This patch changes the default behaviour of the builtin charmap

codec to not apply Latin-1 mappings for keys which are not found
in the mapping dictionaries, but instead treat them as undefined
mappings.

The patch was originally written by Martin v. Loewis with some
additional (cosmetic) changes and an updated test script
by Marc-Andre Lemburg.

The standard codecs were recreated from the most current files
available at the Unicode.org site using the Tools/scripts/gencodec.py
tool.

This patch closes the bugs #116285 and #119960.

1 files changed, 39 insertions, 11 deletions

diff --git a/Tools/scripts/gencodec.py b/Tools/scripts/gencodec.py
index 45b69b0..39b42ff 100644
--- a/Tools/scripts/gencodec.py
+++ b/Tools/scripts/gencodec.py
@@ -1,9 +1,9 @@
 """ Unicode Mapping Parser and Codec Generator.
 
 This script parses Unicode mapping files as available from the Unicode
-site (ftp.unicode.org) and creates Python codec modules from them. The
-codecs use the standard character mapping codec to actually apply the
-mapping.
+site (ftp://ftp.unicode.org/Public/MAPPINGS/) and creates Python codec
+modules from them. The codecs use the standard character mapping codec
+to actually apply the mapping.
 
 Synopsis: gencodec.py dir codec_prefix
 
@@ -18,6 +18,7 @@ same location (with .mapping extension).
 Written by Marc-Andre Lemburg (mal@lemburg.com).
 
 (c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
+(c) Copyright Guido van Rossum, 2000.
 
 """#"
 
@@ -70,6 +71,10 @@ def readmap(filename,
     lines = f.readlines()
     f.close()
     enc2uni = {}
+    identity = []
+    unmapped = range(256)
+    for i in range(256):
+        unmapped[i] = i
     for line in lines:
         line = strip(line)
         if not line or line[0] == '#':
@@ -85,8 +90,22 @@ def readmap(filename,
             comment = ''
         else:
             comment = comment[1:]
-        if enc != uni:
+        if enc < 256:
+            unmapped.remove(enc)
+            if enc == uni:
+                identity.append(enc)
+            else:
+                enc2uni[enc] = (uni,comment)
+        else:
             enc2uni[enc] = (uni,comment)
+    # If there are more identity-mapped entries than unmapped entries,
+    # it pays to generate an identity dictionary first, add add explicit
+    # mappings to None for the rest
+    if len(identity)>=len(unmapped):
+        for enc in unmapped:
+            enc2uni[enc] = (None, "")
+        enc2uni['IDENTITY'] = 256
+
     return enc2uni
 
 def hexrepr(t,
@@ -143,11 +162,12 @@ def codegen(name,map,comments=1):
     """
     l = [
         '''\
-""" Python Character Mapping Codec generated from '%s'.
+""" Python Character Mapping Codec generated from '%s' with gencodec.py.
 
 Written by Marc-Andre Lemburg (mal@lemburg.com).
 
 (c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
+(c) Copyright 2000 Guido van Rossum.
 
 """#"
 
@@ -178,15 +198,23 @@ def getregentry():
     return (Codec().encode,Codec().decode,StreamReader,StreamWriter)
 
 ### Decoding Map
-
-decoding_map = {
 ''' % name,
         ]
+
+    if map.has_key("IDENTITY"):
+        l.append("decoding_map = codecs.make_identity_dict(range(%d))"
+                 % map["IDENTITY"])
+        l.append("decoding_map.update({")
+        splits = 1
+        del map["IDENTITY"]
+    else:
+        l.append("decoding_map = {")
+        splits = 0
+        
     mappings = map.items()
     mappings.sort()
     append = l.append
     i = 0
-    splits = 0
     for e,value in mappings:
         try:
             (u,c) = value
@@ -198,7 +226,7 @@ decoding_map = {
             append('\t%s: %s,\t# %s' % (key,unicoderepr(u),c))
         else:
             append('\t%s: %s,' % (key,unicoderepr(u)))
-        i = i + 1
+        i += 1
         if i == 4096:
             # Split the definition into parts to that the Python
             # parser doesn't dump core
@@ -206,7 +234,7 @@ decoding_map = {
                 append('}')
             else:
                 append('})')
-            append('map.update({')
+            append('decoding_map.update({')
             i = 0
             splits = splits + 1
     if splits == 0:
@@ -265,7 +293,7 @@ def rewritepythondir(dir,prefix='',comments=1):
     
     mapnames = os.listdir(dir)
     for mapname in mapnames:
-        if mapname[-len('.mapping'):] != '.mapping':
+        if not mapname.endswith('.mapping'):
             continue
         codefile = mapname[:-len('.mapping')] + '.py'
         print 'converting %s to %s' % (mapname,