diff -r 3392f250c784 -r ecbd252fd3a7 emul/compact/src/main/java/java/util/ComparableTimSort.java --- a/emul/compact/src/main/java/java/util/ComparableTimSort.java Fri Mar 22 16:59:47 2013 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,896 +0,0 @@ -/* - * Copyright 2009 Google Inc. All Rights Reserved. - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. - * - * This code is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 only, as - * published by the Free Software Foundation. Oracle designates this - * particular file as subject to the "Classpath" exception as provided - * by Oracle in the LICENSE file that accompanied this code. - * - * This code is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License - * version 2 for more details (a copy is included in the LICENSE file that - * accompanied this code). - * - * You should have received a copy of the GNU General Public License version - * 2 along with this work; if not, write to the Free Software Foundation, - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. - * - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA - * or visit www.oracle.com if you need additional information or have any - * questions. - */ - -package java.util; - - -/** - * This is a near duplicate of {@link TimSort}, modified for use with - * arrays of objects that implement {@link Comparable}, instead of using - * explicit comparators. - * - *

If you are using an optimizing VM, you may find that ComparableTimSort - * offers no performance benefit over TimSort in conjunction with a - * comparator that simply returns {@code ((Comparable)first).compareTo(Second)}. - * If this is the case, you are better off deleting ComparableTimSort to - * eliminate the code duplication. (See Arrays.java for details.) - * - * @author Josh Bloch - */ -class ComparableTimSort { - /** - * This is the minimum sized sequence that will be merged. Shorter - * sequences will be lengthened by calling binarySort. If the entire - * array is less than this length, no merges will be performed. - * - * This constant should be a power of two. It was 64 in Tim Peter's C - * implementation, but 32 was empirically determined to work better in - * this implementation. In the unlikely event that you set this constant - * to be a number that's not a power of two, you'll need to change the - * {@link #minRunLength} computation. - * - * If you decrease this constant, you must change the stackLen - * computation in the TimSort constructor, or you risk an - * ArrayOutOfBounds exception. See listsort.txt for a discussion - * of the minimum stack length required as a function of the length - * of the array being sorted and the minimum merge sequence length. - */ - private static final int MIN_MERGE = 32; - - /** - * The array being sorted. - */ - private final Object[] a; - - /** - * When we get into galloping mode, we stay there until both runs win less - * often than MIN_GALLOP consecutive times. - */ - private static final int MIN_GALLOP = 7; - - /** - * This controls when we get *into* galloping mode. It is initialized - * to MIN_GALLOP. The mergeLo and mergeHi methods nudge it higher for - * random data, and lower for highly structured data. - */ - private int minGallop = MIN_GALLOP; - - /** - * Maximum initial size of tmp array, which is used for merging. The array - * can grow to accommodate demand. - * - * Unlike Tim's original C version, we do not allocate this much storage - * when sorting smaller arrays. This change was required for performance. - */ - private static final int INITIAL_TMP_STORAGE_LENGTH = 256; - - /** - * Temp storage for merges. - */ - private Object[] tmp; - - /** - * A stack of pending runs yet to be merged. Run i starts at - * address base[i] and extends for len[i] elements. It's always - * true (so long as the indices are in bounds) that: - * - * runBase[i] + runLen[i] == runBase[i + 1] - * - * so we could cut the storage for this, but it's a minor amount, - * and keeping all the info explicit simplifies the code. - */ - private int stackSize = 0; // Number of pending