public static bool[,] EvaluateLawnMowerProgram(int length, int width, ISymbolicExpressionTree tree) {
bool[,] lawn = new bool[length, width];
var mowerState = new MowerState();
mowerState.Heading = Heading.South;
mowerState.Energy = length * width * 2;
lawn[mowerState.Position.Item1, mowerState.Position.Item2] = true;
EvaluateLawnMowerProgram(tree.Root, mowerState, lawn, tree.Root.Subtrees.Skip(1).ToArray());
return lawn;
}
public static bool[,] EvaluateLawnMowerProgram(int length, int width, ISymbolicExpressionTree tree)
{
bool[,] lawn = new bool[length, width];
var mowerState = new MowerState();
mowerState.Heading = Heading.South;
mowerState.Energy = length * width * 2;
lawn[mowerState.Position.Item1, mowerState.Position.Item2] = true;
EvaluateLawnMowerProgram(tree.Root, mowerState, lawn, tree.Root.Subtrees.Skip(1).ToArray());
return(lawn);
}
private static Tuple <int, int> EvaluateLawnMowerProgram(ISymbolicExpressionTreeNode node, MowerState mowerState, bool[,] lawn, IEnumerable <ISymbolicExpressionTreeNode> adfs)
{
if (mowerState.Energy <= 0)
{
return(Tuple.Create(0, 0));
}
if (node.Symbol is ProgramRootSymbol)
{
return(EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs));
}
else if (node.Symbol is StartSymbol)
{
return(EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs));
}
else if (node.Symbol.Name == "Left")
{
switch (mowerState.Heading)
{
case Heading.East: mowerState.Heading = Heading.North;
break;
case Heading.North: mowerState.Heading = Heading.West;
break;
case Heading.West: mowerState.Heading = Heading.South;
break;
case Heading.South:
mowerState.Heading = Heading.East;
break;
}
return(new Tuple <int, int>(0, 0));
}
else if (node.Symbol.Name == "Forward")
{
int dRow = 0;
int dCol = 0;
switch (mowerState.Heading)
{
case Heading.East:
dCol++;
break;
case Heading.North:
dRow--;
break;
case Heading.West:
dCol--;
break;
case Heading.South:
dRow++;
break;
}
uint newRow = (uint)((mowerState.Position.Item1 + lawn.GetLength(0) + dRow) % lawn.GetLength(0));
uint newColumn = (uint)((mowerState.Position.Item2 + lawn.GetLength(1) + dCol) % lawn.GetLength(1));
mowerState.Position = Tuple.Create(newRow, newColumn);
mowerState.Energy = mowerState.Energy - 1;
lawn[newRow, newColumn] = true;
return(Tuple.Create(0, 0));
}
else if (node.Symbol.Name == "Sum")
{
var p = EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
var q = EvaluateLawnMowerProgram(node.GetSubtree(1), mowerState, lawn, adfs);
return(Tuple.Create(p.Item1 + q.Item1, p.Item2 + q.Item2));
}
else if (node.Symbol.Name == "Prog")
{
EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
return(EvaluateLawnMowerProgram(node.GetSubtree(1), mowerState, lawn, adfs));
}
else if (node.Symbol.Name == "Frog")
{
var p = EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
int x = p.Item1;
int y = p.Item2;
while (x < 0)
{
x += lawn.GetLength(0);
}
while (y < 0)
{
y += lawn.GetLength(1);
}
var newRow = (uint)((mowerState.Position.Item1 + x) % lawn.GetLength(0));
var newCol = (uint)((mowerState.Position.Item2 + y) % lawn.GetLength(1));
mowerState.Position = Tuple.Create(newRow, newCol);
mowerState.Energy = mowerState.Energy - 1;
lawn[newRow, newCol] = true;
return(Tuple.Create(0, 0));
}
else if (node.Symbol is InvokeFunction)
{
var invokeNode = node as InvokeFunctionTreeNode;
// find the function definition for the invoke call
var functionDefinition = (from adf in adfs.Cast <DefunTreeNode>()
where adf.FunctionName == invokeNode.Symbol.FunctionName
select adf).Single();
// clone the function definition because we are replacing the argument nodes
functionDefinition = (DefunTreeNode)functionDefinition.Clone();
// find the argument tree nodes and their parents in the original function definition
// toList is necessary to prevent that newly inserted branches are iterated
var argumentCutPoints = (from parent in functionDefinition.IterateNodesPrefix()
from subtree in parent.Subtrees
where subtree is ArgumentTreeNode
select new { Parent = parent, Argument = subtree.Symbol as Argument, ChildIndex = parent.IndexOfSubtree(subtree) })
.ToList();
// replace all argument tree ndoes with the matching argument of the invoke node
foreach (var cutPoint in argumentCutPoints)
{
cutPoint.Parent.RemoveSubtree(cutPoint.ChildIndex);
cutPoint.Parent.InsertSubtree(cutPoint.ChildIndex, (SymbolicExpressionTreeNode)invokeNode.GetSubtree(cutPoint.Argument.ArgumentIndex).Clone());
}
