diff options
Diffstat (limited to 'src/backend/utils/adt/varlena.c')
| -rw-r--r-- | src/backend/utils/adt/varlena.c | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index 963abf97b3d..27f808712af 100644 --- a/src/backend/utils/adt/varlena.c +++ b/src/backend/utils/adt/varlena.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.45 1998/12/08 06:19:15 thomas Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.46 1998/12/13 23:35:48 thomas Exp $ * *------------------------------------------------------------------------- */ @@ -313,9 +313,8 @@ textcat(text *t1, text *t2) * - starting position (is one-based) * - string length * - * If the starting position is zero or less, then return the entire string. - * XXX Note that this may not be the right behavior: - * if we are calculating the starting position we might want it to start at one. + * If the starting position is zero or less, then return from the start of the string + * adjusting the length to be consistant with the "negative start" per SQL92. * If the length is less than zero, return the remaining string. * * Note that the arguments operate on octet length, @@ -323,6 +322,9 @@ textcat(text *t1, text *t2) * * Added multi-byte support. * - Tatsuo Ishii 1998-4-21 + * Changed behavior if starting position is less than one to conform to SQL92 behavior. + * Formerly returned the entire string; now returns a portion. + * - Thomas Lockhart 1998-12-10 */ text * text_substr(text *string, int32 m, int32 n) @@ -336,7 +338,7 @@ text_substr(text *string, int32 m, int32 n) #endif - if ((string == (text *) NULL) || (m <= 0)) + if (string == (text *) NULL) return string; len = VARSIZE(string) - VARHDRSZ; @@ -344,19 +346,25 @@ text_substr(text *string, int32 m, int32 n) len = pg_mbstrlen_with_len(VARDATA(string), len); #endif - /* m will now become a zero-based starting position */ + /* starting position after the end of the string? */ if (m > len) { - m = 0; + m = 1; n = 0; } - else + /* starting position before the start of the string? + * then offset into the string per SQL92 spec... */ + else if (m < 1) { - m--; - if (((m + n) > len) || (n < 0)) - n = (len - m); + n += (m-1); + m = 1; } + /* m will now become a zero-based starting position */ + m--; + if (((m + n) > len) || (n < 0)) + n = (len - m); + #ifdef MULTIBYTE p = VARDATA(string); for (i = 0; i < m; i++) |