implement variants of the hashes

FUZZY_FLAG_ELIMSEQ: The comparison operation runs eliminate_sequence
    before actually comparing two hashes on both of them. This step can
    be moved to hash generation time using this flag. Suggested by Niels
    Thykier.
FUZZY_FLAG_NOTRUNC: The second part of the hash is truncated to
    SPAMSUM_LENGTH/2 by default. When comparing two hashes with
    different blocksize this can result in a larger edit distance and
    therefore false negatives.

1 files changed, 8 insertions, 3 deletions

diff --git a/pyfuzzy.pyx b/pyfuzzy.pyx
index 2a18786..e9d870e 100644
--- a/pyfuzzy.pyx
+++ b/pyfuzzy.pyx
@@ -21,10 +21,13 @@ import os
 cdef extern from "fuzzy.h":
     struct fuzzy_state
     cdef enum:
+        FUZZY_FLAG_ELIMSEQ
+        FUZZY_FLAG_NOTRUNC
         FUZZY_MAX_RESULT
     cdef extern fuzzy_state *fuzzy_new() nogil
     cdef extern int fuzzy_update(fuzzy_state *, unsigned char *, size_t) nogil
-    cdef extern int fuzzy_digest(fuzzy_state *, char *) nogil
+    cdef extern int fuzzy_digest(fuzzy_state *, char *,
+                                 unsigned int flags) nogil
     cdef extern void fuzzy_free(fuzzy_state *) nogil
 
 class FuzzyError(Exception):
@@ -56,11 +59,13 @@ cdef class FuzzyHash:
             self.state = NULL
             raise FuzzyError(libc.errno.errno)
 
-    def digest(self):
+    def digest(self, elimseq=False, notrunc=False):
         if self.state == NULL:
             raise FuzzyError(libc.errno.EINVAL)
         cdef char result[FUZZY_MAX_RESULT]
-        if fuzzy_digest(self.state, result) != 0:
+        flags = (FUZZY_FLAG_ELIMSEQ if elimseq else 0) | \
+                (FUZZY_FLAG_NOTRUNC if notrunc else 0)
+        if fuzzy_digest(self.state, result, flags) != 0:
             raise FuzzyError(libc.errno.errno)
         return str(result)