Squashed 'third_party/flatbuffers/' content from commit acc9990ab
Change-Id: I48550d40d78fea996ebe74e9723a5d1f910de491
git-subtree-dir: third_party/flatbuffers
git-subtree-split: acc9990abd2206491480291b0f85f925110102ea
diff --git a/java/com/google/flatbuffers/Utf8Safe.java b/java/com/google/flatbuffers/Utf8Safe.java
new file mode 100644
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+++ b/java/com/google/flatbuffers/Utf8Safe.java
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+// 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.flatbuffers;
+
+import java.nio.ByteBuffer;
+import static java.lang.Character.MAX_SURROGATE;
+import static java.lang.Character.MIN_SUPPLEMENTARY_CODE_POINT;
+import static java.lang.Character.MIN_SURROGATE;
+import static java.lang.Character.isSurrogatePair;
+import static java.lang.Character.toCodePoint;
+
+/**
+ * A set of low-level, high-performance static utility methods related
+ * to the UTF-8 character encoding. This class has no dependencies
+ * outside of the core JDK libraries.
+ *
+ * <p>There are several variants of UTF-8. The one implemented by
+ * this class is the restricted definition of UTF-8 introduced in
+ * Unicode 3.1, which mandates the rejection of "overlong" byte
+ * sequences as well as rejection of 3-byte surrogate codepoint byte
+ * sequences. Note that the UTF-8 decoder included in Oracle's JDK
+ * has been modified to also reject "overlong" byte sequences, but (as
+ * of 2011) still accepts 3-byte surrogate codepoint byte sequences.
+ *
+ * <p>The byte sequences considered valid by this class are exactly
+ * those that can be roundtrip converted to Strings and back to bytes
+ * using the UTF-8 charset, without loss: <pre> {@code
+ * Arrays.equals(bytes, new String(bytes, Internal.UTF_8).getBytes(Internal.UTF_8))
+ * }</pre>
+ *
+ * <p>See the Unicode Standard,</br>
+ * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
+ * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
+ */
+final public class Utf8Safe extends Utf8 {
+
+ /**
+ * Returns the number of bytes in the UTF-8-encoded form of {@code sequence}. For a string,
+ * this method is equivalent to {@code string.getBytes(UTF_8).length}, but is more efficient in
+ * both time and space.
+ *
+ * @throws IllegalArgumentException if {@code sequence} contains ill-formed UTF-16 (unpaired
+ * surrogates)
+ */
+ private static int computeEncodedLength(CharSequence sequence) {
+ // Warning to maintainers: this implementation is highly optimized.
+ int utf16Length = sequence.length();
+ int utf8Length = utf16Length;
+ int i = 0;
+
+ // This loop optimizes for pure ASCII.
+ while (i < utf16Length && sequence.charAt(i) < 0x80) {
+ i++;
+ }
+
+ // This loop optimizes for chars less than 0x800.
+ for (; i < utf16Length; i++) {
+ char c = sequence.charAt(i);
+ if (c < 0x800) {
+ utf8Length += ((0x7f - c) >>> 31); // branch free!
+ } else {
+ utf8Length += encodedLengthGeneral(sequence, i);
+ break;
+ }
+ }
+
+ if (utf8Length < utf16Length) {
+ // Necessary and sufficient condition for overflow because of maximum 3x expansion
+ throw new IllegalArgumentException("UTF-8 length does not fit in int: "
+ + (utf8Length + (1L << 32)));
+ }
+ return utf8Length;
+ }
+
+ private static int encodedLengthGeneral(CharSequence sequence, int start) {
+ int utf16Length = sequence.length();
+ int utf8Length = 0;
+ for (int i = start; i < utf16Length; i++) {
+ char c = sequence.charAt(i);
+ if (c < 0x800) {
+ utf8Length += (0x7f - c) >>> 31; // branch free!
+ } else {
+ utf8Length += 2;
+ // jdk7+: if (Character.isSurrogate(c)) {
+ if (Character.MIN_SURROGATE <= c && c <= Character.MAX_SURROGATE) {
+ // Check that we have a well-formed surrogate pair.
+ int cp = Character.codePointAt(sequence, i);
+ if (cp < MIN_SUPPLEMENTARY_CODE_POINT) {
+ throw new Utf8Safe.UnpairedSurrogateException(i, utf16Length);
+ }
+ i++;
+ }
+ }
+ }
+ return utf8Length;
+ }
+
+ private static String decodeUtf8Array(byte[] bytes, int index, int size) {
+ // Bitwise OR combines the sign bits so any negative value fails the check.
