contrib: factor out actual error check for file data of check-code.py

This is a part of preparation to apply checking with check-code.py on
code fragments embedded in *.t test scripts.

Newly added _checkfiledata() will be useful to apply checks on code
fragments embedded in *.t test scripts.

contrib/check-code.py

@@ -1,774 +1,811 b''
 #!/usr/bin/env python
 #
 # check-code - a style and portability checker for Mercurial
 #
 # Copyright 2010 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """style and portability checker for Mercurial
 
 when a rule triggers wrong, do one of the following (prefer one from top):
  * do the work-around the rule suggests
  * doublecheck that it is a false match
  * improve the rule pattern
  * add an ignore pattern to the rule (3rd arg) which matches your good line
    (you can append a short comment and match this, like: #re-raises)
  * change the pattern to a warning and list the exception in test-check-code-hg
  * ONLY use no--check-code for skipping entire files from external sources
 """
 
 from __future__ import absolute_import, print_function
 import glob
 import keyword
 import optparse
 import os
 import re
 import sys
 if sys.version_info[0] < 3:
     opentext = open
 else:
     def opentext(f):
         return open(f, encoding='latin1')
 try:
     xrange
 except NameError:
     xrange = range
 try:
     import re2
 except ImportError:
     re2 = None
 
 def compilere(pat, multiline=False):
     if multiline:
         pat = '(?m)' + pat
     if re2:
         try:
             return re2.compile(pat)
         except re2.error:
             pass
     return re.compile(pat)
 
 # check "rules depending on implementation of repquote()" in each
 # patterns (especially pypats), before changing around repquote()
 _repquotefixedmap = {' ': ' ', '\n': '\n', '.': 'p', ':': 'q',
                      '%': '%', '\\': 'b', '*': 'A', '+': 'P', '-': 'M'}
 def _repquoteencodechr(i):
     if i > 255:
         return 'u'
     c = chr(i)
     if c in _repquotefixedmap:
         return _repquotefixedmap[c]
     if c.isalpha():
         return 'x'
     if c.isdigit():
         return 'n'
     return 'o'
 _repquotett = ''.join(_repquoteencodechr(i) for i in xrange(256))
 
 def repquote(m):
     t = m.group('text')
     t = t.translate(_repquotett)
     return m.group('quote') + t + m.group('quote')
 
 def reppython(m):
     comment = m.group('comment')
     if comment:
         l = len(comment.rstrip())
         return "#" * l + comment[l:]
     return repquote(m)
 
 def repcomment(m):
     return m.group(1) + "#" * len(m.group(2))
 
 def repccomment(m):
     t = re.sub(r"((?<=\n) )|\S", "x", m.group(2))
     return m.group(1) + t + "*/"
 
 def repcallspaces(m):
     t = re.sub(r"\n\s+", "\n", m.group(2))
     return m.group(1) + t
 
 def repinclude(m):
     return m.group(1) + "<foo>"
 
 def rephere(m):
     t = re.sub(r"\S", "x", m.group(2))
     return m.group(1) + t
 
