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package org.basex.query.util.fingertree;
import org.basex.util.*;
/**
* An inner node containing nested sub-nodes.
*
* @author BaseX Team 2005-22, BSD License
* @author Leo Woerteler
*
* @param node type
* @param element type
*/
final class InnerNode implements Node, E> {
/** Child nodes. */
final Node[] children;
/** Right bound for the elements' index in each sub-node. */
final long[] bounds;
/**
* Constructor.
* @param children children array
*/
InnerNode(final Node[] children) {
final int n = children.length;
this.children = children;
bounds = new long[n];
long off = 0;
for(int i = 0; i < n; i++) {
off += children[i].size();
bounds[i] = off;
}
assert 2 <= n && n <= FingerTree.MAX_ARITY;
}
@Override
public long size() {
return bounds[bounds.length - 1];
}
@Override
public int arity() {
return bounds.length;
}
@Override
public Node getSub(final int pos) {
return children[pos];
}
@Override
public InnerNode reverse() {
final int n = children.length;
@SuppressWarnings("unchecked")
final Node[] newChildren = new Node[n];
for(int i = 0; i < n; i++) newChildren[i] = children[n - 1 - i].reverse();
return new InnerNode<>(newChildren);
}
@Override
public InnerNode set(final long pos, final E val) {
int i = 0;
while(pos >= bounds[i]) i++;
final long p = i == 0 ? pos : pos - bounds[i - 1];
final Node[] ch = children.clone();
ch[i] = children[i].set(p, val);
return new InnerNode<>(ch);
}
@Override
public boolean insert(final Node, E>[] siblings, final long index, final E val) {
final Node, E> left = siblings[0], right = siblings[2];
int i = 0;
final int n = bounds.length;
while(index > bounds[i]) i++;
final long off = i == 0 ? index : index - bounds[i - 1];
@SuppressWarnings("unchecked")
final Node[] subs = (Node[]) siblings;
subs[0] = i == 0 ? null : children[i - 1];
subs[2] = i == n - 1 ? null : children[i + 1];
final int l = Math.max(0, i - 1), r = Math.min(i + 1, n - 1);
if(!children[i].insert(subs, off, val)) {
// no split
final Node[] out = children.clone();
Array.copy(subs, i == 0 ? 1 : 0, r - l + 1, out, l);
siblings[0] = left;
siblings[1] = new InnerNode<>(out);
siblings[2] = right;
return false;
}
@SuppressWarnings("unchecked")
final Node[] temp = new Node[n + 1];
if(i == 0) {
Array.copyToStart(subs, 1, 3, temp);
Array.copy(children, 2, n - 2, temp, 3);
} else if(i < n - 1) {
Array.copy(children, l, temp);
Array.copyFromStart(subs, 4, temp, l);
Array.copy(children, r + 1, n - l - 3, temp, l + 4);
} else {
Array.copy(children, n - 2, temp);
Array.copyFromStart(subs, 3, temp, n - 2);
}
if(n < FingerTree.MAX_ARITY) {
// still small enough
siblings[0] = left;
siblings[1] = new InnerNode<>(temp);
siblings[2] = right;
return false;
}
if(left != null) {
final int la = left.arity(), move = (FingerTree.MAX_ARITY - la + 1) / 2;
if(move > 0) {
// left node has capacity
final Node[] ch = ((InnerNode) left).children;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[la + move], rs = new Node[n + 1 - move];
Array.copy(ch, la, ls);
Array.copyFromStart(temp, move, ls, la);
Array.copyToStart(temp, move, rs.length, rs);
siblings[0] = new InnerNode<>(ls);
siblings[1] = new InnerNode<>(rs);
siblings[2] = right;
return false;
}
}
if(right != null) {
final int ra = right.arity(), move = (FingerTree.MAX_ARITY - ra + 1) / 2;
if(move > 0) {
// right node has capacity
final Node[] ch = ((InnerNode) right).children;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[n + 1 - move], rs = new Node[ra + move];
Array.copy(temp, ls.length, ls);
Array.copyToStart(temp, ls.length, move, rs);
Array.copyFromStart(ch, ra, rs, move);
siblings[0] = left;
siblings[1] = new InnerNode<>(ls);
siblings[2] = new InnerNode<>(rs);
return false;
}
}
if(left != null) {
// merge with left neighbor
final Node[] ch = ((InnerNode) left).children;
