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-rw-r--r--js/binary/decoder.js37
-rw-r--r--js/binary/decoder_test.js23
-rw-r--r--js/binary/encoder.js29
3 files changed, 71 insertions, 18 deletions
diff --git a/js/binary/decoder.js b/js/binary/decoder.js
index 41094a36..040cf715 100644
--- a/js/binary/decoder.js
+++ b/js/binary/decoder.js
@@ -895,11 +895,9 @@ jspb.BinaryDecoder.prototype.readEnum = function() {
/**
* Reads and parses a UTF-8 encoded unicode string from the stream.
- * The code is inspired by maps.vectortown.parse.StreamedDataViewReader, with
- * the exception that the implementation here does not get confused if it
- * encounters characters longer than three bytes. These characters are ignored
- * though, as they are extremely rare: three UTF-8 bytes cover virtually all
- * characters in common use (http://en.wikipedia.org/wiki/UTF-8).
+ * The code is inspired by maps.vectortown.parse.StreamedDataViewReader.
+ * Supports codepoints from U+0000 up to U+10FFFF.
+ * (http://en.wikipedia.org/wiki/UTF-8).
* @param {number} length The length of the string to read.
* @return {string} The decoded string.
*/
@@ -907,30 +905,45 @@ jspb.BinaryDecoder.prototype.readString = function(length) {
var bytes = this.bytes_;
var cursor = this.cursor_;
var end = cursor + length;
- var chars = [];
+ var codeUnits = [];
while (cursor < end) {
var c = bytes[cursor++];
if (c < 128) { // Regular 7-bit ASCII.
- chars.push(c);
+ codeUnits.push(c);
} else if (c < 192) {
// UTF-8 continuation mark. We are out of sync. This
// might happen if we attempted to read a character
- // with more than three bytes.
+ // with more than four bytes.
continue;
} else if (c < 224) { // UTF-8 with two bytes.
var c2 = bytes[cursor++];
- chars.push(((c & 31) << 6) | (c2 & 63));
+ codeUnits.push(((c & 31) << 6) | (c2 & 63));
} else if (c < 240) { // UTF-8 with three bytes.
var c2 = bytes[cursor++];
var c3 = bytes[cursor++];
- chars.push(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
+ codeUnits.push(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
+ } else if (c < 248) { // UTF-8 with 4 bytes.
+ var c2 = bytes[cursor++];
+ var c3 = bytes[cursor++];
+ var c4 = bytes[cursor++];
+ // Characters written on 4 bytes have 21 bits for a codepoint.
+ // We can't fit that on 16bit characters, so we use surrogates.
+ var codepoint = ((c & 7) << 18) | ((c2 & 63) << 12) | ((c3 & 63) << 6) | (c4 & 63);
+ // Surrogates formula from wikipedia.
+ // 1. Subtract 0x10000 from codepoint
+ codepoint -= 0x10000;
+ // 2. Split this into the high 10-bit value and the low 10-bit value
+ // 3. Add 0xD800 to the high value to form the high surrogate
+ // 4. Add 0xDC00 to the low value to form the low surrogate:
+ var low = (codepoint & 1023) + 0xDC00;
+ var high = ((codepoint >> 10) & 1023) + 0xD800;
+ codeUnits.push(high, low)
}
}
-
// String.fromCharCode.apply is faster than manually appending characters on
// Chrome 25+, and generates no additional cons string garbage.
- var result = String.fromCharCode.apply(null, chars);
+ var result = String.fromCharCode.apply(null, codeUnits);
this.cursor_ = cursor;
return result;
};
diff --git a/js/binary/decoder_test.js b/js/binary/decoder_test.js
index ac312648..9f947b99 100644
--- a/js/binary/decoder_test.js
+++ b/js/binary/decoder_test.js
@@ -209,7 +209,30 @@ describe('binaryDecoderTest', function() {
assertEquals(hashC, decoder.readFixedHash64());
assertEquals(hashD, decoder.readFixedHash64());
});
+
+ /**
+ * Test encoding and decoding utf-8.
+ */
+ it('testUtf8', function() {
+ var encoder = new jspb.BinaryEncoder();
+ var ascii = "ASCII should work in 3, 2, 1..."
+ var utf8_two_bytes = "©";
+ var utf8_three_bytes = "❄";
+ var utf8_four_bytes = "😁";
+
+ encoder.writeString(ascii);
+ encoder.writeString(utf8_two_bytes);
+ encoder.writeString(utf8_three_bytes);
+ encoder.writeString(utf8_four_bytes);
+
+ var decoder = jspb.BinaryDecoder.alloc(encoder.end());
+
+ assertEquals(ascii, decoder.readString(ascii.length));
+ assertEquals(utf8_two_bytes, decoder.readString(utf8_two_bytes.length));
+ assertEquals(utf8_three_bytes, decoder.readString(utf8_three_bytes.length));
+ assertEquals(utf8_four_bytes, decoder.readString(utf8_four_bytes.length));
+ });
/**
* Verifies that misuse of the decoder class triggers assertions.
diff --git a/js/binary/encoder.js b/js/binary/encoder.js
index c9b0c2ae..d952d714 100644
--- a/js/binary/encoder.js
+++ b/js/binary/encoder.js
@@ -409,19 +409,36 @@ jspb.BinaryEncoder.prototype.writeFixedHash64 = function(hash) {
*/
jspb.BinaryEncoder.prototype.writeString = function(value) {
var oldLength = this.buffer_.length;
-
- // UTF16 to UTF8 conversion loop swiped from goog.crypt.stringToUtf8ByteArray.
+
for (var i = 0; i < value.length; i++) {
+
var c = value.charCodeAt(i);
+
if (c < 128) {
this.buffer_.push(c);
} else if (c < 2048) {
this.buffer_.push((c >> 6) | 192);
this.buffer_.push((c & 63) | 128);
- } else {
- this.buffer_.push((c >> 12) | 224);
- this.buffer_.push(((c >> 6) & 63) | 128);
- this.buffer_.push((c & 63) | 128);
+ } else if (c < 65536) {
+ // Look for surrogates
+ if (c >= 0xD800 && c <= 0xDBFF && i + 1 < value.length) {
+ var second = value.charCodeAt(i + 1);
+ if (second >= 0xDC00 && second <= 0xDFFF) { // low surrogate
+ // http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
+ c = (c - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
+
+ this.buffer_.push((c >> 18) | 240);
+ this.buffer_.push(((c >> 12) & 63 ) | 128);
+ this.buffer_.push(((c >> 6) & 63) | 128);
+ this.buffer_.push((c & 63) | 128);
+ i++;
+ }
+ }
+ else {
+ this.buffer_.push((c >> 12) | 224);
+ this.buffer_.push(((c >> 6) & 63) | 128);
+ this.buffer_.push((c & 63) | 128);
+ }
}
}