 
 testpats = [
   [
     (r'\b(push|pop)d\b', "don't use 'pushd' or 'popd', use 'cd'"),
     (r'\W\$?\(\([^\)\n]*\)\)', "don't use (()) or $(()), use 'expr'"),
     (r'grep.*-q', "don't use 'grep -q', redirect to /dev/null"),
     (r'(?<!hg )grep.* -a', "don't use 'grep -a', use in-line python"),
     (r'sed.*-i', "don't use 'sed -i', use a temporary file"),
     (r'\becho\b.*\\n', "don't use 'echo \\n', use printf"),
     (r'echo -n', "don't use 'echo -n', use printf"),
     (r'(^|\|\s*)\bwc\b[^|]*$\n(?!.*\(re\))', "filter wc output"),
     (r'head -c', "don't use 'head -c', use 'dd'"),
     (r'tail -n', "don't use the '-n' option to tail, just use '-<num>'"),
     (r'sha1sum', "don't use sha1sum, use $TESTDIR/md5sum.py"),
     (r'\bls\b.*-\w*R', "don't use 'ls -R', use 'find'"),
     (r'printf.*[^\\]\\([1-9]|0\d)', r"don't use 'printf \NNN', use Python"),
     (r'printf.*[^\\]\\x', "don't use printf \\x, use Python"),
     (r'\$\(.*\)', "don't use $(expr), use `expr`"),
     (r'rm -rf \*', "don't use naked rm -rf, target a directory"),
     (r'\[[^\]]+==', '[ foo == bar ] is a bashism, use [ foo = bar ] instead'),
     (r'(^|\|\s*)grep (-\w\s+)*[^|]*[(|]\w',
      "use egrep for extended grep syntax"),
     (r'(^|\|\s*)e?grep .*\\S', "don't use \\S in regular expression"),
     (r'(?<!!)/bin/', "don't use explicit paths for tools"),
     (r'#!.*/bash', "don't use bash in shebang, use sh"),
     (r'[^\n]\Z', "no trailing newline"),
     (r'export .*=', "don't export and assign at once"),
     (r'^source\b', "don't use 'source', use '.'"),
     (r'touch -d', "don't use 'touch -d', use 'touch -t' instead"),
     (r'\bls +[^|\n-]+ +-', "options to 'ls' must come before filenames"),
     (r'[^>\n]>\s*\$HGRCPATH', "don't overwrite $HGRCPATH, append to it"),
     (r'^stop\(\)', "don't use 'stop' as a shell function name"),
     (r'(\[|\btest\b).*-e ', "don't use 'test -e', use 'test -f'"),
     (r'\[\[\s+[^\]]*\]\]', "don't use '[[ ]]', use '[ ]'"),
     (r'^alias\b.*=', "don't use alias, use a function"),
     (r'if\s*!', "don't use '!' to negate exit status"),
     (r'/dev/u?random', "don't use entropy, use /dev/zero"),
     (r'do\s*true;\s*done', "don't use true as loop body, use sleep 0"),
     (r'sed (-e )?\'(\d+|/[^/]*/)i(?!\\\n)',
      "put a backslash-escaped newline after sed 'i' command"),
     (r'^diff *-\w*[uU].*$\n(^  \$ |^$)', "prefix diff -u/-U with cmp"),
     (r'^\s+(if)? diff *-\w*[uU]', "prefix diff -u/-U with cmp"),
     (r'[\s="`\']python\s(?!bindings)', "don't use 'python', use '$PYTHON'"),
     (r'seq ', "don't use 'seq', use $TESTDIR/seq.py"),
     (r'\butil\.Abort\b', "directly use error.Abort"),
     (r'\|&', "don't use |&, use 2>&1"),
     (r'\w =  +\w', "only one space after = allowed"),
     (r'\bsed\b.*[^\\]\\n', "don't use 'sed ... \\n', use a \\ and a newline"),
     (r'env.*-u', "don't use 'env -u VAR', use 'unset VAR'"),
     (r'cp.* -r ', "don't use 'cp -r', use 'cp -R'"),
     (r'grep.* -[ABC]', "don't use grep's context flags"),
     (r'find.*-printf',
      "don't use 'find -printf', it doesn't exist on BSD find(1)"),
     (r'\$RANDOM ', "don't use bash-only $RANDOM to generate random values"),
   ],
   # warnings
   [
     (r'^function', "don't use 'function', use old style"),
     (r'^diff.*-\w*N', "don't use 'diff -N'"),
     (r'\$PWD|\${PWD}', "don't use $PWD, use `pwd`"),
     (r'^([^"\'\n]|("[^"\n]*")|(\'[^\'\n]*\'))*\^', "^ must be quoted"),
     (r'kill (`|\$\()', "don't use kill, use killdaemons.py")
   ]
 ]
 
 testfilters = [
     (r"( *)(#([^!][^\n]*\S)?)", repcomment),
     (r"<<(\S+)((.|\n)*?\n\1)", rephere),
 ]
 
