diff options
Diffstat (limited to 'java/src/main/java/com/google/protobuf/RopeByteString.java')
| -rw-r--r-- | java/src/main/java/com/google/protobuf/RopeByteString.java | 957 |
1 files changed, 0 insertions, 957 deletions
diff --git a/java/src/main/java/com/google/protobuf/RopeByteString.java b/java/src/main/java/com/google/protobuf/RopeByteString.java deleted file mode 100644 index d1655b8..0000000 --- a/java/src/main/java/com/google/protobuf/RopeByteString.java +++ /dev/null @@ -1,957 +0,0 @@ -// Protocol Buffers - Google's data interchange format -// Copyright 2008 Google Inc. All rights reserved. -// https://developers.google.com/protocol-buffers/ -// -// Redistribution and use in source and binary forms, with or without -// modification, are permitted provided that the following conditions are -// met: -// -// * Redistributions of source code must retain the above copyright -// notice, this list of conditions and the following disclaimer. -// * Redistributions in binary form must reproduce the above -// copyright notice, this list of conditions and the following disclaimer -// in the documentation and/or other materials provided with the -// distribution. -// * Neither the name of Google Inc. nor the names of its -// contributors may be used to endorse or promote products derived from -// this software without specific prior written permission. -// -// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - -package com.google.protobuf; - -import java.io.IOException; -import java.io.InputStream; -import java.io.OutputStream; -import java.io.UnsupportedEncodingException; -import java.io.ByteArrayInputStream; -import java.nio.ByteBuffer; -import java.util.ArrayList; -import java.util.Arrays; -import java.util.Iterator; -import java.util.List; -import java.util.NoSuchElementException; -import java.util.Stack; - -/** - * Class to represent {@code ByteStrings} formed by concatenation of other - * ByteStrings, without copying the data in the pieces. The concatenation is - * represented as a tree whose leaf nodes are each a {@link LiteralByteString}. - * - * <p>Most of the operation here is inspired by the now-famous paper <a - * href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf"> - * BAP95 </a> Ropes: an Alternative to Strings hans-j. boehm, russ atkinson and - * michael plass - * - * <p>The algorithms described in the paper have been implemented for character - * strings in {@link com.google.common.string.Rope} and in the c++ class {@code - * cord.cc}. - * - * <p>Fundamentally the Rope algorithm represents the collection of pieces as a - * binary tree. BAP95 uses a Fibonacci bound relating depth to a minimum - * sequence length, sequences that are too short relative to their depth cause a - * tree rebalance. More precisely, a tree of depth d is "balanced" in the - * terminology of BAP95 if its length is at least F(d+2), where F(n) is the - * n-the Fibonacci number. Thus for depths 0, 1, 2, 3, 4, 5,... we have minimum - * lengths 1, 2, 3, 5, 8, 13,... - * - * @author carlanton@google.com (Carl Haverl) - */ -class RopeByteString extends ByteString { - - /** - * BAP95. Let Fn be the nth Fibonacci number. A {@link RopeByteString} of - * depth n is "balanced", i.e flat enough, if its length is at least Fn+2, - * e.g. a "balanced" {@link RopeByteString} of depth 1 must have length at - * least 2, of depth 4 must have length >= 8, etc. - * - * <p>There's nothing special about using the Fibonacci numbers for this, but - * they are a reasonable sequence for encapsulating the idea that we are OK - * with longer strings being encoded in deeper binary trees. - * - * <p>For 32-bit integers, this array has length 46. - */ - private static final int[] minLengthByDepth; - - static { - // Dynamically generate the list of Fibonacci numbers the first time this - // class is accessed. - List<Integer> numbers = new ArrayList<Integer>(); - - // we skip the first Fibonacci number (1). So instead of: 1 1 2 3 5 8 ... - // we have: 1 2 3 5 8 ... - int f1 = 1; - int f2 = 1; - - // get all the values until we roll over. - while (f2 > 0) { - numbers.add(f2); - int temp = f1 + f2; - f1 = f2; - f2 = temp; - } - - // we include this here so that we can index this array to [x + 1] in the - // loops below. - numbers.add(Integer.MAX_VALUE); - minLengthByDepth = new int[numbers.size()]; - for (int i = 0; i < minLengthByDepth.length; i++) { - // unbox all the values - minLengthByDepth[i] = numbers.get(i); - } - } - - private final int totalLength; - private final ByteString left; - private final ByteString right; - private final int leftLength; - private final int treeDepth; - - /** - * Create a new RopeByteString, which can be thought of as a new tree node, by - * recording references to the two given strings. - * - * @param left string on the left of this node, should have {@code size() > - * 0} - * @param right string on the right of this node, should have {@code size() > - * 0} - */ - private RopeByteString(ByteString left, ByteString right) { - this.left = left; - this.right = right; - leftLength = left.size(); - totalLength = leftLength + right.size(); - treeDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1; - } - - /** - * Concatenate the given strings while performing various optimizations to - * slow the growth rate of tree depth and tree node count. The result is - * either a {@link LiteralByteString} or a {@link RopeByteString} - * depending on which optimizations, if any, were applied. - * - * <p>Small pieces of length less than {@link - * ByteString#CONCATENATE_BY_COPY_SIZE} may be copied by value here, as in - * BAP95. Large pieces are referenced without copy. - * - * @param left string on the left - * @param right string on the right - * @return concatenation representing the same sequence as the given strings - */ - static ByteString concatenate(ByteString left, ByteString right) { - ByteString result; - RopeByteString leftRope = - (left instanceof RopeByteString) ? (RopeByteString) left : null; - if (right.size() == 0) { - result = left; - } else if (left.size() == 0) { - result = right; - } else { - int newLength = left.size() + right.size(); - if (newLength < ByteString.CONCATENATE_BY_COPY_SIZE) { - // Optimization from BAP95: For short (leaves in paper, but just short - // here) total length, do a copy of data to a new leaf. - result = concatenateBytes(left, right); - } else if (leftRope != null - && leftRope.right.size() + right.size() < CONCATENATE_BY_COPY_SIZE) { - // Optimization from BAP95: As an optimization of the case where the - // ByteString is constructed by repeated concatenate, recognize the case - // where a short string is concatenated to a left-hand node whose - // right-hand branch is short. In the paper this applies to leaves, but - // we just look at the length here. This has the advantage of shedding - // references to unneeded data when substrings have been taken. - // - // When we recognize this case, we do a copy of the data and create a - // new parent node so that the depth of the result is the same as the - // given left tree. - ByteString newRight = concatenateBytes(leftRope.right, right); - result = new RopeByteString(leftRope.left, newRight); - } else if (leftRope != null - && leftRope.left.getTreeDepth() > leftRope.right.getTreeDepth() - && leftRope.getTreeDepth() > right.getTreeDepth()) { - // Typically for concatenate-built strings the left-side is deeper than - // the right. This is our final attempt to concatenate without - // increasing the tree depth. We'll redo the the node on the RHS. This - // is yet another optimization for building the string by repeatedly - // concatenating on the right. - ByteString newRight = new RopeByteString(leftRope.right, right); - result = new RopeByteString(leftRope.left, newRight); - } else { - // Fine, we'll add a node and increase the tree depth--unless we - // rebalance ;^) - int newDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1; - if (newLength >= minLengthByDepth[newDepth]) { - // The tree is shallow enough, so don't rebalance - result = new RopeByteString(left, right); - } else { - result = new Balancer().balance(left, right); - } - } - } - return result; - } - - /** - * Concatenates two strings by copying data values. This is called in a few - * cases in order to reduce the growth of the number of tree nodes. - * - * @param left string on the left - * @param right string on the right - * @return string formed by copying data bytes - */ - private static LiteralByteString concatenateBytes(ByteString left, - ByteString right) { - int leftSize = left.size(); - int rightSize = right.size(); - byte[] bytes = new byte[leftSize + rightSize]; - left.copyTo(bytes, 0, 0, leftSize); - right.copyTo(bytes, 0, leftSize, rightSize); - return new LiteralByteString(bytes); // Constructor wraps bytes - } - - /** - * Create a new RopeByteString for testing