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Add UTF-8 support to the JavaScript API

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This adds an optional argument to generated getters for string fields to
specify the encoding type and overloads the createString() function. It's
now possible to use either JavaScript UTF-16 string objects or C-style
UTF-8 byte arrays (Uint8Array) for string data.
This commit is contained in:
Evan Wallace
2015-10-14 23:07:40 -07:00
parent 79222bf100
commit 4bef5e89c4
5 changed files with 119 additions and 51 deletions
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89
js/flatbuffers.js
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@@ -31,6 +31,14 @@ flatbuffers.SIZEOF_INT = 4;
*/
flatbuffers.FILE_IDENTIFIER_LENGTH = 4;
/**
* @enum {number}
*/
flatbuffers.Encoding = {
UTF8_BYTES: 1,
UTF16_STRING: 2
};
/**
* @type {Int32Array}
* @const
@@ -667,44 +675,49 @@ flatbuffers.Builder.prototype.endVector = function() {
};
/**
* Encode the string `s` in the buffer using UTF-8.
* Encode the string `s` in the buffer using UTF-8. If a Uint8Array is passed
* instead of a string, it is assumed to contain valid UTF-8 encoded data.
*
* @param {string} s The string to encode
* @param {string|Uint8Array} s The string to encode
* @return {flatbuffers.Offset} The offset in the buffer where the encoded string starts
*/
flatbuffers.Builder.prototype.createString = function(s) {
var utf8 = [];
var i = 0;
if (s instanceof Uint8Array) {
var utf8 = s;
} else {
var utf8 = [];
var i = 0;
while (i < s.length) {
var codePoint;
while (i < s.length) {
var codePoint;
// Decode UTF-16
var a = s.charCodeAt(i++);
if (a < 0xD800 || a >= 0xDC00) {
codePoint = a;
} else {
var b = s.charCodeAt(i++);
codePoint = (a << 10) + b + (0x10000 - (0xD800 << 10) - 0xDC00);
}
// Encode UTF-8
if (codePoint < 0x80) {
utf8.push(codePoint);
} else {
if (codePoint < 0x800) {
utf8.push(((codePoint >> 6) & 0x1F) | 0xC0);
// Decode UTF-16
var a = s.charCodeAt(i++);
if (a < 0xD800 || a >= 0xDC00) {
codePoint = a;
} else {
if (codePoint < 0x10000) {
utf8.push(((codePoint >> 12) & 0x0F) | 0xE0);
} else {
utf8.push(
((codePoint >> 18) & 0x07) | 0xF0,
((codePoint >> 12) & 0x3F) | 0x80);
}
utf8.push(((codePoint >> 6) & 0x3F) | 0x80);
var b = s.charCodeAt(i++);
codePoint = (a << 10) + b + (0x10000 - (0xD800 << 10) - 0xDC00);
}
// Encode UTF-8
if (codePoint < 0x80) {
utf8.push(codePoint);
} else {
if (codePoint < 0x800) {
utf8.push(((codePoint >> 6) & 0x1F) | 0xC0);
} else {
if (codePoint < 0x10000) {
utf8.push(((codePoint >> 12) & 0x0F) | 0xE0);
} else {
utf8.push(
((codePoint >> 18) & 0x07) | 0xF0,
((codePoint >> 12) & 0x3F) | 0x80);
}
utf8.push(((codePoint >> 6) & 0x3F) | 0x80);
}
utf8.push((codePoint & 0x3F) | 0x80);
}
utf8.push((codePoint & 0x3F) | 0x80);
}
}
@@ -939,13 +952,19 @@ flatbuffers.ByteBuffer.prototype.__union = function(t, offset) {
};
/**
* Create a JavaScript string from UTF-8 data stored inside the flatbuffer.
* Create a JavaScript string from UTF-8 data stored inside the FlatBuffer.
* This allocates a new string and converts to wide chars upon each access.
*
* To avoid the conversion to UTF-16, pass flatbuffers.Encoding.UTF8_BYTES as
* the "optionalEncoding" argument. This is useful for avoiding conversion to
* and from UTF-16 when the data will just be packaged back up in another
* FlatBuffer later on.
*
* @param {number} offset
* @returns {string}
* @param {flatbuffers.Encoding=} optionalEncoding Defaults to UTF16_STRING
* @returns {string|Uint8Array}
*/
flatbuffers.ByteBuffer.prototype.__string = function(offset) {
flatbuffers.ByteBuffer.prototype.__string = function(offset, optionalEncoding) {
offset += this.readInt32(offset);
var length = this.readInt32(offset);
@@ -954,6 +973,10 @@ flatbuffers.ByteBuffer.prototype.__string = function(offset) {
offset += flatbuffers.SIZEOF_INT;
if (optionalEncoding === flatbuffers.Encoding.UTF8_BYTES) {
return this.bytes_.subarray(offset, offset + length);
}
while (i < length) {
var codePoint;