From 085a61df2ebe26f9555188c452501ecbf349f887 Mon Sep 17 00:00:00 2001
From: Michael Gran <spk121@yahoo.com>
Date: Sun, 10 Jan 2010 15:39:55 -0800
Subject: [PATCH] Add R6RS backslash string escape

R6RS suggests that '\b' should be a string escape for the backslash
character.

* libguile/read.c (scm_read_string): parse backspace escape

* test-suite/tests/strings.test (R6RS backslash escapes): new test
  (Guile extensions backslash escapes): remove R6RS escapes from test.

* doc/ref/api-data.texi (Strings): document new string escape
---
 doc/ref/api-data.texi         | 3 +++
 libguile/read.c               | 3 +++
 test-suite/tests/strings.test | 8 ++++++--
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/doc/ref/api-data.texi b/doc/ref/api-data.texi
index 3fc34c28f..bf25c5981 100755
--- a/doc/ref/api-data.texi
+++ b/doc/ref/api-data.texi
@@ -2649,6 +2649,9 @@ Tab character (ASCII 9).
 @item @nicode{\v}
 Vertical tab character (ASCII 11).
 
+@item @nicode{\b}
+Backspace character (ASCII 8).
+
 @item @nicode{\xHH}
 Character code given by two hexadecimal digits.  For example
 @nicode{\x7f} for an ASCII DEL (127).
diff --git a/libguile/read.c b/libguile/read.c
index dedfed2fe..25aed5458 100644
--- a/libguile/read.c
+++ b/libguile/read.c
@@ -477,6 +477,9 @@ scm_read_string (int chr, SCM port)
             case 'v':
               c = '\v';
               break;
+            case 'b':
+              c = '\010';
+              break;
             case 'x':
               {
                 scm_t_wchar a, b;
diff --git a/test-suite/tests/strings.test b/test-suite/tests/strings.test
index 984178d72..e04c0260d 100644
--- a/test-suite/tests/strings.test
+++ b/test-suite/tests/strings.test
@@ -221,9 +221,13 @@
   (pass-if "R5RS backslash escapes"
     (string=? "\"\\" (string #\" #\\)))
 
+  (pass-if "R6RS backslash escapes"
+    (string=? "\a\b\t\n\v\f\r"
+              (string #\alarm #\backspace #\tab #\newline #\vtab
+                      #\page #\return)))
+
   (pass-if "Guile extensions backslash escapes"
-    (string=? "\0\a\f\n\r\t\v"
-              (apply string (map integer->char '(0 7 12 10 13 9 11))))))
+    (string=? "\0" (string #\nul))))
 
 ;;
 ;; string?