Down-integrate from internal code base.

1 files changed, 1005 insertions, 0 deletions

diff --git a/js/binary/decoder.js b/js/binary/decoder.js
new file mode 100644
index 00000000..9004eff0
--- /dev/null
+++ b/js/binary/decoder.js
@@ -0,0 +1,1005 @@
+// 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.
+
+/**
+ * @fileoverview This file contains utilities for decoding primitive values
+ * (signed and unsigned integers, varints, booleans, enums, hashes, strings,
+ * and raw bytes) embedded in Uint8Arrays into their corresponding Javascript
+ * types.
+ *
+ * Major caveat - Javascript is unable to accurately represent integers larger
+ * than 2^53 due to its use of a double-precision floating point format or all
+ * numbers. If you need to guarantee that 64-bit values survive with all bits
+ * intact, you _must_ read them using one of the Hash64 methods, which return
+ * an 8-character string.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.BinaryDecoder');
+goog.provide('jspb.BinaryIterator');
+
+goog.require('goog.asserts');
+goog.require('jspb.utils');
+
+
+
+/**
+ * Simple helper class for traversing the contents of repeated scalar fields.
+ * that may or may not have been packed into a wire-format blob.
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @constructor
+ * @struct
+ */
+jspb.BinaryIterator = function(opt_decoder, opt_next, opt_elements) {
+  /** @private {jspb.BinaryDecoder} */
+  this.decoder_ = null;
+
+  /**
+   * The BinaryDecoder member function used when iterating over packed data.
+   * @private {?function(this:jspb.BinaryDecoder):(number|boolean|string)}
+   */
+  this.nextMethod_ = null;
+
+  /** @private {Array.<number>} */
+  this.elements_ = null;
+
+  /** @private {number} */
+  this.cursor_ = 0;
+
+  /** @private {number|boolean|string|null} */
+  this.nextValue_ = null;
+
+  /** @private {boolean} */
+  this.atEnd_ = true;
+
+  this.init_(opt_decoder, opt_next, opt_elements);
+};
+
+
+/**
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @private
+ */
+jspb.BinaryIterator.prototype.init_ =
+    function(opt_decoder, opt_next, opt_elements) {
+  if (opt_decoder && opt_next) {
+    this.decoder_ = opt_decoder;
+    this.nextMethod_ = opt_next;
+  }
+  this.elements_ = opt_elements ? opt_elements : null;
+  this.cursor_ = 0;
+  this.nextValue_ = null;
+  this.atEnd_ = !this.decoder_ && !this.elements_;
+
+  this.next();
+};
+
+
+/**
+ * Global pool of BinaryIterator instances.
+ * @private {!Array.<!jspb.BinaryIterator>}
+ */
+jspb.BinaryIterator.instanceCache_ = [];
+
+
+/**
+ * Allocates a BinaryIterator from the cache, creating a new one if the cache
+ * is empty.
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @return {!jspb.BinaryIterator}
+ */
+jspb.BinaryIterator.alloc = function(opt_decoder, opt_next, opt_elements) {
+  if (jspb.BinaryIterator.instanceCache_.length) {
+    var iterator = jspb.BinaryIterator.instanceCache_.pop();
+    iterator.init_(opt_decoder, opt_next, opt_elements);
+    return iterator;
+  } else {
+    return new jspb.BinaryIterator(opt_decoder, opt_next, opt_elements);
+  }
+};
+
+
+/**
+ * Puts this instance back in the instance cache.
+ */
+jspb.BinaryIterator.prototype.free = function() {
+  this.clear();
+  if (jspb.BinaryIterator.instanceCache_.length < 100) {
+    jspb.BinaryIterator.instanceCache_.push(this);
+  }
+};
+
+
+/**
+ * Clears the iterator.
+ */
+jspb.BinaryIterator.prototype.clear = function() {
+  if (this.decoder_) {
+    this.decoder_.free();
+  }
+  this.decoder_ = null;
+  this.nextMethod_ = null;
+  this.elements_ = null;
+  this.cursor_ = 0;
+  this.nextValue_ = null;
+  this.atEnd_ = true;
+};
+
+
+/**
+ * Returns the element at the iterator, or null if the iterator is invalid or
+ * past the end of the decoder/array.
