//Return the offset for the nth member from an Array or Object type
int GetNthOffset(int index)
{
int offset;
byte head = TypeCode;
if (head == 0x13 || head == 0x14)
{
// compact Array or Object
offset = GetNthOffsetFromCompact(index);
}
else if (head == 0x01 || head == 0x0a)
{
// special case: empty Array or empty Object
throw new IndexOutOfRangeException();
}
else
{
long n;
int offsetsize = ObjectArrayUtil.GetOffsetSize(head);
long end = NumberUtil.ToLong(vpack, start + 1, offsetsize);
int dataOffset = FindDataOffset();
if (head <= 0x05)
{
// array with no offset table or length
VPackSlice first = new VPackSlice(vpack, start + dataOffset);
n = (end - dataOffset) / first.GetByteSize();
}
else if (offsetsize < 8)
{
n = NumberUtil.ToLong(vpack, start + 1 + offsetsize, offsetsize);
}
else
{
n = NumberUtil.ToLong(vpack, (int)(start + end - offsetsize), offsetsize);
}
if (index >= n)
{
throw new IndexOutOfRangeException();
}
if (head <= 0x05 || n == 1)
{
// no index table, but all array items have the same length
// or only one item is in the array
// now fetch first item and determine its length
if (dataOffset == 0)
{
dataOffset = FindDataOffset();
}
offset = dataOffset + index * new VPackSlice(vpack, start + dataOffset).GetByteSize();
}
else
{
long ieBase = end - n * offsetsize + index * offsetsize - (offsetsize == 8 ? 8 : 0);
offset = (int)NumberUtil.ToLong(vpack, (int)(start + ieBase), offsetsize);
}
}
return(offset);
}
public VPackSlice ValueAt(int index)
{
if (!IsType(SliceType.Object))
{
throw new VPackValueTypeException(SliceType.Object);
}
VPackSlice key = GetNthKey(index);
return(new VPackSlice(vpack, key.start + key.GetByteSize()));
}
private VPackSlice SearchObjectKeyLinear(
string attribute,
long ieBase,
int offsetsize,
long n)
{
bool useTranslator = attributeTranslator != null;
VPackSlice result = new VPackSlice();
for (long index = 0; index < n; index++)
{
long offset = ieBase + index * offsetsize;
long keyIndex = NumberUtil.ToLong(vpack, (int)(start + offset), offsetsize);
VPackSlice key = new VPackSlice(vpack, (int)(start + keyIndex));
if (key.IsType(SliceType.String))
{
if (!key.IsEqualString(attribute))
{
continue;
}
}
else if (key.IsInteger())
{
// translate key
if (!useTranslator)
{
// no attribute translator
throw new VPackNeedAttributeTranslatorException();
}
if (!key.TranslateUnchecked().IsEqualString(attribute))
{
continue;
}
}
else
{
// invalid key type
result = new VPackSlice();
break;
}
// key is identical. now return value
result = new VPackSlice(vpack, key.start + key.GetByteSize());
break;
}
return(result);
}
VPackSlice SearchObjectKeyBinary(
string attribute,
long ieBase,
int offsetsize,
long n)
{
bool useTranslator = attributeTranslator != null;
VPackSlice result;
long l = 0;
long r = n - 1;
for (;;)
{
// midpoint
long index = l + ((r - l) / 2);
long offset = ieBase + index * offsetsize;
long keyIndex = NumberUtil.ToLong(vpack, (int)(start + offset), offsetsize);
VPackSlice key = new VPackSlice(vpack, (int)(start + keyIndex));
int res = 0;
if (key.IsType(SliceType.String))
{
res = key.CompareString(attribute);
}
else if (key.IsInteger())
{
// translate key
if (!useTranslator)
{
// no attribute translator
throw new VPackNeedAttributeTranslatorException();
}
res = key.TranslateUnchecked().CompareString(attribute);
}
else
{
// invalid key
result = new VPackSlice();
break;
}
if (res == 0)
{
// found
result = new VPackSlice(vpack, key.start + key.GetByteSize());
break;
}
if (res > 0)
{
if (index == 0)
{
result = new VPackSlice();
break;
}
r = index - 1;
}
else
{
l = index + 1;
}
if (r < l)
{
result = new VPackSlice();
break;
}
}
return(result);
}
/// <summary>
/// Return object by attribute name
/// </summary>
/// <param name="attribute"></param>
/// <returns></returns>
public VPackSlice this[string attribute]
{
get
{
if (!IsType(SliceType.Object))
{
throw new VPackValueTypeException(SliceType.Object);
}
byte head = TypeCode;
VPackSlice result = new VPackSlice();
if (head == 0x0a)
{
// special case, empty object
result = new VPackSlice();
}
else if (head == 0x14)
{
// compact Object
result = GetFromCompactObject(attribute);
}
else
{
int offsetsize = ObjectArrayUtil.GetOffsetSize(head);
long end = NumberUtil.ToLong(vpack, start + 1, offsetsize);
long n;
if (offsetsize < 8)
{
n = NumberUtil.ToLong(vpack, start + 1 + offsetsize, offsetsize);
}
else
{
n = NumberUtil.ToLong(vpack, (int)(start + end - offsetsize), offsetsize);
}
if (n == 1)
{
// Just one attribute, there is no index table!
VPackSlice key = new VPackSlice(vpack, start + FindDataOffset());
if (key.IsType(SliceType.String))
{
if (key.IsEqualString(attribute))
{
result = new VPackSlice(vpack, key.start + key.GetByteSize());
}
else
{
// no match
result = new VPackSlice();
}
}
else if (key.IsInteger())
{
// translate key
if (attributeTranslator == null)
{
throw new VPackNeedAttributeTranslatorException();
}
if (key.TranslateUnchecked().IsEqualString(attribute))
{
result = new VPackSlice(vpack, key.start + key.GetByteSize());
}
else
{
// no match
result = new VPackSlice();
}
}
else
{
// no match
result = new VPackSlice();
}
}
else
{
long ieBase = end - n * offsetsize - (offsetsize == 8 ? 8 : 0);
// only use binary search for attributes if we have at least
// this many entries
// otherwise we'll always use the linear search
long sortedSearchEntriesThreshold = 4;
bool sorted = head >= 0x0b && head <= 0x0e;
if (sorted && n >= sortedSearchEntriesThreshold)
{
// This means, we have to handle the special case n == 1
// only in the linear search!
result = SearchObjectKeyBinary(attribute, ieBase, offsetsize, n);
}
else
{
result = SearchObjectKeyLinear(attribute, ieBase, offsetsize, n);
}
}
}
return(result);
}
}