 uprefix = r"^  \$ "
 utestpats = [
   [
     (r'^(\S.*||  [$>] \S.*)[ \t]\n', "trailing whitespace on non-output"),
     (uprefix + r'.*\|\s*sed[^|>\n]*\n',
      "use regex test output patterns instead of sed"),
     (uprefix + r'(true|exit 0)', "explicit zero exit unnecessary"),
     (uprefix + r'.*(?<!\[)\$\?', "explicit exit code checks unnecessary"),
     (uprefix + r'.*\|\| echo.*(fail|error)',
      "explicit exit code checks unnecessary"),
     (uprefix + r'set -e', "don't use set -e"),
     (uprefix + r'(\s|fi\b|done\b)', "use > for continued lines"),
     (uprefix + r'.*:\.\S*/', "x:.y in a path does not work on msys, rewrite "
      "as x://.y, or see `hg log -k msys` for alternatives", r'-\S+:\.|' #-Rxxx
      '# no-msys'), # in test-pull.t which is skipped on windows
     (r'^  [^$>].*27\.0\.0\.1',
      'use $LOCALIP not an explicit loopback address'),
     (r'^  (?![>$] ).*\$LOCALIP.*[^)]$',
      'mark $LOCALIP output lines with (glob) to help tests in BSD jails'),
     (r'^  (cat|find): .*: \$ENOENT\$',
      'use test -f to test for file existence'),
     (r'^  diff -[^ -]*p',
      "don't use (external) diff with -p for portability"),
     (r' readlink ', 'use readlink.py instead of readlink'),
     (r'^  [-+][-+][-+] .* [-+]0000 \(glob\)',
      "glob timezone field in diff output for portability"),
     (r'^  @@ -[0-9]+ [+][0-9]+,[0-9]+ @@',
      "use '@@ -N* +N,n @@ (glob)' style chunk header for portability"),
     (r'^  @@ -[0-9]+,[0-9]+ [+][0-9]+ @@',
      "use '@@ -N,n +N* @@ (glob)' style chunk header for portability"),
     (r'^  @@ -[0-9]+ [+][0-9]+ @@',
      "use '@@ -N* +N* @@ (glob)' style chunk header for portability"),
     (uprefix + r'hg( +-[^ ]+( +[^ ]+)?)* +extdiff'
      r'( +(-[^ po-]+|--(?!program|option)[^ ]+|[^-][^ ]*))*$',
      "use $RUNTESTDIR/pdiff via extdiff (or -o/-p for false-positives)"),
   ],
   # warnings
   [
     (r'^  (?!.*\$LOCALIP)[^*?/\n]* \(glob\)$',
      "glob match with no glob string (?, *, /, and $LOCALIP)"),
   ]
 ]
 
 # transform plain test rules to unified test's
 for i in [0, 1]:
     for tp in testpats[i]:
         p = tp[0]
         m = tp[1]
         if p.startswith(r'^'):
             p = r"^  [$>] (%s)" % p[1:]
         else:
             p = r"^  [$>] .*(%s)" % p
         utestpats[i].append((p, m) + tp[2:])
 
 # don't transform the following rules:
 # "  > \t" and "  \t" should be allowed in unified tests
 testpats[0].append((r'^( *)\t', "don't use tabs to indent"))
 utestpats[0].append((r'^( ?)\t', "don't use tabs to indent"))
 
 utestfilters = [
     (r"<<(\S+)((.|\n)*?\n  > \1)", rephere),
     (r"( +)(#([^!][^\n]*\S)?)", repcomment),
 ]
 
