diff options
| -rw-r--r-- | lib/pure/hashes.nim | 10 | ||||
| -rw-r--r-- | web/news/e031_version_0_16_2.rst | 6 |
2 files changed, 15 insertions, 1 deletions
diff --git a/lib/pure/hashes.nim b/lib/pure/hashes.nim index 11af81149..17d1c6442 100644 --- a/lib/pure/hashes.nim +++ b/lib/pure/hashes.nim @@ -127,6 +127,15 @@ proc hash*(x: string): Hash = h = h !& ord(x[i]) result = !$h +proc hash*(x: cstring): Hash = + ## efficient hashing of null-terminated strings + var h: Hash = 0 + var i = 0 + while x[i] != 0.char: + h = h !& ord(x[i]) + inc i + result = !$h + proc hash*(sBuf: string, sPos, ePos: int): Hash = ## efficient hashing of a string buffer, from starting ## position `sPos` to ending position `ePos` @@ -239,6 +248,7 @@ proc hash*[A](x: set[A]): Hash = when isMainModule: doAssert( hash("aa bb aaaa1234") == hash("aa bb aaaa1234", 0, 13) ) + doAssert( hash("aa bb aaaa1234") == hash(cstring("aa bb aaaa1234")) ) doAssert( hashIgnoreCase("aa bb aaaa1234") == hash("aa bb aaaa1234") ) doAssert( hashIgnoreStyle("aa bb aaaa1234") == hashIgnoreCase("aa bb aaaa1234") ) let xx = @['H','e','l','l','o'] diff --git a/web/news/e031_version_0_16_2.rst b/web/news/e031_version_0_16_2.rst index 5ee40b772..2d725028e 100644 --- a/web/news/e031_version_0_16_2.rst +++ b/web/news/e031_version_0_16_2.rst @@ -18,7 +18,11 @@ Changes affecting backwards compatibility - The IO routines now raise ``EOFError`` for the "end of file" condition. ``EOFError`` is a subtype of ``IOError`` and so it's easier to distinguish between "error during read" and "error due to EOF". - +- A hash procedure has been added for ``cstring`` type in ``hashes`` module. + Previously, hash of a ``cstring`` would be calculated as a hash of the + pointer. Now the hash is calculated from the contents of the string, assuming + ``cstring`` is a null-terminated string. Equal ``string``s and ``cstring``s + produce equal hash value. Library Additions ----------------- |