+ * @return {number|boolean|string|null}
+ */
+jspb.BinaryIterator.prototype.get = function() {
+  return this.nextValue_;
+};
+
+
+/**
+ * Returns true if the iterator is at the end of the decoder/array.
+ * @return {boolean}
+ */
+jspb.BinaryIterator.prototype.atEnd = function() {
+  return this.atEnd_;
+};
+
+
+/**
+ * Returns the element at the iterator and steps to the next element,
+ * equivalent to '*pointer++' in C.
+ * @return {number|boolean|string|null}
+ */
+jspb.BinaryIterator.prototype.next = function() {
+  var lastValue = this.nextValue_;
+  if (this.decoder_) {
+    if (this.decoder_.atEnd()) {
+      this.nextValue_ = null;
+      this.atEnd_ = true;
+    } else {
+      this.nextValue_ = this.nextMethod_.call(this.decoder_);
+    }
+  } else if (this.elements_) {
+    if (this.cursor_ == this.elements_.length) {
+      this.nextValue_ = null;
+      this.atEnd_ = true;
+    } else {
+      this.nextValue_ = this.elements_[this.cursor_++];
+    }
+  }
+  return lastValue;
+};
+
+
+
+/**
+ * BinaryDecoder implements the decoders for all the wire types specified in
+ * https://developers.google.com/protocol-buffers/docs/encoding.
+ *
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @constructor
+ * @struct
+ */
+jspb.BinaryDecoder = function(opt_bytes, opt_start, opt_length) {
+  /**
+   * Typed byte-wise view of the source buffer.
+   * @private {Uint8Array}
+   */
+  this.bytes_ = null;
+
+  /**
+   * Start point of the block to read.
+   * @private {number}
+   */
+  this.start_ = 0;
+
+  /**
+   * End point of the block to read.
+   * @private {number}
+   */
+  this.end_ = 0;
+
+  /**
+   * Current read location in bytes_.
+   * @private {number}
+   */
+  this.cursor_ = 0;
+
+  /**
+   * Temporary storage for the low 32 bits of 64-bit data types that we're
+   * decoding.
+   * @private {number}
+   */
+  this.tempLow_ = 0;
+
+  /**
+   * Temporary storage for the high 32 bits of 64-bit data types that we're
+   * decoding.
+   * @private {number}
+   */
+  this.tempHigh_ = 0;
+
+  /**
+   * Set to true if this decoder encountered an error due to corrupt data.
+   * @private {boolean}
+   */
+  this.error_ = false;
+
+  if (opt_bytes) {
+    this.setBlock(opt_bytes, opt_start, opt_length);
+  }
+};
+
+
+/**
+ * Global pool of BinaryDecoder instances.
+ * @private {!Array.<!jspb.BinaryDecoder>}
+ */
+jspb.BinaryDecoder.instanceCache_ = [];
+
+
+/**
+ * Pops an instance off the instance cache, or creates one if the cache is
+ * empty.
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @return {!jspb.BinaryDecoder}
+ */
+jspb.BinaryDecoder.alloc = function(opt_bytes, opt_start, opt_length) {
+  if (jspb.BinaryDecoder.instanceCache_.length) {
+    var newDecoder = jspb.BinaryDecoder.instanceCache_.pop();
+    if (opt_bytes) {
+      newDecoder.setBlock(opt_bytes, opt_start, opt_length);
+    }
+    return newDecoder;
+  } else {
+    return new jspb.BinaryDecoder(opt_bytes, opt_start, opt_length);
+  }
+};
+
+
+/**
+ * Puts this instance back in the instance cache.
+ */
+jspb.BinaryDecoder.prototype.free = function() {
+  this.clear();
+  if (jspb.BinaryDecoder.instanceCache_.length < 100) {
+    jspb.BinaryDecoder.instanceCache_.push(this);
+  }
+};
+
+
+/**
+ * Makes a copy of this decoder.
+ * @return {!jspb.BinaryDecoder}
+ */
+jspb.BinaryDecoder.prototype.clone = function() {
+  return jspb.BinaryDecoder.alloc(this.bytes_,
+      this.start_, this.end_ - this.start_);
+};
+
+
+/**
+ * Clears the decoder.
