public ExpressionColumnCollection(ExpressionTable table)
: base(table)
{
this.table = table;
}
private ITable ExpressionTableFilter(ITable table, FilterExpression op)
{
// The filter operation which is a function that describes the output
// columns
Expression filterExp = op.Filter;
if (filterExp.Type != ExpressionType.Function)
throw new ApplicationException("Expected a function.");
FunctionExpression functionExp = (FunctionExpression)filterExp;
// Function name and parameter count,
string funName = functionExp.Name;
if (!funName.Equals("table_out"))
throw new ArgumentException();
int paramCount = functionExp.Parameters.Count;
// Create the expression table data source
ExpressionTable expressionTable = new ExpressionTable(table, this);
// The number of parameters,
for (int i = 0; i < paramCount; ++i) {
Expression outExp = (Expression) functionExp.Parameters[i];
// This will always be an aliasvarname with an operation child which is
// the expression we perform for the column.
if (!(outExp is AliasVariableNameExpression))
throw new ApplicationException("Expected ALIASVARNAME.");
// The label,
Variable v = ((AliasVariableNameExpression)outExp).Alias;
string label = v.Name;
// The actual function
Expression funExp = ((AliasVariableNameExpression) outExp).Child;
// Work out the type,
SqlType expType = GetExpressionType(table, funExp);
// Add the column
expressionTable.AddColumn(label, expType, funExp);
}
// Return the operation table
return expressionTable;
}
