correct amount of children that the GPNode requires
if (numChildren != numChildrenInGrammar)
{
es.Output.Fatal("GPNode " + validNode.ToStringForHumans() + " requires "
+ numChildren + " children. "
+ numChildrenInGrammar
+ " children found in the grammar.");
}
//check to see if it is an ERC node
if (validNode is ERC)
{
// have we exceeded the length of the genome? No point in going further.
if (index[0] >= genome.Count)
{
throw new BigTreeException();
}
// ** do we actually need to maintain two vlaues ? key and originalVal ?
// ** there is no problem if we use the originalVal for both ERCBank and
// ** ercMapsForFancyPrint, moreover, this will also make the reverse-mapping case
// ** easier -- khaled
// these below two lines are from the original code --
// key for ERC hashtable look ups is the current index within the genome. Consume it.
//int key = genome[index[0]] - (int)GetMinGene(index[0]);
//int originalVal = genome[index[0]];
// this single line is khaled's mod --
int genomeVal = genome[index[0]];
index[0]++;
validNode = ObtainERC(es, genomeVal, threadNum, validNode, ercMapsForFancyPrint);
}
//non ERC node
else
{
validNode = validNode.LightClone();
}
//get the rest.
for (int j = 0, childNumber = 0; j < funcgrammarnode.GetNumArguments(); j++)
{
//get and link children to the current GPNode
validNode.Children[childNumber] = MakeSubtree(index, genome, es, gpfs,
(GrammarRuleNode)funcgrammarnode.GetArgument(j), treeNum, threadNum,
ercMapsForFancyPrint, validNode, (byte)childNumber);
if (validNode.Children[childNumber] == null)
{
return(null);
}
childNumber++;
}
validNode.ArgPosition = argPosition;
validNode.Parent = parent;
return(validNode);
}
}
