index.js

'use strict';

module.exports = Pbf;

var Buffer = global.Buffer || require('./buffer');

function Pbf(buf) {
    this.buf = !Buffer.isBuffer(buf) ? new Buffer(buf || 0) : buf;
    this.pos = 0;
    this.length = this.buf.length;
}

Pbf.Varint  = 0; // varint: int32, int64, uint32, uint64, sint32, sint64, bool, enum
Pbf.Fixed64 = 1; // 64-bit: double, fixed64, sfixed64
Pbf.Bytes   = 2; // length-delimited: string, bytes, embedded messages, packed repeated fields
Pbf.Fixed32 = 5; // 32-bit: float, fixed32, sfixed32

var SHIFT_LEFT_32 = (1 << 16) * (1 << 16),
    SHIFT_RIGHT_32 = 1 / SHIFT_LEFT_32,
    POW_2_63 = Math.pow(2, 63);

Pbf.prototype = {

    destroy: function() {
        this.buf = null;
    },

    // === READING =================================================================

    readFields: function(readField, result, end) {
        end = end || this.length;

        while (this.pos < end) {
            var val = this.readVarint(),
                tag = val >> 3,
                startPos = this.pos;

            readField(tag, result, this);

            if (this.pos === startPos) this.skip(val);
        }
        return result;
    },

    readMessage: function(readField, result) {
        return this.readFields(readField, result, this.readVarint() + this.pos);
    },

    readFixed32: function() {
        var val = this.buf.readUInt32LE(this.pos);
        this.pos += 4;
        return val;
    },

    readSFixed32: function() {
        var val = this.buf.readInt32LE(this.pos);
        this.pos += 4;
        return val;
    },

    // 64-bit int handling is based on github.com/dpw/node-buffer-more-ints (MIT-licensed)

    readFixed64: function() {
        var val = this.buf.readUInt32LE(this.pos) + this.buf.readUInt32LE(this.pos + 4) * SHIFT_LEFT_32;
        this.pos += 8;
        return val;
    },

    readSFixed64: function() {
        var val = this.buf.readUInt32LE(this.pos) + this.buf.readInt32LE(this.pos + 4) * SHIFT_LEFT_32;
        this.pos += 8;
        return val;
    },

    readFloat: function() {
        var val = this.buf.readFloatLE(this.pos);
        this.pos += 4;
        return val;
    },

    readDouble: function() {
        var val = this.buf.readDoubleLE(this.pos);
        this.pos += 8;
        return val;
    },

    readVarint: function() {
        var buf = this.buf,
            val, b, b0, b1, b2, b3;

        b0 = buf[this.pos++]; if (b0 < 0x80) return b0;                 b0 = b0 & 0x7f;
        b1 = buf[this.pos++]; if (b1 < 0x80) return b0 | b1 << 7;       b1 = (b1 & 0x7f) << 7;
        b2 = buf[this.pos++]; if (b2 < 0x80) return b0 | b1 | b2 << 14; b2 = (b2 & 0x7f) << 14;
        b3 = buf[this.pos++]; if (b3 < 0x80) return b0 | b1 | b2 | b3 << 21;

        val = b0 | b1 | b2 | (b3 & 0x7f) << 21;

        b = buf[this.pos++]; val += (b & 0x7f) * 0x10000000;         if (b < 0x80) return val;
        b = buf[this.pos++]; val += (b & 0x7f) * 0x800000000;        if (b < 0x80) return val;
        b = buf[this.pos++]; val += (b & 0x7f) * 0x40000000000;      if (b < 0x80) return val;
        b = buf[this.pos++]; val += (b & 0x7f) * 0x2000000000000;    if (b < 0x80) return val;
        b = buf[this.pos++]; val += (b & 0x7f) * 0x100000000000000;  if (b < 0x80) return val;
        b = buf[this.pos++]; val += (b & 0x7f) * 0x8000000000000000; if (b < 0x80) return val;

        throw new Error('Expected varint not more than 10 bytes');
    },

    readVarint64: function() {
        var startPos = this.pos,
            val = this.readVarint();

        if (val < POW_2_63) return val;

        var pos = this.pos - 2;
        while (this.buf[pos] === 0xff) pos--;
        if (pos < startPos) pos = startPos;

        val = 0;
        for (var i = 0; i < pos - startPos + 1; i++) {
            var b = ~this.buf[startPos + i] & 0x7f;
            val += i < 4 ? b << i * 7 : b * Math.pow(2, i * 7);
        }

        return -val - 1;
    },

    readSVarint: function() {
        var num = this.readVarint();
        return num % 2 === 1 ? (num + 1) / -2 : num / 2; // zigzag encoding
    },

    readBoolean: function() {
        return Boolean(this.readVarint());
    },

    readString: function() {
        var end = this.readVarint() + this.pos,
            str = this.buf.toString('utf8', this.pos, end);
        this.pos = end;
        return str;
    },

    readBytes: function() {
        var end = this.readVarint() + this.pos,
            buffer = this.buf.slice(this.pos, end);
        this.pos = end;
        return buffer;
    },