+ */
+jspb.BinaryDecoder.prototype.clear = function() {
+  this.bytes_ = null;
+  this.start_ = 0;
+  this.end_ = 0;
+  this.cursor_ = 0;
+  this.error_ = false;
+};
+
+
+/**
+ * Returns the raw buffer.
+ * @return {Uint8Array} The raw buffer.
+ */
+jspb.BinaryDecoder.prototype.getBuffer = function() {
+  return this.bytes_;
+};
+
+
+/**
+ * Changes the block of bytes we're decoding.
+ * @param {!jspb.ByteSource} data The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ */
+jspb.BinaryDecoder.prototype.setBlock =
+    function(data, opt_start, opt_length) {
+  this.bytes_ = jspb.utils.byteSourceToUint8Array(data);
+  this.start_ = goog.isDef(opt_start) ? opt_start : 0;
+  this.end_ =
+      goog.isDef(opt_length) ? this.start_ + opt_length : this.bytes_.length;
+  this.cursor_ = this.start_;
+};
+
+
+/**
+ * @return {number}
+ */
+jspb.BinaryDecoder.prototype.getEnd = function() {
+  return this.end_;
+};
+
+
+/**
+ * @param {number} end
+ */
+jspb.BinaryDecoder.prototype.setEnd = function(end) {
+  this.end_ = end;
+};
+
+
+/**
+ * Moves the read cursor back to the start of the block.
+ */
+jspb.BinaryDecoder.prototype.reset = function() {
+  this.cursor_ = this.start_;
+};
+
+
+/**
+ * Returns the internal read cursor.
+ * @return {number} The internal read cursor.
+ */
+jspb.BinaryDecoder.prototype.getCursor = function() {
+  return this.cursor_;
+};
+
+
+/**
+ * Returns the internal read cursor.
+ * @param {number} cursor The new cursor.
+ */
+jspb.BinaryDecoder.prototype.setCursor = function(cursor) {
+  this.cursor_ = cursor;
+};
+
+
+/**
+ * Advances the stream cursor by the given number of bytes.
+ * @param {number} count The number of bytes to advance by.
+ */
+jspb.BinaryDecoder.prototype.advance = function(count) {
+  this.cursor_ += count;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+};
+
+
+/**
+ * Returns true if this decoder is at the end of the block.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.atEnd = function() {
+  return this.cursor_ == this.end_;
+};
+
+
+/**
+ * Returns true if this decoder is at the end of the block.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.pastEnd = function() {
+  return this.cursor_ > this.end_;
+};
+
+
+/**
+ * Returns true if this decoder encountered an error due to corrupt data.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.getError = function() {
+  return this.error_ ||
+         (this.cursor_ < 0) ||
+         (this.cursor_ > this.end_);
+};
+
+
+/**
+ * Reads an unsigned varint from the binary stream and stores it as a split
+ * 64-bit integer. Since this does not convert the value to a number, no
+ * precision is lost.
+ *
+ * It's possible for an unsigned varint to be incorrectly encoded - more than
+ * 64 bits' worth of data could be present. If this happens, this method will
+ * throw an error.
+ *
+ * Decoding varints requires doing some funny base-128 math - for more
+ * details on the format, see
+ * https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @private
+ */
+jspb.BinaryDecoder.prototype.readSplitVarint64_ = function() {
+  var temp;
+  var lowBits = 0;
+  var highBits = 0;
+
+  // Read the first four bytes of the varint, stopping at the terminator if we
+  // see it.
+  for (var i = 0; i < 4; i++) {
+    temp = this.bytes_[this.cursor_++];
+    lowBits |= (temp & 0x7F) << (i * 7);
+    if (temp < 128) {
+      this.tempLow_ = lowBits >>> 0;
+      this.tempHigh_ = 0;
+      return;
+    }
+  }
+
+  // Read the fifth byte, which straddles the low and high dwords.
+  temp = this.bytes_[this.cursor_++];
+  lowBits |= (temp & 0x7F) << 28;
+  highBits |= (temp & 0x7F) >> 4;
+  if (temp < 128) {
+    this.tempLow_ = lowBits >>> 0;
+    this.tempHigh_ = highBits >>> 0;
+    return;
+  }
+
+  // Read the sixth through tenth byte.
