src/reader.js
"use strict";
module.exports = Reader;
var util = require("./util/minimal");
var BufferReader; // cyclic
var LongBits = util.LongBits,
utf8 = util.utf8;
/* istanbul ignore next */
function indexOutOfRange(reader, writeLength) {
return RangeError("index out of range: " + reader.pos + " + " + (writeLength || 1) + " > " + reader.len);
}
/**
* Constructs a new reader instance using the specified buffer.
* @classdesc Wire format reader using `Uint8Array` if available, otherwise `Array`.
* @constructor
* @param {Uint8Array} buffer Buffer to read from
*/
function Reader(buffer) {
/**
* Read buffer.
* @type {Uint8Array}
*/
this.buf = buffer;
/**
* Read buffer position.
* @type {number}
*/
this.pos = 0;
/**
* Read buffer length.
* @type {number}
*/
this.len = buffer.length;
}
var create_array = typeof Uint8Array !== "undefined"
? function create_typed_array(buffer) {
if (buffer instanceof Uint8Array || Array.isArray(buffer))
return new Reader(buffer);
throw Error("illegal buffer");
}
/* istanbul ignore next */
: function create_array(buffer) {
if (Array.isArray(buffer))
return new Reader(buffer);
throw Error("illegal buffer");
};
var create = function create() {
return util.Buffer
? function create_buffer_setup(buffer) {
return (Reader.create = function create_buffer(buffer) {
return util.Buffer.isBuffer(buffer)
? new BufferReader(buffer)
/* istanbul ignore next */
: create_array(buffer);
})(buffer);
}
/* istanbul ignore next */
: create_array;
};
/**
* Creates a new reader using the specified buffer.
* @function
* @param {Uint8Array|Buffer} buffer Buffer to read from
* @returns {Reader|BufferReader} A {@link BufferReader} if `buffer` is a Buffer, otherwise a {@link Reader}
* @throws {Error} If `buffer` is not a valid buffer
*/
Reader.create = create();
Reader.prototype._slice = util.Array.prototype.subarray || /* istanbul ignore next */ util.Array.prototype.slice;
/**
* Reads a varint as an unsigned 32 bit value.
* @function
* @returns {number} Value read
*/
Reader.prototype.uint32 = (function read_uint32_setup() {
var value = 4294967295; // optimizer type-hint, tends to deopt otherwise (?!)
return function read_uint32() {
value = ( this.buf[this.pos] & 127 ) >>> 0; if (this.buf[this.pos++] < 128) return value;
value = (value | (this.buf[this.pos] & 127) << 7) >>> 0; if (this.buf[this.pos++] < 128) return value;
value = (value | (this.buf[this.pos] & 127) << 14) >>> 0; if (this.buf[this.pos++] < 128) return value;
value = (value | (this.buf[this.pos] & 127) << 21) >>> 0; if (this.buf[this.pos++] < 128) return value;
value = (value | (this.buf[this.pos] & 15) << 28) >>> 0; if (this.buf[this.pos++] < 128) return value;
/* istanbul ignore if */
if ((this.pos += 5) > this.len) {
this.pos = this.len;
throw indexOutOfRange(this, 10);
}
return value;
};
})();
/**
* Reads a varint as a signed 32 bit value.
* @returns {number} Value read
*/
Reader.prototype.int32 = function read_int32() {
return this.uint32() | 0;
};
/**
* Reads a zig-zag encoded varint as a signed 32 bit value.
* @returns {number} Value read
*/
Reader.prototype.sint32 = function read_sint32() {
var value = this.uint32();
return value >>> 1 ^ -(value & 1) | 0;
};
/* eslint-disable no-invalid-this */
function readLongVarint() {
// tends to deopt with local vars for octet etc.
var bits = new LongBits(0, 0);
var i = 0;
if (this.len - this.pos > 4) { // fast route (lo)
for (; i < 4; ++i) {
// 1st..4th
bits.lo = (bits.lo | (this.buf[this.pos] & 127) << i * 7) >>> 0;
if (this.buf[this.pos++] < 128)
return bits;
}
// 5th
bits.lo = (bits.lo | (this.buf[this.pos] & 127) << 28) >>> 0;
bits.hi = (bits.hi | (this.buf[this.pos] & 127) >> 4) >>> 0;
if (this.buf[this.pos++] < 128)
return bits;
i = 0;
} else {
for (; i < 3; ++i) {
/* istanbul ignore if */
if (this.pos >= this.len)
throw indexOutOfRange(this);
// 1st..3th
bits.lo = (bits.lo | (this.buf[this.pos] & 127) << i * 7) >>> 0;
if (this.buf[this.pos++] < 128)
return bits;
}
// 4th
bits.lo = (bits.lo | (this.buf[this.pos++] & 127) << i * 7) >>> 0;
return bits;
}
if (this.len - this.pos > 4) { // fast route (hi)
for (; i < 5; ++i) {
// 6th..10th
bits.hi = (bits.hi | (this.buf[this.pos] & 127) << i * 7 + 3) >>> 0;
if (this.buf[this.pos++] < 128)
return bits;
}
} else {
for (; i < 5; ++i) {
/* istanbul ignore if */
if (this.pos >= this.len)
throw indexOutOfRange(this);
// 6th..10th
bits.hi = (bits.hi | (this.buf[this.pos] & 127) << i * 7 + 3) >>> 0;
if (this.buf[this.pos++] < 128)
return bits;
}
}
/* istanbul ignore next */
throw Error("invalid varint encoding");
}
/* eslint-enable no-invalid-this */
/**
* Reads a varint as a signed 64 bit value.
