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/* Blob.js
 * A Blob implementation.
 * 2013-01-23
 * 
 * By Eli Grey, http://eligrey.com
 * By Devin Samarin, https://github.com/eboyjr
 * License: X11/MIT
 *   See LICENSE.md
 */

/*global self, unescape */
/*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
  plusplus: true */

/*! @source http://purl.eligrey.com/github/Blob.js/blob/master/Blob.js */

if (typeof Blob !== "function")
var Blob = (function (view) {
        "use strict";

        var BlobBuilder = view.BlobBuilder || view.WebKitBlobBuilder || view.MozBlobBuilder || view.MSBlobBuilder || (function(view) {
                var
                          get_class = function(object) {
                                return Object.prototype.toString.call(object).match(/^\[object\s(.*)\]$/)[1];
                        }
                        , FakeBlobBuilder = function BlobBuilder() {
                                this.data = [];
                        }
                        , FakeBlob = function Blob(data, type, encoding) {
                                this.data = data;
                                this.size = data.length;
                                this.type = type;
                                this.encoding = encoding;
                        }
                        , FBB_proto = FakeBlobBuilder.prototype
                        , FB_proto = FakeBlob.prototype
                        , FileReaderSync = view.FileReaderSync
                        , FileException = function(type) {
                                this.code = this[this.name = type];
                        }
                        , file_ex_codes = (
                                  "NOT_FOUND_ERR SECURITY_ERR ABORT_ERR NOT_READABLE_ERR ENCODING_ERR "
                                + "NO_MODIFICATION_ALLOWED_ERR INVALID_STATE_ERR SYNTAX_ERR"
                        ).split(" ")
                        , file_ex_code = file_ex_codes.length
                        , real_URL = view.URL || view.webkitURL || view
                        , real_create_object_URL = real_URL.createObjectURL
                        , real_revoke_object_URL = real_URL.revokeObjectURL
                        , URL = real_URL
                        , btoa = view.btoa
                        , atob = view.atob
                        , can_apply_typed_arrays = false
                        , can_apply_typed_arrays_test = function(pass) {
                                can_apply_typed_arrays = !pass;
                        }
                        
                        , ArrayBuffer = view.ArrayBuffer
                        , Uint8Array = view.Uint8Array
                ;
                FakeBlob.fake = FB_proto.fake = true;
                while (file_ex_code--) {
                        FileException.prototype[file_ex_codes[file_ex_code]] = file_ex_code + 1;
                }
                try {
                        if (Uint8Array) {
                                can_apply_typed_arrays_test.apply(0, new Uint8Array(1));
                        }
                } catch (ex) {}
                if (!real_URL.createObjectURL) {
                        URL = view.URL = {};
                }
                URL.createObjectURL = function(blob) {
                        var
                                  type = blob.type
                                , data_URI_header
                        ;
                        if (type === null) {
                                type = "application/octet-stream";
                        }
                        if (blob instanceof FakeBlob) {
                                data_URI_header = "data:" + type;
                                if (blob.encoding === "base64") {
                                        return data_URI_header + ";base64," + blob.data;
                                } else if (blob.encoding === "URI") {
                                        return data_URI_header + "," + decodeURIComponent(blob.data);
                                } if (btoa) {
                                        return data_URI_header + ";base64," + btoa(blob.data);
                                } else {
                                        return data_URI_header + "," + encodeURIComponent(blob.data);
                                }
                        } else if (real_create_object_URL) {
                                return real_create_object_URL.call(real_URL, blob);
                        }
                };
                URL.revokeObjectURL = function(object_URL) {
                        if (object_URL.substring(0, 5) !== "data:" && real_revoke_object_URL) {
                                real_revoke_object_URL.call(real_URL, object_URL);
                        }
                };
                FBB_proto.append = function(data/*, endings*/) {
                        var bb = this.data;
                        // decode data to a binary string
                        if (Uint8Array && (data instanceof ArrayBuffer || data instanceof Uint8Array)) {
                                if (can_apply_typed_arrays) {
                                        bb.push(String.fromCharCode.apply(String, new Uint8Array(data)));
                                } else {
                                        var
                                                  str = ""
                                                , buf = new Uint8Array(data)
                                                , i = 0
                                                , buf_len = buf.length
                                        ;
                                        for (; i < buf_len; i++) {
                                                str += String.fromCharCode(buf[i]);
                                        }
                                }
                        } else if (get_class(data) === "Blob" || get_class(data) === "File") {
                                if (FileReaderSync) {
                                        var fr = new FileReaderSync;
                                        bb.push(fr.readAsBinaryString(data));
                                } else {
                                        // async FileReader won't work as BlobBuilder is sync
                                        throw new FileException("NOT_READABLE_ERR");
                                }
                        } else if (data instanceof FakeBlob) {
                                if (data.encoding === "base64" && atob) {
                                        bb.push(atob(data.data));
                                } else if (data.encoding === "URI") {
                                        bb.push(decodeURIComponent(data.data));
                                } else if (data.encoding === "raw") {
                                        bb.push(data.data);
                                }
                        } else {
                                if (typeof data !== "string") {
                                        data += ""; // convert unsupported types to strings
                                }
                                // decode UTF-16 to binary string
                                bb.push(unescape(encodeURIComponent(data)));
                        }
                };
                FBB_proto.getBlob = function(type) {
                        if (!arguments.length) {
                                type = null;
                        }
                        return new FakeBlob(this.data.join(""), type, "raw");
                };
                FBB_proto.toString = function() {
                        return "[object BlobBuilder]";
                };
                FB_proto.slice = function(start, end, type) {
                        var args = arguments.length;
                        if (args < 3) {
                                type = null;
                        }
                        return new FakeBlob(
                                  this.data.slice(start, args > 1 ? end : this.data.length)
                                , type
                                , this.encoding
                        );
                };
                FB_proto.toString = function() {
                        return "[object Blob]";
                };
                return FakeBlobBuilder;
        }(view));

        return function Blob(blobParts, options) {
                var type = options ? (options.type || "") : "";
                var builder = new BlobBuilder();
                if (blobParts) {
                        for (var i = 0, len = blobParts.length; i < len; i++) {
                                builder.append(blobParts[i]);
                        }
                }
                return builder.getBlob(type);
        };
}(self));