/// <summary>
/// Produces a hash for the paths of adjacent bnodes for a bnode,
/// incorporating all information about its subgraph of bnodes.
/// </summary>
/// <remarks>
/// Produces a hash for the paths of adjacent bnodes for a bnode,
/// incorporating all information about its subgraph of bnodes. This method
/// will recursively pick adjacent bnode permutations that produce the
/// lexicographically-least 'path' serializations.
/// </remarks>
/// <param name="id">the ID of the bnode to hash paths for.</param>
/// <param name="bnodes">the map of bnode quads.</param>
/// <param name="namer">the canonical bnode namer.</param>
/// <param name="pathNamer">the namer used to assign names to adjacent bnodes.</param>
/// <param name="callback">(err, result) called once the operation completes.</param>
private static NormalizeUtils.HashResult HashPaths(string id, IDictionary <string, IDictionary <string, object> > bnodes, UniqueNamer namer, UniqueNamer pathNamer)
{
#if !PORTABLE
MessageDigest md = null;
try
{
// create SHA-1 digest
md = MessageDigest.GetInstance("SHA-1");
JObject groups = new JObject();
IList <string> groupHashes;
IList <RDFDataset.Quad> quads = (IList <RDFDataset.Quad>)bnodes[id]["quads"];
for (int hpi = 0; ; hpi++)
{
if (hpi == quads.Count)
{
// done , hash groups
groupHashes = new List <string>(groups.GetKeys());
((List <string>)groupHashes).Sort(StringComparer.CurrentCultureIgnoreCase);
for (int hgi = 0; ; hgi++)
{
if (hgi == groupHashes.Count)
{
NormalizeUtils.HashResult res = new NormalizeUtils.HashResult();
res.hash = EncodeHex(md.Digest());
res.pathNamer = pathNamer;
return(res);
}
// digest group hash
string groupHash = groupHashes[hgi];
md.Update(JsonLD.JavaCompat.GetBytesForString(groupHash, "UTF-8"));
// choose a path and namer from the permutations
string chosenPath = null;
UniqueNamer chosenNamer = null;
NormalizeUtils.Permutator permutator = new NormalizeUtils.Permutator((JArray)groups[groupHash]);
while (true)
{
bool contPermutation = false;
bool breakOut = false;
JArray permutation = permutator.Next();
UniqueNamer pathNamerCopy = pathNamer.Clone();
// build adjacent path
string path = string.Empty;
JArray recurse = new JArray();
foreach (string bnode in permutation)
{
// use canonical name if available
if (namer.IsNamed(bnode))
{
path += namer.GetName(bnode);
}
else
{
// recurse if bnode isn't named in the path
// yet
if (!pathNamerCopy.IsNamed(bnode))
{
recurse.Add(bnode);
}
path += pathNamerCopy.GetName(bnode);
}
// skip permutation if path is already >= chosen
// path
if (chosenPath != null && path.Length >= chosenPath.Length && string.CompareOrdinal
(path, chosenPath) > 0)
{
// return nextPermutation(true);
if (permutator.HasNext())
{
contPermutation = true;
}
else
{
// digest chosen path and update namer
md.Update(JsonLD.JavaCompat.GetBytesForString(chosenPath, "UTF-8"));
pathNamer = chosenNamer;
// hash the nextGroup
breakOut = true;
}
break;
}
}
// if we should do the next permutation
if (contPermutation)
{
continue;
}
// if we should stop processing this group
if (breakOut)
{
break;
}
// does the next recursion
for (int nrn = 0; ; nrn++)
{
if (nrn == recurse.Count)
{
// return nextPermutation(false);
if (chosenPath == null || string.CompareOrdinal(path, chosenPath) < 0)
{
chosenPath = path;
chosenNamer = pathNamerCopy;
}
if (!permutator.HasNext())
{
// digest chosen path and update namer