* @name Reader#int64
* @function
* @returns {Long} Value read
*/
/**
* Reads a varint as an unsigned 64 bit value.
* @name Reader#uint64
* @function
* @returns {Long} Value read
*/
/**
* Reads a zig-zag encoded varint as a signed 64 bit value.
* @name Reader#sint64
* @function
* @returns {Long} Value read
*/
/**
* Reads a varint as a boolean.
* @returns {boolean} Value read
*/
Reader.prototype.bool = function read_bool() {
return this.uint32() !== 0;
};
function readFixed32_end(buf, end) { // note that this uses `end`, not `pos`
return (buf[end - 4]
| buf[end - 3] << 8
| buf[end - 2] << 16
| buf[end - 1] << 24) >>> 0;
}
/**
* Reads fixed 32 bits as an unsigned 32 bit integer.
* @returns {number} Value read
*/
Reader.prototype.fixed32 = function read_fixed32() {
/* istanbul ignore if */
if (this.pos + 4 > this.len)
throw indexOutOfRange(this, 4);
return readFixed32_end(this.buf, this.pos += 4);
};
/**
* Reads fixed 32 bits as a signed 32 bit integer.
* @returns {number} Value read
*/
Reader.prototype.sfixed32 = function read_sfixed32() {
/* istanbul ignore if */
if (this.pos + 4 > this.len)
throw indexOutOfRange(this, 4);
return readFixed32_end(this.buf, this.pos += 4) | 0;
};
/* eslint-disable no-invalid-this */
function readFixed64(/* this: Reader */) {
/* istanbul ignore if */
if (this.pos + 8 > this.len)
throw indexOutOfRange(this, 8);
return new LongBits(readFixed32_end(this.buf, this.pos += 4), readFixed32_end(this.buf, this.pos += 4));
}
/* eslint-enable no-invalid-this */
/**
* Reads fixed 64 bits.
* @name Reader#fixed64
* @function
* @returns {Long} Value read
*/
/**
* Reads zig-zag encoded fixed 64 bits.
* @name Reader#sfixed64
* @function
* @returns {Long} Value read
*/
/**
* Reads a float (32 bit) as a number.
* @function
* @returns {number} Value read
*/
Reader.prototype.float = function read_float() {
/* istanbul ignore if */
if (this.pos + 4 > this.len)
throw indexOutOfRange(this, 4);
var value = util.float.readFloatLE(this.buf, this.pos);
this.pos += 4;
return value;
};
/**
* Reads a double (64 bit float) as a number.
* @function
* @returns {number} Value read
*/
Reader.prototype.double = function read_double() {
/* istanbul ignore if */
if (this.pos + 8 > this.len)
throw indexOutOfRange(this, 4);
var value = util.float.readDoubleLE(this.buf, this.pos);
this.pos += 8;
return value;
};
/**
* Reads a sequence of bytes preceeded by its length as a varint.
* @returns {Uint8Array} Value read
*/
Reader.prototype.bytes = function read_bytes() {
var length = this.uint32(),
start = this.pos,
end = this.pos + length;
/* istanbul ignore if */
if (end > this.len)
throw indexOutOfRange(this, length);
this.pos += length;
if (Array.isArray(this.buf)) // plain array
return this.buf.slice(start, end);
if (start === end) { // fix for IE 10/Win8 and others' subarray returning array of size 1
var nativeBuffer = util.Buffer;
return nativeBuffer
? nativeBuffer.alloc(0)
: new this.buf.constructor(0);
}
return this._slice.call(this.buf, start, end);
};
/**
* Reads a string preceeded by its byte length as a varint.
* @returns {string} Value read
*/
Reader.prototype.string = function read_string() {
var bytes = this.bytes();
return utf8.read(bytes, 0, bytes.length);
};
/**
* Skips the specified number of bytes if specified, otherwise skips a varint.
* @param {number} [length] Length if known, otherwise a varint is assumed
* @returns {Reader} `this`
*/
Reader.prototype.skip = function skip(length) {
if (typeof length === "number") {
/* istanbul ignore if */
if (this.pos + length > this.len)
throw indexOutOfRange(this, length);
this.pos += length;
} else {
do {
/* istanbul ignore if */
if (this.pos >= this.len)
throw indexOutOfRange(this);
} while (this.buf[this.pos++] & 128);
}
return this;
};
/**
* Skips the next element of the specified wire type.
* @param {number} wireType Wire type received
* @returns {Reader} `this`
*/
Reader.prototype.skipType = function(wireType) {
switch (wireType) {
case 0:
this.skip();
break;
case 1:
this.skip(8);
break;
case 2:
this.skip(this.uint32());
break;
case 3:
while ((wireType = this.uint32() & 7) !== 4) {
this.skipType(wireType);
}
break;
case 5:
this.skip(4);
break;
/* istanbul ignore next */
default:
throw Error("invalid wire type " + wireType + " at offset " + this.pos);
}
return this;
};
Reader._configure = function(BufferReader_) {
BufferReader = BufferReader_;
Reader.create = create();
BufferReader._configure();
var fn = util.Long ? "toLong" : /* istanbul ignore next */ "toNumber";
util.merge(Reader.prototype, {
int64: function read_int64() {
return readLongVarint.call(this)[fn](false);
},
uint64: function read_uint64() {
return readLongVarint.call(this)[fn](true);
},
sint64: function read_sint64() {
return readLongVarint.call(this).zzDecode()[fn](false);
},
fixed64: function read_fixed64() {
return readFixed64.call(this)[fn](true);
},
sfixed64: function read_sfixed64() {
return readFixed64.call(this)[fn](false);
}
});
};