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package org.hsqldb.lib;

import java.util.NoSuchElementException;

Maintains an ordered  long->long lookup table, consisting of two
columns, one for keys, the other for values. Equal keys are allowed.

The table is sorted on key column.

findXXX() methods return the array index into the list
pair containing a matching key or value, or  or -1 if not found.

Based on org.hsqldb.lib.DoubleIntIndex
Author:
Fred Toussi (fredt@users dot sourceforge.net)
Version:
2.5.0
Since:
1.8.0/**
 * Maintains an ordered  long->long lookup table, consisting of two
 * columns, one for keys, the other for values. Equal keys are allowed.<p>
 *
 * The table is sorted on key column.<p>
 *
 * findXXX() methods return the array index into the list
 * pair containing a matching key or value, or  or -1 if not found.<p>
 *
 * Based on org.hsqldb.lib.DoubleIntIndex
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version 2.5.0
 * @since 1.8.0
 */
public final class DoubleLongIndex implements LongLookup {

    private int     count = 0;
    private int     capacity;
    private boolean sorted = true;
    private long[]  keys;
    private long[]  values;

//
    private long targetSearchValue;

    public DoubleLongIndex(int capacity) {

        this.capacity = capacity;
        keys          = new long[capacity];
        values        = new long[capacity];
    }

    public long getLongKey(int i) {

        if (i < 0 || i >= count) {
            throw new IndexOutOfBoundsException();
        }

        return keys[i];
    }

    public long getLongValue(int i) {

        if (i < 0 || i >= count) {
            throw new IndexOutOfBoundsException();
        }

        return values[i];
    }

    
Modifies an existing pair.
Params:
i – the index
value – the value/**
     * Modifies an existing pair.
     * @param i the index
     * @param value the value
     */
    public void setLongValue(int i, long value) {

        if (i < 0 || i >= count) {
            throw new IndexOutOfBoundsException();
        }

        values[i] = value;
    }

    public int size() {
        return count;
    }

    public boolean addUnsorted(long key, long value) {

        if (count == capacity) {
            doubleCapacity();
        }

        if (sorted && count != 0) {
            if (key < keys[count - 1]) {
                sorted = false;
            }
        }

        keys[count]   = key;
        values[count] = value;

        count++;

        return true;
    }

    public int add(long key, long value) {

        if (count == capacity) {
            doubleCapacity();
        }

        if (!sorted) {
            fastQuickSort();
        }

        targetSearchValue = key;

        int i = binarySlotSearch(true);

        if (count != i) {
            moveRows(i, i + 1, count - i);
        }

        keys[i]   = key;
        values[i] = value;

        count++;

        return i;
    }

    public long lookup(long key) throws NoSuchElementException {

        int i = findFirstEqualKeyIndex(key);

        if (i == -1) {
            throw new NoSuchElementException();
        }

        return getLongValue(i);
    }

    public long lookup(long key, long def) {

        int i = findFirstEqualKeyIndex(key);

        if (i == -1) {
            return def;
        }

        return getLongValue(i);
    }

    public void clear() {

        ArrayUtil.clearArray(ArrayUtil.CLASS_CODE_LONG, keys, 0, count);
        ArrayUtil.clearArray(ArrayUtil.CLASS_CODE_LONG, values, 0, count);

        count  = 0;
        sorted = true;
    }

    
Params:
value – the value
Returns:
the index/**
     * @param value the value
     * @return the index
     */
    public int findFirstGreaterEqualKeyIndex(long value) {

        int index = findFirstGreaterEqualSlotIndex(value);

        return index == count ? -1
                              : index;
    }

    
Params:
value – the value
Returns:
the index/**
     * @param value the value
     * @return the index
     */
    public int findFirstEqualKeyIndex(long value) {

        if (!sorted) {
            fastQuickSort();
        }

        targetSearchValue = value;

        return binaryFirstSearch();
    }

    
This method is similar to findFirstGreaterEqualKeyIndex(int) but
returns the index of the empty row past the end of the array if
the search value is larger than all the values / keys in the searched
column.
Params:
value – the value
Returns:
the index/**
     * This method is similar to findFirstGreaterEqualKeyIndex(int) but
     * returns the index of the empty row past the end of the array if
     * the search value is larger than all the values / keys in the searched
     * column.
     * @param value the value
     * @return the index
     */
    public int findFirstGreaterEqualSlotIndex(long value) {

        if (!sorted) {
            fastQuickSort();
        }

        targetSearchValue = value;

        return binarySlotSearch(false);
    }

    
Returns the index of the lowest element == the given search target,
or -1
Returns:
index or -1 if not found/**
     * Returns the index of the lowest element == the given search target,
     * or -1
     * @return index or -1 if not found
     */
    private int binaryFirstSearch() {

        int low     = 0;
        int high    = count;
        int mid     = 0;
        int compare = 0;
        int found   = count;

        while (low < high) {
            mid     = (low + high) >>> 1;
            compare = compare(mid);

            if (compare < 0) {
                high = mid;
            } else if (compare > 0) {
                low = mid + 1;
            } else {
                high  = mid;
                found = mid;
            }
        }

        return found == count ? -1
                              : found;
    }

    
Returns the index of the lowest element >= the given search target,
or count
    @return the index
/**
     * Returns the index of the lowest element >= the given search target,
     * or count
     *     @return the index
     */
    private int binarySlotSearch(boolean fullCompare) {

        int low     = 0;
        int high    = count;
        int mid     = 0;
        int compare = 0;

        while (low < high) {
            mid     = (low + high) >>> 1;
            compare = compare(mid);

            if (compare <= 0) {
                high = mid;
            } else {
                low = mid + 1;
            }
        }

        return low;
    }

    public void sort() {

        if (count <= 1024 * 16) {
            fastQuickSortRecursive();
        } else {
            fastQuickSort();
        }
    }

    
fast quicksort using a stack on the heap to reduce stack use
/**
     * fast quicksort using a stack on the heap to reduce stack use
     */
    private void fastQuickSort() {

