IronPython.Zlib / src / Decompress.cs

/* ****************************************************************************
 *
 * Copyright (c) Jeff Hardy 2007-2009.
 *
 * This source code is subject to terms and conditions of the Microsoft Public License. A 
 * copy of the license can be found in the License.txt file at the root of this distribution. If 
 * you cannot locate the  Microsoft Public License, please send an email to 
 * jdhardy@gmail.com. By using this source code in any fashion, you are agreeing to be bound 
 * by the terms of the Microsoft Public License.
 *
 * You must not remove this notice, or any other, from this software.
 *
 * ***************************************************************************/

using System;
using System.Runtime.InteropServices;
using ComponentAce.Compression.Libs.ZLib;
using IronPython.Runtime;
using IronPython.Runtime.Operations;
using Microsoft.Scripting.Runtime;

namespace IronPython.Zlib
{
    [PythonType]
    public class Decompress
    {
        private const int Z_OK = ZlibModule.Z_OK;
        private const int Z_STREAM_END = ZlibModule.Z_STREAM_END;
        private const int Z_BUF_ERROR = ZlibModule.Z_BUF_ERROR;

        private const int Z_SYNC_FLUSH = ZlibModule.Z_SYNC_FLUSH;
        private const int Z_FINISH = ZlibModule.Z_FINISH;

        internal Decompress(int wbits)
        {
            zst = new ZStream();
            int err = zst.inflateInit(wbits);
            switch(err)
            {
                case ZlibModule.Z_OK:
                    break;

                case ZlibModule.Z_STREAM_ERROR:
                    throw PythonOps.ValueError("Invalid initialization option");

                default:
                    throw ZlibModule.zlib_error(this.zst, err, "while creating decompression object");
            }

            _unused_data = string.Empty;
            _unconsumed_tail = string.Empty;
        }

        private string _unused_data;
        public string unused_data
        {
            get { return _unused_data; }
        }

        private string _unconsumed_tail;
        public string unconsumed_tail
        {
            get { return _unconsumed_tail; }
        }

        public string decompress(string value)
        {
            return decompress(value, 0);
        }

        [Documentation(@"decompress(data, max_length) -- Return a string containing the decompressed
version of the data.

After calling this function, some of the input data may still be stored in
internal buffers for later processing.
Call the flush() method to clear these buffers.
If the max_length parameter is specified then the return value will be
no longer than max_length.  Unconsumed input data will be stored in
the unconsumed_tail attribute.")]
        public string decompress(string value, int max_length)
        {
            if(max_length < 0) throw new ArgumentException("max_length must be greater than zero");

            byte[] input = ZlibModule.Latin1.GetBytes(value);
            byte[] output = new byte[max_length > 0 ? max_length : ZlibModule.DEFAULTALLOC];

            long start_total_out = zst.total_out;
            zst.next_in = input;
            zst.next_in_index = 0;
            zst.avail_in = input.Length;
            zst.next_out = output;
            zst.next_out_index = 0;
            zst.avail_out = output.Length;

            int err = zst.inflate(FlushStrategy.Z_SYNC_FLUSH);

            while(err == Z_OK && zst.avail_out == 0)
            {
                if(max_length > 0 && output.Length >= max_length)
                    break;

                int old_length = output.Length;
                Array.Resize(ref output, output.Length * 2);
                zst.next_out = output;
                zst.avail_out = old_length;

                err = zst.inflate(FlushStrategy.Z_SYNC_FLUSH);
            }

            if(max_length > 0)
            {
                _unconsumed_tail = ZlibModule.Latin1.GetString(zst.next_in, zst.next_in_index, zst.avail_in);
            }

            if(err == Z_STREAM_END)
            {
                _unused_data += ZlibModule.Latin1.GetString(zst.next_in, zst.next_in_index, zst.avail_in);
            }
            else if(err != Z_OK && err != Z_BUF_ERROR)
            {
                throw ZlibModule.zlib_error(this.zst, err, "while decompressing");
            }

            return ZlibModule.Latin1.GetString(output, 0, (int)(zst.total_out - start_total_out));
        }

        [Documentation(@"flush( [length] ) -- Return a string containing any remaining
decompressed data. length, if given, is the initial size of the
output buffer.

The decompressor object can no longer be used after this call.")]
        public string flush([DefaultParameterValue(ZlibModule.DEFAULTALLOC)]int length)
        {
            if(length < 1)
                throw PythonOps.ValueError("length must be greater than 0.");

            byte[] output = new byte[length];

            long start_total_out = zst.total_out;
            zst.next_out = output;
            zst.next_out_index = 0;
            zst.avail_out = output.Length;

            int err = zst.inflate(FlushStrategy.Z_FINISH);

            while((err == Z_OK || err == Z_BUF_ERROR) &&zst.avail_out == 0)
            {
                int old_length = output.Length;
                Array.Resize(ref output, output.Length * 2);
                zst.next_out = output;
                zst.avail_out = old_length;

                err = zst.inflate(FlushStrategy.Z_FINISH);
            }

            if(err == Z_STREAM_END)
            {
                err = zst.inflateEnd();
                if(err != Z_OK)
                {
                    throw ZlibModule.zlib_error(this.zst, err, "from inflateEnd()");
                }
            }

            return ZlibModule.Latin1.GetString(output, 0, (int)(zst.total_out - start_total_out));
        }

        //[Documentation("copy() -- Return a copy of the decompression object.")]
        //public Compress copy()
        //{
        //    throw new NotImplementedException();
        //}

        private ZStream zst;
    }
}
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