--- /dev/null
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var Buffer = require('buffer').Buffer;
+
+var isBufferEncoding = Buffer.isEncoding
+ || function(encoding) {
+ switch (encoding && encoding.toLowerCase()) {
+ case 'hex': case 'utf8': case 'utf-8': case 'ascii': case 'binary': case 'base64': case 'ucs2': case 'ucs-2': case 'utf16le': case 'utf-16le': case 'raw': return true;
+ default: return false;
+ }
+ }
+
+
+function assertEncoding(encoding) {
+ if (encoding && !isBufferEncoding(encoding)) {
+ throw new Error('Unknown encoding: ' + encoding);
+ }
+}
+
+// StringDecoder provides an interface for efficiently splitting a series of
+// buffers into a series of JS strings without breaking apart multi-byte
+// characters. CESU-8 is handled as part of the UTF-8 encoding.
+//
+// @TODO Handling all encodings inside a single object makes it very difficult
+// to reason about this code, so it should be split up in the future.
+// @TODO There should be a utf8-strict encoding that rejects invalid UTF-8 code
+// points as used by CESU-8.
+var StringDecoder = exports.StringDecoder = function(encoding) {
+ this.encoding = (encoding || 'utf8').toLowerCase().replace(/[-_]/, '');
+ assertEncoding(encoding);
+ switch (this.encoding) {
+ case 'utf8':
+ // CESU-8 represents each of Surrogate Pair by 3-bytes
+ this.surrogateSize = 3;
+ break;
+ case 'ucs2':
+ case 'utf16le':
+ // UTF-16 represents each of Surrogate Pair by 2-bytes
+ this.surrogateSize = 2;
+ this.detectIncompleteChar = utf16DetectIncompleteChar;
+ break;
+ case 'base64':
+ // Base-64 stores 3 bytes in 4 chars, and pads the remainder.
+ this.surrogateSize = 3;
+ this.detectIncompleteChar = base64DetectIncompleteChar;
+ break;
+ default:
+ this.write = passThroughWrite;
+ return;
+ }
+
+ // Enough space to store all bytes of a single character. UTF-8 needs 4
+ // bytes, but CESU-8 may require up to 6 (3 bytes per surrogate).
+ this.charBuffer = new Buffer(6);
+ // Number of bytes received for the current incomplete multi-byte character.
+ this.charReceived = 0;
+ // Number of bytes expected for the current incomplete multi-byte character.
+ this.charLength = 0;
+};
+
+
+// write decodes the given buffer and returns it as JS string that is
+// guaranteed to not contain any partial multi-byte characters. Any partial
+// character found at the end of the buffer is buffered up, and will be
+// returned when calling write again with the remaining bytes.
+//
+// Note: Converting a Buffer containing an orphan surrogate to a String
+// currently works, but converting a String to a Buffer (via `new Buffer`, or
+// Buffer#write) will replace incomplete surrogates with the unicode
+// replacement character. See https://codereview.chromium.org/121173009/ .
+StringDecoder.prototype.write = function(buffer) {
+ var charStr = '';
+ // if our last write ended with an incomplete multibyte character
+ while (this.charLength) {
+ // determine how many remaining bytes this buffer has to offer for this char
+ var available = (buffer.length >= this.charLength - this.charReceived) ?
+ this.charLength - this.charReceived :
+ buffer.length;
+
+ // add the new bytes to the char buffer
+ buffer.copy(this.charBuffer, this.charReceived, 0, available);
+ this.charReceived += available;
+
+ if (this.charReceived < this.charLength) {
+ // still not enough chars in this buffer? wait for more ...
+ return '';
+ }
+
+ // remove bytes belonging to the current character from the buffer
+ buffer = buffer.slice(available, buffer.length);
+
+ // get the character that was split
+ charStr = this.charBuffer.slice(0, this.charLength).toString(this.encoding);
+
+ // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character
+ var charCode = charStr.charCodeAt(charStr.length - 1);
+ if (charCode >= 0xD800 && charCode <= 0xDBFF) {
+ this.charLength += this.surrogateSize;
+ charStr = '';
+ continue;
+ }
+ this.charReceived = this.charLength = 0;
+
+ // if there are no more bytes in this buffer, just emit our char
+ if (buffer.length === 0) {
+ return charStr;
+ }
+ break;
+ }
+
+ // determine and set charLength / charReceived
+ this.detectIncompleteChar(buffer);
+
+ var end = buffer.length;
+ if (this.charLength) {
+ // buffer the incomplete character bytes we got
+ buffer.copy(this.charBuffer, 0, buffer.length - this.charReceived, end);
+ end -= this.charReceived;
+ }
+
+ charStr += buffer.toString(this.encoding, 0, end);
+
+ var end = charStr.length - 1;
+ var charCode = charStr.charCodeAt(end);
+ // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character
+ if (charCode >= 0xD800 && charCode <= 0xDBFF) {
+ var size = this.surrogateSize;
+ this.charLength += size;
+ this.charReceived += size;
+ this.charBuffer.copy(this.charBuffer, size, 0, size);
+ buffer.copy(this.charBuffer, 0, 0, size);
+ return charStr.substring(0, end);
+ }
+
+ // or just emit the charStr
+ return charStr;
+};
+
+// detectIncompleteChar determines if there is an incomplete UTF-8 character at
+// the end of the given buffer. If so, it sets this.charLength to the byte
+// length that character, and sets this.charReceived to the number of bytes
+// that are available for this character.
+StringDecoder.prototype.detectIncompleteChar = function(buffer) {
+ // determine how many bytes we have to check at the end of this buffer
+ var i = (buffer.length >= 3) ? 3 : buffer.length;
+
+ // Figure out if one of the last i bytes of our buffer announces an
+ // incomplete char.
+ for (; i > 0; i--) {
+ var c = buffer[buffer.length - i];
+
+ // See http://en.wikipedia.org/wiki/UTF-8#Description
+
+ // 110XXXXX
+ if (i == 1 && c >> 5 == 0x06) {
+ this.charLength = 2;
+ break;
+ }
+
+ // 1110XXXX
+ if (i <= 2 && c >> 4 == 0x0E) {
+ this.charLength = 3;
+ break;
+ }
+
+ // 11110XXX
+ if (i <= 3 && c >> 3 == 0x1E) {
+ this.charLength = 4;
+ break;
+ }
+ }
+ this.charReceived = i;
+};
+
+StringDecoder.prototype.end = function(buffer) {
+ var res = '';
+ if (buffer && buffer.length)
+ res = this.write(buffer);
+
+ if (this.charReceived) {
+ var cr = this.charReceived;
+ var buf = this.charBuffer;
+ var enc = this.encoding;
+ res += buf.slice(0, cr).toString(enc);
+ }
+
+ return res;
+};
+
+function passThroughWrite(buffer) {
+ return buffer.toString(this.encoding);
+}
+
+function utf16DetectIncompleteChar(buffer) {
+ this.charReceived = buffer.length % 2;
+ this.charLength = this.charReceived ? 2 : 0;
+}
+
+function base64DetectIncompleteChar(buffer) {
+ this.charReceived = buffer.length % 3;
+ this.charLength = this.charReceived ? 3 : 0;
+}
Code Review / simantics / district.git / blobdiff