+  for (var i = 0; i < 5; i++) {
+    temp = this.bytes_[this.cursor_++];
+    highBits |= (temp & 0x7F) << (i * 7 + 3);
+    if (temp < 128) {
+      this.tempLow_ = lowBits >>> 0;
+      this.tempHigh_ = highBits >>> 0;
+      return;
+    }
+  }
+
+  // If we did not see the terminator, the encoding was invalid.
+  goog.asserts.fail('Failed to read varint, encoding is invalid.');
+  this.error_ = true;
+};
+
+
+/**
+ * Skips over a varint in the block without decoding it.
+ */
+jspb.BinaryDecoder.prototype.skipVarint = function() {
+  while (this.bytes_[this.cursor_] & 0x80) {
+    this.cursor_++;
+  }
+  this.cursor_++;
+};
+
+
+/**
+ * Skips backwards over a varint in the block - to do this correctly, we have
+ * to know the value we're skipping backwards over or things are ambiguous.
+ * @param {number} value The varint value to unskip.
+ */
+jspb.BinaryDecoder.prototype.unskipVarint = function(value) {
+  while (value > 128) {
+    this.cursor_--;
+    value = value >>> 7;
+  }
+  this.cursor_--;
+};
+
+
+/**
+ * Reads a 32-bit varint from the binary stream. Due to a quirk of the encoding
+ * format and Javascript's handling of bitwise math, this actually works
+ * correctly for both signed and unsigned 32-bit varints.
+ *
+ * This function is called vastly more frequently than any other in
+ * BinaryDecoder, so it has been unrolled and tweaked for performance.
+ *
+ * If there are more than 32 bits of data in the varint, it _must_ be due to
+ * sign-extension. If we're in debug mode and the high 32 bits don't match the
+ * expected sign extension, this method will throw an error.
+ *
+ * Decoding varints requires doing some funny base-128 math - for more
+ * details on the format, see
+ * https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded unsigned 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint32 = function() {
+  var temp;
+  var bytes = this.bytes_;
+
+  temp = bytes[this.cursor_ + 0];
+  var x = (temp & 0x7F);
+  if (temp < 128) {
+    this.cursor_ += 1;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 1];
+  x |= (temp & 0x7F) << 7;
+  if (temp < 128) {
+    this.cursor_ += 2;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 2];
+  x |= (temp & 0x7F) << 14;
+  if (temp < 128) {
+    this.cursor_ += 3;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 3];
+  x |= (temp & 0x7F) << 21;
+  if (temp < 128) {
+    this.cursor_ += 4;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 4];
+  x |= (temp & 0x0F) << 28;
+  if (temp < 128) {
+    // We're reading the high bits of an unsigned varint. The byte we just read
+    // also contains bits 33 through 35, which we're going to discard. Those
+    // bits _must_ be zero, or the encoding is invalid.
+    goog.asserts.assert((temp & 0xF0) == 0);
+    this.cursor_ += 5;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x >>> 0;
+  }
+
+  // If we get here, we're reading the sign extension of a negative 32-bit int.
+  // We can skip these bytes, as we know in advance that they have to be all
+  // 1's if the varint is correctly encoded. Since we also know the value is
+  // negative, we don't have to coerce it to unsigned before we return it.
+
+  goog.asserts.assert((temp & 0xF0) == 0xF0);
+  goog.asserts.assert(bytes[this.cursor_ + 5] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 6] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 7] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 8] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 9] == 0x01);
+
+  this.cursor_ += 10;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return x;
+};
+
+
+/**
+ * The readUnsignedVarint32 above deals with signed 32-bit varints correctly,
+ * so this is just an alias.
+ *
+ * @return {number} The decoded signed 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint32 =
+    jspb.BinaryDecoder.prototype.readUnsignedVarint32;
+
+
+/**
+ * Reads a 32-bit unsigned variant and returns its value as a string.
+ *
+ * @return {string} The decoded unsigned 32-bit varint as a string.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint32String = function() {
+  // 32-bit integers fit in JavaScript numbers without loss of precision, so
+  // string variants of 32-bit varint readers can simply delegate then convert
+  // to string.
