rbxts-pako/lib/deflate.js

'use strict';


var zlib_deflate = require('./zlib/deflate.js');
var utils = require('./zlib/utils');
var c = require('./zlib/constants');
var msg = require('./zlib/messages');
var zstream = require('./zlib/zstream');


/**
 * Deflate
 *
 * @param {Object} [options] zlib options
 * @constructor
 */
var Deflate = function(options) {

  this.options = utils.assign({
    level: 6,
    method: c.Z_DEFLATED,
    chunkSize: 16384,
    windowBits: 15,
    memLevel: 8,
    strategy: c.Z_DEFAULT_STRATEGY
  }, options || {});

  var opt = this.options;

  if (opt.raw && (opt.windowBits > 0)) {
    opt.windowBits = -opt.windowBits;
  }

  else if (opt.gzip && (opt.windowBits > 0) && (opt.windowBits < 16)) {
    opt.windowBits += 16;
  }

  this.strm = new zstream();

  var status = zlib_deflate.deflateInit2(
    this.strm,
    opt.level,
    opt.method,
    opt.windowBits,
    opt.memLevel,
    opt.strategy
  );

  if (status !== c.Z_OK) {
    throw new Error(msg[status]);
  }
};

/**
 * Compresses the input data and fills output buffer with compressed data.
 */
Deflate.prototype.push = function(data_in) {
  var strm = this.strm;
  var chunkSize = this.options.chunkSize;
  var sliced;

  strm.next_in = data_in;
  strm.next_in_index = 0;
  strm.avail_in = strm.next_in.length;
  strm.next_out = utils.arrayCreate(chunkSize);

  /* run deflate() on input until output buffer not full, finish
   compression if all of source has been read in */
  do {
    strm.avail_out = this.options.chunkSize;
    strm.next_out_index = 0;
    zlib_deflate.deflate(strm, c.Z_NO_FLUSH);
    // TODO: check logic & why onEnd called. Check that onEnd not called twice.
    //var ret = zlib_deflate.deflate(strm, c.Z_NO_FLUSH);    /* no bad return value */
    //if (ret !== c.Z_STREAM_END && ret !== c.Z_OK) {
    //  this.onEnd(ret);
    //}
    if(strm.next_out_index) {
      if (strm.next_out_index === chunkSize) {
        // out buffer completely filled, push it as is
        this.onData(strm.next_out);
      } else {
        // out buffer partially filled, slice it first
        sliced = utils.arrayCreate(strm.next_out_index);
        utils.arraySet(sliced, strm.next_out, 0, strm.next_out_index, 0);
        this.onData(sliced);
      }
      // Allocate buffer for next chunk
      strm.next_out = utils.arrayCreate(this.options.chunkSize);
    }
  } while (strm.avail_in > 0 || strm.avail_out === 0);
};

Deflate.prototype.flush = function() {
  var strm = this.strm;
  var out, status;

  do {
    strm.avail_out = this.options.chunkSize;
    strm.next_out_index = 0;
    status = zlib_deflate.deflate(strm, c.Z_FINISH);    /* no bad return value */
    if (status !== c.Z_STREAM_END && status !== c.Z_OK) {
      this.onEnd(status);
    }

    if(strm.next_out_index) {
      out = utils.arrayCreate(strm.next_out_index);
      utils.arraySet(out, strm.next_out, 0, strm.next_out_index, 0);
      this.onData(out);
    }
  } while (strm.avail_out === 0);
};

Deflate.prototype.finish = function() {
  this.flush();
  zlib_deflate.deflateEnd(this.strm);
  this.onEnd(c.Z_OK);
};

Deflate.prototype.onData = function(/*data_out*/) {

};

Deflate.prototype.onEnd = function(/*err*/) {

};


exports.Deflate = Deflate;


/**
 * Compresses the input data
 * @param input
 * @param [options]
 * @returns {Array|Uint8Array}
 */
function deflate(input, options) {
  var result;
  var chunks = [];
  var deflator = new Deflate(options);

  deflator.onData = function(data_out) {
    chunks.push(data_out);
  };

  deflator.onEnd = function(error) {
    if (error) { throw error; }
    result = utils.flattenChunks(chunks);
  };

  deflator.push(input);
  deflator.finish();

  return result;
}


function deflateRaw(input, options) {
  options = options || {};
  options.raw = true;
  return deflate(input, options);
}


function gzip(input, options) {
  options = options || {};
  options.gzip = true;
  return deflate(input, options);
}


exports.Deflate = Deflate;
exports.deflate = deflate;
exports.deflateRaw = deflateRaw;
exports.gzip = gzip;