flatbuffers
Version:
Memory Efficient Serialization Library
253 lines (252 loc) • 9.96 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ByteBuffer = void 0;
var constants_js_1 = require("./constants.js");
var utils_js_1 = require("./utils.js");
var encoding_js_1 = require("./encoding.js");
var ByteBuffer = /** @class */ (function () {
/**
* Create a new ByteBuffer with a given array of bytes (`Uint8Array`)
*/
function ByteBuffer(bytes_) {
this.bytes_ = bytes_;
this.position_ = 0;
this.text_decoder_ = new TextDecoder();
}
/**
* Create and allocate a new ByteBuffer with a given size.
*/
ByteBuffer.allocate = function (byte_size) {
return new ByteBuffer(new Uint8Array(byte_size));
};
ByteBuffer.prototype.clear = function () {
this.position_ = 0;
};
/**
* Get the underlying `Uint8Array`.
*/
ByteBuffer.prototype.bytes = function () {
return this.bytes_;
};
/**
* Get the buffer's position.
*/
ByteBuffer.prototype.position = function () {
return this.position_;
};
/**
* Set the buffer's position.
*/
ByteBuffer.prototype.setPosition = function (position) {
this.position_ = position;
};
/**
* Get the buffer's capacity.
*/
ByteBuffer.prototype.capacity = function () {
return this.bytes_.length;
};
ByteBuffer.prototype.readInt8 = function (offset) {
return this.readUint8(offset) << 24 >> 24;
};
ByteBuffer.prototype.readUint8 = function (offset) {
return this.bytes_[offset];
};
ByteBuffer.prototype.readInt16 = function (offset) {
return this.readUint16(offset) << 16 >> 16;
};
ByteBuffer.prototype.readUint16 = function (offset) {
return this.bytes_[offset] | this.bytes_[offset + 1] << 8;
};
ByteBuffer.prototype.readInt32 = function (offset) {
return this.bytes_[offset] | this.bytes_[offset + 1] << 8 | this.bytes_[offset + 2] << 16 | this.bytes_[offset + 3] << 24;
};
ByteBuffer.prototype.readUint32 = function (offset) {
return this.readInt32(offset) >>> 0;
};
ByteBuffer.prototype.readInt64 = function (offset) {
return BigInt.asIntN(64, BigInt(this.readUint32(offset)) + (BigInt(this.readUint32(offset + 4)) << BigInt(32)));
};
ByteBuffer.prototype.readUint64 = function (offset) {
return BigInt.asUintN(64, BigInt(this.readUint32(offset)) + (BigInt(this.readUint32(offset + 4)) << BigInt(32)));
};
ByteBuffer.prototype.readFloat32 = function (offset) {
utils_js_1.int32[0] = this.readInt32(offset);
return utils_js_1.float32[0];
};
ByteBuffer.prototype.readFloat64 = function (offset) {
utils_js_1.int32[utils_js_1.isLittleEndian ? 0 : 1] = this.readInt32(offset);
utils_js_1.int32[utils_js_1.isLittleEndian ? 1 : 0] = this.readInt32(offset + 4);
return utils_js_1.float64[0];
};
ByteBuffer.prototype.writeInt8 = function (offset, value) {
this.bytes_[offset] = value;
};
ByteBuffer.prototype.writeUint8 = function (offset, value) {
this.bytes_[offset] = value;
};
ByteBuffer.prototype.writeInt16 = function (offset, value) {
this.bytes_[offset] = value;
this.bytes_[offset + 1] = value >> 8;
};
ByteBuffer.prototype.writeUint16 = function (offset, value) {
this.bytes_[offset] = value;
this.bytes_[offset + 1] = value >> 8;
};
ByteBuffer.prototype.writeInt32 = function (offset, value) {
this.bytes_[offset] = value;
this.bytes_[offset + 1] = value >> 8;
this.bytes_[offset + 2] = value >> 16;
this.bytes_[offset + 3] = value >> 24;
};
ByteBuffer.prototype.writeUint32 = function (offset, value) {
this.bytes_[offset] = value;
this.bytes_[offset + 1] = value >> 8;
this.bytes_[offset + 2] = value >> 16;
this.bytes_[offset + 3] = value >> 24;
};
ByteBuffer.prototype.writeInt64 = function (offset, value) {
this.writeInt32(offset, Number(BigInt.asIntN(32, value)));
this.writeInt32(offset + 4, Number(BigInt.asIntN(32, value >> BigInt(32))));
};
ByteBuffer.prototype.writeUint64 = function (offset, value) {
this.writeUint32(offset, Number(BigInt.asUintN(32, value)));
this.writeUint32(offset + 4, Number(BigInt.asUintN(32, value >> BigInt(32))));
};
ByteBuffer.prototype.writeFloat32 = function (offset, value) {
utils_js_1.float32[0] = value;
this.writeInt32(offset, utils_js_1.int32[0]);
};
ByteBuffer.prototype.writeFloat64 = function (offset, value) {
utils_js_1.float64[0] = value;
this.writeInt32(offset, utils_js_1.int32[utils_js_1.isLittleEndian ? 0 : 1]);
this.writeInt32(offset + 4, utils_js_1.int32[utils_js_1.isLittleEndian ? 1 : 0]);
};
/**
* Return the file identifier. Behavior is undefined for FlatBuffers whose
* schema does not include a file_identifier (likely points at padding or the
* start of a the root vtable).
