/// <summary>
/// Removes the two objects at the top of the stack and subtracts the top most object on the stack from the other.
/// Then, pushes the result on to the top of the stack.
/// </summary>
public override void PerformOperation()
{
base.PerformOperation();
// If we have fewer than 2 objects on the stack we are el-bonerino-ed
Debug.Assert(CelesteStack.StackSize >= 2, "Not enough elements on the stack for subtract operator");
CelesteObject rhs = CelesteStack.Pop();
CelesteObject lhs = CelesteStack.Pop();
// The stack will wrap our subtraction result in a CelesteObject, so just push the actual value of the subtraction
if (lhs.IsNumber() && rhs.IsNumber())
{
CelesteStack.Push(lhs.As <float>() - rhs.As <float>());
}
else if (lhs.IsString() && rhs.IsString())
{
string lhsAsString = lhs.As <string>();
string rhsAsString = rhs.As <string>();
if (lhsAsString.Contains(rhsAsString))
{
// Push the lhs string having removed the rhs string
CelesteStack.Push(lhsAsString.Remove(lhsAsString.IndexOf(rhsAsString), rhsAsString.Length));
}
else
{
// If our lhs does not contain our rhs, we just push the original unaltered lhs string
CelesteStack.Push(lhsAsString);
}
}
else if (lhs.IsList() && rhs.IsList())
{
// The subtract operator for lists removes all elements in the first list who are equal to an element in the second, either by reference or value
List <object> lhsList = lhs.AsList <object>();
List <object> rhsList = rhs.AsList <object>();
// Remove ALL occurrences in the list of any object in the rhs list - otherwise there is non-deterministic behaviour in which instance to remove
lhsList.RemoveAll(x => rhsList.Exists(y => y.Equals(x) || y.ValueEquals(x)));
CelesteStack.Push(lhs);
}
else if (lhs.IsTable() && rhs.IsList())
{
// Subtraction of tables does not make sense
// What does make sense, is subtracting elements in a table using a list of keys
// Subtracting a list from a table will remove any elements in the table with a matching key as an element in our list
Dictionary <object, object> lhsTable = lhs.AsTable();
List <object> rhsList = rhs.AsList <object>();
foreach (object obj in rhsList)
{
if (lhsTable.Contains(new KeyValuePair <object, object>(obj, null), new TableKeyComparer()))
{
lhsTable.Remove(lhsTable.First(x => x.Key.Equals(obj) || x.Key.ValueEquals(obj)));
}
}
CelesteStack.Push(lhs);
}
else
{
Debug.Fail("Invalid parameters to subtract operation.");
}
}
/// <summary>
/// Removes the two objects at the top of the stack and adds them together.
/// Then, pushes the result on to the top of the stack.
/// </summary>
public override void PerformOperation()
{
base.PerformOperation();
// If we have fewer than 2 objects on the stack we are el-bonerino-ed
Debug.Assert(CelesteStack.StackSize >= 2, "Not enough elements on the stack for add operator");
CelesteObject rhs = CelesteStack.Pop();
CelesteObject lhs = CelesteStack.Pop();
// The stack will wrap our addition result in a CelesteObject, so just push the actual value of the addition
if (lhs.IsNumber() && rhs.IsNumber())
{
CelesteStack.Push(lhs.As <float>() + rhs.As <float>());
}
else if (lhs.IsString() && rhs.IsString())
{
CelesteStack.Push(lhs.As <string>() + rhs.As <string>());
}
else if (lhs.IsList() && rhs.IsList())
{
lhs.AsList <object>().AddRange(rhs.AsList <object>());
CelesteStack.Push(lhs);
}
else if (lhs.IsTable() && rhs.IsTable())
{
Dictionary <object, object> lhsTable = lhs.AsTable();
Dictionary <object, object> rhsTable = rhs.AsTable();
// Tables can be added, but only if they are all indexed by number or string completely
// No other way can be used because the reference type of 'object' makes value equality difficult
// These two types of adding are the only two we can realistically support
// Check whether our lhs table has all number keys
if (lhsTable.Keys.Count(x => x is float) == lhsTable.Keys.Count)
{
// If it does, check the rhs table too
if (rhsTable.Keys.Count(x => x is float) == rhsTable.Keys.Count)
{
// We now go through and see if any keys overlap in the two tables
if (lhsTable.Intersect(rhsTable, new TableKeyComparer()).Count() == 0)
{
foreach (KeyValuePair <object, object> pair in rhsTable)
{
lhsTable.Add((float)pair.Key, pair.Value);
}
}
else
{
Debug.Fail("Invalid parameters to add operation. Right hand side table has at least one key the same as the left hand side table");
}
}
else
{
Debug.Fail("Invalid parameters to add operation. Right hand side table has inconsistent key types (should be numbers)");
}
}
// Check whether our lhs table has all string keys
else if (lhsTable.Keys.Count(x => x is string) == lhsTable.Keys.Count)
{
// If it does, check the rhs table too
if (rhsTable.Keys.Count(x => x is string) == rhsTable.Keys.Count)
{
// We now go through and see if any keys overlap in the two tables
if (lhsTable.Intersect(rhsTable, new TableKeyComparer()).Count() == 0)
{
foreach (KeyValuePair <object, object> pair in rhsTable)
{
lhsTable.Add((string)pair.Key, pair.Value);
}
}
else
{
Debug.Fail("Invalid parameters to add operation. Right hand side table has at least one key the same as the left hand side table");
}
}
else
{
Debug.Fail("Invalid parameters to add operation. Right hand side table has inconsistent key types (should be strings)");
}
}
else
{
Debug.Fail("Invalid parameters to add operation. Left hand side table has inconsistent key types (should be numbers or strings)");
}
CelesteStack.Push(lhs);
}
else
{
Debug.Fail("Invalid parameters to add operation.");
}
}