.

software/ors-amarisoft/ru/xbuildout.py

+# Copyright (C) 2023  Nexedi SA and Contributors.
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+"""Package xbuildout provides additional buildout-related utilities.
+
+- encode/decode convert string to/from form, that is suitable to be used in
+  names of buildout sections.
+"""
+
+
+# encode converts string s into form suitable to be used in names of buildout sections.
+#
+# The encoding never fails, does not loose information and can be reversed back via decode.
+def encode(s: str): # -> str
+    s = s.encode('utf-8')
+    outv = []
+    emit = outv.append
+    for c in s:
+        c = bytes([c])  # int -> bytechar
+        # _ serves as escape character
+        if c == b'_':
+            emit(b'__')
+
+        # other characters allowed by buildout go as is
+        elif (b'a' <= c <= b'z')    or  \
+             (b'A' <= c <= b'Z')    or  \
+             (b'0' <= c <= b'9')    or  \
+             (c in b'.-'):
+            emit(c)
+
+        # all other bytes go as escaped hex
+        else:
+            emit(b'_%02x' % ord(c))
+
+    out = b''.join(outv)
+    out = out.decode('utf-8')   # should not fail
+    return out
+
+
+# decode provides reverse operation for encode.
+def decode(s: str): # -> str | ValueError | UnicodeDecodeError
+    s = s.encode('utf-8')
+    outv = []
+    emit = outv.append
+    def bad(reason):
+        raise ValueError(reason)
+    while len(s) > 0:
+        c = s[0:1]
+        s = s[1:]
+
+        if c != b'_':
+            emit(c)
+            continue
+
+        if len(s) < 2:
+            bad("truncated escape sequence")
+        x = s[:2]
+        s = s[2:]
+        i = int(x, 16)  # raises ValueError if not ok
+        c = bytes([i])
+        emit(c)
+
+    out = b''.join(outv)
+    out = out.decode('utf-8')   # raises UnicodeDecodeError if it was invalid UTF-8
+    return out
+
+
+# ----------------------------------------
+
+import re
+
+def test_encode():
+    # verify all ascii characters one by one
+    bok = re.compile(r'[a-zA-Z0-9.-]')  # characters that are ok to use in buildout except '_'
+    for i in range(0x80):
+        c = chr(i)
+        e = encode(c)
+        if bok.match(c):
+            assert e == c
+        elif c == '_':
+            assert e == '__'
+        else:
+            assert e == '_%02x' % i
+        assert decode(e) == c
+
+    # also explicitly test several example cases, including unicode
+    testv = [
+        #  s    encoded
+        ('',     ''),
+        ('a',      'a'),
+        ('ayzAYZ09.-',  'ayzAYZ09.-'),
+        ('_',       '__'),
+        (' ',       '_20'),
+        ('αβγ',     '_ce_b1_ce_b2_ce_b3'),
+        ('a b+c_d'  'a_20b_43c__d'),
+    ]
+
+    for (s, encok) in testv:
+        assert encode(s) == encok
+        assert decode(encok) == s
+
+
+    # XXX decode error
+
+    # XXX UTF-8 error