public void TestNullEvaluate() { var expression = new NullCoalescingExpression( Mock.Of <IExpression>(e => e.Evaluate(It.IsAny <IDictionary <string, object> >()) == (object)null), Mock.Of <IExpression>(e => e.Evaluate(It.IsAny <IDictionary <string, object> >()) == (object)"Now used"), ExpressiveOptions.None); Assert.AreEqual("Now used", expression.Evaluate(null)); }
/// <summary> /// Reads a null coalescing 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="unsafeCode">Indicates whether the code being parsed resides in an unsafe code block.</param> /// <returns>Returns the expression.</returns> private NullCoalescingExpression GetNullCoalescingExpression( Expression leftHandSide, ExpressionPrecedence previousPrecedence, bool unsafeCode) { Param.AssertNotNull(leftHandSide, "leftHandSide"); Param.Ignore(previousPrecedence); Param.Ignore(unsafeCode); NullCoalescingExpression expression = null; // Read the details of the expression. OperatorSymbol operatorToken = this.PeekOperatorToken(); Debug.Assert(operatorToken.SymbolType == OperatorType.NullCoalescingSymbol, "Expected a null-coalescing symbol"); // Check the precedence of the operators to make sure we can gather this statement now. ExpressionPrecedence precedence = this.GetOperatorPrecedence(operatorToken.SymbolType); if (this.CheckPrecedence(previousPrecedence, precedence)) { // Add the operator token to the document and advance the symbol manager up to it. this.symbols.Advance(); this.tokens.Add(operatorToken); // Get the expression on the right-hand side of the operator. Expression rightHandSide = this.GetOperatorRightHandExpression(precedence, unsafeCode); // 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 NullCoalescingExpression(partialTokens, leftHandSide, rightHandSide); } return expression; }