Class: Libdeflate::Compressor

Inherits:
Object
  • Object
show all
Defined in:
ext/libdeflate/libdeflate_ext.c

Instance Method Summary collapse

Constructor Details

#initialize(level = DEFAULT_COMPRESSION) ⇒ Object

Returns a new Libdeflate::Compressor object. level must be in range from 1 to 12, and defaults to DEFAULT_COMPRESSION.

Libdeflate::Compressor.new #=> #<Libdeflate::Compressor:0x007fad31b672c8>



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# File 'ext/libdeflate/libdeflate_ext.c', line 114

static VALUE
rb_compressor_initialize(int argc, VALUE *argv, VALUE self)
{
    VALUE level;
    int compression_level;
    struct libdeflate_compressor *c;

    rb_scan_args(argc, argv, "01", &level);

    compression_level = NIL_P(level) ? DEFAULT_COMPRESSION : FIX2INT(level);

    c = libdeflate_alloc_compressor(compression_level);
    if (c == NULL) {
        rb_raise(rb_eLibdefalteError, "libdeflate_alloc_compressor: compression_level=%d", compression_level);
    }

    DATA_PTR(self) = c;

    return self;
}

Instance Method Details

#compress(str, format = DEFLATE, outbuf = nil) ⇒ String

Compresses the given string into format. Valid values of format are DEFLATE (default), ZLIB and GZIP. If outbuf is given, the resulting compressed data will be written to it.

compressor.compress('foo')                   #=> "\x01\x03\x00\xFC\xFFfoo"
compressor.compress('foo', Libdeflate::ZLIB) #=> "x\x9C\x01\x03\x00\xFC\xFFfoo\x02\x82\x01E"

outbuf = 'bar'
compressor.compress('foo', nil, outbuf) #=> "\x01\x03\x00\xFC\xFFfoo"
outbuf                                  #=> "\x01\x03\x00\xFC\xFFfoo"

Returns:

  • (String) 


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# File 'ext/libdeflate/libdeflate_ext.c', line 156

static VALUE
rb_compressor_compress(int argc, VALUE *argv, VALUE self)
{
    struct libdeflate_compressor *c = check_compressor(self);
    VALUE str, format, outbuf;
    size_t (*compress_func)(struct libdeflate_compressor *, const void *, size_t, void *, size_t);
    size_t (*compress_bound_func)(struct libdeflate_compressor *, size_t);
    size_t out_nbytes, max_out_nbytes;

    rb_scan_args(argc, argv, "12", &str, &format, &outbuf);

    StringValue(str);

    switch (NIL_P(format) ? FORMAT_DEFLATE : FIX2INT(format)) {
        case FORMAT_DEFLATE:
            compress_func = &libdeflate_deflate_compress;
            compress_bound_func = &libdeflate_deflate_compress_bound;
            break;
        case FORMAT_ZLIB:
            compress_func = &libdeflate_zlib_compress;
            compress_bound_func = &libdeflate_zlib_compress_bound;
            break;
        case FORMAT_GZIP:
            compress_func = &libdeflate_gzip_compress;
            compress_bound_func = &libdeflate_gzip_compress_bound;
            break;
        default:
            rb_raise(rb_eLibdefalteError, "unknown compressed data format: %d", FIX2INT(format));
    }

    if (NIL_P(outbuf)) {
        outbuf = rb_str_buf_new(compress_bound_func(c, RSTRING_LEN(str)));
    } else {
        StringValue(outbuf);
        rb_str_modify(outbuf);
    }

    out_nbytes = compress_func(c,
                               RSTRING_PTR(str),
                               RSTRING_LEN(str),
                               RSTRING_PTR(outbuf),
                               rb_str_capacity(outbuf));

    if (out_nbytes > 0) {
        rb_str_set_len(outbuf, out_nbytes);
        return outbuf;
    }

    max_out_nbytes = compress_bound_func(c, RSTRING_LEN(str));
    if (rb_str_capacity(outbuf) >= max_out_nbytes) {
        rb_raise(rb_eLibdefalteError, "failed to compress data");
    }

    rb_str_modify_expand(outbuf, max_out_nbytes - RSTRING_LEN(outbuf));

    out_nbytes = compress_func(c,
                               RSTRING_PTR(str),
                               RSTRING_LEN(str),
                               RSTRING_PTR(outbuf),
                               rb_str_capacity(outbuf));

    if (out_nbytes == 0) {
        rb_raise(rb_eLibdefalteError, "failed to compress data");
    }

    rb_str_set_len(outbuf, out_nbytes);

    return outbuf;
}