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generateTimeBasedUuid.js
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generateTimeBasedUuid.js
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if(!dojo._hasResource["dojox.uuid.generateTimeBasedUuid"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.
dojo._hasResource["dojox.uuid.generateTimeBasedUuid"] = true;
dojo.provide("dojox.uuid.generateTimeBasedUuid");
dojox.uuid.generateTimeBasedUuid = function(/*String?*/ node){
// summary:
// This function generates time-based UUIDs, meaning "version 1" UUIDs.
// description:
// For more info, see
// http://www.webdav.org/specs/draft-leach-uuids-guids-01.txt
// http://www.infonuovo.com/dma/csdocs/sketch/instidid.htm
// http://kruithof.xs4all.nl/uuid/uuidgen
// http://www.opengroup.org/onlinepubs/009629399/apdxa.htm#tagcjh_20
// http://jakarta.apache.org/commons/sandbox/id/apidocs/org/apache/commons/id/uuid/clock/Clock.html
// node:
// A 12-character hex string representing either a pseudo-node or
// hardware-node (an IEEE 802.3 network node). A hardware-node
// will be something like "017bf397618a", always with the first bit
// being 0. A pseudo-node will be something like "f17bf397618a",
// always with the first bit being 1.
// examples:
// string = dojox.uuid.generateTimeBasedUuid();
// string = dojox.uuid.generateTimeBasedUuid("017bf397618a");
// dojox.uuid.generateTimeBasedUuid.setNode("017bf397618a");
// string = dojox.uuid.generateTimeBasedUuid(); // the generated UUID has node == "017bf397618a"
var uuidString = dojox.uuid.generateTimeBasedUuid._generator.generateUuidString(node);
return uuidString; // String
};
dojox.uuid.generateTimeBasedUuid.isValidNode = function(/*String?*/ node){
var HEX_RADIX = 16;
var integer = parseInt(node, HEX_RADIX);
var valid = dojo.isString(node) && node.length == 12 && isFinite(integer);
return valid; // Boolean
};
dojox.uuid.generateTimeBasedUuid.setNode = function(/*String?*/ node){
// summary:
// Sets the 'node' value that will be included in generated UUIDs.
// node: A 12-character hex string representing a pseudoNode or hardwareNode.
dojox.uuid.assert((node === null) || this.isValidNode(node));
this._uniformNode = node;
};
dojox.uuid.generateTimeBasedUuid.getNode = function(){
// summary:
// Returns the 'node' value that will be included in generated UUIDs.
return this._uniformNode; // String (a 12-character hex string representing a pseudoNode or hardwareNode)
};
dojox.uuid.generateTimeBasedUuid._generator = new function(){
// Number of hours between October 15, 1582 and January 1, 1970:
this.GREGORIAN_CHANGE_OFFSET_IN_HOURS = 3394248;
// Number of seconds between October 15, 1582 and January 1, 1970:
// dojox.uuid.generateTimeBasedUuid.GREGORIAN_CHANGE_OFFSET_IN_SECONDS = 12219292800;
// --------------------------------------------------
// Private variables:
var _uuidPseudoNodeString = null;
var _uuidClockSeqString = null;
var _dateValueOfPreviousUuid = null;
var _nextIntraMillisecondIncrement = 0;
var _cachedMillisecondsBetween1582and1970 = null;
var _cachedHundredNanosecondIntervalsPerMillisecond = null;
// --------------------------------------------------
// Private constants:
var HEX_RADIX = 16;
function _carry(/* array */ arrayA){
// summary:
// Given an array which holds a 64-bit number broken into 4 16-bit
// elements, this method carries any excess bits (greater than 16-bits)
// from each array element into the next.
// arrayA: An array with 4 elements, each of which is a 16-bit number.
arrayA[2] += arrayA[3] >>> 16;
arrayA[3] &= 0xFFFF;
arrayA[1] += arrayA[2] >>> 16;
arrayA[2] &= 0xFFFF;
arrayA[0] += arrayA[1] >>> 16;
arrayA[1] &= 0xFFFF;
dojox.uuid.assert((arrayA[0] >>> 16) === 0);
}
function _get64bitArrayFromFloat(/* float */ x){
// summary:
// Given a floating point number, this method returns an array which
// holds a 64-bit number broken into 4 16-bit elements.
var result = new Array(0, 0, 0, 0);
result[3] = x % 0x10000;
x -= result[3];
x /= 0x10000;
result[2] = x % 0x10000;
x -= result[2];
x /= 0x10000;
result[1] = x % 0x10000;
x -= result[1];
x /= 0x10000;
result[0] = x;
return result; // Array with 4 elements, each of which is a 16-bit number.
