github.com/geniusesgroup/libgo@v0.0.0-20220713101832-828057a9d3d4/compress/gzip/decompressor.go (about)

     1  /* For license and copyright information please see LEGAL file in repository */
     2  
     3  package gzip
     4  
     5  import (
     6  	"bytes"
     7  	egzip "compress/gzip"
     8  	"io"
     9  
    10  	"../../protocol"
    11  )
    12  
    13  type Decompressor struct {
    14  	sourceMT         protocol.MediaType
    15  	comBuf           bytes.Buffer
    16  	comLen           int
    17  	zr               egzip.Reader
    18  	decompressedData []byte
    19  }
    20  
    21  func (c *Decompressor) initByCodec(compressed protocol.Codec) {
    22  	c.sourceMT = compressed.MediaType()
    23  	c.comLen = compressed.Len()
    24  	c.comBuf = *bytes.NewBuffer(compressed.Marshal())
    25  	if err := c.zr.Reset(&c.comBuf); err != nil {
    26  		return
    27  	}
    28  }
    29  
    30  func (c *Decompressor) decompressAll() {
    31  	// TODO::: which solution?
    32  	// c.decompressedData, _ = io.ReadAll(gz)
    33  	var decomBuf bytes.Buffer
    34  	if c.comLen < 1 {
    35  		decomBuf.Grow(512) // TODO::: 512 came from io.ReadAll, any suggestion??
    36  	} else {
    37  		decomBuf.Grow(c.comLen)
    38  	}
    39  	decomBuf.ReadFrom(&c.zr)
    40  	c.decompressedData = decomBuf.Bytes()
    41  }
    42  
    43  /*
    44  ********** protocol.Codec interface **********
    45   */
    46  
    47  func (c *Decompressor) MediaType() protocol.MediaType       { return c.sourceMT }
    48  func (c *Decompressor) CompressType() protocol.CompressType { return nil }
    49  
    50  func (c *Decompressor) Decode(reader protocol.Reader) (err protocol.Error) {
    51  	var goErr = c.zr.Reset(reader)
    52  	if goErr != nil {
    53  		// err =
    54  	}
    55  	return
    56  }
    57  func (c *Decompressor) Encode(writer protocol.Writer) (err protocol.Error) {
    58  	var _, goErr = c.WriteTo(writer)
    59  	if goErr != nil {
    60  		// err =
    61  	}
    62  	return
    63  }
    64  func (c *Decompressor) Marshal() (data []byte) {
    65  	if c.decompressedData == nil {
    66  		c.decompressAll()
    67  	}
    68  	return c.decompressedData
    69  }
    70  func (c *Decompressor) MarshalTo(data []byte) []byte {
    71  	if c.decompressedData == nil {
    72  		c.decompressAll()
    73  	}
    74  	return append(data, c.decompressedData...)
    75  }
    76  func (c *Decompressor) Unmarshal(data []byte) (err protocol.Error) {
    77  	c.comLen = len(data)
    78  	c.comBuf = *bytes.NewBuffer(data)
    79  	var goErr = c.zr.Reset(&c.comBuf)
    80  	if goErr != nil {
    81  		// err =
    82  	}
    83  	return
    84  }
    85  func (c *Decompressor) UnmarshalFrom(data []byte) (remaining []byte, err protocol.Error) {
    86  	err = c.Unmarshal(data)
    87  	// TODO::: can return any remaining data?
    88  	return
    89  }
    90  
    91  // Len return length of decompressed data
    92  func (c *Decompressor) Len() (ln int) {
    93  	if c.decompressedData == nil {
    94  		c.decompressAll()
    95  	}
    96  	return len(c.decompressedData)
    97  }
    98  
    99  func (c *Decompressor) Discard() (err protocol.Error) {
   100  	// io.Copy(io.Discard, b)
   101  	return
   102  }
   103  
   104  /*
   105  ********** io package interfaces **********
   106   */
   107  
   108  func (c *Decompressor) ReadFrom(reader io.Reader) (n int64, err error) {
   109  	err = c.zr.Reset(reader)
   110  	return
   111  }
   112  func (c *Decompressor) WriteTo(w io.Writer) (totalWrite int64, err error) {
   113  	return io.Copy(w, &c.zr)
   114  }