// The Nova Project by Ken Beckett.
// Copyright (C) 2007-2012 Inevitable Software, all rights reserved.
// Released under the Common Development and Distribution License, CDDL-1.0: http://opensource.org/licenses/cddl1.php
using Nova.Parsing;
using Nova.Resolving;
namespace Nova.CodeDOM
{
/// <summary>
/// Checks if an <see cref="Expression"/> can be converted to the specified type, returning true if so.
/// </summary>
public class Is : BinaryBooleanOperator
{
#region /* CONSTRUCTORS */
/// <summary>
/// Create an <see cref="Is"/> operator.
/// </summary>
public Is(Expression left, Expression type)
: base(left, type)
{ }
#endregion
#region /* PROPERTIES */
/// <summary>
/// The symbol associated with the operator.
/// </summary>
public override string Symbol
{
get { return ParseToken; }
}
/// <summary>
/// True if the expression is const.
/// </summary>
public override bool IsConst
{
get { return false; }
}
#endregion
#region /* PARSING */
/// <summary>
/// The token used to parse the code object.
/// </summary>
public const string ParseToken = "is";
/// <summary>
/// The precedence of the operator.
/// </summary>
public const int Precedence = 330;
/// <summary>
/// True if the operator is left-associative, or false if it's right-associative.
/// </summary>
public const bool LeftAssociative = true;
internal static new void AddParsePoints()
{
Parser.AddOperatorParsePoint(ParseToken, Precedence, LeftAssociative, false, Parse);
}
/// <summary>
/// Parse an <see cref="Is"/> operator.
/// </summary>
public static Is Parse(Parser parser, CodeObject parent, ParseFlags flags)
{
return new Is(parser, parent);
}
protected Is(Parser parser, CodeObject parent)
: base(parser, parent)
{ }
/// <summary>
/// Get the precedence of the operator.
/// </summary>
public override int GetPrecedence()
{
return Precedence;
}
#endregion
#region /* RESOLVING */
/// <summary>
/// Resolve all child symbolic references, using the specified <see cref="ResolveCategory"/> and <see cref="ResolveFlags"/>.
/// </summary>
public override CodeObject Resolve(ResolveCategory resolveCategory, ResolveFlags flags)
{
if (_left != null)
_left = (Expression)_left.Resolve(ResolveCategory.Expression, flags);
// The decision was made to enforce that the right side of 'is' be a Type at resolution time
// instead of during analysis, meaning that a non-type reference will end up being unresolved.
// If we don't do this, a property with the same name as a type would take precedence.
if (_right != null)
_right = (Expression)_right.Resolve(ResolveCategory.Type, flags);
return this;
}
#endregion
}
}