static TableFragment Combine(LinkedList <TableFragmentTag> startFragmentTags, LinkedList <TableFragmentTag> endFragmentTags)
{
var finalFragments = new LinkedList <TableFragmentTag>();
while (startFragmentTags.Count > 0 && endFragmentTags.Count > 0)
{
var tailNode = startFragmentTags.First;
var leadNode = endFragmentTags.First;
if (tailNode.Value.Fragment == leadNode.Value.Fragment)
{
/*
* if the tailNode and leadNode reference the same fragment, then try to replace one
* of them as bad things happen when overlapping a fragment with itself.
*/
if (leadNode.Next != null)
{
leadNode = leadNode.Next;
}
else if (tailNode.Next != null)
{
tailNode = tailNode.Next;
}
else
{
break;
}
}
var leadEnd = leadNode.Value.EndValue;
var tailStart = tailNode.Value.EndValue;
if (leadEnd < tailStart)
{
endFragmentTags.Remove(leadNode);
}
else if (tailStart < leadEnd)
{
startFragmentTags.Remove(tailNode);
finalFragments.AddLast(tailNode);
}
else
{
endFragmentTags.Remove(leadNode);
startFragmentTags.Remove(tailNode);
TableFragment.Combine(leadNode.Value, tailNode.Value);
}
}
while (startFragmentTags.Count > 0)
{
var node = startFragmentTags.First;
startFragmentTags.Remove(node);
finalFragments.AddLast(node);
}
return(ForceCombine(finalFragments));
}
static void CreateTags(TableFragment fragment, out TableFragmentTag startTag, out TableFragmentTag endTag, out int hash)
{
if (fragment == null)
{
throw new ArgumentNullException(nameof(fragment));
}
var values = fragment._values;
var startIndex = 0;
var startValue = values[0];
var endIndex = 0;
var endValue = values[values.Length - 1];
uint currentHash = 0;
var startSet = false;
for (var i = 0; i < values.Length; i++)
{
var val = values[i];
if (!startSet && val != startValue)
{
startSet = true;
startIndex = i;
}
if (val != endValue)
{
endIndex = i;
}
currentHash = unchecked (((currentHash >> 5) | (currentHash << 27)) ^ (uint)val);
}
startTag = new TableFragmentTag()
{
Fragment = fragment,
EndLen = startSet ? startIndex : values.Length,
EndValue = startValue,
};
endTag = new TableFragmentTag()
{
Fragment = fragment,
EndLen = startSet ? values.Length - endIndex - 1 : values.Length,
EndValue = endValue,
};
startTag.Partner = endTag;
endTag.Partner = startTag;
hash = (int)currentHash;
}
static TableFragment Combine(TableFragment fragment1, TableFragment fragment2, int overlap)
{
var values1 = fragment1._values;
var values2 = fragment2._values;
var states1 = fragment1._states;
var states2 = fragment2._states;
var offsets1 = fragment1._offsets;
var offsets2 = fragment2._offsets;
var offset = values1.Length - overlap;
var values = new int[offset + values2.Length];
var states = new int[states1.Length + states2.Length];
var offsets = new int[states.Length];
Array.Copy(values1, values, offset);
Array.Copy(values2, 0, values, offset, values2.Length);
var read1 = 0;
var read2 = 0;
var write = 0;
while (read1 < states1.Length && read2 < states2.Length)
{
var diff = states1[read1] - states2[read2];
if (diff == 0)
{
throw new InvalidOperationException("attempting to combine 2 fragments that both contain the state " + states1[read1]);
}
if (diff < 0)
{
states[write] = states1[read1];
offsets[write] = offsets1[read1];
write++;
read1++;
}
else
{
states[write] = states2[read2];
offsets[write] = offsets2[read2] + offset;
write++;
read2++;
}
}
while (read1 < states1.Length)
{
states[write] = states1[read1];
offsets[write] = offsets1[read1];
write++;
read1++;
}
while (read2 < states2.Length)
{
states[write] = states2[read2];
offsets[write] = offsets2[read2] + offset;
write++;
read2++;
}
return(new TableFragment(values, states, offsets, Math.Max(fragment1.Skip, fragment2.Skip - offset)));
}
