i18n: check equality of tail '::'-ness between msgid and msgstr

Document generation by runrst in "doc" directory may succeed silently,
even though there is the translated message missing tail '::'. In this
case, it uses "<blockquote>" instead of "<pre>" to surround succeeding
text block unexpectedly in generated HTML file.

This patch adds the checker to check equality of tail '::'-ness
between msgid and msgstr.

To detect also msgstr unexpectedly ending with '::', this checker
doesn't have matching regexp against msgid, and is applied on all
msgid/msgstr pairs.

This checker is categorized as "warning" level, because problem
detected by this is not so serious for usual Mercurial usage.

i18n/check-translation.py

@@ -1,151 +1,173 b''
 #!/usr/bin/env python
 #
 # check-translation.py - check Mercurial specific translation problems
 
 import polib
 import re
 
 checkers = []
 
 def checker(level, msgidpat):
     def decorator(func):
         if msgidpat:
             match = re.compile(msgidpat).search
         else:
             match = lambda msgid: True
         checkers.append((func, level))
         func.match = match
         return func
     return decorator
 
 def match(checker, pe):
     """Examine whether POEntry "pe" is target of specified checker or not
     """
     if not checker.match(pe.msgid):
         return
     # examine suppression by translator comment
     nochecker = 'no-%s-check' % checker.__name__
     for tc in pe.tcomment.split():
         if nochecker == tc:
             return
     return True
 
 ####################
 
 def fatalchecker(msgidpat=None):
     return checker('fatal', msgidpat)
 
 @fatalchecker(r'\$\$')
 def promptchoice(pe):
     """Check translation of the string given to "ui.promptchoice()"
 
     >>> pe = polib.POEntry(
     ...     msgid ='prompt$$missing &sep$$missing &amp$$followed by &none',
     ...     msgstr='prompt  missing &sep$$missing  amp$$followed by none&')
     >>> match(promptchoice, pe)
     True
     >>> for e in promptchoice(pe): print e
     number of choices differs between msgid and msgstr
     msgstr has invalid choice missing '&'
     msgstr has invalid '&' followed by none
     """
     idchoices = [c.rstrip(' ') for c in pe.msgid.split('$$')[1:]]
     strchoices = [c.rstrip(' ') for c in pe.msgstr.split('$$')[1:]]
 
     if len(idchoices) != len(strchoices):
         yield "number of choices differs between msgid and msgstr"
 
     indices = [(c, c.find('&')) for c in strchoices]
     if [c for c, i in indices if i == -1]:
         yield "msgstr has invalid choice missing '&'"
     if [c for c, i in indices if len(c) == i + 1]:
         yield "msgstr has invalid '&' followed by none"
 
 ####################
 
 def warningchecker(msgidpat=None):
     return checker('warning', msgidpat)
 
+@warningchecker()
+def taildoublecolons(pe):
+    """Check equality of tail '::'-ness between msgid and msgstr
+
+    >>> pe = polib.POEntry(
+    ...     msgid ='ends with ::',
+    ...     msgstr='ends with ::')
+    >>> for e in taildoublecolons(pe): print e
+    >>> pe = polib.POEntry(
+    ...     msgid ='ends with ::',
+    ...     msgstr='ends without double-colons')
+    >>> for e in taildoublecolons(pe): print e
+    tail '::'-ness differs between msgid and msgstr
+    >>> pe = polib.POEntry(
+    ...     msgid ='ends without double-colons',
+    ...     msgstr='ends with ::')
+    >>> for e in taildoublecolons(pe): print e
+    tail '::'-ness differs between msgid and msgstr
+    """
+    if pe.msgid.endswith('::') != pe.msgstr.endswith('::'):
+        yield "tail '::'-ness differs between msgid and msgstr"
+
 ####################
 
 def check(pofile, fatal=True, warning=False):
     targetlevel = { 'fatal': fatal, 'warning': warning }
     targetcheckers = [(checker, level)
                       for checker, level in checkers
                       if targetlevel[level]]
     if not targetcheckers:
         return []
 
     detected = []
     for pe in pofile.translated_entries():
         errors = []
         for checker, level in targetcheckers:
             if match(checker, pe):
                 errors.extend((level, checker.__name__, error)
                               for error in checker(pe))
         if errors:
             detected.append((pe, errors))
     return detected
 
 ########################################
 
 if __name__ == "__main__":
     import sys
     import optparse
 
     optparser = optparse.OptionParser("""%prog [options] pofile ...
 
 This checks Mercurial specific translation problems in specified
 '*.po' files.
 
 Each detected problems are shown in the format below::
 
     filename:linenum:type(checker): problem detail .....
 
 "type" is "fatal" or "warning". "checker" is the name of the function
 detecting corresponded error.
 
 Checking by checker "foo" on the specific msgstr can be suppressed by
 the "translator comment" like below. Multiple "no-xxxx-check" should
 be separated by whitespaces::
 
     # no-foo-check
     msgid = "....."
     msgstr = "....."
 """)
     optparser.add_option("", "--warning",
                          help="show also warning level problems",
                          action="store_true")
     optparser.add_option("", "--doctest",
                          help="run doctest of this tool, instead of check",
                          action="store_true")
     (options, args) = optparser.parse_args()
 
     if options.doctest:
         import os
         if 'TERM' in os.environ:
             del os.environ['TERM']
         import doctest
         failures, tests = doctest.testmod()
         sys.exit(failures and 1 or 0)
 
     # replace polib._POFileParser to show linenum of problematic msgstr
     class ExtPOFileParser(polib._POFileParser):
         def process(self, symbol, linenum):
             super(ExtPOFileParser, self).process(symbol, linenum)
             if symbol == 'MS': # msgstr
                 self.current_entry.linenum = linenum
     polib._POFileParser = ExtPOFileParser
 
     detected = []
     warning = options.warning
     for f in args:
         detected.extend((f, pe, errors)
                         for pe, errors in check(polib.pofile(f),
                                                 warning=warning))
     if detected:
         for f, pe, errors in detected:
             for level, checker, error in errors:
                 sys.stderr.write('%s:%d:%s(%s): %s\n'
                                  % (f, pe.linenum, level, checker, error))
         sys.exit(1)