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/* BlobBuilder.js
 * A BlobBuilder implementation.
 * 2012-04-21
 * 
 * By Eli Grey, http://eligrey.com
 * 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/BlobBuilder.js/blob/master/BlobBuilder.js */

var BlobBuilder = BlobBuilder || self.WebKitBlobBuilder || self.MozBlobBuilder || self.MSBlobBuilder || (function(view) {
"use strict";
var
          get_class = function(object) {
                return Object.prototype.toString.call(object).match(/^\[object\s(.*)\]$/)[1];
        }
        , FakeBlobBuilder = function(){
                this.data = [];
        }
        , FakeBlob = function(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
;
FakeBlobBuilder.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) {
                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;
}(self));