 # common patterns to check *.py
 commonpypats = [
   [
     (r'\\$', 'Use () to wrap long lines in Python, not \\'),
     (r'^\s*def\s*\w+\s*\(.*,\s*\(',
      "tuple parameter unpacking not available in Python 3+"),
     (r'lambda\s*\(.*,.*\)',
      "tuple parameter unpacking not available in Python 3+"),
     (r'(?<!def)\s+(cmp)\(', "cmp is not available in Python 3+"),
     (r'(?<!\.)\breduce\s*\(.*', "reduce is not available in Python 3+"),
     (r'\bdict\(.*=', 'dict() is different in Py2 and 3 and is slower than {}',
      'dict-from-generator'),
     (r'\.has_key\b', "dict.has_key is not available in Python 3+"),
     (r'\s<>\s', '<> operator is not available in Python 3+, use !='),
     (r'^\s*\t', "don't use tabs"),
     (r'\S;\s*\n', "semicolon"),
     (r'[^_]_\([ \t\n]*(?:"[^"]+"[ \t\n+]*)+%', "don't use % inside _()"),
     (r"[^_]_\([ \t\n]*(?:'[^']+'[ \t\n+]*)+%", "don't use % inside _()"),
     (r'(\w|\)),\w', "missing whitespace after ,"),
     (r'(\w|\))[+/*\-<>]\w', "missing whitespace in expression"),
     (r'^\s+(\w|\.)+=\w[^,()\n]*$', "missing whitespace in assignment"),
     (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
     ((
         # a line ending with a colon, potentially with trailing comments
         r':([ \t]*#[^\n]*)?\n'
         # one that is not a pass and not only a comment
         r'(?P<indent>[ \t]+)[^#][^\n]+\n'
         # more lines at the same indent level
         r'((?P=indent)[^\n]+\n)*'
         # a pass at the same indent level, which is bogus
         r'(?P=indent)pass[ \t\n#]'
       ), 'omit superfluous pass'),
     (r'[^\n]\Z', "no trailing newline"),
     (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
 #    (r'^\s+[^_ \n][^_. \n]+_[^_\n]+\s*=',
 #     "don't use underbars in identifiers"),
     (r'^\s+(self\.)?[A-Za-z][a-z0-9]+[A-Z]\w* = ',
      "don't use camelcase in identifiers", r'#.*camelcase-required'),
     (r'^\s*(if|while|def|class|except|try)\s[^[\n]*:\s*[^\\n]#\s]+',
      "linebreak after :"),
     (r'class\s[^( \n]+:', "old-style class, use class foo(object)",
      r'#.*old-style'),
     (r'class\s[^( \n]+\(\):',
      "class foo() creates old style object, use class foo(object)",
      r'#.*old-style'),
     (r'\b(%s)\(' % '|'.join(k for k in keyword.kwlist
                             if k not in ('print', 'exec')),
      "Python keyword is not a function"),
     (r',]', "unneeded trailing ',' in list"),
 #    (r'class\s[A-Z][^\(]*\((?!Exception)',
 #     "don't capitalize non-exception classes"),
 #    (r'in range\(', "use xrange"),
 #    (r'^\s*print\s+', "avoid using print in core and extensions"),
     (r'[\x80-\xff]', "non-ASCII character literal"),
     (r'("\')\.format\(', "str.format() has no bytes counterpart, use %"),
     (r'^\s*(%s)\s\s' % '|'.join(keyword.kwlist),
      "gratuitous whitespace after Python keyword"),
     (r'([\(\[][ \t]\S)|(\S[ \t][\)\]])', "gratuitous whitespace in () or []"),
 #    (r'\s\s=', "gratuitous whitespace before ="),
     (r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
      "missing whitespace around operator"),
     (r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\s',
