/// <summary>Extract is called at least once per instance</summary>
/// <param name="input">Wrapper for a Stream</param>
/// <param name="output">IUpdatableRow uses a mutable builder pattern --
/// set individual fields with IUpdatableRow.Set, then build an immutable IRow by
/// calling IUpdatableRow.AsReadOnly.</param>
/// <returns>IEnumerable of IRow, one IRow per SQLIP row.</returns>
public override IEnumerable <IRow> Extract(IUnstructuredReader input, IUpdatableRow output)
{
// Make sure that all requested columns are of type string
IColumn column = output.Schema.FirstOrDefault(col => col.Type != typeof(string));
if (column != null)
{
throw new ArgumentException(string.Format("Column '{0}' must be of type 'string', not '{1}'", column.Name, column.Type.Name));
}
var state = new ParseState();
state.ClearAndJump(ParseLocation.Row);
using (var reader = XmlReader.Create(input.BaseStream))
{
while (reader.Read())
{
switch (state.Location)
{
case ParseLocation.Row:
// when looking for a new row, we are only interested in elements
// whose name matches the requested row element
if (reader.NodeType == XmlNodeType.Element && reader.Name == this.rowPath)
{
// when found, clear the IUpdatableRow's memory
// (this is no provided Clear method)
for (int i = 0; i < output.Schema.Count; i++)
{
output.Set <string>(i, null);
}
state.ClearAndJump(ParseLocation.Column);
}
break;
case ParseLocation.Column:
// When looking for a new column, we are interested in elements
// whose name is a key in the columnPaths map or
// whose name is in the requested output schema.
// This indicates a column whose value needs to be read,
// so prepare for reading it by clearing elementValue.
if (reader.NodeType == XmlNodeType.Element &&
(this.columnPaths.ContainsKey(reader.Name) ||
output.Schema.Select(c => c.Name).Contains(reader.Name)))
{
if (reader.IsEmptyElement)
{
// For an empty element, set an empty string
// and immediately jump to looking for the next column
output.Set(this.columnPaths[reader.Name] ?? reader.Name, state.ReadElementValue());
state.ClearAndJump(ParseLocation.Column);
}
else
{
state.Location = ParseLocation.Data;
state.ElementName = reader.Name;
state.ClearElementValue();
}
}
else if (reader.NodeType == XmlNodeType.EndElement && reader.Name == this.rowPath)
{
// The other interesting case is an end element whose name matches
// the current row element. This indicates the end of a row,
// so yield the now-complete row and jump to looking for
// another row.
yield return(output.AsReadOnly());
state.ClearAndJump(ParseLocation.Row);
}
break;
case ParseLocation.Data:
// Most of the code for reading the value of a column
// deals with re-creating the inner XML from discrete elements.
// The only jump occurs when the reader hits an end element
// whose name matches the current column. In this case, we
// need to write the accumulated value to the appropriate
// column in the output row.
switch (reader.NodeType)
{
case XmlNodeType.EndElement:
if (reader.Name == state.ElementName)
{
output.Set(this.columnPaths[state.ElementName] ?? state.ElementName, state.ReadElementValue());
state.ClearAndJump(ParseLocation.Column);
}
else
{
state.ElementWriter.WriteEndElement();
}
break;
case XmlNodeType.Element:
state.ElementWriter.WriteStartElement(reader.Name);
state.ElementWriter.WriteAttributes(reader, false);
if (reader.IsEmptyElement)
{
state.ElementWriter.WriteEndElement();
}
break;
case XmlNodeType.CDATA:
state.ElementWriter.WriteCData(reader.Value);
break;
case XmlNodeType.Comment:
state.ElementWriter.WriteComment(reader.Value);
break;
case XmlNodeType.ProcessingInstruction:
state.ElementWriter.WriteProcessingInstruction(reader.Name, reader.Value);
break;
default:
state.ElementWriter.WriteString(reader.Value);
break;
}
break;
default:
throw new NotImplementedException("StreamFromXml has not implemented a new member of the ParseLocation enum");
}
}
if (state.Location != ParseLocation.Row)
{
throw new ArgumentException("XML document ended without proper closing tags");
}
}
