[Chicken-hackers] [PATCH 2/2] extras/pretty-print: escape control characters in strings

[Florian Zumbiehl]

Make pretty-print encode control characters in strings as escape sequences
rather than as literal bytes, the same way write does it.
---
 extras.scm |   29 +++++++++++++++++++----------
 1 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/extras.scm b/extras.scm
index 0e8b144..8cdbf4a 100644
--- a/extras.scm
+++ b/extras.scm
@@ -343,17 +343,26 @@
                                                       (out "\\"
                                                            (out 
(##sys#substring obj i j)
                                                                 col)))
-                                                (cond ((assq c '((#\tab . 
"\\t")
-                                                                 (#\newline . 
"\\n")
-                                                                 (#\return . 
"\\r")))
-                                                       =>
-                                                       (lambda (a)
-                                                         (let ((col2
+                                                (if (or (char<? c #\x20)
+                                                        (char=? c #\x7f))
+                                                  (loop (fx+ j 1)
+                                                        (fx+ j 1)
+                                                        (let ((col2
                                                                 (out 
(##sys#substring obj i j) col)))
-                                                           (loop (fx+ j 1)
-                                                                 (fx+ j 1)
-                                                                 (out (cdr a) 
col2)))))
-                                                      (else (loop i (fx+ j 1) 
col)))))
+                                                          (cond ((assq c 
'((#\tab . "\\t")
+                                                                           
(#\newline . "\\n")
+                                                                           
(#\return . "\\r")
+                                                                           
(#\vtab . "\\v")
+                                                                           
(#\page . "\\f")
+                                                                           
(#\alarm . "\\b")))
+                                                                 =>
+                                                                 (lambda (a)
+                                                                   (out (cdr 
a) col2)))
+                                                                (else
+                                                                  (out 
(number->string (char->integer c) 16)
+                                                                       (out 
(if (char<? c #\x10) "0" "")
+                                                                            
(out "\\x" col2)))))))
+                                                  (loop i (fx+ j 1) col))))
                                          (out "\""
                                               (out (##sys#substring obj i j) 
col))))))
            ((char? obj)        (if display?
-- 
1.7.2.5