      "missing whitespace around operator"),
     (r'\s(\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
      "missing whitespace around operator"),
     (r'[^^+=*/!<>&| %-](\s=|=\s)[^= ]',
      "wrong whitespace around ="),
     (r'\([^()]*( =[^=]|[^<>!=]= )',
      "no whitespace around = for named parameters"),
     (r'raise [^,(]+, (\([^\)]+\)|[^,\(\)]+)$',
      "don't use old-style two-argument raise, use Exception(message)"),
     (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"),
     (r' [=!]=\s+(True|False|None)',
      "comparison with singleton, use 'is' or 'is not' instead"),
     (r'^\s*(while|if) [01]:',
      "use True/False for constant Boolean expression"),
     (r'^\s*if False(:| +and)', 'Remove code instead of using `if False`'),
     (r'(?:(?<!def)\s+|\()hasattr\(',
      'hasattr(foo, bar) is broken on py2, use util.safehasattr(foo, bar) '
      'instead', r'#.*hasattr-py3-only'),
     (r'opener\([^)]*\).read\(',
      "use opener.read() instead"),
     (r'opener\([^)]*\).write\(',
      "use opener.write() instead"),
     (r'(?i)descend[e]nt', "the proper spelling is descendAnt"),
     (r'\.debug\(\_', "don't mark debug messages for translation"),
     (r'\.strip\(\)\.split\(\)', "no need to strip before splitting"),
     (r'^\s*except\s*:', "naked except clause", r'#.*re-raises'),
     (r'^\s*except\s([^\(,]+|\([^\)]+\))\s*,',
      'legacy exception syntax; use "as" instead of ","'),
     (r'release\(.*wlock, .*lock\)', "wrong lock release order"),
     (r'\bdef\s+__bool__\b', "__bool__ should be __nonzero__ in Python 2"),
     (r'os\.path\.join\(.*, *(""|\'\')\)',
      "use pathutil.normasprefix(path) instead of os.path.join(path, '')"),
     (r'\s0[0-7]+\b', 'legacy octal syntax; use "0o" prefix instead of "0"'),
     # XXX only catch mutable arguments on the first line of the definition
     (r'def.*[( ]\w+=\{\}', "don't use mutable default arguments"),
     (r'\butil\.Abort\b', "directly use error.Abort"),
     (r'^@(\w*\.)?cachefunc', "module-level @cachefunc is risky, please avoid"),
     (r'^import Queue', "don't use Queue, use pycompat.queue.Queue + "
                        "pycompat.queue.Empty"),
     (r'^import cStringIO', "don't use cStringIO.StringIO, use util.stringio"),
     (r'^import urllib', "don't use urllib, use util.urlreq/util.urlerr"),
     (r'^import SocketServer', "don't use SockerServer, use util.socketserver"),
     (r'^import urlparse', "don't use urlparse, use util.urlreq"),
     (r'^import xmlrpclib', "don't use xmlrpclib, use util.xmlrpclib"),
     (r'^import cPickle', "don't use cPickle, use util.pickle"),
     (r'^import pickle', "don't use pickle, use util.pickle"),
     (r'^import httplib', "don't use httplib, use util.httplib"),
     (r'^import BaseHTTPServer', "use util.httpserver instead"),
     (r'^(from|import) mercurial\.(cext|pure|cffi)',
      "use mercurial.policy.importmod instead"),
     (r'\.next\(\)', "don't use .next(), use next(...)"),
     (r'([a-z]*).revision\(\1\.node\(',
      "don't convert rev to node before passing to revision(nodeorrev)"),
     (r'platform\.system\(\)', "don't use platform.system(), use pycompat"),
 
