On Thu, 10 Dec 2009, Michael Hind wrote:
> I don't know if this is relevant but it is defined in pobj.h as:
Here is the relevant structure (where the first 3 elements are deliberately
the same as in the Buffer structure):
struct parrot_string_t {
Parrot_UInt flags;
void * _bufstart;
size_t _buflen;
char *strstart;
UINTVAL bufused;
UINTVAL strlen;
UINTVAL hashval; /* cached hash value computation */
/* parrot_string_representation_t representation;*/
const struct _encoding *encoding;
const struct _charset *charset;
};
My point is that I don't think it's guaranteed that _bufstart == strstart.
They are equal when the string is initially created, but not guaranteed
to stay that way. For example, in src/string/api.c, in the function
Parrot_str_substr(), there is this excerpt:
/* do in-place i.e. reuse existing header if one */
if (replace_dest && d && *d) {
PARROT_ASSERT(src->encoding == Parrot_fixed_8_encoding_ptr);
dest = *d;
dest->encoding = src->encoding;
dest->charset = src->charset;
dest->strstart = (char *)src->strstart + true_offset;
dest->bufused = true_length;
dest->strlen = true_length;
dest->hashval = 0;
}
where strstart is moved, but bufstart isn't.
Hence my concern that this patch is wrong in simply replacing strstart by
bufstart.
--
Andy Dougherty [email protected]
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