runs on stack - private final int[] runBase; - private final int[] runLen; - - /** - * Creates a TimSort instance to maintain the state of an ongoing sort. - * - * @param a the array to be sorted - */ - private ComparableTimSort(Object[] a) { - this.a = a; - - // Allocate temp storage (which may be increased later if necessary) - int len = a.length; - @SuppressWarnings({"unchecked", "UnnecessaryLocalVariable"}) - Object[] newArray = new Object[len < 2 * INITIAL_TMP_STORAGE_LENGTH ? - len >>> 1 : INITIAL_TMP_STORAGE_LENGTH]; - tmp = newArray; - - /* - * Allocate runs-to-be-merged stack (which cannot be expanded). The - * stack length requirements are described in listsort.txt. The C - * version always uses the same stack length (85), but this was - * measured to be too expensive when sorting "mid-sized" arrays (e.g., - * 100 elements) in Java. Therefore, we use smaller (but sufficiently - * large) stack lengths for smaller arrays. The "magic numbers" in the - * computation below must be changed if MIN_MERGE is decreased. See - * the MIN_MERGE declaration above for more information. - */ - int stackLen = (len < 120 ? 5 : - len < 1542 ? 10 : - len < 119151 ? 19 : 40); - runBase = new int[stackLen]; - runLen = new int[stackLen]; - } - - /* - * The next two methods (which are package private and static) constitute - * the entire API of this class. Each of these methods obeys the contract - * of the public method with the same signature in java.util.Arrays. - */ - - static void sort(Object[] a) { - sort(a, 0, a.length); - } - - static void sort(Object[] a, int lo, int hi) { - rangeCheck(a.length, lo, hi); - int nRemaining = hi - lo; - if (nRemaining < 2) - return; // Arrays of size 0 and 1 are always sorted - - // If array is small, do a "mini-TimSort" with no merges - if (nRemaining < MIN_MERGE) { - int initRunLen = countRunAndMakeAscending(a, lo, hi); - binarySort(a, lo, hi, lo + initRunLen); - return; - } - - /** - * March over the array once, left to right, finding natural runs, - * extending short natural runs to minRun elements, and merging runs - * to maintain stack invariant. - */ - ComparableTimSort ts = new ComparableTimSort(a); - int minRun = minRunLength(nRemaining); - do { - // Identify next run - int runLen = countRunAndMakeAscending(a, lo, hi); - - // If run is short, extend to min(minRun, nRemaining) - if (runLen < minRun) { - int force = nRemaining <= minRun ? nRemaining : minRun; - binarySort(a, lo, lo + force, lo + runLen); - runLen = force; - } - - // Push run onto pending-run stack, and maybe merge - ts.pushRun(lo, runLen); - ts.mergeCollapse(); - - // Advance to find next run - lo += runLen; - nRemaining -= runLen; - } while (nRemaining != 0); - - // Merge all remaining runs to complete sort - assert lo == hi; - ts.mergeForceCollapse(); - assert ts.stackSize == 1; - } - - /** - * Sorts the specified portion of the specified array using a binary - * insertion sort. This is the best method for sorting small numbers - * of elements. It requires O(n log n) compares, but O(n^2) data - * movement (worst case). - * - * If the initial part of the specified range is already sorted, - * this method can take advantage of it: the method assumes that the - * elements from index {@code lo}, inclusive, to {@code start}, - * exclusive are already sorted. - * - * @param a the array in which a range is to be sorted - * @param lo the index of the first element in the range to be sorted - * @param hi the index after the last element in the range to be sorted - * @param start the index of the first element in the range that is - * not already known to be sorted ({@code lo <= start <= hi}) - */ - @SuppressWarnings("fallthrough") - private static void binarySort(Object[] a, int lo, int hi, int start) { - assert lo <= start && start <= hi; - if (start == lo) - start++; - for ( ; start < hi; start++) { - @SuppressWarnings("unchecked") - Comparable pivot = (Comparable) a[start]; - - // Set left (and right) to the index where a[start] (pivot) belongs - int left = lo; - int right = start; - assert left <= right; - /* - * Invariants: - * pivot >= all in [lo, left). - * pivot < all in [right, start). - */ - while (left < right) { - int mid = (left + right) >>> 1; - if (pivot.compareTo(a[mid]) < 0) - right = mid; - else - left = mid + 1; - } - assert left == right; - - /* - * The invariants still hold: pivot >= all in [lo, left) and - * pivot < all in [left, start), so pivot belongs at left. Note - * that if there are elements equal to pivot, left points to the - * first slot after them -- that's why this sort is stable. - * Slide elements over to make room for pivot. - */ - int n = start - left; // The number of elements to move - // Switch is just an optimization for arraycopy in default case - switch (n) { - case 2: a[left + 2] = a[left + 1]; - case 1: a[left + 1] = a[left]; - break; - default: System.arraycopy(a, left, a, left + 1, n); - } - a[left] = pivot; - } - } - - /** - * Returns the length of the run beginning at the specified position in - * the specified array and reverses the run if it is descending (ensuring - * that the run will always be ascending when the method returns). - * - * A run is the longest ascending sequence with: - * - * a[lo] <= a[lo + 1] <= a[lo + 2] <= ... - * - * or the longest descending sequence with: - * - * a[lo] > a[lo + 1] > a[lo + 2] > ... - * - * For its intended use in a stable mergesort, the strictness of the - * definition of "descending" is needed so that the call can safely - * reverse a descending sequence without violating stability. - * - * @param a the array in which a run is to be counted and possibly reversed - * @param lo index of the first element in the run - * @param hi index after the last element that may be contained in the run. - It is required that {@code lo < hi}. - * @return the length of the run beginning at the specified position in - * the specified array - */ - @SuppressWarnings("unchecked") - private static int countRunAndMakeAscending(Object[] a, int lo, int hi) { - assert lo < hi; - int runHi = lo + 1; - if (runHi == hi) - return 1; - - // Find end of run, and reverse range if descending - if (((Comparable) a[runHi++]).compareTo(a[lo]) < 0) { // Descending - while (runHi < hi && ((Comparable) a[runHi]).compareTo(a[runHi - 1]) < 0) - runHi++; - reverseRange(a, lo, runHi); - } else { // Ascending - while (runHi < hi && ((Comparable) a[runHi]).compareTo(a[runHi - 1]) >= 0) - runHi++; - } - - return runHi - lo; - } - - /** - * Reverse the specified range of the specified array. - * - * @param a the array in which a range is to be reversed - * @param lo the index of the first element in the range to be reversed - * @param hi the index after the last element in the range to be reversed - */ - private static void reverseRange(Object[] a, int lo, int hi) { - hi--; - while (lo < hi) { - Object t = a[lo]; - a[lo++] = a[hi]; - a[hi--] = t; - } - } - - /** - * Returns the minimum acceptable run length for an array of the specified - * length. Natural runs shorter than this will be extended with - * {@link #binarySort}. - * - * Roughly speaking, the computation is: - * - * If n < MIN_MERGE, return n (it's too small to bother with fancy stuff). - * Else if n is an exact power of 2, return MIN_MERGE/2. - * Else return an int k, MIN_MERGE/2 <= k <= MIN_MERGE, such that n/k - * is close to, but strictly less than, an exact power of 2. - * - * For the rationale, see listsort.txt. - * - * @param n the length of the array to be sorted - * @return the length of the minimum run to be merged - */ - private static int minRunLength(int n) { - assert n >= 0; - int r = 0; // Becomes 1 if any 1 bits are shifted off - while (n >= MIN_MERGE) { - r |= (n & 1); - n >>= 1; - } - return n + r; - } - - /** - * Pushes the specified run onto the pending-run stack. - * - * @param runBase index of the first element in the run - * @param runLen the number of elements in the run - */ - private void pushRun(int runBase, int runLen) { - this.runBase[stackSize] = runBase; - this.runLen[stackSize] = runLen; - stackSize++; - } - - /** - * Examines the stack of runs waiting to be merged