/**
* Calculates the new distance value for the given node.
*
* @param preAfter the current PRE value of the node (after structural updates have been applied)
* @return new distance for the given node
*/
private int calculateNewDistance(final int preAfter) {
final int kind = data.kind(preAfter);
final int distanceBefore = data.dist(preAfter, kind);
final int preBefore = calculatePreValue(preAfter, true);
final int parentBefore = preBefore - distanceBefore;
final int parentAfter = calculatePreValue(parentBefore, false);
return preAfter - parentAfter;
}
/**
* Executes the updates. Resolving text node adjacency can be skipped if adjacent text nodes are
* not to be expected.
*
* @param mergeTexts adjacent text nodes are to be expected and must be merged
*/
public void execute(final boolean mergeTexts) {
check();
optimize();
applyValueUpdates();
if (cacheDistanceUpdates) data.cache = true;
applyStructuralUpdates();
updateDistances();
if (mergeTexts) resolveTextAdjacency();
data.cache = false;
}
@Override
public boolean indexAccessible(final IndexInfo ii) {
/* If the following conditions yield true, the index is accessed:
* - all query terms are statically available
* - no FTTimes option is specified
* - explicitly set case, diacritics and stemming match options do not
* conflict with index options. */
data = ii.ic.data;
final MetaData md = data.meta;
final FTOpt fto = ftt.opt;
/* Index will be applied if no explicit match options have been set
* that conflict with the index options. As a consequence, though, index-
* based querying might yield other results than sequential scanning. */
if (occ != null
|| fto.cs != null && md.casesens == (fto.cs == FTCase.INSENSITIVE)
|| fto.isSet(DC) && md.diacritics != fto.is(DC)
|| fto.isSet(ST) && md.stemming != fto.is(ST)
|| fto.ln != null && !fto.ln.equals(md.language)) return false;
// adopt database options to tokenizer
fto.copy(md);
// estimate costs if text is not known at compile time
if (tokens == null) {
ii.costs = Math.max(2, data.meta.size / 30);
return true;
}
// summarize number of hits; break loop if no hits are expected
final FTLexer ft = new FTLexer(fto);
ii.costs = 0;
for (byte[] t : tokens) {
ft.init(t);
while (ft.hasNext()) {
final byte[] tok = ft.nextToken();
if (fto.sw != null && fto.sw.contains(tok)) continue;
if (fto.is(WC)) {
// don't use index if one of the terms starts with a wildcard
t = ft.get();
if (t[0] == '.') return false;
// don't use index if certain characters or more than 1 dot are found
int d = 0;
for (final byte w : t) {
if (w == '{' || w == '\\' || w == '.' && ++d > 1) return false;
}
}
// favor full-text index requests over exact queries
final int costs = data.costs(ft);
if (costs != 0) ii.costs += Math.max(2, costs / 100);
}
}
return true;
}
@Override
public BasicNodeIter iter(final QueryContext qc) {
final boolean text = index.type() == IndexType.TEXT;
final byte kind = text ? Data.TEXT : Data.ATTR;
final Data data = ictx.data;
final int ml = data.meta.maxlen;
final IndexIterator ii =
index.min.length <= ml
&& index.max.length <= ml
&& (text ? data.meta.textindex : data.meta.attrindex)
? data.iter(index)
: scan();
return new BasicNodeIter() {
@Override
public ANode next() {
return ii.more() ? new DBNode(data, ii.pre(), kind) : null;
}
};
}
/**
* Updates distances to restore parent-child relationships that have been invalidated by
* structural updates.
*
* <p>Each structural update (insert/delete) leads to a shift of higher PRE values. This
* invalidates parent-child relationships. Distances are only updated after all structural updates
* have been carried out to make sure each node (that has to be updated) is only touched once.
*/
public void updateDistances() {
accumulatePreValueShifts();
final IntSet alreadyUpdatedNodes = new IntSet();
for (final BasicUpdate update : updStructural) {
int newPreOfAffectedNode = update.preOfAffectedNode + update.accumulatedShifts;
/* Update distance for the affected node and all following siblings of nodes
* on the ancestor-or-self axis. */
while (newPreOfAffectedNode < data.meta.size) {
if (alreadyUpdatedNodes.contains(newPreOfAffectedNode)) break;
data.dist(
newPreOfAffectedNode,
data.kind(newPreOfAffectedNode),
calculateNewDistance(newPreOfAffectedNode));
alreadyUpdatedNodes.add(newPreOfAffectedNode);
newPreOfAffectedNode += data.size(newPreOfAffectedNode, data.kind(newPreOfAffectedNode));
}
}
}
/**
* Removes superfluous update operations. If a node T is deleted or replaced, all updates on the
* descendant axis of T can be left out as they won't affect the database after all.
*
* <p>Superfluous updates can have a minimum PRE value of pre(T)+1 and a maximum PRE value of
* pre(T)+size(T).
*
* <p>An update with location pre(T)+size(T) can only be removed if the update is an atomic insert
* and the inserted node is then part of the subtree of T.
