/// <summary>
/// Initializes a new instance of the DefaultQueryHandler class.
/// </summary>
/// <param name="sourcer">The query expression sourcer to use.</param>
/// <param name="authorizer">The query expression authorizer to use.</param>
/// <param name="expander">The query expression expander to use.</param>
/// <param name="processor">The query expression processor to use.</param>
public DefaultQueryHandler(IQueryExpressionSourcer sourcer,
IQueryExpressionAuthorizer authorizer = null,
IQueryExpressionExpander expander = null,
IQueryExpressionProcessor processor = null)
{
Ensure.NotNull(sourcer, nameof(sourcer));
this.authorizer = authorizer;
this.expander = expander;
this.processor = processor;
this.sourcer = sourcer;
}
public QueryExpressionVisitor(QueryContext context,
IQueryExpressionSourcer sourcer,
IQueryExpressionAuthorizer authorizer = null,
IQueryExpressionExpander expander = null,
IQueryExpressionProcessor processor = null)
{
Ensure.NotNull(sourcer, nameof(sourcer));
this.context = new QueryExpressionContext(context);
this.authorizer = authorizer;
this.expander = expander;
this.processor = processor;
this.sourcer = sourcer;
processedExpressions = new Dictionary <Expression, Expression>();
}
private Expression Expand(Expression visited)
{
if (this.expander == null)
{
this.expander = this.context.QueryContext
.GetApiService <IQueryExpressionExpander>();
}
if (expander == null)
{
return(visited);
}
var expanded = expander.Expand(this.context);
var callback = this.context.AfterNestedVisitCallback;
this.context.AfterNestedVisitCallback = null;
if (expanded != null && expanded != visited)
{
if (!visited.Type.IsAssignableFrom(expanded.Type))
{
throw new InvalidOperationException(
Resources.ExpanderCannotChangeExpressionType);
}
this.context.PushVisitedNode(null);
expanded = this.Visit(expanded);
this.context.PopVisitedNode();
if (callback != null)
{
callback();
}
return(expanded);
}
return(visited);
}
private Expression Expand(Expression visited)
{
if (this.expander == null)
{
this.expander = this.context.QueryContext
.GetHookHandler<IQueryExpressionExpander>();
}
if (expander == null)
{
return visited;
}
var expanded = expander.Expand(this.context);
var callback = this.context.AfterNestedVisitCallback;
this.context.AfterNestedVisitCallback = null;
if (expanded != null && expanded != visited)
{
if (!visited.Type.IsAssignableFrom(expanded.Type))
{
throw new InvalidOperationException(
Resources.ExpanderCannotChangeExpressionType);
}
this.context.PushVisitedNode(null);
expanded = this.Visit(expanded);
this.context.PopVisitedNode();
if (callback != null)
{
callback();
}
return expanded;
}
return visited;
}