Change lpad() and rpad() to behave more Oracle-compatibly when target

length is less than original string length.

diff --git a/src/backend/utils/adt/oracle_compat.c b/src/backend/utils/adt/oracle_compat.c
index e85110262064b2e6992dd1a481e597714cf695d6..5a83c56687f6273952c5041db668e171886f2ab4 100644 (file)
--- a/src/backend/utils/adt/oracle_compat.c
+++ b/src/backend/utils/adt/oracle_compat.c
@@ -1,14 +1,14 @@
 /*
  * Edmund Mergl 
  *
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/oracle_compat.c,v 1.29 2000/12/03 20:45:36 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/oracle_compat.c,v 1.30 2000/12/07 23:22:56 tgl Exp $
  *
  */
 
-#include 
-
 #include "postgres.h"
 
+#include 
+
 #include "utils/builtins.h"
 
 
@@ -140,7 +140,8 @@ initcap(PG_FUNCTION_ARGS)
  * Purpose:
  *
  *  Returns string1, left-padded to length len with the sequence of
- *  characters in string2.
+ *  characters in string2.  If len is less than the length of string1,
+ *  instead truncate (on the right) to len.
  *
  ********************************************************************/
 
@@ -153,31 +154,49 @@ lpad(PG_FUNCTION_ARGS)
    text       *ret;
    char       *ptr1,
               *ptr2,
+              *ptr2end,
               *ptr_ret;
    int         m,
-               n;
+               s1len,
+               s2len;
+
+   /* Negative len is silently taken as zero */
+   if (len < 0)
+       len = 0;
+
+   s1len = VARSIZE(string1) - VARHDRSZ;
+   if (s1len < 0)
+       s1len = 0;              /* shouldn't happen */
+
+   s2len = VARSIZE(string2) - VARHDRSZ;
+   if (s2len < 0)
+       s2len = 0;              /* shouldn't happen */
 
-   if (((VARSIZE(string1) - VARHDRSZ) < 0) ||
-       ((m = len - (VARSIZE(string1) - VARHDRSZ)) <= 0) ||
-       ((VARSIZE(string2) - VARHDRSZ) <= 0))
-       PG_RETURN_TEXT_P(string1);
+   if (s1len > len)
+       s1len = len;            /* truncate string1 to len chars */
+
+   if (s2len <= 0)
+       len = s1len;            /* nothing to pad with, so don't pad */
 
    ret = (text *) palloc(VARHDRSZ + len);
    VARATT_SIZEP(ret) = VARHDRSZ + len;
 
+   m = len - s1len;
+
    ptr2 = VARDATA(string2);
+   ptr2end = ptr2 + s2len;
    ptr_ret = VARDATA(ret);
 
    while (m--)
    {
-       *ptr_ret++ = *ptr2;
-       ptr2 = (ptr2 == VARDATA(string2) + VARSIZE(string2) - VARHDRSZ - 1) ? VARDATA(string2) : ++ptr2;
+       *ptr_ret++ = *ptr2++;
+       if (ptr2 == ptr2end)    /* wrap around at end of s2 */
+           ptr2 = VARDATA(string2);
    }
 
-   n = VARSIZE(string1) - VARHDRSZ;
    ptr1 = VARDATA(string1);
 
-   while (n--)
+   while (s1len--)
        *ptr_ret++ = *ptr1++;
 
    PG_RETURN_TEXT_P(ret);
@@ -195,7 +214,8 @@ lpad(PG_FUNCTION_ARGS)
  * Purpose:
  *
  *  Returns string1, right-padded to length len with the sequence of
- *  characters in string2.
+ *  characters in string2.  If len is less than the length of string1,
+ *  instead truncate (on the right) to len.
  *
  ********************************************************************/
 
@@ -208,31 +228,49 @@ rpad(PG_FUNCTION_ARGS)
    text       *ret;
    char       *ptr1,
               *ptr2,
+              *ptr2end,
               *ptr_ret;
    int         m,
-               n;
+               s1len,
+               s2len;
+
+   /* Negative len is silently taken as zero */
+   if (len < 0)
+       len = 0;
+
+   s1len = VARSIZE(string1) - VARHDRSZ;
+   if (s1len < 0)
+       s1len = 0;              /* shouldn't happen */
 
-   if (((VARSIZE(string1) - VARHDRSZ) < 0) ||
-       ((m = len - (VARSIZE(string1) - VARHDRSZ)) <= 0) ||
-       ((VARSIZE(string2) - VARHDRSZ) <= 0))
-       PG_RETURN_TEXT_P(string1);
+   s2len = VARSIZE(string2) - VARHDRSZ;
+   if (s2len < 0)
+       s2len = 0;              /* shouldn't happen */
+
+   if (s1len > len)
+       s1len = len;            /* truncate string1 to len chars */
+
+   if (s2len <= 0)
+       len = s1len;            /* nothing to pad with, so don't pad */
 
    ret = (text *) palloc(VARHDRSZ + len);
    VARATT_SIZEP(ret) = VARHDRSZ + len;
 
-   n = VARSIZE(string1) - VARHDRSZ;
+   m = len - s1len;
+
    ptr1 = VARDATA(string1);
    ptr_ret = VARDATA(ret);
 
-   while (n--)
+   while (s1len--)
        *ptr_ret++ = *ptr1++;
 
    ptr2 = VARDATA(string2);
+   ptr2end = ptr2 + s2len;
 
    while (m--)
    {
-       *ptr_ret++ = *ptr2;
-       ptr2 = (ptr2 == VARDATA(string2) + VARSIZE(string2) - VARHDRSZ - 1) ? VARDATA(string2) : ++ptr2;
+       *ptr_ret++ = *ptr2++;
+       if (ptr2 == ptr2end)    /* wrap around at end of s2 */
+           ptr2 = VARDATA(string2);
    }
 
    PG_RETURN_TEXT_P(ret);