> Author: brane
> Date: Thu Nov 22 14:00:48 2012
> New Revision: 1412554
> Modified: subversion/trunk/subversion/libsvn_subr/string.c
> svn_cstring__similarity(const char *stra, const char *strb,
> svn_membuf_t *buffer, apr_size_t *rlcs)
> {
> - const apr_size_t lena = strlen(stra);
> - const apr_size_t lenb = strlen(strb);
> + const svn_string_t stringa = {stra, strlen(stra)};
> + const svn_string_t stringb = {strb, strlen(strb)};
Unfortunately our C'89 coding standard doesn't allow us to use non-constant
initializers, and there are some compilers occasionally used to build
Subversion that don't accept it.
> + return svn_string__similarity(&stringa, &stringb, buffer, rlcs);
> +}
> +
> +unsigned int
> +svn_string__similarity(const svn_string_t *stringa,
> + const svn_string_t *stringb,
> + svn_membuf_t *buffer, apr_size_t *rlcs)
> +{
> + const char *stra = stringa->data;
> + const char *strb = stringb->data;
> + const apr_size_t lena = stringa->len;
> + const apr_size_t lenb = stringb->len;
> const apr_size_t total = lena + lenb;
> const char *enda = stra + lena;
> const char *endb = strb + lenb;
> @@ -1200,11 +1212,13 @@ svn_cstring__similarity(const char *stra
> }
>
> /* ... and the common suffix */
> - while (stra < enda && strb < endb && *enda == *endb)
> - {
> - --enda; --endb;
> - ++lcs;
> - }
> + if (stra < enda && strb < endb)
> + do
> + {
> + --enda; --endb;
> + ++lcs;
> + }
> + while (stra < enda && strb < endb && *enda == *endb);
Both "before" and "after" versions of this block appear to strip off (and count
in LCS) not only the common suffix but also one non-matching character as well
iff such a non-matching character remains in each string. Is that the
intention? It looks wrong so please document it if so.
> if (stra < enda && strb < endb)
> {
> @@ -1254,7 +1268,7 @@ svn_cstring__similarity(const char *stra
> }
> }
>
> - /* The common suffix matcher always finds the nul terminator,
> + /* The common suffix matcher always incremnts the lcs
It incremented it *one more than the true common-suffix count* is the relevant
point. (And then only if there was still at least one character remaining in
each string at that time; but that's the condition of the outer "if" guarding
this block, so necessarily true here.)
> so subtract 1 from the result. */
> lcs += prev[slots] - 1;
> }
- Julian