    // verbose for performance reasons; doesn't affect gzipped size

    readPackedVarint: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readVarint());
        return arr;
    },
    readPackedSVarint: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readSVarint());
        return arr;
    },
    readPackedBoolean: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readBoolean());
        return arr;
    },
    readPackedFloat: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readFloat());
        return arr;
    },
    readPackedDouble: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readDouble());
        return arr;
    },
    readPackedFixed32: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readFixed32());
        return arr;
    },
    readPackedSFixed32: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readSFixed32());
        return arr;
    },
    readPackedFixed64: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readFixed64());
        return arr;
    },
    readPackedSFixed64: function() {
        var end = this.readVarint() + this.pos, arr = [];
        while (this.pos < end) arr.push(this.readSFixed64());
        return arr;
    },

    skip: function(val) {
        var type = val & 0x7;
        if (type === Pbf.Varint) while (this.buf[this.pos++] > 0x7f) {}
        else if (type === Pbf.Bytes) this.pos = this.readVarint() + this.pos;
        else if (type === Pbf.Fixed32) this.pos += 4;
        else if (type === Pbf.Fixed64) this.pos += 8;
        else throw new Error('Unimplemented type: ' + type);
    },

    // === WRITING =================================================================

    writeTag: function(tag, type) {
        this.writeVarint((tag << 3) | type);
    },

    realloc: function(min) {
        var length = this.length || 16;

        while (length < this.pos + min) length *= 2;

        if (length !== this.length) {
            var buf = new Buffer(length);
            this.buf.copy(buf);
            this.buf = buf;
            this.length = length;
        }
    },

    finish: function() {
        this.length = this.pos;
        this.pos = 0;
        return this.buf.slice(0, this.length);
    },

    writeFixed32: function(val) {
        this.realloc(4);
        this.buf.writeUInt32LE(val, this.pos);
        this.pos += 4;
    },

    writeSFixed32: function(val) {
        this.realloc(4);
        this.buf.writeInt32LE(val, this.pos);
        this.pos += 4;
    },

    writeFixed64: function(val) {
        this.realloc(8);
        this.buf.writeInt32LE(val & -1, this.pos);
        this.buf.writeUInt32LE(Math.floor(val * SHIFT_RIGHT_32), this.pos + 4);
        this.pos += 8;
    },

    writeSFixed64: function(val) {
        this.realloc(8);
        this.buf.writeInt32LE(val & -1, this.pos);
        this.buf.writeInt32LE(Math.floor(val * SHIFT_RIGHT_32), this.pos + 4);
        this.pos += 8;
    },

    writeVarint: function(val) {
        val = +val;

        if (val <= 0x7f) {
            this.realloc(1);
            this.buf[this.pos++] = val;

        } else if (val <= 0x3fff) {
            this.realloc(2);
            this.buf[this.pos++] = ((val >>> 0) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 7) & 0x7f);

        } else if (val <= 0x1fffff) {
            this.realloc(3);
            this.buf[this.pos++] = ((val >>> 0) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 7) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 14) & 0x7f);

        } else if (val <= 0xfffffff) {
            this.realloc(4);
            this.buf[this.pos++] = ((val >>> 0) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 7) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 14) & 0x7f) | 0x80;
            this.buf[this.pos++] = ((val >>> 21) & 0x7f);

        } else {
            var pos = this.pos;
            while (val >= 0x80) {
                this.realloc(1);
                this.buf[this.pos++] = (val & 0xff) | 0x80;
                val /= 0x80;
            }
            this.realloc(1);
            this.buf[this.pos++] = val | 0;
            if (this.pos - pos > 10) throw new Error('Given varint doesn\'t fit into 10 bytes');
        }
    },

    writeSVarint: function(val) {
        this.writeVarint(val < 0 ? -val * 2 - 1 : val * 2);
    },

    writeBoolean: function(val) {
        this.writeVarint(Boolean(val));
    },

    writeString: function(str) {
        str = String(str);
        var bytes = Buffer.byteLength(str);
        this.writeVarint(bytes);
        this.realloc(bytes);
        this.buf.write(str, this.pos);
        this.pos += bytes;
    },

    writeFloat: function(val) {
        this.realloc(4);
        this.buf.writeFloatLE(val, this.pos);
        this.pos += 4;
    },

    writeDouble: function(val) {
        this.realloc(8);
        this.buf.writeDoubleLE(val, this.pos);
        this.pos += 8;
    },

    writeBytes: function(buffer) {
        var len = buffer.length;
        this.writeVarint(len);
        this.realloc(len);
        for (var i = 0; i < len; i++) this.buf[this.pos++] = buffer[i];
    },

    writeRawMessage: function(fn, obj) {
        this.pos++; // reserve 1 byte for short message length