*/
public void optimize() {
if (opt) return;
check();
// traverse from lowest to highest PRE value
int i = updStructural.size() - 1;
while (i >= 0) {
final BasicUpdate u = updStructural.get(i);
// If this update can lead to superfluous updates ...
if (u.destructive()) {
// we determine the lowest and highest PRE values of a superfluous update
final int pre = u.location;
final int fol = pre + data.size(pre, data.kind(pre));
i--;
// and have a look at the next candidate
while (i >= 0) {
final BasicUpdate desc = updStructural.get(i);
final int descpre = desc.location;
// if the candidate operates on the subtree of T and inserts a node ...
if (descpre <= fol
&& (desc instanceof Insert || desc instanceof InsertAttr)
&& desc.parent() >= pre
&& desc.parent() < fol) {
// it is removed.
updStructural.remove(i--);
// Other updates (not inserting a node) that operate on the subtree of T can
// only have a PRE value that is smaller than the following PRE of T
} else if (descpre < fol) {
// these we delete.
updStructural.remove(i--);
// Else there's nothing to delete
} else break;
}
} else i--;
}
opt = true;
}
/**
* Returns atomic text node merging operations if necessary for the given node PRE and its right
* neighbor PRE+1.
*
* @param a node PRE value
* @param d target data reference
* @return list of text merging operations
*/
private AtomicUpdateList necessaryMerges(final int a, final Data d) {
final AtomicUpdateList mergeTwoNodes = new AtomicUpdateList(d);
final int s = d.meta.size;
final int b = a + 1;
// don't leave table
if (a >= s || b >= s || a < 0 || b < 0) return mergeTwoNodes;
// only merge texts
if (d.kind(a) != Data.TEXT || d.kind(b) != Data.TEXT) return mergeTwoNodes;
// only merge neighboring texts
if (d.parent(a, Data.TEXT) != d.parent(b, Data.TEXT)) return mergeTwoNodes;
mergeTwoNodes.addDelete(b);
mergeTwoNodes.addUpdateValue(a, Data.TEXT, Token.concat(d.text(a, true), d.text(b, true)));
return mergeTwoNodes;
}
/**
* Inserts a data instance at the specified pre value. Note that the specified data instance must
* differ from this instance.
*
* @param ipre value at which to insert new data
* @param ipar parent pre value of node
* @param clip data clip
*/
public final void insert(final int ipre, final int ipar, final DataClip clip) {
meta.update();
// update value and document indexes
if (meta.updindex) indexBegin();
resources.insert(ipre, clip);
final int dsize = clip.size();
final int buf = Math.min(dsize, IO.BLOCKSIZE >> IO.NODEPOWER);
// resize buffer to cache more entries
buffer(buf);
// find all namespaces in scope to avoid duplicate declarations
final TokenMap nsScope = nspaces.scope(ipar, this);
// loop through all entries
final IntList preStack = new IntList();
final NSNode nsRoot = nspaces.current();
final HashSet<NSNode> newNodes = new HashSet<NSNode>();
final IntList flagPres = new IntList();
// indicates if database only contains a dummy node
final Data data = clip.data;
int c = 0;
for (int dpre = clip.start; dpre < clip.end; ++dpre, ++c) {
if (c != 0 && c % buf == 0) insert(ipre + c - buf);
final int pre = ipre + c;
final int dkind = data.kind(dpre);
final int dpar = data.parent(dpre, dkind);
// ipar < 0 if document nodes on top level are added
final int dis = dpar >= 0 ? dpre - dpar : ipar >= 0 ? pre - ipar : 0;
final int par = dis == 0 ? -1 : pre - dis;
if (c == 0) nspaces.root(par, this);
while (!preStack.isEmpty() && preStack.peek() > par) nspaces.close(preStack.pop());
switch (dkind) {
case DOC:
// add document
nspaces.prepare();
final int s = data.size(dpre, dkind);
doc(pre, s, data.text(dpre, true));
meta.ndocs++;
preStack.push(pre);
break;
case ELEM:
// add element
nspaces.prepare();
boolean ne = false;
if (data.nsFlag(dpre)) {
final Atts at = data.ns(dpre);
for (int a = 0; a < at.size(); ++a) {
// see if prefix has been declared/ is part of current ns scope
final byte[] old = nsScope.get(at.name(a));
if (old == null || !eq(old, at.value(a))) {
// we have to keep track of all new NSNodes that are added
// to the Namespace structure, as their pre values must not
// be updated. I.e. if an NSNode N with pre value 3 existed
// prior to inserting and two new nodes are inserted at
// location pre == 3 we have to make sure N and only N gets
// updated.