md.Update(JsonLD.JavaCompat.GetBytesForString(chosenPath, "UTF-8"));
pathNamer = chosenNamer;
// hash the nextGroup
breakOut = true;
}
break;
}
// do recursion
string bnode_1 = (string)recurse[nrn];
NormalizeUtils.HashResult result = HashPaths(bnode_1, bnodes, namer, pathNamerCopy);
path += pathNamerCopy.GetName(bnode_1) + "<" + result.hash + ">";
pathNamerCopy = result.pathNamer;
// skip permutation if path is already >= chosen
// path
if (chosenPath != null && path.Length >= chosenPath.Length && string.CompareOrdinal
(path, chosenPath) > 0)
{
// return nextPermutation(true);
if (!permutator.HasNext())
{
// digest chosen path and update namer
md.Update(JsonLD.JavaCompat.GetBytesForString(chosenPath, "UTF-8"));
pathNamer = chosenNamer;
// hash the nextGroup
breakOut = true;
}
break;
}
}
// do next recursion
// if we should stop processing this group
if (breakOut)
{
break;
}
}
}
}
// get adjacent bnode
IDictionary <string, object> quad = (IDictionary <string, object>)quads[hpi];
string bnode_2 = GetAdjacentBlankNodeName((IDictionary <string, object>)quad["subject"
], id);
string direction = null;
if (bnode_2 != null)
{
// normal property
direction = "p";
}
else
{
bnode_2 = GetAdjacentBlankNodeName((IDictionary <string, object>)quad["object"], id
);
if (bnode_2 != null)
{
// reverse property
direction = "r";
}
}
if (bnode_2 != null)
{
// get bnode name (try canonical, path, then hash)
string name;
if (namer.IsNamed(bnode_2))
{
name = namer.GetName(bnode_2);
}
else
{
if (pathNamer.IsNamed(bnode_2))
{
name = pathNamer.GetName(bnode_2);
}
else
{
name = HashQuads(bnode_2, bnodes, namer);
}
}
// hash direction, property, end bnode name/hash
using (MessageDigest md1 = MessageDigest.GetInstance("SHA-1"))
{
// String toHash = direction + (String) ((Map<String,
// Object>) quad.get("predicate")).get("value") + name;
md1.Update(JsonLD.JavaCompat.GetBytesForString(direction, "UTF-8"));
md1.Update(JsonLD.JavaCompat.GetBytesForString(((string)((IDictionary <string, object>)quad["predicate"])["value"]), "UTF-8"));
md1.Update(JsonLD.JavaCompat.GetBytesForString(name, "UTF-8"));
string groupHash = EncodeHex(md1.Digest());
if (groups.ContainsKey(groupHash))
{
((JArray)groups[groupHash]).Add(bnode_2);
}
else
{
JArray tmp = new JArray();
tmp.Add(bnode_2);
groups[groupHash] = tmp;
}
}
}
}
}
catch
{
// TODO: i don't expect that SHA-1 is even NOT going to be
// available?
// look into this further
throw;
}
finally
{
md?.Dispose();
}
#else
throw new PlatformNotSupportedException();
#endif
}
private IDictionary <string, Object> hashNDegreeQuads(IdentifierIssuer issuer, string id)
{
/*
* 1) Create a hash to related blank nodes map for storing hashes that
* identify related blank nodes.
* Note: 2) and 3) handled within `createHashToRelated`
*/
IDictionary <string, IList <string> > hashToRelated = this.createHashToRelated(issuer, id);
/*
* 4) Create an empty string, data to hash.
* Note: We create a hash object instead.
*/
string mdString = "";
/*
* 5) For each related hash to blank node list mapping in hash to
* related blank nodes map, sorted lexicographically by related hash:
*/
sortMapKeys(hashToRelated);
foreach (var hash in hashToRelated.Keys)
{
var blankNodes = hashToRelated[hash];
// 5.1) Append the related hash to the data to hash.
mdString += hash;
// 5.2) Create a string chosen path.
string chosenPath = " ";
// 5.3) Create an unset chosen issuer variable.
