/// <summary>
/// return a new <seealso cref="Assignment"/> with Left and Right assigned.
/// </summary>
/// <param name="left"></param>
/// <param name="right"></param>
/// <returns></returns>
public Assignment WithOperands(LaxExpression left, LaxExpression right)
{
var op = new Assignment(this);
op.Left = left;
op.Right = right;
op.CodeRange = CodeRange.Expand2(left).Expand2(right);
return op;
}
static LaxExpression EvaluateAssignment(Assignment s)
{
var val = Evaluate(s.Right);
if (val == s.Right)
return s; //no optimization
return s.WithOperands(s.Left, val);
}
Literal EvaluateAssignment(Assignment expr)
{
var identifier = expr.Left as Identifier;
if (identifier == null)
throw new SemanticError(expr.Left, "Expected identifier");
if (variables.ContainsKey(identifier) == false)
throw new SemanticError(expr.Left, "Undefined variable");
var value = Evaluate(expr.Right);
variables[identifier] = value;
return value;
}
string FormatAssignment(Assignment expr)
{
return Format(expr.Left) + " = " + Format(expr.Right);
}
/// <summary>
/// Asign
/// </summary>
/// <param name="s"></param>
void EvalAssignmentOperator(Assignment a)
{
var id = (Identifier)a.Left;
var variable = block.Variables[id];
Eval(a.Right);
var t = a.Right.ValueType;
a.Left.ValueType = t;
//Make sure the variable is not assigned a value
if (variable.ValueType != null)
{
if (variable.ValueType != t)
throw new SemanticError(a.Left, "Type mismatch");
}
variable.ValueType = t;
}