/// <summary>
/// Creates a unary expression with symbol scope, context, script refernce set.
/// </summary>
/// <param name="name"></param>
/// <param name="token"></param>
/// <returns></returns>
public static Expr Binary(Expr left, Operator op, Expr right, TokenData token)
{
var exp = new BinaryExpr();
exp.Left = left;
exp.Op = op;
exp.Right = right;
SetupContext(exp, token);
return exp;
}
/// <summary>
/// Visits the binary expression tree
/// </summary>
/// <param name="exp"></param>
public object VisitBinary(BinaryExpr exp)
{
_callBackOnNodeStart(exp);
_callBackOnNodeStart(exp.Left);
_callBackOnNodeStart(exp.Right);
return null;
}
/// <summary>
/// Checks for division by zero.
/// </summary>
/// <param name="semActs"></param>
/// <param name="exp"></param>
private SemanticCheckResult CheckDivisionByZero(SemActs semActs, BinaryExpr exp)
{
if(exp.Op != Operator.Divide) return SemanticCheckResult.Valid;
if (!(exp.Right.IsNodeType(NodeTypes.SysConstant))) return SemanticCheckResult.Valid;
var val = (LObject)((ConstantExpr)exp.Right).Value;
if (val.Type == LTypes.Number)
{
var d = ((LNumber)val).Value;
if (d == 0)
AddError("Division by zero", exp.Right);
}
return SemanticCheckResult.Valid;
}
/// <summary>
/// Evaluate * / + - %
/// </summary>
/// <returns></returns>
public static object EvalBinary(BinaryExpr expr)
{
// Validate
object result = 0;
var node = expr;
var op = expr.Op;
var left = (LObject)expr.Left.Evaluate();
var right = (LObject)expr.Right.Evaluate();
// Case 1: Both numbers
if (IsTypeMatch(LTypes.Number, left, right))
{
result = EvalHelper.CalcNumbers(node, (LNumber)left, (LNumber)right, op);
}
// Case 2: Both times
else if (IsTypeMatch(LTypes.Time, left, right))
{
result = EvalHelper.CalcTimes(node, (LTime)left, (LTime)right, op);
}
// Case 3: Both dates
else if (IsTypeMatch(LTypes.Date, left, right))
{
result = EvalHelper.CalcDates(node, (LDate)left, (LDate)right, op);
}
// Case 4: Both strings.
else if (IsTypeMatch(LTypes.String, left, right))
{
var strleft = ((LString)left).Value;
var strright = ((LString)right).Value;
// Check string limit.
Ctx.Limits.CheckStringLength(node, strleft, strright);
result = new LString(strleft + strright);
}
// MIXED TYPES
// TODO: Needs to be improved with new code for types.
// Case 5 : Double and Bool
else if (left.Type == LTypes.Number && right.Type == LTypes.Bool)
{
var r = ((LBool)right).Value;
var rval = r ? 1 : 0;
result = EvalHelper.CalcNumbers(node, (LNumber)left, new LNumber(rval), op);
}
// Bool Double
else if (left.Type == LTypes.Bool && right.Type == LTypes.Number)
{
var l = ((LBool)left).Value;
var lval = l ? 1 : 0;
result = EvalHelper.CalcNumbers(node, new LNumber(lval), (LNumber)right, op);
}
// Append as strings.
else if (left.Type == LTypes.String && right.Type == LTypes.Bool)
{
var st1 = ((LString)left).Value + ((LBool)right).Value.ToString().ToLower();
result = new LString(st1);
}
// Append as strings.
else if (left.Type == LTypes.Bool && right.Type == LTypes.String)
{
var st2 = ((LBool)left).Value.ToString().ToLower() + ((LString)right).Value;
result = new LString(st2);
}
// TODO: Need to handle LUnit and LVersion better
//else if (left.Type == LTypes.Unit && right.Type == LTypes.Unit)
else if (left.Type.Name == "LUnit" && right.Type.Name == "LUnit")
{
result = EvalHelper.CalcUnits(node, (LUnit)((LClass)left).Value, (LUnit)((LClass)right).Value, op, Ctx.Units);
}
else
{
var st3 = left.GetValue().ToString() + right.GetValue().ToString();
result = new LString(st3);
}
return result;
}
/// <summary>
/// Creates a unary expression with symbol scope, context, script refernce set.
/// </summary>
/// <param name="name"></param>
/// <param name="token"></param>
/// <returns></returns>
public Expr ToBinaryExpr(Expr left, Operator op, Expr right, TokenData token)
{
var exp = new BinaryExpr(left, op, right);
this.SetupContext(exp, token);
return exp;
}