[pypy-commit] lang-scheme default: Fix strings: Allow escaped backslash

[boemmels]

Author: Juergen Boemmels <boemmels at web.de>
Branch: 
Changeset: r7:0e79d2ada637
Date: 2011-09-06 22:58 +0200
http://bitbucket.org/pypy/lang-scheme/changeset/0e79d2ada637/

Log:	Fix strings: Allow escaped backslash

diff --git a/scheme/ssparser.py b/scheme/ssparser.py
--- a/scheme/ssparser.py
+++ b/scheme/ssparser.py
@@ -2,18 +2,25 @@
 from pypy.rlib.parsing.makepackrat import BacktrackException, Status
 from scheme.object import W_Pair, W_Integer, W_String, symbol, \
         w_nil, W_Boolean, W_Real, quote, qq, unquote, unquote_splicing, \
-        w_ellipsis
+        w_ellipsis, SchemeSyntaxError
 
 def str_unquote(s):
     str_lst = []
-    last_ch = ''
-    for c in s[1:]:
-        if last_ch == '\\' and c == '"':
-            pass
+    pos = 1
+    last = len(s)-1
+    while pos < last:
+        ch = s[pos]
+        if ch == '\\':
+            pos += 1
+            ch = s[pos]
+            if ch == '\\' or ch == '\"':
+                str_lst.append(ch)
+            else:
+                raise SchemeSyntaxError
         else:
-            str_lst.append(last_ch)
+            str_lst.append(ch)
 
-        last_ch = c
+        pos += 1
 
     return ''.join(str_lst)
 
diff --git a/scheme/test/test_parser.py b/scheme/test/test_parser.py
--- a/scheme/test/test_parser.py
+++ b/scheme/test/test_parser.py
@@ -62,6 +62,16 @@
     assert isinstance(t, W_String)
     assert unwrap(t) == 'don\'t believe "them"'
 
+    more_strings = [(r'''"simple string"''', r'''simple string'''),
+                    (r'''"\\ backslash"''', r'''\ backslash'''),
+                    (r'''"\\\\"''',r'''\\'''),
+                    (r'''"with \"quotes\""''', r'''with "quotes"'''),
+                   ]
+    for code, contents in more_strings:
+        w_string = parse_sexpr(code)
+        assert isinstance(w_string, W_String)
+        assert unwrap(w_string) == contents
+
 def test_objects():
     w_fixnum = parse_sexpr('-12345')
     assert isinstance(w_fixnum, W_Integer)