}
function _addTwo64bitArrays(/* array */ arrayA, /* array */ arrayB){
// summary:
// Takes two arrays, each of which holds a 64-bit number broken into 4
// 16-bit elements, and returns a new array that holds a 64-bit number
// that is the sum of the two original numbers.
// arrayA: An array with 4 elements, each of which is a 16-bit number.
// arrayB: An array with 4 elements, each of which is a 16-bit number.
dojox.uuid.assert(dojo.isArray(arrayA));
dojox.uuid.assert(dojo.isArray(arrayB));
dojox.uuid.assert(arrayA.length == 4);
dojox.uuid.assert(arrayB.length == 4);
var result = new Array(0, 0, 0, 0);
result[3] = arrayA[3] + arrayB[3];
result[2] = arrayA[2] + arrayB[2];
result[1] = arrayA[1] + arrayB[1];
result[0] = arrayA[0] + arrayB[0];
_carry(result);
return result; // Array with 4 elements, each of which is a 16-bit number.
}
function _multiplyTwo64bitArrays(/* array */ arrayA, /* array */ arrayB){
// summary:
// Takes two arrays, each of which holds a 64-bit number broken into 4
// 16-bit elements, and returns a new array that holds a 64-bit number
// that is the product of the two original numbers.
// arrayA: An array with 4 elements, each of which is a 16-bit number.
// arrayB: An array with 4 elements, each of which is a 16-bit number.
dojox.uuid.assert(dojo.isArray(arrayA));
dojox.uuid.assert(dojo.isArray(arrayB));
dojox.uuid.assert(arrayA.length == 4);
dojox.uuid.assert(arrayB.length == 4);
var overflow = false;
if(arrayA[0] * arrayB[0] !== 0){ overflow = true; }
if(arrayA[0] * arrayB[1] !== 0){ overflow = true; }
if(arrayA[0] * arrayB[2] !== 0){ overflow = true; }
if(arrayA[1] * arrayB[0] !== 0){ overflow = true; }
if(arrayA[1] * arrayB[1] !== 0){ overflow = true; }
if(arrayA[2] * arrayB[0] !== 0){ overflow = true; }
dojox.uuid.assert(!overflow);
var result = new Array(0, 0, 0, 0);
result[0] += arrayA[0] * arrayB[3];
_carry(result);
result[0] += arrayA[1] * arrayB[2];
_carry(result);
result[0] += arrayA[2] * arrayB[1];
_carry(result);
result[0] += arrayA[3] * arrayB[0];
_carry(result);
result[1] += arrayA[1] * arrayB[3];
_carry(result);
result[1] += arrayA[2] * arrayB[2];
_carry(result);
result[1] += arrayA[3] * arrayB[1];
_carry(result);
result[2] += arrayA[2] * arrayB[3];
_carry(result);
result[2] += arrayA[3] * arrayB[2];
_carry(result);
result[3] += arrayA[3] * arrayB[3];
_carry(result);
return result; // Array with 4 elements, each of which is a 16-bit number.
}
function _padWithLeadingZeros(/* string */ string, /* int */ desiredLength){
// summary:
// Pads a string with leading zeros and returns the result.
// string: A string to add padding to.
// desiredLength: The number of characters the return string should have.
// examples:
// result = _padWithLeadingZeros("abc", 6);
// dojox.uuid.assert(result == "000abc");
while(string.length < desiredLength){
string = "0" + string;
}
return string; // string
}
function _generateRandomEightCharacterHexString() {
// summary:
// Returns a randomly generated 8-character string of hex digits.
// FIXME: This probably isn't a very high quality random number.
// Make random32bitNumber be a randomly generated floating point number
// between 0 and (4,294,967,296 - 1), inclusive.
var random32bitNumber = Math.floor( (Math.random() % 1) * Math.pow(2, 32) );
var eightCharacterString = random32bitNumber.toString(HEX_RADIX);
while(eightCharacterString.length < 8){
eightCharacterString = "0" + eightCharacterString;
}
return eightCharacterString; // String (an 8-character hex string)
}
this.generateUuidString = function(/*String?*/ node){
// summary:
// Generates a time-based UUID, meaning a version 1 UUID.
// description:
// JavaScript code running in a browser doesn't have access to the
// IEEE 802.3 address of the computer, so if a node value isn't
// supplied, we generate a random pseudonode value instead.
