protobuf.js/src/reader.js

"use strict";
module.exports = Reader;

var util      = require("./util/runtime");

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;
}

/**
 * Creates a new reader using the specified buffer.
 * @function
 * @param {Uint8Array} buffer Buffer to read from
 * @returns {BufferReader|Reader} A {@link BufferReader} if `buffer` is a Buffer, otherwise a {@link Reader}
 */
Reader.create = util.Buffer
    ? function create_buffer_setup(buffer) {
        if (!BufferReader)
            BufferReader = require("./reader_buffer");
        return (Reader.create = function create_buffer(buffer) {
            return new BufferReader(buffer);
        })(buffer);
    }
    : function create_array(buffer) {
        return new Reader(buffer);
    };

/** @alias Reader.prototype */
var ReaderPrototype = Reader.prototype;

ReaderPrototype._slice = util.Array.prototype.subarray || util.Array.prototype.slice;

/**
 * Reads a varint as an unsigned 32 bit value.
 * @function
 * @returns {number} Value read
 */
ReaderPrototype.uint32 = (function read_uint32_setup() { // eslint-disable-line wrap-iife
    var value = 0xffffffff >>> 0; // 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 next */
        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
 */
ReaderPrototype.int32 = function read_int32() {
    return this.uint32() | 0;
};

/**
 * Reads a zig-zag encoded varint as a signed 32 bit value.
 * @returns {number} Value read
 */
ReaderPrototype.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, 0 >>> 0);
    var i = 0;
    if (this.len - this.pos > 4) { // fast route (lo)
        for (i = 0; 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;
    } else {
        for (i = 0; i < 4; ++i) {
            /* istanbul ignore next */
            if (this.pos >= this.len)
                throw indexOutOfRange(this);
            // 1st..4th
            bits.lo = (bits.lo | (this.buf[this.pos] & 127) << i * 7) >>> 0;
            if (this.buf[this.pos++] < 128)
                return bits;
        }
        /* istanbul ignore next */
        if (this.pos >= this.len)
            throw indexOutOfRange(this);
        // 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;
    }
    if (this.len - this.pos > 4) { // fast route (hi)
        for (i = 0; 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 = 0; i < 5; ++i) {
            /* istanbul ignore next */
            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;
        }
    }
    throw Error("invalid varint encoding");
}

function read_int64_long() {
    return readLongVarint.call(this).toLong();
}

function read_int64_number() {
    return readLongVarint.call(this).toNumber();
}

function read_uint64_long() {
    return readLongVarint.call(this).toLong(true);
}

function read_uint64_number() {
    return readLongVarint.call(this).toNumber(true);
}

function read_sint64_long() {
    return readLongVarint.call(this).zzDecode().toLong();
}

function read_sint64_number() {
    return readLongVarint.call(this).zzDecode().toNumber();
}

/* eslint-enable no-invalid-this */

/**
 * Reads a varint as a signed 64 bit value.
 * @name Reader#int64
 * @function
 * @returns {Long|number} Value read
 */

/**
 * Reads a varint as an unsigned 64 bit value.
 * @name Reader#uint64
 * @function
 * @returns {Long|number} Value read
 */

/**
 * Reads a zig-zag encoded varint as a signed 64 bit value.
 * @name Reader#sint64
 * @function
 * @returns {Long|number} Value read
 */

/**
 * Reads a varint as a boolean.
 * @returns {boolean} Value read
 */
ReaderPrototype.bool = function read_bool() {
    return this.uint32() !== 0;
};

function readFixed32(buf, end) {
    return (buf[end - 4]
          | buf[end - 3] << 8
          | buf[end - 2] << 16
          | buf[end - 1] << 24) >>> 0;
}

/**
 * Reads fixed 32 bits as a number.
 * @returns {number} Value read
 */
ReaderPrototype.fixed32 = function read_fixed32() {

    /* istanbul ignore next */
    if (this.pos + 4 > this.len)
        throw indexOutOfRange(this, 4);

    return readFixed32(this.buf, this.pos += 4);
};

/**
 * Reads zig-zag encoded fixed 32 bits as a number.
 * @returns {number} Value read
 */
ReaderPrototype.sfixed32 = function read_sfixed32() {
    var value = this.fixed32();
    return value >>> 1 ^ -(value & 1);
};

/* eslint-disable no-invalid-this */

function readFixed64(/* this: Reader */) {

    /* istanbul ignore next */
    if (this.pos + 8 > this.len)
        throw indexOutOfRange(this, 8);

    return new LongBits(readFixed32(this.buf, this.pos += 4), readFixed32(this.buf, this.pos += 4));
}

function read_fixed64_long() {
    return readFixed64.call(this).toLong(true);
}

function read_fixed64_number() {
    return readFixed64.call(this).toNumber(true);
}

function read_sfixed64_long() {
    return readFixed64.call(this).zzDecode().toLong();
}

function read_sfixed64_number() {
    return readFixed64.call(this).zzDecode().toNumber();
}

/* eslint-enable no-invalid-this */

/**
 * Reads fixed 64 bits.
 * @name Reader#fixed64
 * @function
 * @returns {Long|number} Value read
 */

