class Zlib::Inflate

Parent:: Zlib::ZStream

Zlib:Inflate is the class for decompressing compressed data. Unlike Zlib::Deflate, an instance of this class is not able to duplicate (clone, dup) itself.

Public Class Methods

inflate(string) Show source

Zlib::Inflate.inflate(string)

static VALUE
rb_inflate_s_inflate(VALUE obj, VALUE src)
{
    struct zstream z;
    VALUE dst, args[2];
    int err;

    StringValue(src);
    zstream_init_inflate(&z);
    err = inflateInit(&z.stream);
    if (err != Z_OK) {
        raise_zlib_error(err, z.stream.msg);
    }
    ZSTREAM_READY(&z);

    args[0] = (VALUE)&z;
    args[1] = src;
    dst = rb_ensure(inflate_run, (VALUE)args, zstream_ensure_end, (VALUE)&z);

    return dst;
}

Decompresses string. Raises a Zlib::NeedDict exception if a preset dictionary is needed for decompression.

This method is almost equivalent to the following code:

def inflate(string)
  zstream = Zlib::Inflate.new
  buf = zstream.inflate(string)
  zstream.finish
  zstream.close
  buf
end

Example

open "compressed.file" do |compressed_io|
  zi = Zlib::Inflate.new(Zlib::MAX_WBITS + 32)

  begin
    open "uncompressed.file", "w+" do |uncompressed_io|
      uncompressed_io << zi.inflate(compressed_io.read)
    end
  ensure
    zi.close
  end
end

Public Instance Methods

<<(p1) Show source

static VALUE
rb_inflate_addstr(VALUE obj, VALUE src)
{
    struct zstream *z = get_zstream(obj);

    if (ZSTREAM_IS_FINISHED(z)) {
        if (!NIL_P(src)) {
            StringValue(src);
            zstream_append_buffer2(z, src);
        }
    }
    else {
        do_inflate(z, src);
        if (ZSTREAM_IS_FINISHED(z)) {
            zstream_passthrough_input(z);
        }
    }

    return obj;
}

Same as IO.

add_dictionary(string) Show source

static VALUE
rb_inflate_add_dictionary(VALUE obj, VALUE dictionary)
{
    VALUE dictionaries = rb_ivar_get(obj, id_dictionaries);
    VALUE checksum = do_checksum(1, &dictionary, adler32);

    rb_hash_aset(dictionaries, checksum, dictionary);

    return obj;
}

Provide the inflate stream with a dictionary that may be required in the future. Multiple dictionaries may be provided. The inflate stream will automatically choose the correct user-provided dictionary based on the stream's required dictionary.

inflate(deflate_string, buffer: nil) → String Show source

inflate(deflate_string, buffer: nil) { |chunk| ... } → nil

static VALUE
rb_inflate_inflate(int argc, VALUE* argv, VALUE obj)
{
    struct zstream *z = get_zstream(obj);
    VALUE dst, src, opts, buffer = Qnil;

    if (OPTHASH_GIVEN_P(opts)) {
        VALUE buf;
        rb_get_kwargs(opts, &id_buffer, 0, 1, &buf);
        if (buf != Qundef && buf != Qnil) {
            buffer = StringValue(buf);
        }
    }
    if (buffer != Qnil) {
        if (!(ZSTREAM_REUSE_BUFFER_P(z) && z->buf == buffer)) {
            long len = RSTRING_LEN(buffer);
            if (len >= ZSTREAM_AVAIL_OUT_STEP_MAX) {
                rb_str_modify(buffer);
            }
            else {
                len = ZSTREAM_AVAIL_OUT_STEP_MAX - len;
                rb_str_modify_expand(buffer, len);
            }
            rb_str_set_len(buffer, 0);
            z->flags |= ZSTREAM_REUSE_BUFFER;
            z->buf = buffer;
        }
    } else if (ZSTREAM_REUSE_BUFFER_P(z)) {
        z->flags &= ~ZSTREAM_REUSE_BUFFER;
        z->buf = Qnil;
    }
    rb_scan_args(argc, argv, "10", &src);

    if (ZSTREAM_IS_FINISHED(z)) {
        if (NIL_P(src)) {
            dst = zstream_detach_buffer(z);
        }
        else {
            StringValue(src);
            zstream_append_buffer2(z, src);
            if (ZSTREAM_REUSE_BUFFER_P(z)) {
                dst = rb_str_resize(buffer, 0);
            } else {
                dst = rb_str_new(0, 0);
            }
        }
    }
    else {
        do_inflate(z, src);
        dst = zstream_detach_buffer(z);
        if (ZSTREAM_IS_FINISHED(z)) {
            zstream_passthrough_input(z);
        }
    }

    return dst;
}

Inputs deflate_string into the inflate stream and returns the output from the stream. Calling this method, both the input and the output buffer of the stream are flushed. If string is nil, this method finishes the stream, just like Zlib::ZStream#finish.

If a block is given consecutive inflated chunks from the deflate_string are yielded to the block and nil is returned.

If a :buffer keyword argument is given and not nil:

The :buffer keyword should be a String, and will used as the output buffer. Using this option can reuse the memory required during inflation.
When not passing a block, the return value will be the same object as the :buffer keyword argument.
When passing a block, the yielded chunks will be the same value as the :buffer keyword argument.

Raises a Zlib::NeedDict exception if a preset dictionary is needed to decompress. Set the dictionary by Zlib::Inflate#set_dictionary and then call this method again with an empty string to flush the stream:

inflater = Zlib::Inflate.new

begin
  out = inflater.inflate compressed
rescue Zlib::NeedDict
  # ensure the dictionary matches the stream's required dictionary
  raise unless inflater.adler == Zlib.adler32(dictionary)

  inflater.set_dictionary dictionary
  inflater.inflate ''
end

# ...

inflater.close