// node: An optional 12-character string to use as the node in the new UUID.
if(node){
dojox.uuid.assert(dojox.uuid.generateTimeBasedUuid.isValidNode(node));
}else{
if(dojox.uuid.generateTimeBasedUuid._uniformNode){
node = dojox.uuid.generateTimeBasedUuid._uniformNode;
}else{
if(!_uuidPseudoNodeString){
var pseudoNodeIndicatorBit = 0x8000;
var random15bitNumber = Math.floor( (Math.random() % 1) * Math.pow(2, 15) );
var leftmost4HexCharacters = (pseudoNodeIndicatorBit | random15bitNumber).toString(HEX_RADIX);
_uuidPseudoNodeString = leftmost4HexCharacters + _generateRandomEightCharacterHexString();
}
node = _uuidPseudoNodeString;
}
}
if(!_uuidClockSeqString){
var variantCodeForDCEUuids = 0x8000; // 10--------------, i.e. uses only first two of 16 bits.
var random14bitNumber = Math.floor( (Math.random() % 1) * Math.pow(2, 14) );
_uuidClockSeqString = (variantCodeForDCEUuids | random14bitNumber).toString(HEX_RADIX);
}
// Maybe we should think about trying to make the code more readable to
// newcomers by creating a class called "WholeNumber" that encapsulates
// the methods and data structures for working with these arrays that
// hold 4 16-bit numbers? And then these variables below have names
// like "wholeSecondsPerHour" rather than "arraySecondsPerHour"?
var now = new Date();
var millisecondsSince1970 = now.valueOf(); // milliseconds since midnight 01 January, 1970 UTC.
var nowArray = _get64bitArrayFromFloat(millisecondsSince1970);
if(!_cachedMillisecondsBetween1582and1970){
var arraySecondsPerHour = _get64bitArrayFromFloat(60 * 60);
var arrayHoursBetween1582and1970 = _get64bitArrayFromFloat(dojox.uuid.generateTimeBasedUuid._generator.GREGORIAN_CHANGE_OFFSET_IN_HOURS);
var arraySecondsBetween1582and1970 = _multiplyTwo64bitArrays(arrayHoursBetween1582and1970, arraySecondsPerHour);
var arrayMillisecondsPerSecond = _get64bitArrayFromFloat(1000);
_cachedMillisecondsBetween1582and1970 = _multiplyTwo64bitArrays(arraySecondsBetween1582and1970, arrayMillisecondsPerSecond);
_cachedHundredNanosecondIntervalsPerMillisecond = _get64bitArrayFromFloat(10000);
}
var arrayMillisecondsSince1970 = nowArray;
var arrayMillisecondsSince1582 = _addTwo64bitArrays(_cachedMillisecondsBetween1582and1970, arrayMillisecondsSince1970);
var arrayHundredNanosecondIntervalsSince1582 = _multiplyTwo64bitArrays(arrayMillisecondsSince1582, _cachedHundredNanosecondIntervalsPerMillisecond);
if(now.valueOf() == _dateValueOfPreviousUuid){
arrayHundredNanosecondIntervalsSince1582[3] += _nextIntraMillisecondIncrement;
_carry(arrayHundredNanosecondIntervalsSince1582);
_nextIntraMillisecondIncrement += 1;
if (_nextIntraMillisecondIncrement == 10000) {
// If we've gotten to here, it means we've already generated 10,000
// UUIDs in this single millisecond, which is the most that the UUID
// timestamp field allows for. So now we'll just sit here and wait
// for a fraction of a millisecond, so as to ensure that the next
// time this method is called there will be a different millisecond
// value in the timestamp field.
while (now.valueOf() == _dateValueOfPreviousUuid) {
now = new Date();
}
}
}else{
_dateValueOfPreviousUuid = now.valueOf();
_nextIntraMillisecondIncrement = 1;
}
var hexTimeLowLeftHalf = arrayHundredNanosecondIntervalsSince1582[2].toString(HEX_RADIX);
var hexTimeLowRightHalf = arrayHundredNanosecondIntervalsSince1582[3].toString(HEX_RADIX);
var hexTimeLow = _padWithLeadingZeros(hexTimeLowLeftHalf, 4) + _padWithLeadingZeros(hexTimeLowRightHalf, 4);
var hexTimeMid = arrayHundredNanosecondIntervalsSince1582[1].toString(HEX_RADIX);
hexTimeMid = _padWithLeadingZeros(hexTimeMid, 4);
var hexTimeHigh = arrayHundredNanosecondIntervalsSince1582[0].toString(HEX_RADIX);
hexTimeHigh = _padWithLeadingZeros(hexTimeHigh, 3);
var hyphen = "-";
var versionCodeForTimeBasedUuids = "1"; // binary2hex("0001")
var resultUuid = hexTimeLow + hyphen + hexTimeMid + hyphen +
versionCodeForTimeBasedUuids + hexTimeHigh + hyphen +
_uuidClockSeqString + hyphen + node;
resultUuid = resultUuid.toLowerCase();
return resultUuid; // String (a 36 character string, which will look something like "b4308fb0-86cd-11da-a72b-0800200c9a66")
}
}();
}

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