   ],
   # warnings
   [
   ]
 ]
 
 # patterns to check normal *.py files
 pypats = [
   [
     # Ideally, these should be placed in "commonpypats" for
     # consistency of coding rules in Mercurial source tree.
     # But on the other hand, these are not so seriously required for
     # python code fragments embedded in test scripts. Fixing test
     # scripts for these patterns requires many changes, and has less
     # profit than effort.
     (r'.{81}', "line too long"),
     (r'raise Exception', "don't raise generic exceptions"),
     (r'[\s\(](open|file)\([^)]*\)\.read\(',
      "use util.readfile() instead"),
     (r'[\s\(](open|file)\([^)]*\)\.write\(',
      "use util.writefile() instead"),
     (r'^[\s\(]*(open(er)?|file)\([^)]*\)(?!\.close\(\))',
      "always assign an opened file to a variable, and close it afterwards"),
     (r'[\s\(](open|file)\([^)]*\)\.(?!close\(\))',
      "always assign an opened file to a variable, and close it afterwards"),
     (r':\n(    )*( ){1,3}[^ ]', "must indent 4 spaces"),
     (r'^import atexit', "don't use atexit, use ui.atexit"),
 
     # rules depending on implementation of repquote()
     (r' x+[xpqo%APM][\'"]\n\s+[\'"]x',
      'string join across lines with no space'),
     (r'''(?x)ui\.(status|progress|write|note|warn)\(
          [ \t\n#]*
          (?# any strings/comments might precede a string, which
            # contains translatable message)
          ((['"]|\'\'\'|""")[ \npq%bAPMxno]*(['"]|\'\'\'|""")[ \t\n#]+)*
          (?# sequence consisting of below might precede translatable message
            # - formatting string: "% 10s", "%05d", "% -3.2f", "%*s", "%%" ...
            # - escaped character: "\\", "\n", "\0" ...
            # - character other than '%', 'b' as '\', and 'x' as alphabet)
          (['"]|\'\'\'|""")
          ((%([ n]?[PM]?([np]+|A))?x)|%%|b[bnx]|[ \nnpqAPMo])*x
          (?# this regexp can't use [^...] style,
            # because _preparepats forcibly adds "\n" into [^...],
            # even though this regexp wants match it against "\n")''',
      "missing _() in ui message (use () to hide false-positives)"),
   ] + commonpypats[0],
   # warnings
   [
     # rules depending on implementation of repquote()
     (r'(^| )pp +xxxxqq[ \n][^\n]', "add two newlines after '.. note::'"),
   ] + commonpypats[1]
 ]
 
 # common filters to convert *.py
 commonpyfilters = [
     (r"""(?msx)(?P<comment>\#.*?$)|
          ((?P<quote>('''|\"\"\"|(?<!')'(?!')|(?<!")"(?!")))
           (?P<text>(([^\\]|\\.)*?))
           (?P=quote))""", reppython),
 ]
 
 # filters to convert normal *.py files
 pyfilters = [
 ] + commonpyfilters
 
 # non-filter patterns
 pynfpats = [
     [
     (r'pycompat\.osname\s*[=!]=\s*[\'"]nt[\'"]', "use pycompat.iswindows"),
     (r'pycompat\.osname\s*[=!]=\s*[\'"]posix[\'"]', "use pycompat.isposix"),
     (r'pycompat\.sysplatform\s*[!=]=\s*[\'"]darwin[\'"]',
      "use pycompat.isdarwin"),
     ],
     # warnings
     [],
 ]
 
 # extension non-filter patterns
 pyextnfpats = [
     [(r'^"""\n?[A-Z]', "don't capitalize docstring title")],
     # warnings
     [],
 ]
 
 txtfilters = []
 
 txtpats = [
   [
     (r'\s$', 'trailing whitespace'),
     ('.. note::[ \n][^\n]', 'add two newlines after note::')
   ],
   []
 ]
 
 cpats = [
   [
     (r'//', "don't use //-style comments"),
     (r'\S\t', "don't use tabs except for indent"),
     (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
     (r'.{81}', "line too long"),
     (r'(while|if|do|for)\(', "use space after while/if/do/for"),
     (r'return\(', "return is not a function"),
     (r' ;', "no space before ;"),
     (r'[^;] \)', "no space before )"),
     (r'[)][{]', "space between ) and {"),
     (r'\w+\* \w+', "use int *foo, not int* foo"),
     (r'\W\([^\)]+\) \w+', "use (int)foo, not (int) foo"),
     (r'\w+ (\+\+|--)', "use foo++, not foo ++"),
     (r'\w,\w', "missing whitespace after ,"),
     (r'^[^#]\w[+/*]\w', "missing whitespace in expression"),
     (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
     (r'^#\s+\w', "use #foo, not # foo"),
     (r'[^\n]\Z', "no trailing newline"),
     (r'^\s*#import\b', "use only #include in standard C code"),
     (r'strcpy\(', "don't use strcpy, use strlcpy or memcpy"),
     (r'strcat\(', "don't use strcat"),
 
