/// <summary>
/// Returns the recursive list of expressions (whether binary, unary, or relational)
/// within the current XML element. Returns NULL if there is a failure.
/// </summary>
public static IList <Expression> AllExpressonsAsXml(XElement xExpression)
{
IList <Expression> expressions = new List <Expression>();
foreach (XElement xExpressionRelation in XmlHelper.Children(xExpression, "ExpressionRelational"))
{
ExpressionRelational expressionRelational = new ExpressionRelational();
if (!expressionRelational.ReadAsXml(xExpressionRelation))
{
return(null);
}
expressions.Add(expressionRelational);
}
foreach (XElement xExpressionBinary in XmlHelper.Children(xExpression, "ExpressionBinary"))
{
ExpressionBinary expressionBinary = new ExpressionBinary();
if (!expressionBinary.ReadAsXml(xExpressionBinary))
{
return(null);
}
expressions.Add(expressionBinary);
}
foreach (XElement xExpressionUnary in XmlHelper.Children(xExpression, "ExpressionUnary"))
{
ExpressionUnary expressionUnary = new ExpressionUnary();
if (!expressionUnary.ReadAsXml(xExpressionUnary))
{
return(null);
}
expressions.Add(expressionUnary);
}
return(expressions);
}
/// <summary>
/// Parses and returns a relational expression.
/// </summary>
private static Expression ParseRelational(IList <string> expressionTokens, ref int index)
{
IList <Expression> operands = new List <Expression>();
Expression operand = ParseOperand(expressionTokens, ref index);
if (operand != null)
{
operands.Add(operand);
}
string relationalOperator = Token(expressionTokens, index, true);
if (RelationalOperators.Contains(relationalOperator))
{
index++;
operand = ParseOperand(expressionTokens, ref index);
if (operand != null)
{
operands.Add(operand);
}
}
return(ExpressionRelational.Build(operands, relationalOperator));
}