newNodes.add(nspaces.add(at.name(a), at.value(a), pre));
ne = true;
}
}
}
byte[] nm = data.name(dpre, dkind);
elem(
dis,
tagindex.index(nm, null, false),
data.attSize(dpre, dkind),
data.size(dpre, dkind),
nspaces.uri(nm, true),
ne);
preStack.push(pre);
break;
case TEXT:
case COMM:
case PI:
// add text
text(pre, dis, data.text(dpre, true), dkind);
break;
case ATTR:
// add attribute
nm = data.name(dpre, dkind);
// check if prefix already in nsScope or not
final byte[] attPref = prefix(nm);
// check if prefix of attribute has already been declared, otherwise
// add declaration to parent node
if (data.nsFlag(dpre) && nsScope.get(attPref) == null) {
nspaces.add(
par,
preStack.isEmpty() ? -1 : preStack.peek(),
attPref,
data.nspaces.uri(data.uri(dpre, dkind)),
this);
// save pre value to set ns flag later for this node. can't be done
// here as direct table access would interfere with the buffer
flagPres.add(par);
}
attr(
pre,
dis,
atnindex.index(nm, null, false),
data.text(dpre, false),
nspaces.uri(nm, false),
false);
break;
}
}
// finalize and update namespace structure
while (!preStack.isEmpty()) nspaces.close(preStack.pop());
nspaces.root(nsRoot);
if (bp != 0) insert(ipre + c - 1 - (c - 1) % buf);
// reset buffer to old size
buffer(1);
// set ns flags
for (int f = 0; f < flagPres.size(); f++) {
final int fl = flagPres.get(f);
table.write2(fl, 1, name(fl) | 1 << 15);
}
// increase size of ancestors
int p = ipar;
while (p >= 0) {
final int k = kind(p);
size(p, k, size(p, k) + dsize);
p = parent(p, k);
}
if (meta.updindex) {
// add the entries to the ID -> PRE mapping:
idmap.insert(ipre, id(ipre), dsize);
indexEnd();
}
if (!cache) updateDist(ipre + dsize, dsize);
// propagate PRE value shifts to namespaces
if (ipar != -1) nspaces.insert(ipre, dsize, newNodes);
}
/**
* Replaces parts of the database with the specified data instance.
*
* @param rpre pre value to be replaced
* @param clip data clip
*/
public final void replace(final int rpre, final DataClip clip) {
meta.update();
final int dsize = clip.size();
final Data data = clip.data;
final int rkind = kind(rpre);
final int rsize = size(rpre, rkind);
final int rpar = parent(rpre, rkind);
final int diff = dsize - rsize;
buffer(dsize);
resources.replace(rpre, rsize, clip);
if (meta.updindex) {
// update index
indexDelete(rpre, rsize);
indexBegin();
}
for (int dpre = clip.start; dpre < clip.end; ++dpre) {
final int dkind = data.kind(dpre);
final int dpar = data.parent(dpre, dkind);
final int pre = rpre + dpre - clip.start;
final int dis = dpar >= 0 ? dpre - dpar : pre - rpar;
switch (dkind) {
case DOC:
// add document
doc(pre, data.size(dpre, dkind), data.text(dpre, true));
meta.ndocs++;
break;
case ELEM:
// add element
byte[] nm = data.name(dpre, dkind);
elem(
dis,
tagindex.index(nm, null, false),
data.attSize(dpre, dkind),
data.size(dpre, dkind),
nspaces.uri(nm, true),
false);
break;
case TEXT:
case COMM:
case PI:
// add text
text(pre, dis, data.text(dpre, true), dkind);
break;
case ATTR:
// add attribute
nm = data.name(dpre, dkind);
attr(
pre,
dis,
atnindex.index(nm, null, false),
data.text(dpre, false),
nspaces.uri(nm, false),
false);
break;
}
}
if (meta.updindex) {
indexEnd();
// update ID -> PRE map:
idmap.delete(rpre, id(rpre), -rsize);
idmap.insert(rpre, meta.lastid - dsize + 1, dsize);
}
// update table:
table.replace(rpre, buffer(), rsize);
buffer(1);
// no distance/size update if the two subtrees are of equal size
if (diff == 0) return;
// increase/decrease size of ancestors, adjust distances of siblings
int p = rpar;
while (p >= 0) {
final int k = kind(p);
size(p, k, size(p, k) + diff);
p = parent(p, k);
}
if (!cache) updateDist(rpre + dsize, diff);
// adjust attribute size of parent if attributes inserted. attribute size
// of parent cannot be reduced via a replace expression.
int dpre = clip.start;
if (data.kind(dpre) == ATTR) {
int d = 0;
while (dpre < clip.end && data.kind(dpre++) == ATTR) d++;
if (d > 1) attSize(rpar, kind(rpar), d + 1);
}
}
/**
* Adds a replace atomic to the list.
*
* @param pre PRE value of the target node/update location
* @param d insertion sequence data reference
*/
public void addReplace(final int pre, final Data d) {
final int oldsize = data.size(pre, data.kind(pre));
final int newsize = d.meta.size;
add(new Replace(pre, newsize - oldsize, pre + oldsize, d), true);
}
/**
* Adds a delete atomic to the list.
*
* @param pre PRE value of the target node/update location
*/
public void addDelete(final int pre) {
final int k = data.kind(pre);
final int s = data.size(pre, k);
add(new Delete(pre, -s, pre + s), true);
}