Fix unportable use of isxdigit() with char (rather than unsigned char)

argument, per warnings from buildfarm member pika.  Also clean up code
formatting a trifle.

src/backend/parser/scan.l

@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.165 2010/01/02 16:57:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.166 2010/01/16 17:39:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1137,7 +1137,7 @@ process_integer_literal(const char *token, YYSTYPE *lval)
 	return ICONST;
 }
 
-static int
+static unsigned int
 hexval(unsigned char c)
 {
 	if (c >= '0' && c <= '9')
@@ -1194,7 +1194,7 @@ addunicode(pg_wchar c, core_yyscan_t yyscanner)
 			yyerror("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8");
 		yyextra->saw_non_ascii = true;
 	}
-	unicode_to_utf8(c, (unsigned char *)buf);
+	unicode_to_utf8(c, (unsigned char *) buf);
 	addlit(buf, pg_mblen(buf), yyscanner);
 }
 
@@ -1241,9 +1241,17 @@ litbuf_udeescape(unsigned char escape, core_yyscan_t yyscanner)
 				*out++ = escape;
 				in += 2;
 			}
-			else if (isxdigit(in[1]) && isxdigit(in[2]) && isxdigit(in[3]) && isxdigit(in[4]))
+			else if (isxdigit((unsigned char) in[1]) &&
+					 isxdigit((unsigned char) in[2]) &&
+					 isxdigit((unsigned char) in[3]) &&
+					 isxdigit((unsigned char) in[4]))
 			{
-				pg_wchar unicode = hexval(in[1]) * 16*16*16 + hexval(in[2]) * 16*16 + hexval(in[3]) * 16 + hexval(in[4]);
+				pg_wchar unicode;
+
+				unicode = (hexval(in[1]) << 12) +
+					(hexval(in[2]) << 8) +
+					(hexval(in[3]) << 4) +
+					hexval(in[4]);
 				check_unicode_value(unicode, in, yyscanner);
 				if (pair_first)
 				{
@@ -1270,13 +1278,22 @@ litbuf_udeescape(unsigned char escape, core_yyscan_t yyscanner)
 				}
 				in += 5;
 			}
-			else if (in[1] == '+'
-					 && isxdigit(in[2]) && isxdigit(in[3])
-					 && isxdigit(in[4]) && isxdigit(in[5])
-					 && isxdigit(in[6]) && isxdigit(in[7]))
+			else if (in[1] == '+' &&
+					 isxdigit((unsigned char) in[2]) &&
+					 isxdigit((unsigned char) in[3]) &&
+					 isxdigit((unsigned char) in[4]) &&
+					 isxdigit((unsigned char) in[5]) &&
+					 isxdigit((unsigned char) in[6]) &&
+					 isxdigit((unsigned char) in[7]))
 			{
-				pg_wchar unicode = hexval(in[2]) * 16*16*16*16*16 + hexval(in[3]) * 16*16*16*16 + hexval(in[4]) * 16*16*16
-									+ hexval(in[5]) * 16*16 + hexval(in[6]) * 16 + hexval(in[7]);
+				pg_wchar unicode;
+
+				unicode = (hexval(in[2]) << 20) +
+					(hexval(in[3]) << 16) +
+					(hexval(in[4]) << 12) +
+					(hexval(in[5]) << 8) +
+					(hexval(in[6]) << 4) +
+					hexval(in[7]);
 				check_unicode_value(unicode, in, yyscanner);
 				if (pair_first)
 				{