/// <summary>
/// Reads an is expression.
/// </summary>
/// <param name="leftHandSide">
/// The expression on the left hand side of the operator.
/// </param>
/// <param name="previousPrecedence">
/// The precedence of the expression just before this one.
/// </param>
/// <param name="parentReference">
/// The parent code unit.
/// </param>
/// <param name="unsafeCode">
/// Indicates whether the code being parsed resides in an unsafe code block.
/// </param>
/// <returns>
/// Returns the expression.
/// </returns>
private IsExpression GetIsExpression(Expression leftHandSide, ExpressionPrecedence previousPrecedence, Reference<ICodePart> parentReference, bool unsafeCode)
{
Param.AssertNotNull(leftHandSide, "leftHandSide");
Param.Ignore(previousPrecedence);
Param.AssertNotNull(parentReference, "parentReference");
Param.Ignore(unsafeCode);
IsExpression expression = null;
// Check the previous precedence to see if we are allowed to gather up the is expression.
if (CheckPrecedence(previousPrecedence, ExpressionPrecedence.Relational))
{
Reference<ICodePart> expressionReference = new Reference<ICodePart>();
// Make sure the left hand side has at least one token.
Debug.Assert(leftHandSide.Tokens.First != null, "The left hand side should not be empty");
// Get the is symbol.
this.tokens.Add(this.GetToken(CsTokenType.Is, SymbolType.Is, parentReference, expressionReference));
// The next token must be the type.
this.GetNextSymbol(SymbolType.Other, expressionReference);
// Get the expression representing the type.
LiteralExpression rightHandSide = this.GetTypeTokenExpression(expressionReference, unsafeCode, true, true);
if (rightHandSide == null || rightHandSide.Tokens.First == null)
{
throw this.CreateSyntaxException();
}
// Create the partial token list for the expression.
CsTokenList partialTokens = new CsTokenList(this.tokens, leftHandSide.Tokens.First, this.tokens.Last);
// Create and return the expression.
expression = new IsExpression(partialTokens, leftHandSide, rightHandSide);
expressionReference.Target = expression;
}
return expression;
}
/// <summary>
/// The save.
/// </summary>
/// <param name="isExpression">
/// The is expression.
/// </param>
private void Save(IsExpression isExpression)
{
this.cppWriter.Write("dynamic_cast<");
this.Save(isExpression.Type, this.cppWriter, SavingOptions.None);
this.cppWriter.Write(">(");
@switch(isExpression.Value);
this.cppWriter.Write(") != nullptr");
}