static TeaFile <T> Append(Stream stream, bool ownsStream, Stream headerReadStream, ItemDescriptionElements elementsToValidate = ItemDescriptionElements.All)
{
var tf = new TeaFile <T>();
try
{
TeaFileDescription description;
tf.core = new TeaFileCore(stream, ownsStream);
// A file opened for appending, cannot be read. Therefore we create a second file, read it and assign its description to the current TeaFile<> instance.
using (var tfheader = OpenRead(headerReadStream, false, elementsToValidate)) // we pass headerStream ownership to tfheader, so it will be closed after header reaeding.
{
description = tfheader.Description;
if (!tfheader.core.CanAppend)
{
throw new IOException("Cannot append to file because it has preallocated space between the end of the item area and the end of the file.");
}
tf.core.Assign(tfheader.ItemAreaStart, tfheader.core.ItemAreaEndMarker);
}
// if the stream is a filestream that was opened in FileMode.Append, this call is redundant.
// this line is here for the allowed case were the stream and headerstream point to the same stream.
tf.SetFilePointerToEnd();
tf.core.Description = description;
tf.buffer = new SafeBuffer <T>(stream);
return(tf);
}
catch (Exception)
{
tf.Dispose();
throw;
}
}
static TeaFile <T> OpenRead(Stream stream, bool ownsStream, ItemDescriptionElements elementsToValidate)
{
var tf = new TeaFile <T>();
try
{
tf.core = new TeaFileCore(stream, ownsStream);
tf.buffer = new SafeBuffer <T>(stream);
tf.core.ReadHeader();
// reflecting the current type incurs some cost, so we do it only if we are asked to consider
// current item layout to check it against to layout described in the file
ItemDescription accessorDescription = null;
if (elementsToValidate != ItemDescriptionElements.None)
{
accessorDescription = ItemDescription.FromAnalysis <T>();
}
tf.core.IsAccessibleWith(accessorDescription, elementsToValidate);
return(tf);
}
catch (Exception)
{
tf.Dispose();
throw;
}
}
/// <summary>
/// Creates a TeaFile, using the specified stream as the underlying storage media.
/// </summary>
/// <param name="stream">The stream.</param>
/// <param name="ownsStream">If true, the instance returned owns the stream, such that disposing the returned instance also disposes <paramref name="stream"/>.</param>
/// <param name="contentDescription">The content description.</param>
/// <param name="nameValues">The name values.</param>
/// <param name="includeItemDescription">if set to <c>true</c> [include item description].</param>
/// <returns></returns>
/// <remarks>
/// Instead of creating a new <see cref="FileStream"/>, this method takes the <see cref="Stream"/> passed. This provides
/// more control over the stream, like setting specific <see cref="FileShare"/> attributes. It also allows usage of
/// alternative storage medias like <see cref="MemoryStream"/>.
/// </remarks>
public static TeaFile <T> Create(Stream stream, bool ownsStream, string contentDescription = null, NameValueCollection nameValues = null, bool includeItemDescription = true)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
var tf = new TeaFile <T>();
try
{
tf.core = new TeaFileCore(stream, ownsStream);
tf.buffer = new SafeBuffer <T>(stream);
if (includeItemDescription)
{
tf.Description.ItemDescription = ItemDescription.FromAnalysis <T>();
}
tf.Description.ContentDescription = contentDescription;
tf.Description.NameValues = nameValues;
tf.Description.Timescale = Time.Scale; // The
tf.core.WriteHeader();
tf.Flush();
return(tf);
}
catch (Exception)
{
tf.Dispose();
throw;
}
}
static TeaFile <T> OpenWrite(Stream stream, bool ownsStream, ItemDescriptionElements elementsToValidate)
{
var tf = new TeaFile <T>();
try
{
tf.buffer = new SafeBuffer <T>(stream);
tf.core = new TeaFileCore(stream, ownsStream);
tf.core.ReadHeader();
tf.core.IsAccessibleWith(ItemDescription.FromAnalysis <T>(), elementsToValidate);
// filepointer is at begin of item area. finally, the user might want to read.
// using filepointer is essential here.
// check the item api to allow this.
return(tf);
}
catch (Exception)
{
tf.Dispose();
throw;
}
}
static TeaFile OpenRead(Stream stream, bool ownsStream)
{
var tf = new TeaFile();
try
{
tf.core = new TeaFileCore(stream, ownsStream);
tf.core.ReadHeader();
// protect against empty Item structs
if (tf.Description.ItemDescription != null)
{
if (!tf.Description.ItemDescription.Fields.Any())
{
throw new ItemException("Cannot read this file because the item has no fields according to its item description in the file.");
}
}
tf.reader = new BinaryReader(tf.core.Stream);
if (tf.Description.ItemDescription != null)
{
// A field might occupy equal or more bytes than the size of its type due to padding bytes
// inserted between the fields or between items in the ItemArray. The paddingBytes array
// holds the number of bytes that will be read after reading a field in order to set the
// file pointer to the next field.
tf.fieldSpacings = tf.GetFieldSpacings();
}
return(tf);
}
catch
{
tf.Dispose(); // since we will not hand out the disposable TeaFile instance,
// we must close the filestream if header reading failed!
throw;
}
}
static TeaFile OpenRead(Stream stream, bool ownsStream)
{
var tf = new TeaFile();
try
{
tf.core = new TeaFileCore(stream, ownsStream);
tf.core.ReadHeader();
// protect against empty Item structs
if (tf.Description.ItemDescription != null)
{
if (!tf.Description.ItemDescription.Fields.Any())
{
throw new ItemException("Cannot read this file because the item has no fields according to its item description in the file.");
}
}
tf.reader = new BinaryReader(tf.core.Stream);
if (tf.Description.ItemDescription != null)
{
// A field might occupy equal or more bytes than the size of its type due to padding bytes
// inserted between the fields or between items in the ItemArray. The paddingBytes array
// holds the number of bytes that will be read after reading a field in order to set the
// file pointer to the next field.
tf.fieldSpacings = tf.GetFieldSpacings();
}
return tf;
}
catch
{
tf.Dispose(); // since we will not hand out the disposable TeaFile instance,
// we must close the filestream if header reading failed!
throw;
}
}