+ if ((index | size | bytes.length - index - size) < 0) {
+ throw new ArrayIndexOutOfBoundsException(
+ String.format("buffer length=%d, index=%d, size=%d", bytes.length, index, size));
+ }
+
+ int offset = index;
+ final int limit = offset + size;
+
+ // The longest possible resulting String is the same as the number of input bytes, when it is
+ // all ASCII. For other cases, this over-allocates and we will truncate in the end.
+ char[] resultArr = new char[size];
+ int resultPos = 0;
+
+ // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this).
+ // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII).
+ while (offset < limit) {
+ byte b = bytes[offset];
+ if (!DecodeUtil.isOneByte(b)) {
+ break;
+ }
+ offset++;
+ DecodeUtil.handleOneByte(b, resultArr, resultPos++);
+ }
+
+ while (offset < limit) {
+ byte byte1 = bytes[offset++];
+ if (DecodeUtil.isOneByte(byte1)) {
+ DecodeUtil.handleOneByte(byte1, resultArr, resultPos++);
+ // It's common for there to be multiple ASCII characters in a run mixed in, so add an
+ // extra optimized loop to take care of these runs.
+ while (offset < limit) {
+ byte b = bytes[offset];
+ if (!DecodeUtil.isOneByte(b)) {
+ break;
+ }
+ offset++;
+ DecodeUtil.handleOneByte(b, resultArr, resultPos++);
+ }
+ } else if (DecodeUtil.isTwoBytes(byte1)) {
+ if (offset >= limit) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleTwoBytes(byte1, /* byte2 */ bytes[offset++], resultArr, resultPos++);
+ } else if (DecodeUtil.isThreeBytes(byte1)) {
+ if (offset >= limit - 1) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleThreeBytes(
+ byte1,
+ /* byte2 */ bytes[offset++],
+ /* byte3 */ bytes[offset++],
+ resultArr,
+ resultPos++);
+ } else {
+ if (offset >= limit - 2) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleFourBytes(
+ byte1,
+ /* byte2 */ bytes[offset++],
+ /* byte3 */ bytes[offset++],
+ /* byte4 */ bytes[offset++],
+ resultArr,
+ resultPos++);
+ // 4-byte case requires two chars.
+ resultPos++;
+ }
+ }
+
+ return new String(resultArr, 0, resultPos);
+ }
+
+ private static String decodeUtf8Buffer(ByteBuffer buffer, int offset,
+ int length) {
+ // Bitwise OR combines the sign bits so any negative value fails the check.
+ if ((offset | length | buffer.limit() - offset - length) < 0) {
+ throw new ArrayIndexOutOfBoundsException(
+ String.format("buffer limit=%d, index=%d, limit=%d", buffer.limit(),
+ offset, length));
+ }
+
+ final int limit = offset + length;
+
+ // The longest possible resulting String is the same as the number of input bytes, when it is
+ // all ASCII. For other cases, this over-allocates and we will truncate in the end.
+ char[] resultArr = new char[length];
+ int resultPos = 0;
+
+ // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this).
+ // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII).
+ while (offset < limit) {
+ byte b = buffer.get(offset);
+ if (!DecodeUtil.isOneByte(b)) {
+ break;
+ }
+ offset++;
+ DecodeUtil.handleOneByte(b, resultArr, resultPos++);
+ }
+
+ while (offset < limit) {
+ byte byte1 = buffer.get(offset++);
+ if (DecodeUtil.isOneByte(byte1)) {
+ DecodeUtil.handleOneByte(byte1, resultArr, resultPos++);
+ // It's common for there to be multiple ASCII characters in a run mixed in, so add an
+ // extra optimized loop to take care of these runs.
