Add routines to help with single-byte (internal) character type support.

Thomas G. Lockhart · Thomas G. Lockhart · commit afa71c766198 · 1998-12-14T00:13:56.000Z
diff --git a/src/backend/utils/adt/char.c b/src/backend/utils/adt/char.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/char.c,v 1.19 1998/09/01 03:25:50 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/char.c,v 1.19.2.1 1998/12/14 00:13:55 thomas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,7 +29,7 @@ int32
 charin(char *ch)
 {
 	if (ch == NULL)
-		return (int32) NULL;
+		return (int32) '\0';
 	return (int32) *ch;
 }
 
@@ -153,3 +153,21 @@ cideq(int8 arg1, int8 arg2)
 {
 	return arg1 == arg2;
 }
+
+int8
+text_char(text *arg1)
+{
+	return ((int8) *(VARDATA(arg1)));
+}
+
+text *
+char_text(int8 arg1)
+{
+	text *result;
+
+	result = palloc(VARHDRSZ+1);
+	VARSIZE(result) = VARHDRSZ+1;
+	*(VARDATA(result)) = arg1;
+
+	return result;
+}
diff --git 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 1.44 1998/10/08 18:30:12 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.44.2.1 1998/12/14 00:13:56 thomas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -313,16 +313,18 @@ 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,
  *	so not aware of multi-byte character sets.
  *
  * 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)
@@ -336,27 +338,33 @@ 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;
 #ifdef MULTIBYTE
 	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++)

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/utils/adt/char.c,v 1.19 1998/09/01 03:25:50 momjian Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/char.c,v 1.19.2.1 1998/12/14 00:13:55 thomas Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -29,7 +29,7 @@ int32`
`29`	`29`	`charin(char *ch)`
`30`	`30`	`{`
`31`	`31`	`if (ch == NULL)`
`32`		`- return (int32) NULL;`
	`32`	`+ return (int32) '\0';`
`33`	`33`	`return (int32) *ch;`
`34`	`34`	`}`
`35`	`35`
`@@ -153,3 +153,21 @@ cideq(int8 arg1, int8 arg2)`
`153`	`153`	`{`
`154`	`154`	`return arg1 == arg2;`
`155`	`155`	`}`
	`156`	`+`
	`157`	`+int8`
	`158`	`+text_char(text *arg1)`
	`159`	`+{`
	`160`	`+ return ((int8) *(VARDATA(arg1)));`
	`161`	`+}`
	`162`	`+`
	`163`	`+text *`
	`164`	`+char_text(int8 arg1)`
	`165`	`+{`
	`166`	`+ text *result;`
	`167`	`+`
	`168`	`+ result = palloc(VARHDRSZ+1);`
	`169`	`+ VARSIZE(result) = VARHDRSZ+1;`
	`170`	`+ *(VARDATA(result)) = arg1;`
	`171`	`+`
	`172`	`+ return result;`
	`173`	`+}`