v0.2.0-preview.1

Everything new here is preview and carries [Experimental]. Deflate, zlib and gzip meet the size target and are below the reference speed; the bzip2 decoder meets both. The README has the measurements.

Added

• Deflate (RFC 1951), zlib (RFC 1950) and gzip (RFC 1952): decoder and encoder at levels 0-12 with strategies, preset dictionaries and flushes, in three layers (ONECOMPRESS003).
• bzip2 decoder: multi-stream and randomized blocks, with limits for hostile input (ONECOMPRESS004).
• LZMA and LZMA2 (ONECOMPRESS005), xz with CRC32, CRC64 and SHA-256 checks, the branch filters (x86, ARM, ARM-Thumb, ARM64, PowerPC, SPARC, IA-64, RISC-V) and Delta (ONECOMPRESS006), and lzip (ONECOMPRESS007): decoders and encoders at every preset.
• OneArchive (ONEARCHIVE001): Archive.Open, Archive.Extract and Archive.Create, with detection by content, extraction that never writes outside the target, and limits on size, ratio, entry count, path length and nesting.
  • tar: v7, ustar, pax and GNU (long names, sparse files), read and write.
  • zip: read and write with store, Deflate and Zstandard, zip64 and data descriptors; LZMA, xz and bzip2 entries read.
  • 7z: read, with Copy, Deflate, BZip2, LZMA, LZMA2, Delta, the branch filters and Zstandard, solid folders and encoded headers.
  • Single streams: gz, zst and lz4 (read and write) and bz2 (read), and tar inside them.
• Lz4BlockEncoder, a reusable block compressor, and a length-prefixed block form read back by Lz4PrefixedBlock (not an LZ4 frame). Lz4Dictionary.Train.
• ZstdCompressionDictionary.ForDecompression and ToArray, so one trained dictionary serves both directions.
• ZstdCompressionOptions.SizeHint: an estimate of a stream's length that sizes the window and tables without being written to the frame.

Changed

• Zstandard encoder memory: a stream of unknown length no longer reserves its whole window and binary-tree tables up front (level 22 took 384 MiB for a 1 KiB frame, 640 MiB with a small dictionary; now 129 MiB), and a dictionary's search index is sized by the dictionary, not the source (4 KiB at level 22: 256 MiB, now under 1 MiB). Compressed bytes are unchanged.
• Zstandard and Deflate speed work; compressed bytes of Zstandard are unchanged.

Not supported

• PPMd (zip method 98, 7z PPMD), BCJ2, Deflate64 and encryption are listed but refused with a typed "unsupported method" error.