+  var value = this.readUnsignedVarint32();
+  return value.toString();
+};
+
+/**
+ * Reads a 32-bit signed variant and returns its value as a string.
+ *
+ * @return {string} The decoded signed 32-bit varint as a string.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint32String = function() {
+  // 32-bit integers fit in JavaScript numbers without loss of precision, so
+  // string variants of 32-bit varint readers can simply delegate then convert
+  // to string.
+  var value = this.readSignedVarint32();
+  return value.toString();
+};
+
+
+/**
+ * Reads a signed, zigzag-encoded 32-bit varint from the binary stream.
+ *
+ * Zigzag encoding is a modification of varint encoding that reduces the
+ * storage overhead for small negative integers - for more details on the
+ * format, see https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded signed, zigzag-encoded 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readZigzagVarint32 = function() {
+  var result = this.readUnsignedVarint32();
+  return (result >>> 1) ^ - (result & 1);
+};
+
+
+/**
+ * Reads an unsigned 64-bit varint from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the varint is larger than 2^53.
+ *
+ * @return {number} The decoded unsigned varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinUint64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads an unsigned 64-bit varint from the binary stream and returns the value
+ * as a decimal string.
+ *
+ * @return {string} The decoded unsigned varint as a decimal string.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint64String = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinUnsignedDecimalString(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a signed 64-bit varint from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the varint is larger than 2^53.
+ *
+ * @return {number} The decoded signed varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinInt64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads an signed 64-bit varint from the binary stream and returns the value
+ * as a decimal string.
+ *
+ * @return {string} The decoded signed varint as a decimal string.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint64String = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinSignedDecimalString(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a signed, zigzag-encoded 64-bit varint from the binary stream. Note
+ * that since Javascript represents all numbers as double-precision floats,
+ * there will be precision lost if the absolute value of the varint is larger
+ * than 2^53.
+ *
+ * Zigzag encoding is a modification of varint encoding that reduces the
+ * storage overhead for small negative integers - for more details on the
+ * format, see https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded zigzag varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readZigzagVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinZigzag64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a raw unsigned 8-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 8-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint8 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  this.cursor_ += 1;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return a;
+};
+
+
+/**
+ * Reads a raw unsigned 16-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 16-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint16 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  this.cursor_ += 2;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 0) | (b << 8);
+};
+
+
+/**
+ * Reads a raw unsigned 32-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 32-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint32 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  var c = this.bytes_[this.cursor_ + 2];
+  var d = this.bytes_[this.cursor_ + 3];
+  this.cursor_ += 4;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return ((a << 0) | (b << 8) | (c << 16) | (d << 24)) >>> 0;
+};
+
+
+/**
+ * Reads a raw unsigned 64-bit integer from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the integer is larger than 2^53.
+ *
+ * @return {number} The unsigned 64-bit integer read from the binary stream.
+ *     Precision will be lost if the integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readUint64 = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinUint64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a raw signed 8-bit integer from the binary stream.
+ *
+ * @return {number} The signed 8-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt8 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  this.cursor_ += 1;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 24) >> 24;
+};
+
+
+/**
+ * Reads a raw signed 16-bit integer from the binary stream.
+ *
+ * @return {number} The signed 16-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt16 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  this.cursor_ += 2;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (((a << 0) | (b << 8)) << 16) >> 16;
+};
+
+
+/**
+ * Reads a raw signed 32-bit integer from the binary stream.
+ *
+ * @return {number} The signed 32-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt32 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  var c = this.bytes_[this.cursor_ + 2];
+  var d = this.bytes_[this.cursor_ + 3];
+  this.cursor_ += 4;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 0) | (b << 8) | (c << 16) | (d << 24);
+};
+
+
+/**
+ * Reads a raw signed 64-bit integer from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute vlaue of the integer is larger than 2^53.
+ *
+ * @return {number} The signed 64-bit integer read from the binary stream.
+ *     Precision will be lost if the integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readInt64 = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinInt64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a 32-bit floating-point number from the binary stream, using the
+ * temporary buffer to realign the data.