     # rules depending on implementation of repquote()
   ],
   # warnings
   [
     # rules depending on implementation of repquote()
   ]
 ]
 
 cfilters = [
     (r'(/\*)(((\*(?!/))|[^*])*)\*/', repccomment),
     (r'''(?P<quote>(?<!")")(?P<text>([^"]|\\")+)"(?!")''', repquote),
     (r'''(#\s*include\s+<)([^>]+)>''', repinclude),
     (r'(\()([^)]+\))', repcallspaces),
 ]
 
 inutilpats = [
   [
     (r'\bui\.', "don't use ui in util"),
   ],
   # warnings
   []
 ]
 
 inrevlogpats = [
   [
     (r'\brepo\.', "don't use repo in revlog"),
   ],
   # warnings
   []
 ]
 
 webtemplatefilters = []
 
 webtemplatepats = [
   [],
   [
     (r'{desc(\|(?!websub|firstline)[^\|]*)+}',
      'follow desc keyword with either firstline or websub'),
   ]
 ]
 
 allfilesfilters = []
 
 allfilespats = [
   [
     (r'(http|https)://[a-zA-Z0-9./]*selenic.com/',
      'use mercurial-scm.org domain URL'),
     (r'mercurial@selenic\.com',
      'use mercurial-scm.org domain for mercurial ML address'),
     (r'mercurial-devel@selenic\.com',
      'use mercurial-scm.org domain for mercurial-devel ML address'),
   ],
   # warnings
   [],
 ]
 
 py3pats = [
   [
     (r'os\.environ', "use encoding.environ instead (py3)", r'#.*re-exports'),
     (r'os\.name', "use pycompat.osname instead (py3)"),
     (r'os\.getcwd', "use encoding.getcwd instead (py3)", r'#.*re-exports'),
     (r'os\.sep', "use pycompat.ossep instead (py3)"),
     (r'os\.pathsep', "use pycompat.ospathsep instead (py3)"),
     (r'os\.altsep', "use pycompat.osaltsep instead (py3)"),
     (r'sys\.platform', "use pycompat.sysplatform instead (py3)"),
     (r'getopt\.getopt', "use pycompat.getoptb instead (py3)"),
     (r'os\.getenv', "use encoding.environ.get instead"),
     (r'os\.setenv', "modifying the environ dict is not preferred"),
     (r'(?<!pycompat\.)xrange', "use pycompat.xrange instead (py3)"),
   ],
   # warnings
   [],
 ]
 
 checks = [
     ('python', r'.*\.(py|cgi)$', r'^#!.*python', pyfilters, pypats),
     ('python', r'.*\.(py|cgi)$', r'^#!.*python', [], pynfpats),
     ('python', r'.*hgext.*\.py$', '', [], pyextnfpats),
     ('python 3', r'.*(hgext|mercurial)/(?!demandimport|policy|pycompat).*\.py',
      '', pyfilters, py3pats),
     ('test script', r'(.*/)?test-[^.~]*$', '', testfilters, testpats),
     ('c', r'.*\.[ch]$', '', cfilters, cpats),
     ('unified test', r'.*\.t$', '', utestfilters, utestpats),
     ('layering violation repo in revlog', r'mercurial/revlog\.py', '',
      pyfilters, inrevlogpats),
     ('layering violation ui in util', r'mercurial/util\.py', '', pyfilters,
      inutilpats),
     ('txt', r'.*\.txt$', '', txtfilters, txtpats),
     ('web template', r'mercurial/templates/.*\.tmpl', '',
      webtemplatefilters, webtemplatepats),
     ('all except for .po', r'.*(?<!\.po)$', '',
      allfilesfilters, allfilespats),
 ]
 
 def _preparepats():
     def preparefailandwarn(failandwarn):
         for pats in failandwarn:
             for i, pseq in enumerate(pats):
                 # fix-up regexes for multi-line searches
                 p = pseq[0]
                 # \s doesn't match \n (done in two steps)
                 # first, we replace \s that appears in a set already
                 p = re.sub(r'\[\\s', r'[ \\t', p)
                 # now we replace other \s instances.
                 p = re.sub(r'(?<!(\\|\[))\\s', r'[ \\t]', p)
                 # [^...] doesn't match newline
                 p = re.sub(r'(?<!\\)\[\^', r'[^\\n', p)
 
                 pats[i] = (re.compile(p, re.MULTILINE),) + pseq[1:]
 
     def preparefilters(filters):
         for i, flt in enumerate(filters):
             filters[i] = re.compile(flt[0]), flt[1]
 
     for cs in (checks,):
         for c in cs:
             failandwarn = c[-1]
             preparefailandwarn(failandwarn)
 
             filters = c[-2]
             preparefilters(filters)
 
 class norepeatlogger(object):
     def __init__(self):
         self._lastseen = None
 
     def log(self, fname, lineno, line, msg, blame):
         """print error related a to given line of a given file.
 
