Re: patch: (read "\x1b") => #\esc

[prj@po.cwru.edu (Paul Jarc)]

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Marius Vollmer <mvo@zagadka.de> wrote:
> What about this change, tho: instead of ignoring a \x sequence that
> does not have two hexadecmal digits, we could signal an error.
> Likewise, we could signal errors for all unrecognized \ sequences.

Here it is.

	* read.c (scm_lreadr): Signal an error for invalid escape
	sequences in strings.  Code cleanups too.


paul

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Index: guile-core/libguile/read.c
===================================================================
RCS file: /cvsroot/guile/guile/guile-core/libguile/read.c,v
retrieving revision 1.92
diff -u -r1.92 read.c
--- guile-core/libguile/read.c	16 Nov 2003 21:01:57 -0000	1.92
+++ guile-core/libguile/read.c	25 Nov 2003 17:06:09 -0000
@@ -524,28 +524,27 @@
 		break;
 	      case 'x':
 		{
-		  int a, b, a_09 = 0, b_09 = 0, a_AF = 0, b_AF = 0, a_af = 0,
-		    b_af = 0;
+		  int a, b;
 		  a = scm_getc (port);
 		  if (a == EOF) goto str_eof;
 		  b = scm_getc (port);
 		  if (b == EOF) goto str_eof;
-		  if      ('0' <= a && a <= '9') a_09 = 1;
-		  else if ('A' <= a && a <= 'F') a_AF = 1;
-		  else if ('a' <= a && a <= 'f') a_af = 1;
-		  if      ('0' <= b && b <= '9') b_09 = 1;
-		  else if ('A' <= b && b <= 'F') b_AF = 1;
-		  else if ('a' <= b && b <= 'f') b_af = 1;
-		  if ((a_09 || a_AF || a_af) && (b_09 || b_AF || b_af))
-		    c = (a_09? a - '0': a_AF? a - 'A' + 10: a - 'a' + 10) * 16
-		      + (b_09? b - '0': b_AF? b - 'A' + 10: b - 'a' + 10);
-		  else
-		    {
-		      scm_ungetc (b, port);
-		      scm_ungetc (a, port);
-		    }
+		  if      ('0' <= a && a <= '9') a -= '0';
+		  else if ('A' <= a && a <= 'F') a = a - 'A' + 10;
+		  else if ('a' <= a && a <= 'f') a = a - 'a' + 10;
+		  else goto bad_escaped;
+		  if      ('0' <= b && b <= '9') b -= '0';
+		  else if ('A' <= b && b <= 'F') b = b - 'A' + 10;
+		  else if ('a' <= b && b <= 'f') b = b - 'a' + 10;
+		  else goto bad_escaped;
+		  c = a * 16 + b;
 		  break;
 		}
+	      default:
+	      bad_escaped:
+		scm_input_error(FUNC_NAME, port,
+				"illegal character in escape sequence: ~S",
+				scm_list_1 (SCM_MAKE_CHAR (c)));
 	      }
 	  SCM_STRING_CHARS (*tok_buf)[j] = c;
 	  ++j;

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