+ while (offset < limit) {
+ byte b = buffer.get(offset);
+ if (!DecodeUtil.isOneByte(b)) {
+ break;
+ }
+ offset++;
+ DecodeUtil.handleOneByte(b, resultArr, resultPos++);
+ }
+ } else if (DecodeUtil.isTwoBytes(byte1)) {
+ if (offset >= limit) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleTwoBytes(
+ byte1, /* byte2 */ buffer.get(offset++), resultArr, resultPos++);
+ } else if (DecodeUtil.isThreeBytes(byte1)) {
+ if (offset >= limit - 1) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleThreeBytes(
+ byte1,
+ /* byte2 */ buffer.get(offset++),
+ /* byte3 */ buffer.get(offset++),
+ resultArr,
+ resultPos++);
+ } else {
+ if (offset >= limit - 2) {
+ throw new IllegalArgumentException("Invalid UTF-8");
+ }
+ DecodeUtil.handleFourBytes(
+ byte1,
+ /* byte2 */ buffer.get(offset++),
+ /* byte3 */ buffer.get(offset++),
+ /* byte4 */ buffer.get(offset++),
+ resultArr,
+ resultPos++);
+ // 4-byte case requires two chars.
+ resultPos++;
+ }
+ }
+
+ return new String(resultArr, 0, resultPos);
+ }
+
+ @Override
+ public int encodedLength(CharSequence in) {
+ return computeEncodedLength(in);
+ }
+
+ /**
+ * Decodes the given UTF-8 portion of the {@link ByteBuffer} into a {@link String}.
+ *
+ * @throws IllegalArgumentException if the input is not valid UTF-8.
+ */
+ @Override
+ public String decodeUtf8(ByteBuffer buffer, int offset, int length)
+ throws IllegalArgumentException {
+ if (buffer.hasArray()) {
+ return decodeUtf8Array(buffer.array(), buffer.arrayOffset() + offset, length);
+ } else {
+ return decodeUtf8Buffer(buffer, offset, length);
+ }
+ }
+
+
+ private static void encodeUtf8Buffer(CharSequence in, ByteBuffer out) {
+ final int inLength = in.length();
+ int outIx = out.position();
+ int inIx = 0;
+
+ // Since ByteBuffer.putXXX() already checks boundaries for us, no need to explicitly check
+ // access. Assume the buffer is big enough and let it handle the out of bounds exception
+ // if it occurs.
+ try {
+ // Designed to take advantage of
+ // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination
+ for (char c; inIx < inLength && (c = in.charAt(inIx)) < 0x80; ++inIx) {
+ out.put(outIx + inIx, (byte) c);
+ }
+ if (inIx == inLength) {
+ // Successfully encoded the entire string.
+ out.position(outIx + inIx);
+ return;
+ }
+
+ outIx += inIx;
+ for (char c; inIx < inLength; ++inIx, ++outIx) {
+ c = in.charAt(inIx);
+ if (c < 0x80) {
+ // One byte (0xxx xxxx)
+ out.put(outIx, (byte) c);
+ } else if (c < 0x800) {
+ // Two bytes (110x xxxx 10xx xxxx)
+
+ // Benchmarks show put performs better than putShort here (for HotSpot).
+ out.put(outIx++, (byte) (0xC0 | (c >>> 6)));
+ out.put(outIx, (byte) (0x80 | (0x3F & c)));
+ } else if (c < MIN_SURROGATE || MAX_SURROGATE < c) {
+ // Three bytes (1110 xxxx 10xx xxxx 10xx xxxx)
+ // Maximum single-char code point is 0xFFFF, 16 bits.
+
+ // Benchmarks show put performs better than putShort here (for HotSpot).
+ out.put(outIx++, (byte) (0xE0 | (c >>> 12)));
+ out.put(outIx++, (byte) (0x80 | (0x3F & (c >>> 6))));
+ out.put(outIx, (byte) (0x80 | (0x3F & c)));
+ } else {
+ // Four bytes (1111 xxxx 10xx xxxx 10xx xxxx 10xx xxxx)
+
+ // Minimum code point represented by a surrogate pair is 0x10000, 17 bits, four UTF-8
+ // bytes
+ final char low;
+ if (inIx + 1 == inLength || !isSurrogatePair(c, (low = in.charAt(++inIx)))) {
+ throw new UnpairedSurrogateException(inIx, inLength);
+ }
+ // TODO(nathanmittler): Consider using putInt() to improve performance.
+ int codePoint = toCodePoint(c, low);
+ out.put(outIx++, (byte) ((0xF << 4) | (codePoint >>> 18)));
+ out.put(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 12))));
+ out.put(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 6))));
+ out.put(outIx, (byte) (0x80 | (0x3F & codePoint)));
+ }
+ }
+
+ // Successfully encoded the entire string.
+ out.position(outIx);
+ } catch (IndexOutOfBoundsException e) {
+ // TODO(nathanmittler): Consider making the API throw IndexOutOfBoundsException instead.