and merges adjacent runs - * until the stack invariants are reestablished: - * - * 1. runLen[i - 3] > runLen[i - 2] + runLen[i - 1] - * 2. runLen[i - 2] > runLen[i - 1] - * - * This method is called each time a new run is pushed onto the stack, - * so the invariants are guaranteed to hold for i < stackSize upon - * entry to the method. - */ - private void mergeCollapse() { - while (stackSize > 1) { - int n = stackSize - 2; - if (n > 0 && runLen[n-1] <= runLen[n] + runLen[n+1]) { - if (runLen[n - 1] < runLen[n + 1]) - n--; - mergeAt(n); - } else if (runLen[n] <= runLen[n + 1]) { - mergeAt(n); - } else { - break; // Invariant is established - } - } - } - - /** - * Merges all runs on the stack until only one remains. This method is - * called once, to complete the sort. - */ - private void mergeForceCollapse() { - while (stackSize > 1) { - int n = stackSize - 2; - if (n > 0 && runLen[n - 1] < runLen[n + 1]) - n--; - mergeAt(n); - } - } - - /** - * Merges the two runs at stack indices i and i+1. Run i must be - * the penultimate or antepenultimate run on the stack. In other words, - * i must be equal to stackSize-2 or stackSize-3. - * - * @param i stack index of the first of the two runs to merge - */ - @SuppressWarnings("unchecked") - private void mergeAt(int i) { - assert stackSize >= 2; - assert i >= 0; - assert i == stackSize - 2 || i == stackSize - 3; - - int base1 = runBase[i]; - int len1 = runLen[i]; - int base2 = runBase[i + 1]; - int len2 = runLen[i + 1]; - assert len1 > 0 && len2 > 0; - assert base1 + len1 == base2; - - /* - * Record the length of the combined runs; if i is the 3rd-last - * run now, also slide over the last run (which isn't involved - * in this merge). The current run (i+1) goes away in any case. - */ - runLen[i] = len1 + len2; - if (i == stackSize - 3) { - runBase[i + 1] = runBase[i + 2]; - runLen[i + 1] = runLen[i + 2]; - } - stackSize--; - - /* - * Find where the first element of run2 goes in run1. Prior elements - * in run1 can be ignored (because they're already in place). - */ - int k = gallopRight((Comparable) a[base2], a, base1, len1, 0); - assert k >= 0; - base1 += k; - len1 -= k; - if (len1 == 0) - return; - - /* - * Find where the last element of run1 goes in run2. Subsequent elements - * in run2 can be ignored (because they're already in place). - */ - len2 = gallopLeft((Comparable) a[base1 + len1 - 1], a, - base2, len2, len2 - 1); - assert len2 >= 0; - if (len2 == 0) - return; - - // Merge remaining runs, using tmp array with min(len1, len2) elements - if (len1 <= len2) - mergeLo(base1, len1, base2, len2); - else - mergeHi(base1, len1, base2, len2); - } - - /** - * Locates the position at which to insert the specified key into the - * specified sorted range; if the range contains an element equal to key, - * returns the index of the leftmost equal element. - * - * @param key the key whose insertion point to search for - * @param a the array in which to search - * @param base the index of the first element in the range - * @param len the length of the range; must be > 0 - * @param hint the index at which to begin the search, 0 <= hint < n. - * The closer hint is to the result, the faster this method will run. - * @return the int k, 0 <= k <= n such that a[b + k - 1] < key <= a[b + k], - * pretending that a[b - 1] is minus infinity and a[b + n] is infinity. - * In other words, key belongs at index b + k; or in other words, - * the first k elements of a should precede key, and the last n - k - * should follow it. - */ - private static int gallopLeft(Comparable key, Object[] a, - int base, int len, int hint) { - assert len > 0 && hint >= 0 && hint < len; - - int lastOfs = 0; - int ofs = 1; - if (key.compareTo(a[base + hint]) > 0) { - // Gallop right until a[base+hint+lastOfs] < key <= a[base+hint+ofs] - int maxOfs = len - hint; - while (ofs < maxOfs && key.compareTo(a[base + hint + ofs]) > 0) { - lastOfs = ofs; - ofs = (ofs << 1) + 1; - if (ofs <= 0) // int overflow - ofs = maxOfs; - } - if (ofs > maxOfs) - ofs = maxOfs; - - // Make offsets relative to base - lastOfs += hint; - ofs += hint; - } else { // key <= a[base + hint] - // Gallop left until a[base+hint-ofs] < key <= a[base+hint-lastOfs] - final int maxOfs = hint + 1; - while (ofs < maxOfs && key.compareTo(a[base + hint - ofs]) <= 0) { - lastOfs = ofs; - ofs = (ofs << 1) + 1; - if (ofs <= 0) // int overflow - ofs = maxOfs; - } - if (ofs > maxOfs) - ofs = maxOfs; - - // Make offsets relative to base - int tmp = lastOfs; - lastOfs = hint - ofs; - ofs = hint - tmp; - } - assert -1 <= lastOfs && lastOfs < ofs && ofs <= len; - - /* - * Now a[base+lastOfs] < key <= a[base+ofs], so key belongs somewhere - * to the right of lastOfs but no farther right than ofs. Do a binary - * search, with invariant a[base + lastOfs - 1] < key <= a[base + ofs]. - */ - lastOfs++; - while (lastOfs < ofs) { - int m = lastOfs + ((ofs - lastOfs) >>> 1); - - if (key.compareTo(a[base + m]) > 0) - lastOfs = m + 1; // a[base + m] < key - else - ofs = m; // key <= a[base + m] - } - assert lastOfs == ofs; // so a[base + ofs - 1] < key <= a[base + ofs] - return ofs; - } - - /** - * Like gallopLeft, except that if the range contains an element equal to - * key, gallopRight returns the index after the rightmost equal element. - * - * @param key the key whose insertion point to search for - * @param a the array in which to search - * @param base the index of the first element in the range - * @param len the length of the range; must be > 0 - * @param hint the index at which to begin the search, 0 <= hint < n. - * The closer hint is to the result, the faster this method will run. - * @return the int k, 0 <= k <= n such that a[b + k - 1] <= key < a[b + k] - */ - private static int gallopRight(Comparable key, Object[] a, - int base, int len, int hint) { - assert len > 0 && hint >= 0 && hint < len; - - int ofs = 1; - int lastOfs = 0; - if (key.compareTo(a[base + hint]) < 0) { - // Gallop left until a[b+hint - ofs] <= key < a[b+hint - lastOfs] - int maxOfs = hint + 1; - while (ofs < maxOfs && key.compareTo(a[base + hint - ofs]) < 0) { - lastOfs = ofs; - ofs = (ofs << 1) + 1; - if (ofs <= 0) // int overflow - ofs = maxOfs; - } - if (ofs > maxOfs) - ofs = maxOfs; - - // Make offsets relative to b - int tmp = lastOfs; - lastOfs = hint - ofs; - ofs = hint - tmp; - } else { // a[b + hint] <= key - // Gallop right until a[b+hint + lastOfs] <= key < a[b+hint + ofs] - int maxOfs = len - hint; - while (ofs < maxOfs && key.compareTo(a[base + hint + ofs]) >= 0) { - lastOfs = ofs; - ofs = (ofs << 1) + 1; - if (ofs <= 0) // int overflow - ofs = maxOfs; - } - if (ofs > maxOfs) - ofs = maxOfs; - - // Make offsets relative to b - lastOfs += hint; - ofs += hint; - } - assert -1 <= lastOfs && lastOfs < ofs && ofs <= len; - - /* - * Now a[b + lastOfs] <= key < a[b + ofs], so key belongs somewhere to - * the right of lastOfs but no farther right than ofs. Do a binary - * search, with invariant a[b + lastOfs - 1] <= key < a[b + ofs]. - */ - lastOfs++; - while (lastOfs < ofs) { - int m = lastOfs + ((ofs - lastOfs) >>> 1); - - if (key.compareTo(a[base + m]) < 0) - ofs = m; // key < a[b + m] - else - lastOfs = m + 1; // a[b + m] <= key - } - assert lastOfs == ofs; // so a[b + ofs - 1] <= key < a[b + ofs] - return ofs; - } - - /** - * Merges two adjacent runs in place, in a stable fashion. The first - * element of the first run must be greater than the first element of the - * second run (a[base1] > a[base2]), and the last element of the first run - * (a[base1 + len1-1]) must be greater than all elements of the second run. - * - * For performance, this method should be called only when len1 <= len2; - * its twin, mergeHi should be called if len1 >= len2. (Either method - * may be called if len1 == len2.) - * - * @param base1 index of first element in first run to be merged - * @param len1 length of first run to be merged (must be > 0) - * @param base2 index of first element in second run to be merged - * (must be aBase + aLen) - * @param len2 length of second run to be merged (must be > 0) - */ - @SuppressWarnings("unchecked") - private void mergeLo(int base1, int len1, int