-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Simple, fast binary diff/patch
--   
--   Compute a patch between two ByteStrings which can later be applied to
--   the first to produce the second. This can be used to save bandwidth
--   and disk space when many strings differing by a small number of bytes
--   need to be transmitted or stored.
--   
--   The underlying implementation is written in C, and can also be found
--   at <a>http://ccan.ozlabs.org/info/bdelta.html</a>.
--   
--   Currently, a patch does not save any space when two strings differ by
--   more than 1000 bytes. This arbitrary limit serves to keep applications
--   from spiking in memory and CPU usage, as the algorithm uses quadratic
--   space and time with respect to the length of the patch. A better
--   algorithm may be introduced in a future version of bdelta.
@package bdelta
@version 0.1


-- | Binary diff/patch for <a>ByteString</a>s.
--   
--   The <a>diff</a> function takes two <a>ByteString</a>s, and produces a
--   "patch" that can later be applied with the <a>patch</a> function to
--   the first string to produce the second string. It exploits common
--   subsequences between the two strings, and can be used to save
--   bandwidth and disk space when many strings differing by a small number
--   of bytes need to be transmitted or stored.
--   
--   Deltas produced by this version of the library can be applied using
--   current or future versions, but may not be compatible with past
--   versions.
--   
--   bdelta implements the algorithm described in <i>An O(ND) Difference
--   Algorithm and Its Variations</i> by Eugene W. Myers. Because its
--   memory usage and expected running time are O(N + D^2), it works well
--   only when the strings differ by a small number of bytes. This
--   implementation stops trying when the strings differ by more than 1000
--   bytes, and falls back to producing a patch that simply emits the new
--   string.
--   
--   Thus, bdelta does not save any space when given two strings that
--   differ by more than 1000 bytes. This may be improved in a future
--   version of the library.
module Data.BDelta

-- | Compute a delta between two <a>ByteString</a>s.
--   
--   <pre>
--   patch old (diff old new) == Right new
--   </pre>
diff :: ByteString -> ByteString -> ByteString

-- | Apply a delta produced by <a>diff</a>.
--   
--   If the patch cannot be applied, this function returns <tt>Left
--   errmsg</tt>, where <tt>errmsg</tt> is a string describing the error.
patch :: ByteString -> ByteString -> Either String ByteString