only while bypassing all the - * defenses of {@link #concatenate(ByteString, ByteString)}. This allows - * testing trees of specific structure. We are also able to insert empty - * leaves, though these are dis-allowed, so that we can make sure the - * implementation can withstand their presence. - * - * @param left string on the left of this node - * @param right string on the right of this node - * @return an unsafe instance for testing only - */ - static RopeByteString newInstanceForTest(ByteString left, ByteString right) { - return new RopeByteString(left, right); - } - - /** - * Gets the byte at the given index. - * Throws {@link ArrayIndexOutOfBoundsException} for backwards-compatibility - * reasons although it would more properly be {@link - * IndexOutOfBoundsException}. - * - * @param index index of byte - * @return the value - * @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size - */ - @Override - public byte byteAt(int index) { - if (index < 0) { - throw new ArrayIndexOutOfBoundsException("Index < 0: " + index); - } - if (index > totalLength) { - throw new ArrayIndexOutOfBoundsException( - "Index > length: " + index + ", " + totalLength); - } - - byte result; - // Find the relevant piece by recursive descent - if (index < leftLength) { - result = left.byteAt(index); - } else { - result = right.byteAt(index - leftLength); - } - return result; - } - - @Override - public int size() { - return totalLength; - } - - // ================================================================= - // Pieces - - @Override - protected int getTreeDepth() { - return treeDepth; - } - - /** - * Determines if the tree is balanced according to BAP95, which means the tree - * is flat-enough with respect to the bounds. Note that this definition of - * balanced is one where sub-trees of balanced trees are not necessarily - * balanced. - * - * @return true if the tree is balanced - */ - @Override - protected boolean isBalanced() { - return totalLength >= minLengthByDepth[treeDepth]; - } - - /** - * Takes a substring of this one. This involves recursive descent along the - * left and right edges of the substring, and referencing any wholly contained - * segments in between. Any leaf nodes entirely uninvolved in the substring - * will not be referenced by the substring. - * - * <p>Substrings of {@code length < 2} should result in at most a single - * recursive call chain, terminating at a leaf node. Thus the result will be a - * {@link LiteralByteString}. {@link #RopeByteString(ByteString, - * ByteString)}. - * - * @param beginIndex start at this index - * @param endIndex the last character is the one before this index - * @return substring leaf node or tree - */ - @Override - public ByteString substring(int beginIndex, int endIndex) { - if (beginIndex < 0) { - throw new IndexOutOfBoundsException( - "Beginning index: " + beginIndex + " < 0"); - } - if (endIndex > totalLength) { - throw new IndexOutOfBoundsException( - "End index: " + endIndex + " > " + totalLength); - } - int substringLength = endIndex - beginIndex; - if (substringLength < 0) { - throw new IndexOutOfBoundsException( - "Beginning index larger than ending index: " + beginIndex + ", " - + endIndex); - } - - ByteString result; - if (substringLength == 0) { - // Empty substring - result = ByteString.EMPTY; - } else if (substringLength == totalLength) { - // The whole string - result = this; - } else { - // Proper substring - if (endIndex <= leftLength) { - // Substring on the left - result = left.substring(beginIndex, endIndex); - } else if (beginIndex >= leftLength) { - // Substring on the right - result = right - .substring(beginIndex - leftLength, endIndex - leftLength); - } else { - // Split substring - ByteString leftSub = left.substring(beginIndex); - ByteString rightSub = right.substring(0, endIndex - leftLength); - // Intentionally not rebalancing, since in many cases these two - // substrings will already be less deep than the top-level - // RopeByteString we're taking a substring of. - result = new RopeByteString(leftSub, rightSub); - } - } - return result; - } - - // ================================================================= - // ByteString -> byte[] - - @Override - protected void copyToInternal(byte[] target, int sourceOffset, - int targetOffset, int numberToCopy) { - if (sourceOffset + numberToCopy <= leftLength) { - left.copyToInternal(target, sourceOffset, targetOffset, numberToCopy); - } else