return(EvaluateLawnMowerProgram(functionDefinition.GetSubtree(0), mowerState, lawn, adfs));
}
else
{
// try to parse as ephemeral random const with format: "x,y" (x, y in [0..32[)
int x, y;
var tokens = node.Symbol.Name.Split(',');
if (tokens.Length == 2 &&
int.TryParse(tokens[0], out x) &&
int.TryParse(tokens[1], out y))
{
return(Tuple.Create(x, y));
}
else
{
throw new ArgumentException("Invalid symbol in the lawn mower program.");
}
}
}
private static Tuple<int, int> EvaluateLawnMowerProgram(ISymbolicExpressionTreeNode node, MowerState mowerState, bool[,] lawn, IEnumerable<ISymbolicExpressionTreeNode> adfs) {
if (mowerState.Energy <= 0) return Tuple.Create(0, 0);
if (node.Symbol is ProgramRootSymbol) {
return EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
} else if (node.Symbol is StartSymbol) {
return EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
} else if (node.Symbol.Name == "Left") {
switch (mowerState.Heading) {
case Heading.East: mowerState.Heading = Heading.North;
break;
case Heading.North: mowerState.Heading = Heading.West;
break;
case Heading.West: mowerState.Heading = Heading.South;
break;
case Heading.South:
mowerState.Heading = Heading.East;
break;
}
return new Tuple<int, int>(0, 0);
} else if (node.Symbol.Name == "Forward") {
int dRow = 0;
int dCol = 0;
switch (mowerState.Heading) {
case Heading.East:
dCol++;
break;
case Heading.North:
dRow--;
break;
case Heading.West:
dCol--;
break;
case Heading.South:
dRow++;
break;
}
uint newRow = (uint)((mowerState.Position.Item1 + lawn.GetLength(0) + dRow) % lawn.GetLength(0));
uint newColumn = (uint)((mowerState.Position.Item2 + lawn.GetLength(1) + dCol) % lawn.GetLength(1));
mowerState.Position = Tuple.Create(newRow, newColumn);
mowerState.Energy = mowerState.Energy - 1;
lawn[newRow, newColumn] = true;
return Tuple.Create(0, 0);
} else if (node.Symbol.Name == "Sum") {
var p = EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
var q = EvaluateLawnMowerProgram(node.GetSubtree(1), mowerState, lawn, adfs);
return Tuple.Create(p.Item1 + q.Item1, p.Item2 + q.Item2);
} else if (node.Symbol.Name == "Prog") {
EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
return EvaluateLawnMowerProgram(node.GetSubtree(1), mowerState, lawn, adfs);
} else if (node.Symbol.Name == "Frog") {
var p = EvaluateLawnMowerProgram(node.GetSubtree(0), mowerState, lawn, adfs);
int x = p.Item1;
int y = p.Item2;
while (x < 0) x += lawn.GetLength(0);
while (y < 0) y += lawn.GetLength(1);
var newRow = (uint)((mowerState.Position.Item1 + x) % lawn.GetLength(0));
var newCol = (uint)((mowerState.Position.Item2 + y) % lawn.GetLength(1));
mowerState.Position = Tuple.Create(newRow, newCol);
mowerState.Energy = mowerState.Energy - 1;
lawn[newRow, newCol] = true;
return Tuple.Create(0, 0);
} else if (node.Symbol is InvokeFunction) {
var invokeNode = node as InvokeFunctionTreeNode;
// find the function definition for the invoke call
var functionDefinition = (from adf in adfs.Cast<DefunTreeNode>()
where adf.FunctionName == invokeNode.Symbol.FunctionName
select adf).Single();
// clone the function definition because we are replacing the argument nodes
functionDefinition = (DefunTreeNode)functionDefinition.Clone();
// find the argument tree nodes and their parents in the original function definition
// toList is necessary to prevent that newly inserted branches are iterated
var argumentCutPoints = (from parent in functionDefinition.IterateNodesPrefix()
from subtree in parent.Subtrees
where subtree is ArgumentTreeNode
select new { Parent = parent, Argument = subtree.Symbol as Argument, ChildIndex = parent.IndexOfSubtree(subtree) })
.ToList();
// replace all argument tree ndoes with the matching argument of the invoke node
foreach (var cutPoint in argumentCutPoints) {
cutPoint.Parent.RemoveSubtree(cutPoint.ChildIndex);
cutPoint.Parent.InsertSubtree(cutPoint.ChildIndex, (SymbolicExpressionTreeNode)invokeNode.GetSubtree(cutPoint.Argument.ArgumentIndex).Clone());
}
return EvaluateLawnMowerProgram(functionDefinition.GetSubtree(0), mowerState, lawn, adfs);
} else {
// try to parse as ephemeral random const with format: "x,y" (x, y in [0..32[)
int x, y;
var tokens = node.Symbol.Name.Split(',');
if (tokens.Length == 2 &&
int.TryParse(tokens[0], out x) &&
int.TryParse(tokens[1], out y)) {
return Tuple.Create(x, y);
} else {
throw new ArgumentException("Invalid symbol in the lawn mower program.");
}
}
}