*/
ByteBuffer.prototype.getBufferIdentifier = function () {
if (this.bytes_.length < this.position_ + constants_js_1.SIZEOF_INT +
constants_js_1.FILE_IDENTIFIER_LENGTH) {
throw new Error('FlatBuffers: ByteBuffer is too short to contain an identifier.');
}
var result = "";
for (var i = 0; i < constants_js_1.FILE_IDENTIFIER_LENGTH; i++) {
result += String.fromCharCode(this.readInt8(this.position_ + constants_js_1.SIZEOF_INT + i));
}
return result;
};
/**
* Look up a field in the vtable, return an offset into the object, or 0 if the
* field is not present.
*/
ByteBuffer.prototype.__offset = function (bb_pos, vtable_offset) {
var vtable = bb_pos - this.readInt32(bb_pos);
return vtable_offset < this.readInt16(vtable) ? this.readInt16(vtable + vtable_offset) : 0;
};
/**
* Initialize any Table-derived type to point to the union at the given offset.
*/
ByteBuffer.prototype.__union = function (t, offset) {
t.bb_pos = offset + this.readInt32(offset);
t.bb = this;
return t;
};
/**
* 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 string, pass Encoding.UTF8_BYTES as the
* "optionalEncoding" argument. This is useful for avoiding conversion when
* the data will just be packaged back up in another FlatBuffer later on.
*
* @param offset
* @param opt_encoding Defaults to UTF16_STRING
*/
ByteBuffer.prototype.__string = function (offset, opt_encoding) {
offset += this.readInt32(offset);
var length = this.readInt32(offset);
offset += constants_js_1.SIZEOF_INT;
var utf8bytes = this.bytes_.subarray(offset, offset + length);
if (opt_encoding === encoding_js_1.Encoding.UTF8_BYTES)
return utf8bytes;
else
return this.text_decoder_.decode(utf8bytes);
};
/**
* Handle unions that can contain string as its member, if a Table-derived type then initialize it,
* if a string then return a new one
*
* WARNING: strings are immutable in JS so we can't change the string that the user gave us, this
* makes the behaviour of __union_with_string different compared to __union
*/
ByteBuffer.prototype.__union_with_string = function (o, offset) {
if (typeof o === 'string') {
return this.__string(offset);
}
return this.__union(o, offset);
};
/**
* Retrieve the relative offset stored at "offset"
*/
ByteBuffer.prototype.__indirect = function (offset) {
return offset + this.readInt32(offset);
};
/**
* Get the start of data of a vector whose offset is stored at "offset" in this object.
*/
ByteBuffer.prototype.__vector = function (offset) {
return offset + this.readInt32(offset) + constants_js_1.SIZEOF_INT; // data starts after the length
};
/**
* Get the length of a vector whose offset is stored at "offset" in this object.
*/
ByteBuffer.prototype.__vector_len = function (offset) {
return this.readInt32(offset + this.readInt32(offset));
};
ByteBuffer.prototype.__has_identifier = function (ident) {
if (ident.length != constants_js_1.FILE_IDENTIFIER_LENGTH) {
throw new Error('FlatBuffers: file identifier must be length ' +
constants_js_1.FILE_IDENTIFIER_LENGTH);
}
for (var i = 0; i < constants_js_1.FILE_IDENTIFIER_LENGTH; i++) {
if (ident.charCodeAt(i) != this.readInt8(this.position() + constants_js_1.SIZEOF_INT + i)) {
return false;
}
}
return true;
};
/**
* A helper function for generating list for obj api
*/
ByteBuffer.prototype.createScalarList = function (listAccessor, listLength) {
var ret = [];
for (var i = 0; i < listLength; ++i) {
var val = listAccessor(i);
if (val !== null) {
ret.push(val);
}
}
return ret;
};
/**
* A helper function for generating list for obj api
* @param listAccessor function that accepts an index and return data at that index
* @param listLength listLength
* @param res result list
*/
ByteBuffer.prototype.createObjList = function (listAccessor, listLength) {
var ret = [];
for (var i = 0; i < listLength; ++i) {
var val = listAccessor(i);
if (val !== null) {
ret.push(val.unpack());
}
}
return ret;
};
return ByteBuffer;
}());
exports.ByteBuffer = ByteBuffer;