+
+ // If we failed in the outer ASCII loop, outIx will not have been updated. In this case,
+ // use inIx to determine the bad write index.
+ int badWriteIndex = out.position() + Math.max(inIx, outIx - out.position() + 1);
+ throw new ArrayIndexOutOfBoundsException(
+ "Failed writing " + in.charAt(inIx) + " at index " + badWriteIndex);
+ }
+ }
+
+ private static int encodeUtf8Array(CharSequence in, byte[] out,
+ int offset, int length) {
+ int utf16Length = in.length();
+ int j = offset;
+ int i = 0;
+ int limit = offset + length;
+ // Designed to take advantage of
+ // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination
+ for (char c; i < utf16Length && i + j < limit && (c = in.charAt(i)) < 0x80; i++) {
+ out[j + i] = (byte) c;
+ }
+ if (i == utf16Length) {
+ return j + utf16Length;
+ }
+ j += i;
+ for (char c; i < utf16Length; i++) {
+ c = in.charAt(i);
+ if (c < 0x80 && j < limit) {
+ out[j++] = (byte) c;
+ } else if (c < 0x800 && j <= limit - 2) { // 11 bits, two UTF-8 bytes
+ out[j++] = (byte) ((0xF << 6) | (c >>> 6));
+ out[j++] = (byte) (0x80 | (0x3F & c));
+ } else if ((c < Character.MIN_SURROGATE || Character.MAX_SURROGATE < c) && j <= limit - 3) {
+ // Maximum single-char code point is 0xFFFF, 16 bits, three UTF-8 bytes
+ out[j++] = (byte) ((0xF << 5) | (c >>> 12));
+ out[j++] = (byte) (0x80 | (0x3F & (c >>> 6)));
+ out[j++] = (byte) (0x80 | (0x3F & c));
+ } else if (j <= limit - 4) {
+ // Minimum code point represented by a surrogate pair is 0x10000, 17 bits,
+ // four UTF-8 bytes
+ final char low;
+ if (i + 1 == in.length()
+ || !Character.isSurrogatePair(c, (low = in.charAt(++i)))) {
+ throw new UnpairedSurrogateException((i - 1), utf16Length);
+ }
+ int codePoint = Character.toCodePoint(c, low);
+ out[j++] = (byte) ((0xF << 4) | (codePoint >>> 18));
+ out[j++] = (byte) (0x80 | (0x3F & (codePoint >>> 12)));
+ out[j++] = (byte) (0x80 | (0x3F & (codePoint >>> 6)));
+ out[j++] = (byte) (0x80 | (0x3F & codePoint));
+ } else {
+ // If we are surrogates and we're not a surrogate pair, always throw an
+ // UnpairedSurrogateException instead of an ArrayOutOfBoundsException.
+ if ((Character.MIN_SURROGATE <= c && c <= Character.MAX_SURROGATE)
+ && (i + 1 == in.length()
+ || !Character.isSurrogatePair(c, in.charAt(i + 1)))) {
+ throw new UnpairedSurrogateException(i, utf16Length);
+ }
+ throw new ArrayIndexOutOfBoundsException("Failed writing " + c + " at index " + j);
+ }
+ }
+ return j;
+ }
+
+ /**
+ * Encodes the given characters to the target {@link ByteBuffer} using UTF-8 encoding.
+ *
+ * <p>Selects an optimal algorithm based on the type of {@link ByteBuffer} (i.e. heap or direct)
+ * and the capabilities of the platform.
+ *
+ * @param in the source string to be encoded
+ * @param out the target buffer to receive the encoded string.
+ */
+ @Override
+ public void encodeUtf8(CharSequence in, ByteBuffer out) {
+ if (out.hasArray()) {
+ int start = out.arrayOffset();
+ int end = encodeUtf8Array(in, out.array(), start + out.position(),
+ out.remaining());
+ out.position(end - start);
+ } else {
+ encodeUtf8Buffer(in, out);
+ }
+ }
+
+ // These UTF-8 handling methods are copied from Guava's Utf8Unsafe class with
+ // a modification to throw a local exception. This exception can be caught
+ // to fallback to more lenient behavior.
+ static class UnpairedSurrogateException extends IllegalArgumentException {
+ UnpairedSurrogateException(int index, int length) {
+ super("Unpaired surrogate at index " + index + " of " + length);
+ }
+ }
+}