private static bool IsEqual(ConstantExpression left, ConstantExpression right)
{
if (left.ConstantType != right.ConstantType)
{
return(false);
}
if (left.ConstantType == ConstantType.Boolean)
{
BooleanConstantExpression leftBoolean = (BooleanConstantExpression)left;
BooleanConstantExpression rightBoolean = (BooleanConstantExpression)right;
return(leftBoolean.Value == rightBoolean.Value);
}
else if (left.ConstantType == ConstantType.Integer)
{
IntegerConstantExpression leftInteger = (IntegerConstantExpression)left;
IntegerConstantExpression rightInteger = (IntegerConstantExpression)right;
return(leftInteger.Value == rightInteger.Value);
}
else if (left.ConstantType == ConstantType.String)
{
StringConstantExpression leftString = (StringConstantExpression)left;
StringConstantExpression rightString = (StringConstantExpression)right;
return(string.Equals(leftString.Value, rightString.Value, StringComparison.OrdinalIgnoreCase));
}
else
{
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture, "Comparing {0} constants is not supported.", left.ConstantType));
}
}
Expression IExpressionVisitor.VisitLogical(LogicalExpression node)
{
BooleanConstantExpression left = Visit(node.Left) as BooleanConstantExpression;
if (left == null)
{
return(BooleanConstantExpression.False);
}
switch (node.NodeType)
{
case ExpressionType.AndAlso:
if (!left.Value)
{
return(left);
}
break;
case ExpressionType.OrElse:
if (left.Value)
{
return(left);
}
break;
default:
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture, "{0} is not a supported logical expression.", node.NodeType));
}
BooleanConstantExpression right = Visit(node.Right) as BooleanConstantExpression;
return(right ?? BooleanConstantExpression.False);
}
Expression IExpressionVisitor.VisitUnary(UnaryExpression node)
{
ConstantExpression expression = Visit(node.Expression) as ConstantExpression;
if (expression == null)
{
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture,
"The {0} operand must be a ConstantExpression, actual type: {1}",
node.NodeType, node.Expression?.GetType().ToString() ?? "null"));
}
if (expression.ConstantType == ConstantType.UndefinedVariable)
{
return(expression);
}
if (node.NodeType == ExpressionType.Not)
{
if (expression.ConstantType != ConstantType.Boolean)
{
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture,
"The {0} operand must be a Boolean constant, actual value: {1}",
expression.NodeType, expression.ConstantType));
}
BooleanConstantExpression booleanConstant = (BooleanConstantExpression)expression;
return(new BooleanConstantExpression(!booleanConstant.Value));
}
else if (node.NodeType == ExpressionType.Negate || node.NodeType == ExpressionType.UnaryPlus)
{
if (expression.ConstantType != ConstantType.Integer)
{
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture,
"The {0} operand must be an Integer constant, actual value: {1}",
expression.NodeType, expression.ConstantType));
}
IntegerConstantExpression integerConstant = (IntegerConstantExpression)expression;
switch (node.NodeType)
{
case ExpressionType.Negate:
return(new IntegerConstantExpression(-integerConstant.Value));
case ExpressionType.UnaryPlus:
return(new IntegerConstantExpression(+integerConstant.Value));
default:
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture, "{0} is not a supported unary operator.", expression.NodeType));
}
}
else
{
throw new EnableInfoException(string.Format(CultureInfo.InvariantCulture, "{0} is not a supported unary operator.", expression.NodeType));
}
}
private BooleanConstantExpression VisitInFunction(ReadOnlyCollection <Expression> args)
{
if (args != null && args.Count >= 2)
{
// The EnableInfo documentation states that the 'in' function returns true
// if the first parameter is equal to at least one of the following parameters.
ConstantExpression first = Visit(args[0]) as ConstantExpression;
if (first != null)
{
if (first.ConstantType == ConstantType.String)
{
string firstParameter = ((StringConstantExpression)first).Value;
for (int i = 1; i < args.Count; i++)
{
StringConstantExpression parameter = Visit(args[i]) as StringConstantExpression;
if (parameter != null && string.Equals(firstParameter, parameter.Value, StringComparison.OrdinalIgnoreCase))
{
return(BooleanConstantExpression.True);
}
}
}
else if (first.ConstantType == ConstantType.Integer)
{
int firstParameter = ((IntegerConstantExpression)first).Value;
for (int i = 1; i < args.Count; i++)
{
IntegerConstantExpression parameter = Visit(args[i]) as IntegerConstantExpression;
if (parameter != null && firstParameter == parameter.Value)
{
return(BooleanConstantExpression.True);
}
}
}
else if (first.ConstantType == ConstantType.Boolean)
{
bool firstParameter = ((BooleanConstantExpression)first).Value;
for (int i = 1; i < args.Count; i++)
{
BooleanConstantExpression parameter = Visit(args[i]) as BooleanConstantExpression;
if (parameter != null && firstParameter == parameter.Value)
{
return(BooleanConstantExpression.True);
}
}
}
}
}
return(BooleanConstantExpression.False);
}
/// <summary>
/// Evaluates the specified enable info expression.
/// </summary>
/// <param name="node">The expression to evaluate.</param>
/// <returns>A <see cref="bool"/> indicating the result of the enable info expression.</returns>
/// <exception cref="ArgumentNullException"><paramref name="node"/> is null.</exception>
/// <exception cref="EnableInfoException">The specified expression is not valid.</exception>
public bool Evaluate(Expression node)
{
if (node is null)
{
throw new ArgumentNullException(nameof(node));
}
BooleanConstantExpression result = Visit(node) as BooleanConstantExpression;
if (result is null)
{
return(false);
}
return(result.Value);
}
private BooleanConstantExpression VisitDimFunction(ReadOnlyCollection <Expression> args)
{
BooleanConstantExpression result = BooleanConstantExpression.False;
if (args != null && args.Count == 2)
{
// The EnableInfo documentation does not provide any information on how the 'dim' function is used.
// After using a filter to test the 'dim' function behavior in Photoshop 5.0 it appears that the
// function returns true if the first parameter evaluates to true and the second parameter evaluates to false.
BooleanConstantExpression first = Visit(args[0]) as BooleanConstantExpression;
BooleanConstantExpression second = Visit(args[1]) as BooleanConstantExpression;
if (first != null && second != null)
{
result = new BooleanConstantExpression(first.Value && !second.Value);
}
}
return(result);
}