source: Dev/branches/rest-dojo-ui/client/dojox/uuid/generateTimeBasedUuid.js @ 256

define([ 'dojo/_base/lang', './_base'], function(lang){

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 = lang.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(lang.isArray(arrayA));
                dojox.uuid.assert(lang.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(lang.isArray(arrayA));
                dojox.uuid.assert(lang.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")
        }

}();

return dojox.uuid.generateTimeBasedUuid;

});