public static LCAResultForTwoStatements GetCommonAncestorForSyntaxStatements(StatementSyntax x, StatementSyntax y)
{
x.ThrowOnNull(nameof(x));
y.ThrowOnNull(nameof(y));
//Depth is average O(log n) operation, worst case is O(n) but it isn't the case for the syntax tree which is wide but not very deep.
//For statements we could consider depth constrained by MethodDeclarationSyntax
int depthX = x.Depth <MethodDeclarationSyntax, StatementSyntax>();
int depthY = y.Depth <MethodDeclarationSyntax, StatementSyntax>();
StatementSyntax currentX = x, prevX = null;
StatementSyntax currentY = y, prevY = null;
while (depthX != depthY) //First get nodes on the equal levels of depth
{
if (depthX > depthY)
{
prevX = currentX;
currentX = currentX.Parent <StatementSyntax>();
depthX--;
}
else
{
prevY = currentY;
currentY = currentY.Parent <StatementSyntax>();
depthY--;
}
}
while (currentX != currentY) //Then move up the branches until nodes coincide
{
prevX = currentX;
prevY = currentY;
currentX = currentX.Parent <StatementSyntax>();
currentY = currentY.Parent <StatementSyntax>();
}
return(new LCAResultForTwoStatements(currentX, prevX, prevY));
}