/**
 * Reads zig-zag encoded fixed 64 bits.
 * @name Reader#sfixed64
 * @function
 * @returns {Long|number} Value read
 */

var readFloat = typeof Float32Array !== "undefined"
    ? (function() { // eslint-disable-line wrap-iife
        var f32 = new Float32Array(1),
            f8b = new Uint8Array(f32.buffer);
        f32[0] = -0;
        return f8b[3] // already le?
            ? function readFloat_f32(buf, pos) {
                f8b[0] = buf[pos    ];
                f8b[1] = buf[pos + 1];
                f8b[2] = buf[pos + 2];
                f8b[3] = buf[pos + 3];
                return f32[0];
            }
            : function readFloat_f32_le(buf, pos) {
                f8b[3] = buf[pos    ];
                f8b[2] = buf[pos + 1];
                f8b[1] = buf[pos + 2];
                f8b[0] = buf[pos + 3];
                return f32[0];
            };
    })()
    : function readFloat_ieee754(buf, pos) {
        var uint = readFixed32(buf, pos + 4),
            sign = (uint >> 31) * 2 + 1,
            exponent = uint >>> 23 & 255,
            mantissa = uint & 8388607;
        return exponent === 255
            ? mantissa
              ? NaN
              : sign * Infinity
            : exponent === 0 // denormal
              ? sign * 1.401298464324817e-45 * mantissa
              : sign * Math.pow(2, exponent - 150) * (mantissa + 8388608);
    };

/**
 * Reads a float (32 bit) as a number.
 * @function
 * @returns {number} Value read
 */
ReaderPrototype.float = function read_float() {

    /* istanbul ignore next */
    if (this.pos + 4 > this.len)
        throw indexOutOfRange(this, 4);

    var value = readFloat(this.buf, this.pos);
    this.pos += 4;
    return value;
};

var readDouble = typeof Float64Array !== "undefined"
    ? (function() { // eslint-disable-line wrap-iife
        var f64 = new Float64Array(1),
            f8b = new Uint8Array(f64.buffer);
        f64[0] = -0;
        return f8b[7] // already le?
            ? function readDouble_f64(buf, pos) {
                f8b[0] = buf[pos    ];
                f8b[1] = buf[pos + 1];
                f8b[2] = buf[pos + 2];
                f8b[3] = buf[pos + 3];
                f8b[4] = buf[pos + 4];
                f8b[5] = buf[pos + 5];
                f8b[6] = buf[pos + 6];
                f8b[7] = buf[pos + 7];
                return f64[0];
            }
            : function readDouble_f64_le(buf, pos) {
                f8b[7] = buf[pos    ];
                f8b[6] = buf[pos + 1];
                f8b[5] = buf[pos + 2];
                f8b[4] = buf[pos + 3];
                f8b[3] = buf[pos + 4];
                f8b[2] = buf[pos + 5];
                f8b[1] = buf[pos + 6];
                f8b[0] = buf[pos + 7];
                return f64[0];
            };
    })()
    : function readDouble_ieee754(buf, pos) {
        var lo = readFixed32(buf, pos + 4),
            hi = readFixed32(buf, pos + 8);
        var sign = (hi >> 31) * 2 + 1,
            exponent = hi >>> 20 & 2047,
            mantissa = 4294967296 * (hi & 1048575) + lo;
        return exponent === 2047
            ? mantissa
              ? NaN
              : sign * Infinity
            : exponent === 0 // denormal
              ? sign * 5e-324 * mantissa
              : sign * Math.pow(2, exponent - 1075) * (mantissa + 4503599627370496);
    };

/**
 * Reads a double (64 bit float) as a number.
 * @function
 * @returns {number} Value read
 */
ReaderPrototype.double = function read_double() {

    /* istanbul ignore next */
    if (this.pos + 8 > this.len)
        throw indexOutOfRange(this, 4);

    var value = readDouble(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
 */
ReaderPrototype.bytes = function read_bytes() {
    var length = this.uint32(),
        start  = this.pos,
        end    = this.pos + length;

    /* istanbul ignore next */
    if (end > this.len)
        throw indexOutOfRange(this, length);

    this.pos += length;
    return start === end // fix for IE 10/Win8 and others' subarray returning array of size 1
        ? new this.buf.constructor(0)
        : this._slice.call(this.buf, start, end);
};

/**
 * Reads a string preceeded by its byte length as a varint.
 * @returns {string} Value read
 */
ReaderPrototype.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`
 */
ReaderPrototype.skip = function skip(length) {
    if (typeof length === "number") {
        /* istanbul ignore next */
        if (this.pos + length > this.len)
            throw indexOutOfRange(this, length);
        this.pos += length;
    } else {
        do {
            /* istanbul ignore next */
            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`
 */
ReaderPrototype.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:
            do { // eslint-disable-line no-constant-condition
                if ((wireType = this.uint32() & 7) === 4)
                    break;
                this.skipType(wireType);
            } while (true);
            break;
        case 5:
            this.skip(4);
            break;
        
        /* istanbul ignore next */
        default:
            throw Error("invalid wire type: " + wireType);
    }
    return this;
};

function configure() {
    if (util.Long) {
        ReaderPrototype.int64 = read_int64_long;
        ReaderPrototype.uint64 = read_uint64_long;
        ReaderPrototype.sint64 = read_sint64_long;
        ReaderPrototype.fixed64 = read_fixed64_long;
        ReaderPrototype.sfixed64 = read_sfixed64_long;
    } else {
        ReaderPrototype.int64 = read_int64_number;
        ReaderPrototype.uint64 = read_uint64_number;
        ReaderPrototype.sint64 = read_sint64_number;
        ReaderPrototype.fixed64 = read_fixed64_number;
        ReaderPrototype.sfixed64 = read_sfixed64_number;
    }
}

Reader._configure = configure;

configure();