+ *
+ * @return {number} The float read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readFloat = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = 0;
+  return jspb.utils.joinFloat32(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a 64-bit floating-point number from the binary stream, using the
+ * temporary buffer to realign the data.
+ *
+ * @return {number} The double read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readDouble = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinFloat64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a boolean value from the binary stream.
+ * @return {boolean} The boolean read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readBool = function() {
+  return !!this.bytes_[this.cursor_++];
+};
+
+
+/**
+ * Reads an enum value from the binary stream, which are always encoded as
+ * signed varints.
+ * @return {number} The enum value read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readEnum = function() {
+  return this.readSignedVarint32();
+};
+
+
+/**
+ * Reads and parses a UTF-8 encoded unicode string from the stream.
+ * The code is inspired by maps.vectortown.parse.StreamedDataViewReader, with
+ * the exception that the implementation here does not get confused if it
+ * encounters characters longer than three bytes. These characters are ignored
+ * though, as they are extremely rare: three UTF-8 bytes cover virtually all
+ * characters in common use (http://en.wikipedia.org/wiki/UTF-8).
+ * @param {number} length The length of the string to read.
+ * @return {string} The decoded string.
+ */
+jspb.BinaryDecoder.prototype.readString = function(length) {
+  var bytes = this.bytes_;
+  var cursor = this.cursor_;
+  var end = cursor + length;
+  var chars = [];
+
+  while (cursor < end) {
+    var c = bytes[cursor++];
+    if (c < 128) { // Regular 7-bit ASCII.
+      chars.push(c);
+    } else if (c < 192) {
+      // UTF-8 continuation mark. We are out of sync. This
+      // might happen if we attempted to read a character
+      // with more than three bytes.
+      continue;
+    } else if (c < 224) { // UTF-8 with two bytes.
+      var c2 = bytes[cursor++];
+      chars.push(((c & 31) << 6) | (c2 & 63));
+    } else if (c < 240) { // UTF-8 with three bytes.
+      var c2 = bytes[cursor++];
+      var c3 = bytes[cursor++];
+      chars.push(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
+    }
+  }
+
+  // String.fromCharCode.apply is faster than manually appending characters on
+  // Chrome 25+, and generates no additional cons string garbage.
+  var result = String.fromCharCode.apply(null, chars);
+  this.cursor_ = cursor;
+  return result;
+};
+
+
+/**
+ * Reads and parses a UTF-8 encoded unicode string (with length prefix) from
+ * the stream.
+ * @return {string} The decoded string.
+ */
+jspb.BinaryDecoder.prototype.readStringWithLength = function() {
+  var length = this.readUnsignedVarint32();
+  return this.readString(length);
+};
+
+
+/**
+ * Reads a block of raw bytes from the binary stream.
+ *
+ * @param {number} length The number of bytes to read.
+ * @return {Uint8Array} The decoded block of bytes, or null if the length was
+ *     invalid.
+ */
+jspb.BinaryDecoder.prototype.readBytes = function(length) {
+  if (length < 0 ||
+      this.cursor_ + length > this.bytes_.length) {
+    this.error_ = true;
+    return null;
+  }
+
+  var result = this.bytes_.subarray(this.cursor_, this.cursor_ + length);
+
+  this.cursor_ += length;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return result;
+};
+
+
+/**
+ * Reads a 64-bit varint from the stream and returns it as an 8-character
+ * Unicode string for use as a hash table key.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryDecoder.prototype.readVarintHash64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinHash64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a 64-bit fixed-width value from the stream and returns it as an
+ * 8-character Unicode string for use as a hash table key.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryDecoder.prototype.readFixedHash64 = function() {
+  var bytes = this.bytes_;
+  var cursor = this.cursor_;
+
+  var a = bytes[cursor + 0];
+  var b = bytes[cursor + 1];
+  var c = bytes[cursor + 2];
+  var d = bytes[cursor + 3];
+  var e = bytes[cursor + 4];
+  var f = bytes[cursor + 5];
+  var g = bytes[cursor + 6];
+  var h = bytes[cursor + 7];
+
+  this.cursor_ += 8;
+
+  return String.fromCharCode(a, b, c, d, e, f, g, h);
+};