        // write the message directly to the buffer and see how much was written
        var startPos = this.pos;
        fn(obj, this);
        var len = this.pos - startPos;

        var varintLen =
            len <= 0x7f ? 1 :
            len <= 0x3fff ? 2 :
            len <= 0x1fffff ? 3 :
            len <= 0xfffffff ? 4 : Math.ceil(Math.log(len) / (Math.LN2 * 7));

        // if 1 byte isn't enough for encoding message length, shift the data to the right
        if (varintLen > 1) {
            this.realloc(varintLen - 1);
            for (var i = this.pos - 1; i >= startPos; i--) this.buf[i + varintLen - 1] = this.buf[i];
        }

        // finally, write the message length in the reserved place and restore the position
        this.pos = startPos - 1;
        this.writeVarint(len);
        this.pos += len;
    },

    writeMessage: function(tag, fn, obj) {
        this.writeTag(tag, Pbf.Bytes);
        this.writeRawMessage(fn, obj);
    },

    writePackedVarint:   function(tag, arr) { this.writeMessage(tag, writePackedVarint, arr);   },
    writePackedSVarint:  function(tag, arr) { this.writeMessage(tag, writePackedSVarint, arr);  },
    writePackedBoolean:  function(tag, arr) { this.writeMessage(tag, writePackedBoolean, arr);  },
    writePackedFloat:    function(tag, arr) { this.writeMessage(tag, writePackedFloat, arr);    },
    writePackedDouble:   function(tag, arr) { this.writeMessage(tag, writePackedDouble, arr);   },
    writePackedFixed32:  function(tag, arr) { this.writeMessage(tag, writePackedFixed32, arr);  },
    writePackedSFixed32: function(tag, arr) { this.writeMessage(tag, writePackedSFixed32, arr); },
    writePackedFixed64:  function(tag, arr) { this.writeMessage(tag, writePackedFixed64, arr);  },
    writePackedSFixed64: function(tag, arr) { this.writeMessage(tag, writePackedSFixed64, arr); },

    writeBytesField: function(tag, buffer) {
        this.writeTag(tag, Pbf.Bytes);
        this.writeBytes(buffer);
    },
    writeFixed32Field: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed32);
        this.writeFixed32(val);
    },
    writeSFixed32Field: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed32);
        this.writeSFixed32(val);
    },
    writeFixed64Field: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed64);
        this.writeFixed64(val);
    },
    writeSFixed64Field: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed64);
        this.writeSFixed64(val);
    },
    writeVarintField: function(tag, val) {
        this.writeTag(tag, Pbf.Varint);
        this.writeVarint(val);
    },
    writeSVarintField: function(tag, val) {
        this.writeTag(tag, Pbf.Varint);
        this.writeSVarint(val);
    },
    writeStringField: function(tag, str) {
        this.writeTag(tag, Pbf.Bytes);
        this.writeString(str);
    },
    writeFloatField: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed32);
        this.writeFloat(val);
    },
    writeDoubleField: function(tag, val) {
        this.writeTag(tag, Pbf.Fixed64);
        this.writeDouble(val);
    },
    writeBooleanField: function(tag, val) {
        this.writeVarintField(tag, Boolean(val));
    }
};

function writePackedVarint(arr, pbf)   { for (var i = 0; i < arr.length; i++) pbf.writeVarint(arr[i]);   }
function writePackedSVarint(arr, pbf)  { for (var i = 0; i < arr.length; i++) pbf.writeSVarint(arr[i]);  }
function writePackedFloat(arr, pbf)    { for (var i = 0; i < arr.length; i++) pbf.writeFloat(arr[i]);    }
function writePackedDouble(arr, pbf)   { for (var i = 0; i < arr.length; i++) pbf.writeDouble(arr[i]);   }
function writePackedBoolean(arr, pbf)  { for (var i = 0; i < arr.length; i++) pbf.writeBoolean(arr[i]);  }
function writePackedFixed32(arr, pbf)  { for (var i = 0; i < arr.length; i++) pbf.writeFixed32(arr[i]);  }
function writePackedSFixed32(arr, pbf) { for (var i = 0; i < arr.length; i++) pbf.writeSFixed32(arr[i]); }
function writePackedFixed64(arr, pbf)  { for (var i = 0; i < arr.length; i++) pbf.writeFixed64(arr[i]);  }
function writePackedSFixed64(arr, pbf) { for (var i = 0; i < arr.length; i++) pbf.writeSFixed64(arr[i]); }