if (sourceOffset >= leftLength) { - right.copyToInternal(target, sourceOffset - leftLength, targetOffset, - numberToCopy); - } else { - int leftLength = this.leftLength - sourceOffset; - left.copyToInternal(target, sourceOffset, targetOffset, leftLength); - right.copyToInternal(target, 0, targetOffset + leftLength, - numberToCopy - leftLength); - } - } - - @Override - public void copyTo(ByteBuffer target) { - left.copyTo(target); - right.copyTo(target); - } - - @Override - public ByteBuffer asReadOnlyByteBuffer() { - ByteBuffer byteBuffer = ByteBuffer.wrap(toByteArray()); - return byteBuffer.asReadOnlyBuffer(); - } - - @Override - public List<ByteBuffer> asReadOnlyByteBufferList() { - // Walk through the list of LiteralByteString's that make up this - // rope, and add each one as a read-only ByteBuffer. - List<ByteBuffer> result = new ArrayList<ByteBuffer>(); - PieceIterator pieces = new PieceIterator(this); - while (pieces.hasNext()) { - LiteralByteString byteString = pieces.next(); - result.add(byteString.asReadOnlyByteBuffer()); - } - return result; - } - - @Override - public void writeTo(OutputStream outputStream) throws IOException { - left.writeTo(outputStream); - right.writeTo(outputStream); - } - - @Override - void writeToInternal(OutputStream out, int sourceOffset, - int numberToWrite) throws IOException { - if (sourceOffset + numberToWrite <= leftLength) { - left.writeToInternal(out, sourceOffset, numberToWrite); - } else if (sourceOffset >= leftLength) { - right.writeToInternal(out, sourceOffset - leftLength, numberToWrite); - } else { - int numberToWriteInLeft = leftLength - sourceOffset; - left.writeToInternal(out, sourceOffset, numberToWriteInLeft); - right.writeToInternal(out, 0, numberToWrite - numberToWriteInLeft); - } - } - - @Override - public String toString(String charsetName) - throws UnsupportedEncodingException { - return new String(toByteArray(), charsetName); - } - - // ================================================================= - // UTF-8 decoding - - @Override - public boolean isValidUtf8() { - int leftPartial = left.partialIsValidUtf8(Utf8.COMPLETE, 0, leftLength); - int state = right.partialIsValidUtf8(leftPartial, 0, right.size()); - return state == Utf8.COMPLETE; - } - - @Override - protected int partialIsValidUtf8(int state, int offset, int length) { - int toIndex = offset + length; - if (toIndex <= leftLength) { - return left.partialIsValidUtf8(state, offset, length); - } else if (offset >= leftLength) { - return right.partialIsValidUtf8(state, offset - leftLength, length); - } else { - int leftLength = this.leftLength - offset; - int leftPartial = left.partialIsValidUtf8(state, offset, leftLength); - return right.partialIsValidUtf8(leftPartial, 0, length - leftLength); - } - } - - // ================================================================= - // equals() and hashCode() - - @Override - public boolean equals(Object other) { - if (other == this) { - return true; - } - if (!(other instanceof ByteString)) { - return false; - } - - ByteString otherByteString = (ByteString) other; - if (totalLength != otherByteString.size()) { - return false; - } - if (totalLength == 0) { - return true; - } - - // You don't really want to be calling equals on long strings, but since - // we cache the hashCode, we effectively cache inequality. We use the cached - // hashCode if it's already computed. It's arguable we should compute the - // hashCode here, and if we're going to be testing a bunch of byteStrings, - // it might even make sense. - if (hash != 0) { - int cachedOtherHash = otherByteString.peekCachedHashCode(); - if (cachedOtherHash != 0 && hash != cachedOtherHash) { - return false; - } - } - - return equalsFragments(otherByteString); - } - - /** - * Determines if this string is equal to another of the same length by - * iterating over the leaf nodes. On each step of the iteration, the - * overlapping segments of the leaves are compared. - * - * @param other string of the same length as this one - * @return true if the values of this string equals the value of the given - * one - */ - private boolean equalsFragments(ByteString other) { - int thisOffset = 0; - Iterator<LiteralByteString> thisIter = new PieceIterator(this); - LiteralByteString thisString = thisIter.next(); - - int thatOffset = 0; - Iterator<LiteralByteString> thatIter = new PieceIterator(other); - LiteralByteString thatString = thatIter.next(); - - int pos = 