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;
}
/// <remarks>
/// check for fragments with the same values, if one is found then combine them, otherwise add startTag to the list.
/// </remarks>
static bool AddEquivilenceList(List <TableFragmentTag> list, TableFragmentTag startTag)
{
for (var i = 0; i < list.Count; i++)
{
var existingTag = list[i];
var existing = existingTag.Fragment;
var fragment = startTag.Fragment;
if (ValuesEquivilent(existing._values, fragment._values))
{
existingTag.Partner.Fragment = existingTag.Fragment = Combine(existing, fragment, existing.Count);
return(true);
}
}
list.Add(startTag);
return(false);
}
/// <summary>
/// Replace the TableFragments referenced by the two tags with a single fragment that
/// contains their combined values.
/// </summary>
/// <remarks>
/// The end of tag1 will be made to overlap the start of tag2 as far as possible.
/// </remarks>
static void Combine(TableFragmentTag tag1, TableFragmentTag tag2)
{
int overlap;
if (tag1.EndValue != tag2.EndValue)
{
overlap = 0;
}
else
{
overlap = Math.Min(tag1.EndLen, tag2.EndLen);
}
var fragment = Combine(tag1.Fragment, tag2.Fragment, overlap);
tag1.Partner.Fragment = fragment;
tag2.Partner.Fragment = fragment;
tag1.Partner.Partner = tag2.Partner;
tag2.Partner.Partner = tag1.Partner;
}
static int Comparison(TableFragmentTag tag1, TableFragmentTag tag2)
{
var diff = tag1.EndValue - tag2.EndValue;
return(diff != 0 ? diff : tag2.EndLen - tag1.EndLen);
}