}
/// <summary>Extract is called at least once per instance</summary>
/// <param name="input">Wrapper for a Stream</param>
/// <param name="output">IUpdatableRow uses a mutable builder pattern --
/// set individual fields with IUpdatableRow.Set, then build an immutable IRow by
/// calling IUpdatableRow.AsReadOnly.</param>
/// <returns>IEnumerable of IRow, one IRow per SQLIP row.</returns>
public override IEnumerable<IRow> Extract(IUnstructuredReader input, IUpdatableRow output)
{
// Make sure that all requested columns are of type string
IColumn column = output.Schema.FirstOrDefault(col => col.Type != typeof(string));
if (column != null)
{
throw new ArgumentException(string.Format("Column '{0}' must be of type 'string', not '{1}'", column.Name, column.Type.Name));
}
var state = new ParseState();
state.ClearAndJump(ParseLocation.Row);
using (var reader = XmlReader.Create(input.BaseStream))
{
while (reader.Read())
{
switch (state.Location)
{
case ParseLocation.Row:
// when looking for a new row, we are only interested in elements
// whose name matches the requested row element
if (reader.NodeType == XmlNodeType.Element && reader.Name == this.rowPath)
{
// when found, clear the IUpdatableRow's memory
// (this is no provided Clear method)
for (int i = 0; i < output.Schema.Count; i++)
{
output.Set<string>(i, null);
}
state.ClearAndJump(ParseLocation.Column);
}
break;
case ParseLocation.Column:
// When looking for a new column, we are interested in elements
// whose name is a key in the columnPaths map or
// whose name is in the requested output schema.
// This indicates a column whose value needs to be read,
// so prepare for reading it by clearing elementValue.
if (reader.NodeType == XmlNodeType.Element
&& (this.columnPaths.ContainsKey(reader.Name)
|| output.Schema.Select(c => c.Name).Contains(reader.Name)))
{
if (reader.IsEmptyElement)
{
// For an empty element, set an empty string
// and immediately jump to looking for the next column
output.Set(this.columnPaths[reader.Name] ?? reader.Name, state.ReadElementValue());
state.ClearAndJump(ParseLocation.Column);
}
else
{
state.Location = ParseLocation.Data;
state.ElementName = reader.Name;
state.ClearElementValue();
}
}
else if (reader.NodeType == XmlNodeType.EndElement && reader.Name == this.rowPath)
{
// The other interesting case is an end element whose name matches
// the current row element. This indicates the end of a row,
// so yield the now-complete row and jump to looking for
// another row.
yield return output.AsReadOnly();
state.ClearAndJump(ParseLocation.Row);
}
break;
case ParseLocation.Data:
// Most of the code for reading the value of a column
// deals with re-creating the inner XML from discrete elements.
// The only jump occurs when the reader hits an end element
// whose name matches the current column. In this case, we
// need to write the accumulated value to the appropriate
// column in the output row.
switch (reader.NodeType)
{
case XmlNodeType.EndElement:
if (reader.Name == state.ElementName)
{
output.Set(this.columnPaths[state.ElementName] ?? state.ElementName, state.ReadElementValue());
state.ClearAndJump(ParseLocation.Column);
}
else
{
state.ElementWriter.WriteEndElement();
}
break;
case XmlNodeType.Element:
state.ElementWriter.WriteStartElement(reader.Name);
state.ElementWriter.WriteAttributes(reader, false);
if (reader.IsEmptyElement)
{
state.ElementWriter.WriteEndElement();
}
break;
case XmlNodeType.CDATA:
state.ElementWriter.WriteCData(reader.Value);
break;
case XmlNodeType.Comment:
state.ElementWriter.WriteComment(reader.Value);
break;
case XmlNodeType.ProcessingInstruction:
state.ElementWriter.WriteProcessingInstruction(reader.Name, reader.Value);
break;
default:
state.ElementWriter.WriteString(reader.Value);
break;
}
break;
default:
throw new NotImplementedException("StreamFromXml has not implemented a new member of the ParseLocation enum");
}
}
if (state.Location != ParseLocation.Row)
{
throw new ArgumentException("XML document ended without proper closing tags");
}
}
}