0; - while (true) { - int thisRemaining = thisString.size() - thisOffset; - int thatRemaining = thatString.size() - thatOffset; - int bytesToCompare = Math.min(thisRemaining, thatRemaining); - - // At least one of the offsets will be zero - boolean stillEqual = (thisOffset == 0) - ? thisString.equalsRange(thatString, thatOffset, bytesToCompare) - : thatString.equalsRange(thisString, thisOffset, bytesToCompare); - if (!stillEqual) { - return false; - } - - pos += bytesToCompare; - if (pos >= totalLength) { - if (pos == totalLength) { - return true; - } - throw new IllegalStateException(); - } - // We always get to the end of at least one of the pieces - if (bytesToCompare == thisRemaining) { // If reached end of this - thisOffset = 0; - thisString = thisIter.next(); - } else { - thisOffset += bytesToCompare; - } - if (bytesToCompare == thatRemaining) { // If reached end of that - thatOffset = 0; - thatString = thatIter.next(); - } else { - thatOffset += bytesToCompare; - } - } - } - - /** - * Cached hash value. Intentionally accessed via a data race, which is safe - * because of the Java Memory Model's "no out-of-thin-air values" guarantees - * for ints. - */ - private int hash = 0; - - @Override - public int hashCode() { - int h = hash; - - if (h == 0) { - h = totalLength; - h = partialHash(h, 0, totalLength); - if (h == 0) { - h = 1; - } - hash = h; - } - return h; - } - - @Override - protected int peekCachedHashCode() { - return hash; - } - - @Override - protected int partialHash(int h, int offset, int length) { - int toIndex = offset + length; - if (toIndex <= leftLength) { - return left.partialHash(h, offset, length); - } else if (offset >= leftLength) { - return right.partialHash(h, offset - leftLength, length); - } else { - int leftLength = this.leftLength - offset; - int leftPartial = left.partialHash(h, offset, leftLength); - return right.partialHash(leftPartial, 0, length - leftLength); - } - } - - // ================================================================= - // Input stream - - @Override - public CodedInputStream newCodedInput() { - return CodedInputStream.newInstance(new RopeInputStream()); - } - - @Override - public InputStream newInput() { - return new RopeInputStream(); - } - - /** - * This class implements the balancing algorithm of BAP95. In the paper the - * authors use an array to keep track of pieces, while here we use a stack. - * The tree is balanced by traversing subtrees in left to right order, and the - * stack always contains the part of the string we've traversed so far. - * - * <p>One surprising aspect of the algorithm is the result of balancing is not - * necessarily balanced, though it is nearly balanced. For details, see - * BAP95. - */ - private static class Balancer { - // Stack containing the part of the string, starting from the left, that - // we've already traversed. The final string should be the equivalent of - // concatenating the strings on the stack from bottom to top. - private final Stack<ByteString> prefixesStack = new Stack<ByteString>(); - - private ByteString balance(ByteString left, ByteString right) { - doBalance(left); - doBalance(right); - - // Sweep stack to gather the result - ByteString partialString = prefixesStack.pop(); - while (!prefixesStack.isEmpty()) { - ByteString newLeft = prefixesStack.pop(); - partialString = new RopeByteString(newLeft, partialString); - } - // We should end up with a RopeByteString since at a minimum we will - // create one from concatenating left and right - return partialString; - } - - private void doBalance(ByteString root) { - // BAP95: Insert balanced subtrees whole. This means the result might not - // be balanced, leading to repeated rebalancings on concatenate. However, - // these rebalancings are shallow due to ignoring balanced subtrees, and - // relatively few calls to insert() result. - if (root.isBalanced()) { - insert(root); - } else if (root instanceof RopeByteString) { - RopeByteString rbs = (RopeByteString) root; - doBalance(rbs.left); - doBalance(rbs.right); - } else { - throw new IllegalArgumentException( - "Has a new type of ByteString been created? Found " + - root.getClass()); - } - } - - /** - * Push a string on the balance stack (BAP95). BAP95 uses an array and - * calls the elements in the array 'bins'. We instead use a stack, so the - * 'bins' of lengths are represented by differences between the elements of - * minLengthByDepth. - * - * <p>If the