/// <summary>
/// Visits a <see cref="FieldReferenceSqlExpression"/> expression.
/// </summary>
/// <param name="node">
/// The node.
/// </param>
/// <returns>
/// The node, or a new version of the node.
/// </returns>
protected internal override Node VisitFieldReferenceSqlExpression(FieldReferenceSqlExpression node)
{
var replacer = this.Data.GetFieldReplacer(node);
if (replacer != null)
{
return(this.Visit(replacer));
}
this.Data.SetType(node, new TypeDescriptor(typeof(object)));
this.Data.SetScope(node, this.Scope.IsGroupByExpression(node) ? NodeScope.Group : NodeScope.Row);
if (node.Source == null)
{
this.AddError(node, $"Field {node.Name} must have a source.");
return(node);
}
var source = this.Scope.GetSource(node.Source);
if (source == null)
{
this.AddError(node, $"Source {node.Source} is referenced before it is declared.");
}
this.Data.Set(node, "Source", source);
return(node);
}
/// <summary>
/// Checks if the node is a grouped node, and adds it to the list of grouped nodes if so.
/// </summary>
/// <typeparam name="T">
/// The type of the node.
/// </typeparam>
/// <param name="node">
/// The node.
/// </param>
/// <param name="baseCall">
/// The method to call when the expression is not a grouped node.
/// </param>
/// <returns>
/// The node or the result of the <paramref name="baseCall"/>.
/// </returns>
private Node CheckForGroups <T>(T node, Func <T, Node> baseCall)
where T : SqlExpressionBase
{
var isGrouping = this.select.Groupings.Contains(node);
if ((this.data.GetScope(node) == NodeScope.Row) || isGrouping)
{
if (this.groupedNodes.IndexOf(node) == -1)
{
this.groupedNodes.Add(node);
}
var field = new FieldReferenceSqlExpression($"group{this.groupedNodes.IndexOf(node)}");
if (!isGrouping || this.visitingGroupings > 0)
{
return(field);
}
var fields = new List <SqlExpressionBase>
{
field,
};
var result = new FunctionCallSqlExpression("$GROUP_FIRST", new ReadOnlyCollection <SqlExpressionBase>(fields));
this.data.MarkAsGroupFunction(result);
this.data.SetScope(node, NodeScope.Group);
this.data.SetFunction(result, new FunctionDescriptor(result.Name, false, (Expression <Func <IAsyncEnumerable <object>, Task <object> > >)(objs => objs.FirstAsync())));
return(result);
}
if (this.data.GetScope(node) == NodeScope.Group && node is FunctionCallSqlExpression)
{
this.visitingGroupings++;
}
var nodeResult = baseCall(node);
if (this.data.GetScope(node) == NodeScope.Group && node is FunctionCallSqlExpression)
{
this.visitingGroupings--;
}
if (!ReferenceEquals(node, nodeResult))
{
this.data.CopyValues(node, nodeResult);
}
return(nodeResult);
}
/// <summary>
/// Visits a <see cref="FieldReferenceSqlExpression"/> expression.
/// </summary>
/// <param name="node">
/// The node.
/// </param>
/// <returns>
/// The node, or a new version of the node.
/// </returns>
protected internal virtual Node VisitFieldReferenceSqlExpression([NotNull] FieldReferenceSqlExpression node)
{
return(node.VisitChildren(this));
}
/// <summary>
/// Visits a <see cref="FieldReferenceSqlExpression"/> expression.
/// </summary>
/// <param name="node">
/// The node.
/// </param>
/// <returns>
/// The node, or a new version of the node.
/// </returns>
protected internal override Node VisitFieldReferenceSqlExpression(FieldReferenceSqlExpression node)
{
return(this.CheckForGroups(node, n => base.VisitFieldReferenceSqlExpression(n)));
}
protected internal override Node VisitFieldReferenceSqlExpression([NotNull] FieldReferenceSqlExpression node)
{
this.Builder.Append(node.Source == null ? $"[{node.Name}]" : $"[{node.Source}].[{node.Name}]");
return(node);
}
/// <summary>
/// Visits a <see cref="FieldReferenceSqlExpression"/> expression.
/// </summary>
/// <param name="node">
/// The node.
/// </param>
/// <returns>
/// The node, or a new version of the node.
/// </returns>
protected internal override Node VisitFieldReferenceSqlExpression(FieldReferenceSqlExpression node)
{
return(this.VisitImplementation(node) ?? base.VisitFieldReferenceSqlExpression(node));
}
/// <summary>
/// Sets the expression that will replace a <see cref="FieldReferenceSqlExpression"/> in an ORDER BY clause.
/// </summary>
/// <param name="dataProvider">
/// The data provider.
/// </param>
/// <param name="field">
/// The field.
/// </param>
/// <param name="expression">
/// The expression.
/// </param>
public static void SetFieldReplacer([NotNull] this INodeDataProvider dataProvider, FieldReferenceSqlExpression field, SqlExpressionBase expression)
{
dataProvider.Set(field, "FieldReplacer", expression);
}
public static SqlExpressionBase GetFieldReplacer([NotNull] this INodeDataProvider dataProvider, FieldReferenceSqlExpression field)
{
return(dataProvider.TryGet(field, "FieldReplacer", out SqlExpressionBase result) ? result : null);
}
