/// <summary>
/// Creates an n-dimensional System.Array from PG binary representation.
/// This function reads the array header and sets up an n-dimensional System.Array object to hold its data.
/// PopulateArrayFromBinaryArray() is then called to carry out array population.
/// </summary>
public object ArrayBinaryToArray(NpgsqlBackendTypeInfo TypeInfo, byte[] BackendData, Int32 fieldValueSize, Int32 TypeModifier)
{
// Sanity check.
if (BackendData.Length < 4)
{
throw new Exception("Insuffient backend data to describe dimension count in binary array header");
}
// Offset 0 holds an integer dscribing the number of dimensions in the array.
int nDims = PGUtil.ReadInt32(BackendData, 0);
// Sanity check.
if (nDims < 0)
{
throw new NpgsqlException("Invalid array dimension count encountered in binary array header");
}
// {PG handles 0-dimension arrays, but .net does not. Return a 0-size 1-dimensional array.
if (nDims == 0)
{
return(Array.CreateInstance(_elementConverter.FrameworkType, 0));
}
int dimOffset;
// Offset 12 begins an array of {int,int} objects, of length nDims.
int dataOffset = 12;
// Sanity check.
if (BackendData.Length < dataOffset + nDims * 8)
{
throw new NpgsqlException("Insuffient backend data to describe all expected dimensions in binary array header");
}
int[] dimLengths;
int[] dimLBounds;
dimLengths = new int[nDims];
dimLBounds = new int[nDims];
// Populate array dimension lengths and lower bounds.
for (dimOffset = 0; dimOffset < nDims; dimOffset++)
{
dimLengths[dimOffset] = PGUtil.ReadInt32(BackendData, dataOffset);
dataOffset += 4;
// Lower bounds is 1-based in SQL, 0-based in .NET.
dimLBounds[dimOffset] = PGUtil.ReadInt32(BackendData, dataOffset) - 1;
dataOffset += 4;
}
Array dst;
int[] dstOffsets;
dst = Array.CreateInstance(_elementConverter.FrameworkType, dimLengths, dimLBounds);
dstOffsets = new int[nDims];
// Right after the dimension descriptors begins array data.
// Populate the new array.
PopulateArrayFromBinaryArray(TypeInfo, BackendData, fieldValueSize, TypeModifier, ref dataOffset, dimLengths, dimLBounds, 0, dst, dstOffsets);
return(dst);
}
/// <summary>
/// Recursively populates an array from PB binary data representation.
/// </summary>
private void PopulateArrayFromBinaryArray(NpgsqlBackendTypeInfo TypeInfo, byte[] backendData, Int32 fieldValueSize, Int32 TypeModifier, ref int dataOffset, int[] dimLengths, int[] dimLBounds, int dimOffset, Array dst, int[] dstOffsets)
{
int dimensionLBound = dimLBounds[dimOffset];
int end = dimensionLBound + dimLengths[dimOffset];
if (dimOffset < dimLengths.Length - 1)
{
// Drill down recursively until we hit a single dimension array.
for (int i = dimensionLBound; i < end; i++)
{
dstOffsets[dimOffset] = i;
PopulateArrayFromBinaryArray(TypeInfo, backendData, fieldValueSize, TypeModifier, ref dataOffset, dimLengths, dimLBounds, dimOffset + 1, dst, dstOffsets);
}
}
else
{
// Populate a single dimension array.
for (int i = dimensionLBound; i < end; i++)
{
// Sanity check.
if (backendData.Length < dataOffset + 4)
{
throw new NpgsqlException("Out of backend data while reading binary array");
}
int elementLength;
// Each element consists of an int length identifier, followed by that many bytes of raw data.
// Length -1 indicates a NULL value, and is naturally followed by no data.
elementLength = PGUtil.ReadInt32(backendData, dataOffset);
dataOffset += 4;
if (elementLength == -1)
{
// This currently throws an exception on value types.
dst.SetValue(DBNull.Value, dstOffsets);
}
else
{
// Sanity check.
if (backendData.Length < dataOffset + elementLength)
{
throw new NpgsqlException("Out of backend data while reading binary array");
}
byte[] elementBinary;
// Get element data from backend data.
elementBinary = PGUtil.ReadBytes(backendData, dataOffset, elementLength);
object elementNative;
elementNative = _elementConverter.ConvertBackendBinaryToNative(elementBinary, fieldValueSize, TypeModifier);
dstOffsets[dimOffset] = i;
dst.SetValue(elementNative, dstOffsets);
dataOffset += elementLength;
}
}
}
}
/// <summary>
/// Create a new ArrayBackendToNativeTypeConverter
/// </summary>
/// <param name="elementConverter"><see cref="NpgsqlBackendTypeInfo"/> for the element type.</param>
public ArrayBackendToNativeTypeConverter(NpgsqlBackendTypeInfo elementConverter)
{
_elementConverter = elementConverter;
}