length bin for our string, and all shorter length bins, are - * empty, we just push it on the stack. Otherwise, we need to start - * concatenating, putting the given string in the "middle" and continuing - * until we land in an empty length bin that matches the length of our - * concatenation. - * - * @param byteString string to place on the balance stack - */ - private void insert(ByteString byteString) { - int depthBin = getDepthBinForLength(byteString.size()); - int binEnd = minLengthByDepth[depthBin + 1]; - - // BAP95: Concatenate all trees occupying bins representing the length of - // our new piece or of shorter pieces, to the extent that is possible. - // The goal is to clear the bin which our piece belongs in, but that may - // not be entirely possible if there aren't enough longer bins occupied. - if (prefixesStack.isEmpty() || prefixesStack.peek().size() >= binEnd) { - prefixesStack.push(byteString); - } else { - int binStart = minLengthByDepth[depthBin]; - - // Concatenate the subtrees of shorter length - ByteString newTree = prefixesStack.pop(); - while (!prefixesStack.isEmpty() - && prefixesStack.peek().size() < binStart) { - ByteString left = prefixesStack.pop(); - newTree = new RopeByteString(left, newTree); - } - - // Concatenate the given string - newTree = new RopeByteString(newTree, byteString); - - // Continue concatenating until we land in an empty bin - while (!prefixesStack.isEmpty()) { - depthBin = getDepthBinForLength(newTree.size()); - binEnd = minLengthByDepth[depthBin + 1]; - if (prefixesStack.peek().size() < binEnd) { - ByteString left = prefixesStack.pop(); - newTree = new RopeByteString(left, newTree); - } else { - break; - } - } - prefixesStack.push(newTree); - } - } - - private int getDepthBinForLength(int length) { - int depth = Arrays.binarySearch(minLengthByDepth, length); - if (depth < 0) { - // It wasn't an exact match, so convert to the index of the containing - // fragment, which is one less even than the insertion point. - int insertionPoint = -(depth + 1); - depth = insertionPoint - 1; - } - - return depth; - } - } - - /** - * This class is a continuable tree traversal, which keeps the state - * information which would exist on the stack in a recursive traversal instead - * on a stack of "Bread Crumbs". The maximum depth of the stack in this - * iterator is the same as the depth of the tree being traversed. - * - * <p>This iterator is used to implement - * {@link RopeByteString#equalsFragments(ByteString)}. - */ - private static class PieceIterator implements Iterator<LiteralByteString> { - - private final Stack<RopeByteString> breadCrumbs = - new Stack<RopeByteString>(); - private LiteralByteString next; - - private PieceIterator(ByteString root) { - next = getLeafByLeft(root); - } - - private LiteralByteString getLeafByLeft(ByteString root) { - ByteString pos = root; - while (pos instanceof RopeByteString) { - RopeByteString rbs = (RopeByteString) pos; - breadCrumbs.push(rbs); - pos = rbs.left; - } - return (LiteralByteString) pos; - } - - private LiteralByteString getNextNonEmptyLeaf() { - while (true) { - // Almost always, we go through this loop exactly once. However, if - // we discover an empty string in the rope, we toss it and try again. - if (breadCrumbs.isEmpty()) { - return null; - } else { - LiteralByteString result = getLeafByLeft(breadCrumbs.pop().right); - if (!result.isEmpty()) { - return result; - } - } - } - } - - public boolean hasNext() { - return next != null; - } - - /** - * Returns the next item and advances one {@code LiteralByteString}. - * - * @return next non-empty LiteralByteString or {@code null} - */ - public LiteralByteString next() { - if (next == null) { - throw new NoSuchElementException(); - } - LiteralByteString result = next; - next = getNextNonEmptyLeaf(); - return result; - } - - public void remove() { - throw new UnsupportedOperationException(); - } - } - - // ================================================================= - // ByteIterator - - @Override - public ByteIterator iterator() { - return new RopeByteIterator(); - } - - private class RopeByteIterator implements ByteString.ByteIterator { - - private final PieceIterator pieces; - private ByteIterator bytes; - int bytesRemaining; - - private RopeByteIterator() { - pieces = new PieceIterator(RopeByteString.this); - bytes = pieces.next().iterator(); - bytesRemaining = size(); - } - - public boolean hasNext() { - return (bytesRemaining > 0); - } - - public Byte next() { - return nextByte(); // Does not instantiate a Byte - } - - public byte nextByte() { - if (!bytes.hasNext()) { - bytes = pieces.next().iterator(); - } - --bytesRemaining; - return bytes.nextByte(); - } - - public void remove() { - throw new UnsupportedOperationException(); - } - } - - /** - * This class is the {@link RopeByteString} equivalent for - * {@link ByteArrayInputStream}. - */ - private class RopeInputStream extends InputStream { - // Iterates through the pieces of the rope - private PieceIterator pieceIterator; - // The current piece - private LiteralByteString currentPiece; - // The size of the current piece - private int currentPieceSize; - // The index of the next byte to read in the current piece - private int currentPieceIndex; - // The offset of the start of the current piece in the rope byte string - private int currentPieceOffsetInRope; - // Offset in the buffer at which user called mark(); - private int mark; - - public RopeInputStream() { - initialize(); - } - - @Override - public int read(byte b[], int offset, int length) { - if (b == null) { - throw new NullPointerException(); - } else if (offset < 0 || length < 0 || length > b.length - offset) { - throw new IndexOutOfBoundsException(); - } - return readSkipInternal(b, offset, length); - } - - @Override - public long skip(long length) { - if (length < 0) { - throw new IndexOutOfBoundsException(); - } else if (length > Integer.MAX_VALUE) { - length = Integer.MAX_VALUE; - } - return readSkipInternal(null, 0, (int) length); - } - - /** - * Internal implementation of read and skip. If b != null, then read the - * next {@code length} bytes into the buffer {@code b} at - * offset {@code offset}. If b == null, then skip the next {@code length) - * bytes. - * <p> - * This method assumes that all error checking has already happened. - * <p> - * Returns the actual number of bytes read or skipped. - */ - private int readSkipInternal(byte b[], int offset, int length) { - int bytesRemaining = length; - while (bytesRemaining > 0) { - advanceIfCurrentPieceFullyRead(); - if (currentPiece == null) { - if (bytesRemaining == length) { - // We didn't manage to read anything - return -1; - } - break; - } else { - // Copy the bytes from this piece. - int currentPieceRemaining = currentPieceSize - currentPieceIndex; - int count = Math.min(currentPieceRemaining, bytesRemaining); - if (b != null) { - currentPiece.copyTo(b, currentPieceIndex, offset, count); - offset += count; - } - currentPieceIndex += count; - bytesRemaining -= count; - } - } - // Return the number of bytes read. - return length - bytesRemaining; - } - - @Override - public int read() throws IOException { - advanceIfCurrentPieceFullyRead(); - if (currentPiece == null) { - return -1; - } else { - return currentPiece.byteAt(currentPieceIndex++) & 0xFF; - } - } - - @Override - public int available() throws IOException { - int bytesRead = currentPieceOffsetInRope + currentPieceIndex; - return RopeByteString.this.size() - bytesRead; - } - - @Override - public boolean markSupported() { - return true; - } - - @Override - public void mark(int readAheadLimit) { - // Set the mark to our position in the byte string - mark = currentPieceOffsetInRope + currentPieceIndex; - } - - @Override - public synchronized void reset() { - // Just reinitialize and skip the specified number of bytes. - initialize(); - readSkipInternal(null, 0, mark); - } - - /** Common initialization code used by both the constructor and reset() */ - private void initialize() { - pieceIterator = new PieceIterator(RopeByteString.this); - currentPiece = pieceIterator.next(); - currentPieceSize = currentPiece.size(); - currentPieceIndex = 0; - currentPieceOffsetInRope = 0; - } - - /** - * Skips to the next piece if we have read all the data in the current - * piece. Sets currentPiece to null if we have reached the end of the - * input. - */ - private void advanceIfCurrentPieceFullyRead() { - if (currentPiece != null && currentPieceIndex == currentPieceSize) { - // Generally, we can only go through this loop at most once, since - // empty strings can't end up in a rope. But better to test. - currentPieceOffsetInRope += currentPieceSize; - currentPieceIndex = 0; - if (pieceIterator.hasNext()) { - currentPiece = pieceIterator.next(); - currentPieceSize = currentPiece.size(); - } else { - currentPiece = null; - currentPieceSize = 0; - } - } - } - } -} |