IdentifierIssuer chosenIssuer = null;
// 5.4) For each permutation of blank node list:
string path = "";
List <string> recursionList = null;
IdentifierIssuer issuerCopy = null;
bool skipToNextPerm = false;
NormalizeUtils.Permutator permutator = new NormalizeUtils.Permutator(JArray.FromObject(blankNodes));
while (permutator.HasNext())
{
var permutation = permutator.Next();
// 5.4.1) Create a copy of issuer, issuer copy.
issuerCopy = (IdentifierIssuer)issuer.Clone();
// 5.4.2) Create a string path.
path = "";
/*
* 5.4.3) Create a recursion list, to store blank node
* identifiers that must be recursively processed by this
* algorithm.
*/
recursionList = new List <string>();
// 5.4.4) For each related in permutation:
foreach (var related in permutation)
{
/*
* 5.4.4.1) If a canonical identifier has been issued for
* related, append it to path.
*/
if (this.canonicalIssuer.hasID(related.ToString()))
{
path += this.canonicalIssuer.getId(related.ToString());
}
// 5.4.4.2) Otherwise:
else
{
/*
* 5.4.4.2.1) If issuer copy has not issued an
* identifier for related, append related to recursion
* list.
*/
if (!issuerCopy.hasID(related.ToString()))
{
recursionList.Add(related.ToString());
}
/*
* 5.4.4.2.2) Use the Issue Identifier algorithm,
* passing issuer copy and related and append the result
* to path.
*/
path += issuerCopy.getId(related.ToString());
}
/*
* 5.4.4.3) If chosen path is not empty and the length of
* path is greater than or equal to the length of chosen
* path and path is lexicographically greater than chosen
* path, then skip to the next permutation.
*/
if (chosenPath.Length != 0 && path.Length >= chosenPath.Length && path.CompareTo(chosenPath) == 1)
{
skipToNextPerm = true;
break;
}
}
}
if (skipToNextPerm)
{
continue;
}
// 5.4.5) For each related in recursion list:
foreach (var related in recursionList)
{
/*
* 5.4.5.1) Set result to the result of recursively
* executing the Hash N-Degree Quads algorithm, passing
* related for identifier and issuer copy for path
* identifier issuer.
*/
IDictionary <string, object> result = hashNDegreeQuads(issuerCopy, related);
/*
* 5.4.5.2) Use the Issue Identifier algorithm, passing
* issuer copy and related and append the result to path.
*/
path += "<" + (string)result["hash"] + ">";
/*
* 5.4.5.4) Set issuer copy to the identifier issuer in
* result.
*/
issuerCopy = (IdentifierIssuer)result["issuer"];
/*
* 5.4.5.5) If chosen path is not empty and the length of
* path is greater than or equal to the length of chosen
* path and path is lexicographically greater than chosen
* path, then skip to the next permutation.
*/
if (chosenPath.Length != 0 && path.Length >= chosenPath.Length && path.CompareTo(chosenPath) == 1)
{
skipToNextPerm = true;
break;
}
}
if (skipToNextPerm)
{
continue;
}
/*
* 5.4.6) If chosen path is empty or path is lexicographically
* less than chosen path, set chosen path to path and chosen
* issuer to issuer copy.
*/
if (chosenPath.Length == 0 || path.CompareTo(chosenPath) == -1)
{
chosenPath = path;
chosenIssuer = issuerCopy;
}
// 5.5) Append chosen path to data to hash.
mdString += chosenPath;
// 5.6) Replace issuer, by reference, with chosen issuer.
issuer = chosenIssuer;
/*
* 6) Return issuer and the hash that results from passing data to hash
* through the hash algorithm.
*/
}
/*
* 6) Return issuer and the hash that results from passing data to hash
* through the hash algorithm.
*/
IDictionary <string, object> hashQuad = new Dictionary <string, object>();
hashQuad.Add("hash", NormalizeUtils.sha256Hash(Encoding.ASCII.GetBytes(mdString)));
hashQuad.Add("issuer", issuer);
return(hashQuad);
}
