private static RavenJObject GetJson(IFilter filter)
{
// initialize a buffer for text results
const int defaultBufferSize = 4096;
var buffer = new StringBuilder(defaultBufferSize);
// Initialize the json writers
using (var textWriter = new RavenJTokenWriter())
using (var propWriter = new RavenJTokenWriter())
{
// Write the beginning of the json arrays
textWriter.WriteStartArray();
propWriter.WriteStartArray();
string last = null;
// Outer loop will read chunks from the document.
// For those chunks that have text, the contents will be written to json.
while (true)
{
// Try to get a chunk of data
STAT_CHUNK statChunk;
var chunkStatus = filter.GetChunk(out statChunk);
switch (chunkStatus)
{
case IFilterReturnCodes.S_OK:
// We have a good chunk of data
break;
case IFilterReturnCodes.FILTER_E_END_OF_CHUNKS:
// No more data.
if (buffer.Length > 0)
{
// Make sure we have no unwritten data first.
textWriter.WriteLines(buffer.ToString());
buffer.Clear();
}
// close the json array and flush the writers
textWriter.WriteEndArray();
propWriter.WriteEndArray();
textWriter.Flush();
propWriter.Flush();
// assemble and return the document
return new RavenJObject
{
//{ "Properties", propWriter.Token }, // TODO: restore this when properties can be retrieved
{ "Text", textWriter.Token }
};
case IFilterReturnCodes.FILTER_E_EMBEDDING_UNAVAILABLE:
case IFilterReturnCodes.FILTER_E_LINK_UNAVAILABLE:
// Ignore these warnings
continue;
default:
// Something else - throw an exception
throw new COMException("IFilter COM error while getting a chunk of data: " + chunkStatus);
}
//// Handle property value chunks TODO: make this work so we can index properties in addition to text
//if (statChunk.flags.HasFlag(CHUNKSTATE.CHUNK_VALUE))
//{
// // get the property name TODO: This doesn't seem to work
// var propInfo = statChunk.attribute.psProperty;
// var propName = propInfo.ulKind == 0 ? Marshal.PtrToStringAuto(propInfo.lpwstr) : propInfo.propid.ToString();
//
// // will this help?
// var propGuid = statChunk.attribute.guidPropSet;
// // get the value TODO: This doesn't seem to work
// PROPVARIANT ppPropValue;
// var valueStatus = filter.GetValue(out ppPropValue);
// if (valueStatus == IFilterReturnCodes.S_OK || valueStatus == IFilterReturnCodes.FILTER_S_LAST_VALUES)
// {
// // write the value to json
// propWriter.WriteStartObject();
// propWriter.WritePropertyName(propName);
// propWriter.WriteValue(ppPropValue.Value);
// propWriter.WriteEndObject();
// // free unmanaged memory from the PropVariant
// ppPropValue.Clear();
// }
//}
// the rest of this code is for text chunks only
if (!statChunk.flags.HasFlag(CHUNKSTATE.CHUNK_TEXT))
continue;
// Check for white space items and add the appropriate breaks.
switch (statChunk.breakType)
{
case CHUNK_BREAKTYPE.CHUNK_EOW:
if (buffer.Length > 0 && !char.IsWhiteSpace(buffer[buffer.Length - 1]))
buffer.Append(' ');
break;
case CHUNK_BREAKTYPE.CHUNK_EOC:
case CHUNK_BREAKTYPE.CHUNK_EOP:
case CHUNK_BREAKTYPE.CHUNK_EOS:
// Each chapter, paragraph or sentence break can be in a new json value in our array.
// This will keep any one string from getting too big.
if (buffer.Length > 0)
{
textWriter.WriteLines(buffer.ToString());
buffer.Clear();
}
break;
}
while (true)
{
// Create a temporary string buffer we can use for the parsing algorithm.
int cBuffer = defaultBufferSize;
var sbBuffer = new StringBuilder(defaultBufferSize);
// Read the next piece of data up to the size of our local buffer.
var textStatus = filter.GetText(ref cBuffer, sbBuffer);
if (textStatus == IFilterReturnCodes.S_OK || textStatus == IFilterReturnCodes.FILTER_S_LAST_TEXT)
{
// If any data was returned, add it to the buffer.
buffer.Append(sbBuffer.ToString(), 0, cBuffer);
}
// Once all data is exhausted, we are done so terminate the loop.
if (textStatus == IFilterReturnCodes.FILTER_S_LAST_TEXT || textStatus == IFilterReturnCodes.FILTER_E_NO_MORE_TEXT)
break;
}
}
}
}