        DoubleIntIndex indices   = new DoubleIntIndex(32768);
        int            threshold = 16;

        indices.push(0, count - 1);

        while (indices.size() > 0) {
            int start = indices.peekKey();
            int end   = indices.peekValue();

            indices.pop();

            if (end - start >= threshold) {
                int pivot = partition(start, end);

                indices.push(start, pivot - 1);
                indices.push(pivot + 1, end);
            }
        }

        insertionSort(0, count - 1);

        sorted = true;
    }

    private int partition(int start, int end) {

        int pivot = (start + end) >>> 1;

        // pivot is median of three values
        if (keys[pivot] < keys[(start + pivot) >>> 1]) {
            swap(pivot, (start + pivot) >>> 1);
        }

        if (keys[(end + pivot) >>> 1] < keys[(start + pivot) >>> 1]) {
            swap((end + pivot) >>> 1, (start + pivot) >>> 1);
        }

        if (keys[(end + pivot) >>> 1] < keys[pivot]) {
            swap((end + pivot) >>> 1, pivot);
        }

        long pivotValue = keys[pivot];
        int  i          = start - 1;
        int  j          = end;

        swap(pivot, end);

        for (;;) {
            while (keys[++i] < pivotValue) {}

            while (pivotValue < keys[--j]) {}

            if (j < i) {
                break;
            }

            swap(i, j);
        }

        swap(i, end);

        return i;
    }

    
fast quicksort with recursive quicksort implementation
/**
     * fast quicksort with recursive quicksort implementation
     */
    private void fastQuickSortRecursive() {

        quickSort(0, count - 1);
        insertionSort(0, count - 1);

        sorted = true;
    }

    private void quickSort(int l, int r) {

        int M = 16;
        int i;
        int j;
        int v;

        if ((r - l) > M) {
            i = (r + l) >>> 1;

            if (lessThan(i, l)) {
                swap(l, i);    // Tri-Median Method!
            }

            if (lessThan(r, l)) {
                swap(l, r);
            }

            if (lessThan(r, i)) {
                swap(i, r);
            }

            j = r - 1;

            swap(i, j);

            i = l;
            v = j;

            for (;;) {
                while (lessThan(++i, v)) {}

                while (lessThan(v, --j)) {}

                if (j < i) {
                    break;
                }

                swap(i, j);
            }

            swap(i, r - 1);
            quickSort(l, j);
            quickSort(i + 1, r);
        }
    }

    private void insertionSort(int lo0, int hi0) {

        int i;
        int j;

        for (i = lo0 + 1; i <= hi0; i++) {
            j = i;

            while ((j > lo0) && lessThan(i, j - 1)) {
                j--;
            }

            if (i != j) {
                moveAndInsertRow(i, j);
            }
        }
    }

    private void moveAndInsertRow(int i, int j) {

        long col1 = keys[i];
        long col2 = values[i];

        moveRows(j, j + 1, i - j);

        keys[j]   = col1;
        values[j] = col2;
    }

    private void swap(int i1, int i2) {

        long col1 = keys[i1];
        long col2 = values[i1];

        keys[i1]   = keys[i2];
        values[i1] = values[i2];
        keys[i2]   = col1;
        values[i2] = col2;
    }

    
Check if targeted column value in the row indexed i is less than the
search target object.
Params:
i – the index
Returns:
-1, 0 or +1/**
     * Check if targeted column value in the row indexed i is less than the
     * search target object.
     * @param i the index
     * @return -1, 0 or +1
     */
    private int compare(int i) {

        if (targetSearchValue > keys[i]) {
            return 1;
        } else if (targetSearchValue < keys[i]) {
            return -1;
        }

        return 0;
    }

    
Check if row indexed i is less than row indexed j
Params:
i – the first index
j – the second index
Returns:
true or false/**
     * Check if row indexed i is less than row indexed j
     * @param i the first index
     * @param j the second index
     * @return true or false
     */
    private boolean lessThan(int i, int j) {

        if (keys[i] < keys[j]) {
            return true;
        }

        return false;
    }

    private void moveRows(int fromIndex, int toIndex, int rows) {
        System.arraycopy(keys, fromIndex, keys, toIndex, rows);
        System.arraycopy(values, fromIndex, values, toIndex, rows);
    }

    private void doubleCapacity() {

        keys     = (long[]) ArrayUtil.resizeArray(keys, capacity * 2);
        values   = (long[]) ArrayUtil.resizeArray(values, capacity * 2);
        capacity *= 2;
    }

    public boolean addUnsorted(LongLookup other) {

        if (!ensureCapacityToAdd(other.size())) {
            return false;
        }

        sorted = false;

        for (int i = 0; i < other.size(); i++) {
            long key   = other.getLongKey(i);
            long value = other.getLongValue(i);

            this.addUnsorted(key, value);
        }

        return true;
    }

    private boolean ensureCapacityToAdd(int extra) {

        if (count + extra > capacity) {
            while (count + extra > capacity) {
                doubleCapacity();
            }
        }

        return true;
    }
}