base2, int len2) { - assert len1 > 0 && len2 > 0 && base1 + len1 == base2; - - // Copy first run into temp array - Object[] a = this.a; // For performance - Object[] tmp = ensureCapacity(len1); - System.arraycopy(a, base1, tmp, 0, len1); - - int cursor1 = 0; // Indexes into tmp array - int cursor2 = base2; // Indexes int a - int dest = base1; // Indexes int a - - // Move first element of second run and deal with degenerate cases - a[dest++] = a[cursor2++]; - if (--len2 == 0) { - System.arraycopy(tmp, cursor1, a, dest, len1); - return; - } - if (len1 == 1) { - System.arraycopy(a, cursor2, a, dest, len2); - a[dest + len2] = tmp[cursor1]; // Last elt of run 1 to end of merge - return; - } - - int minGallop = this.minGallop; // Use local variable for performance - outer: - while (true) { - int count1 = 0; // Number of times in a row that first run won - int count2 = 0; // Number of times in a row that second run won - - /* - * Do the straightforward thing until (if ever) one run starts - * winning consistently. - */ - do { - assert len1 > 1 && len2 > 0; - if (((Comparable) a[cursor2]).compareTo(tmp[cursor1]) < 0) { - a[dest++] = a[cursor2++]; - count2++; - count1 = 0; - if (--len2 == 0) - break outer; - } else { - a[dest++] = tmp[cursor1++]; - count1++; - count2 = 0; - if (--len1 == 1) - break outer; - } - } while ((count1 | count2) < minGallop); - - /* - * One run is winning so consistently that galloping may be a - * huge win. So try that, and continue galloping until (if ever) - * neither run appears to be winning consistently anymore. - */ - do { - assert len1 > 1 && len2 > 0; - count1 = gallopRight((Comparable) a[cursor2], tmp, cursor1, len1, 0); - if (count1 != 0) { - System.arraycopy(tmp, cursor1, a, dest, count1); - dest += count1; - cursor1 += count1; - len1 -= count1; - if (len1 <= 1) // len1 == 1 || len1 == 0 - break outer; - } - a[dest++] = a[cursor2++]; - if (--len2 == 0) - break outer; - - count2 = gallopLeft((Comparable) tmp[cursor1], a, cursor2, len2, 0); - if (count2 != 0) { - System.arraycopy(a, cursor2, a, dest, count2); - dest += count2; - cursor2 += count2; - len2 -= count2; - if (len2 == 0) - break outer; - } - a[dest++] = tmp[cursor1++]; - if (--len1 == 1) - break outer; - minGallop--; - } while (count1 >= MIN_GALLOP | count2 >= MIN_GALLOP); - if (minGallop < 0) - minGallop = 0; - minGallop += 2; // Penalize for leaving gallop mode - } // End of "outer" loop - this.minGallop = minGallop < 1 ? 1 : minGallop; // Write back to field - - if (len1 == 1) { - assert len2 > 0; - System.arraycopy(a, cursor2, a, dest, len2); - a[dest + len2] = tmp[cursor1]; // Last elt of run 1 to end of merge - } else if (len1 == 0) { - throw new IllegalArgumentException( - "Comparison method violates its general contract!"); - } else { - assert len2 == 0; - assert len1 > 1; - System.arraycopy(tmp, cursor1, a, dest, len1); - } - } - - /** - * Like mergeLo, except that this method should be called only if - * len1 >= len2; mergeLo should be called if len1 <= len2. (Either method - * may be called if len1 == len2.) - * - * @param base1 index of first element in first run to be merged - * @param len1 length of first run to be merged (must be > 0) - * @param base2 index of first element in second run to be merged - * (must be aBase + aLen) - * @param len2 length of second run to be merged (must be > 0) - */ - @SuppressWarnings("unchecked") - private void mergeHi(int base1, int len1, int base2, int len2) { - assert len1 > 0 && len2 > 0 && base1 + len1 == base2; - - // Copy second run into temp array - Object[] a = this.a; // For performance - Object[] tmp = ensureCapacity(len2); - System.arraycopy(a, base2, tmp, 0, len2); - - int cursor1 = base1 + len1 - 1; // Indexes into a - int cursor2 = len2 - 1; // Indexes into tmp array - int dest = base2 + len2 - 1; // Indexes into a - - // Move last element of first run and deal with degenerate cases - a[dest--] = a[cursor1--]; - if (--len1 == 0) { - System.arraycopy(tmp, 0, a, dest - (len2 - 1), len2); - return; - } - if (len2 == 1) { - dest -= len1; - cursor1 -= len1; - System.arraycopy(a, cursor1 + 1, a, dest + 1, len1); - a[dest] = tmp[cursor2]; - return; - } - - int minGallop = this.minGallop; // Use local variable for performance - outer: - while (true) { - int count1 = 0; // Number of times in a row that first run won - int count2 = 0; // Number of times in a row that second run won - - /* - * Do the straightforward thing until (if ever) one run - * appears to win consistently. - */ - do { - assert len1 > 0 && len2 > 1; - if (((Comparable) tmp[cursor2]).compareTo(a[cursor1]) < 0) { - a[dest--] = a[cursor1--]; - count1++; - count2 = 0; - if (--len1 == 0) - break outer; - } else { - a[dest--] = tmp[cursor2--]; - count2++; - count1 = 0; - if (--len2 == 1) - break outer; - } - } while ((count1 | count2) < minGallop); - - /* - * One run is winning so consistently that galloping may be a - * huge win. So try that, and continue galloping until (if ever) - * neither run appears to be winning consistently anymore. - */ - do { - assert len1 > 0 && len2 > 1; - count1 = len1 - gallopRight((Comparable) tmp[cursor2], a, base1, len1, len1 - 1); - if (count1 != 0) { - dest -= count1; - cursor1 -= count1; - len1 -= count1; - System.arraycopy(a, cursor1 + 1, a, dest + 1, count1); - if (len1 == 0) - break outer; - } - a[dest--] = tmp[cursor2--]; - if (--len2 == 1) - break outer; - - count2 = len2 - gallopLeft((Comparable) a[cursor1], tmp, 0, len2, len2 - 1); - if (count2 != 0) { - dest -= count2; - cursor2 -= count2; - len2 -= count2; - System.arraycopy(tmp, cursor2 + 1, a, dest + 1, count2); - if (len2 <= 1) - break outer; // len2 == 1 || len2 == 0 - } - a[dest--] = a[cursor1--]; - if (--len1 == 0) - break outer; - minGallop--; - } while (count1 >= MIN_GALLOP | count2 >= MIN_GALLOP); - if (minGallop < 0) - minGallop = 0; - minGallop += 2; // Penalize for leaving gallop mode - } // End of "outer" loop - this.minGallop = minGallop < 1 ? 1 : minGallop; // Write back to field - - if (len2 == 1) { - assert len1 > 0; - dest -= len1; - cursor1 -= len1; - System.arraycopy(a, cursor1 + 1, a, dest + 1, len1); - a[dest] = tmp[cursor2]; // Move first elt of run2 to front of merge - } else if (len2 == 0) { - throw new IllegalArgumentException( - "Comparison method violates its general contract!"); - } else { - assert len1 == 0; - assert len2 > 0; - System.arraycopy(tmp, 0, a, dest - (len2 - 1), len2); - } - } - - /** - * Ensures that the external array tmp has at least the specified - * number of elements, increasing its size if necessary. The size - * increases exponentially to ensure amortized linear time complexity. - * - * @param minCapacity the minimum required capacity of the tmp array - * @return tmp, whether or not it grew - */ - private Object[] ensureCapacity(int minCapacity) { - if (tmp.length < minCapacity) { - // Compute smallest power of 2 > minCapacity - int newSize = minCapacity; - newSize |= newSize >> 1; - newSize |= newSize >> 2; - newSize |= newSize >> 4; - newSize |= newSize >> 8; - newSize |= newSize >> 16; - newSize++; - - if (newSize < 0) // Not bloody likely! - newSize = minCapacity; - else - newSize = Math.min(newSize, a.length >>> 1); - - @SuppressWarnings({"unchecked", "UnnecessaryLocalVariable"}) - Object[] newArray = new Object[newSize]; - tmp = newArray; - } - return tmp; - } - - /** - * Checks that fromIndex and toIndex are in range, and throws an - * appropriate exception if they aren't. - * - * @param arrayLen the length of the array - * @param fromIndex the index of the first element of the range - * @param toIndex the index after the last element of the range - * @throws IllegalArgumentException if fromIndex > toIndex - * @throws ArrayIndexOutOfBoundsException if fromIndex < 0 - * or toIndex > arrayLen - */ - private static void rangeCheck(int arrayLen, int fromIndex, int toIndex) { - if (fromIndex > toIndex) - throw new IllegalArgumentException("fromIndex(" + fromIndex + - ") > toIndex(" + toIndex+")"); - if (fromIndex < 0) - throw new ArrayIndexOutOfBoundsException(fromIndex); - if (toIndex > arrayLen) - throw new ArrayIndexOutOfBoundsException(toIndex); - } -}