final int la = ch.length, k = la + n + 1, ml = k / 3, ll = k - 2 * ml, inL = la - ll;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[ll], mid1 = new Node[ml], mid2 = new Node[ml];
Array.copy(ch, ll, ls);
Array.copyToStart(ch, ll, inL, mid1);
Array.copyFromStart(temp, ml - inL, mid1, inL);
Array.copyToStart(temp, ml - inL, ml, mid2);
siblings[0] = inL == 0 ? left : new InnerNode<>(ls);
siblings[1] = new InnerNode<>(mid1);
siblings[2] = new InnerNode<>(mid2);
siblings[3] = right;
return true;
}
if(right != null) {
// merge with right neighbor
final Node[] ch = ((InnerNode) right).children;
final int ra = ch.length, k = n + 1 + ra, ml = k / 3, rl = k - 2 * ml, inR = ra - rl;
@SuppressWarnings("unchecked")
final Node[] mid1 = new Node[ml], mid2 = new Node[ml], rs = new Node[rl];
Array.copy(temp, ml, mid1);
Array.copyToStart(temp, ml, ml - inR, mid2);
Array.copyFromStart(ch, inR, mid2, ml - inR);
Array.copyToStart(ch, inR, rl, rs);
siblings[0] = null;
siblings[1] = new InnerNode<>(mid1);
siblings[2] = new InnerNode<>(mid2);
siblings[3] = inR == 0 ? right : new InnerNode<>(rs);
return true;
}
// split the node
final int ll = (n + 1) / 2, rl = n + 1 - ll;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[ll], rs = new Node[rl];
Array.copy(temp, ll, ls);
Array.copyToStart(temp, ll, rl, rs);
siblings[0] = null;
siblings[1] = new InnerNode<>(ls);
siblings[2] = new InnerNode<>(rs);
siblings[3] = null;
return true;
}
@Override
public NodeLike, E>[] remove(final Node, E> left,
final Node, E> right, final long pos) {
int i = 0;
final int n = bounds.length;
while(pos >= bounds[i]) i++;
final long off = i == 0 ? pos : pos - bounds[i - 1];
final NodeLike[] res = children[i].remove(
i == 0 ? null : children[i - 1],
i == n - 1 ? null : children[i + 1], off);
@SuppressWarnings("unchecked")
final NodeLike, E>[] out = (NodeLike, E>[]) res;
final Node l = (Node) res[0], m = (Node) res[1], r = (Node) res[2];
if(m != null) {
// no underflow
final Node[] ch = children.clone();
if(i > 0) ch[i - 1] = l;
ch[i] = m;
if(i < n - 1) ch[i + 1] = r;
out[0] = left;
out[1] = new InnerNode<>(ch);
out[2] = right;
return out;
}
if(n > 2) {
// still big enough
@SuppressWarnings("unchecked")
final Node[] ch = new Node[n - 1];
if(i > 0) {
Array.copy(children, i - 1, ch);
ch[i - 1] = l;
}
if(i < n - 1) {
ch[i] = r;
Array.copy(children, i + 2, n - i - 2, ch, i + 1);
}
out[0] = left;
out[1] = new InnerNode<>(ch);
out[2] = right;
return out;
}
// only one sub-node left
final Node single = i == 0 ? r : l;
if(left != null && left.arity() > 2) {
// refill from left sibling
final Node[] ch = ((InnerNode) left).children;
final int a = ch.length, move = (a - 1) / 2;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[a - move], ms = new Node[move + 1];
Array.copy(ch, a - move, ls);
Array.copyToStart(ch, a - move, move, ms);
ms[move] = single;
out[0] = new InnerNode<>(ls);
out[1] = new InnerNode<>(ms);
out[2] = right;
return out;
}
if(right != null && right.arity() > 2) {
// refill from right sibling
final Node[] ch = ((InnerNode) right).children;
final int a = ch.length, move = (a - 1) / 2;
@SuppressWarnings("unchecked")
final Node[] ms = new Node[move + 1], rs = new Node[a - move];
ms[0] = single;
Array.copyFromStart(ch, move, ms, 1);
Array.copyToStart(ch, move, rs.length, rs);
out[0] = left;
out[1] = new InnerNode<>(ms);
out[2] = new InnerNode<>(rs);
return out;
}
if(left != null) {
// merge with left sibling
final Node[] ch = ((InnerNode) left).children;
final int a = ch.length;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[a + 1];
Array.copy(ch, a, ls);
ls[a] = single;
out[0] = new InnerNode<>(ls);
out[2] = right;
return out;
}
if(right != null) {
// merge with right sibling
final Node[] ch = ((InnerNode) right).children;
final int a = ch.length;
@SuppressWarnings("unchecked")
final Node[] rs = new Node[a + 1];
rs[0] = single;
Array.copyFromStart(ch, a, rs, 1);
out[0] = null;
out[2] = new InnerNode<>(rs);
return out;
}
// underflow
out[0] = null;
out[1] = new PartialInnerNode<>(single);
out[2] = null;
return out;
}
@Override
@SuppressWarnings("unchecked")
public NodeLike, E> slice(final long start, final long len) {
// find the range of affected sub-nodes
int p = 0;
while(start >= bounds[p]) p++;
final long off = p == 0 ? start : start - bounds[p - 1], end = start + len - 1;
final int l = p;
while(end >= bounds[p]) p++;
final int r = p;
// first node can be partial
final Node first = children[l];
final long inFst = Math.min(bounds[l] - start, len);
final NodeLike fst = inFst == first.size() ? first : first.slice(off, inFst);
if(l == r) return new PartialInnerNode<>(fst);
// more than one node affected
final NodeLike[] buffer = new NodeLike[r - l + 1];
buffer[0] = fst;
int inBuffer = 1;
for(int i = l + 1; i < r; i++) inBuffer = children[i].append(buffer, inBuffer);
final Node last = children[r];
final long inLst = start + len - bounds[r - 1];
final NodeLike lst = inLst == last.size() ? last : last.slice(0, inLst);
inBuffer = lst.append(buffer, inBuffer);
if(inBuffer == 1) {
// merged into a single sub-node
return new PartialInnerNode<>(buffer[0]);
}
// enough children for a full node
final Node[] subs = new Node[inBuffer];
Array.copy(buffer, inBuffer, subs);
return new InnerNode<>(subs);
}
@Override
public long checkInvariants() {
final int a = children.length;
if(a < 2 || a > FingerTree.MAX_ARITY) throw new AssertionError("Wrong arity: " + a);
long b = 0;
for(int i = 0; i < a; i++) {
final Node ch = children[i];
b += ch.checkInvariants();
if(b != bounds[i]) throw new AssertionError("Wrong boundary: " + b);
}
return b;
}
@Override
public int append(final NodeLike, E>[] nodes, final int pos) {
if(pos == 0 || nodes[pos - 1] instanceof InnerNode) {
nodes[pos] = this;
return pos + 1;
}
final NodeLike sub = ((PartialInnerNode) nodes[pos - 1]).sub;
final int n = children.length;
final Node a, b;
if(sub instanceof Node) {
a = (Node) sub;
b = children[0];
} else {
@SuppressWarnings("unchecked")
final NodeLike[] buffer = (NodeLike[]) nodes;
buffer[pos - 1] = sub;
if(children[0].append(buffer, pos) == pos) {
nodes[pos - 1] = replaceFirst((Node) buffer[pos - 1]);
return pos;
}
a = (Node) buffer[pos - 1];
b = (Node) buffer[pos];
}
if(n < FingerTree.MAX_ARITY) {
@SuppressWarnings("unchecked")
final Node[] ch = new Node[n + 1];
Array.copy(children, 1, n - 1, ch, 2);
ch[0] = a;
ch[1] = b;
nodes[pos - 1] = new InnerNode<>(ch);
nodes[pos] = null;
return pos;
}
final int rl = (n + 1) / 2, ll = n + 1 - rl;
@SuppressWarnings("unchecked")
final Node[] ls = new Node[ll], rs = new Node[rl];
Array.copy(children, 1, ll - 2, ls, 2);
ls[0] = a;
ls[1] = b;
Array.copyToStart(children, ll - 1, rl, rs);
nodes[pos - 1] = new InnerNode<>(ls);
nodes[pos] = new InnerNode<>(rs);
return pos + 1;
}
/**
* Recursive helper method for {@link #toString()}.
* @param sb string builder
* @param indent indentation depth
*/
public void toString(final StringBuilder sb, final int indent) {
sb.append(" ".repeat(indent)).append("Node(").append(size()).append(")[\n");
for(final Node sub : children) {
FingerTree.toString(sub, sb, indent + 1);
sb.append('\n');
}
sb.append(" ".repeat(indent)).append(']');
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder();
toString(sb, 0);
return sb.toString();
}
/**
* Returns a version of this node where the first sub-node is the given one.
* @param newFirst new first sub-node
* @return resulting node
*/
InnerNode replaceFirst(final Node newFirst) {
final Node[] copy = children.clone();
copy[0] = newFirst;
return new InnerNode<>(copy);
}
/**
* Returns a version of this node where the last sub-node is the given one.
* @param newLast new last sub-node
* @return resulting node
*/
InnerNode replaceLast(final Node newLast) {
final Node[] copy = children.clone();
copy[copy.length - 1] = newLast;
return new InnerNode<>(copy);
}
}