         The faulty line will also be printed but only once in the case
         of multiple errors.
 
         :fname: filename
         :lineno: line number
         :line: actual content of the line
         :msg: error message
         """
         msgid = fname, lineno, line
         if msgid != self._lastseen:
             if blame:
                 print("%s:%d (%s):" % (fname, lineno, blame))
             else:
                 print("%s:%d:" % (fname, lineno))
             print(" > %s" % line)
             self._lastseen = msgid
         print(" " + msg)
 
 _defaultlogger = norepeatlogger()
 
 def getblame(f):
     lines = []
     for l in os.popen('hg annotate -un %s' % f):
         start, line = l.split(':', 1)
         user, rev = start.split()
         lines.append((line[1:-1], user, rev))
     return lines
 
 def checkfile(f, logfunc=_defaultlogger.log, maxerr=None, warnings=False,
               blame=False, debug=False, lineno=True):
     """checks style and portability of a given file
 
     :f: filepath
     :logfunc: function used to report error
               logfunc(filename, linenumber, linecontent, errormessage)
     :maxerr: number of error to display before aborting.
              Set to false (default) to report all errors
 
     return True if no error is found, False otherwise.
     """
-    blamecache = None
     result = True
 
     try:
         with opentext(f) as fp:
             try:
                 pre = fp.read()
             except UnicodeDecodeError as e:
                 print("%s while reading %s" % (e, f))
                 return result
     except IOError as e:
         print("Skipping %s, %s" % (f, str(e).split(':', 1)[0]))
         return result
 
+    # context information shared while single checkfile() invocation
+    context = {'blamecache': None}
+
     for name, match, magic, filters, pats in checks:
-        post = pre # discard filtering result of previous check
         if debug:
             print(name, f)
-        fc = 0
         if not (re.match(match, f) or (magic and re.search(magic, pre))):
             if debug:
                 print("Skipping %s for %s it doesn't match %s" % (
                        name, match, f))
             continue
         if "no-" "check-code" in pre:
             # If you're looking at this line, it's because a file has:
             # no- check- code
             # but the reason to output skipping is to make life for
             # tests easier. So, instead of writing it with a normal
             # spelling, we write it with the expected spelling from
             # tests/test-check-code.t
             print("Skipping %s it has no-che?k-code (glob)" % f)
             return "Skip" # skip checking this file
+
+        if not _checkfiledata(name, f, pre, filters, pats, context,
+                              logfunc, maxerr, warnings, blame, debug, lineno):
+            result = False
+
+    return result
+
+def _checkfiledata(name, f, filedata, filters, pats, context,
+                   logfunc, maxerr, warnings, blame, debug, lineno):
+    """Execute actual error check for file data
+
+    :name: of the checking category
+    :f: filepath
+    :filedata: content of a file
+    :filters: to be applied before checking
+    :pats: to detect errors
+    :context: a dict of information shared while single checkfile() invocation
+              Valid keys: 'blamecache'.
+    :logfunc: function used to report error
+              logfunc(filename, linenumber, linecontent, errormessage)
+    :maxerr: number of error to display before aborting, or False to
+             report all errors
+    :warnings: whether warning level checks should be applied
+    :blame: whether blame information should be displayed at error reporting
+    :debug: whether debug information should be displayed
+    :lineno: whether lineno should be displayed at error reporting
+
+    return True if no error is found, False otherwise.
+    """
+    blamecache = context['blamecache']
+
+    fc = 0
+    pre = post = filedata
+    result = True
+
+    if True: # TODO: get rid of this redundant 'if' block
         for p, r in filters:
             post = re.sub(p, r, post)
         nerrs = len(pats[0]) # nerr elements are errors
         if warnings:
             pats = pats[0] + pats[1]
         else:
             pats = pats[0]
         # print post # uncomment to show filtered version
 
         if debug:
             print("Checking %s for %s" % (name, f))
 
         prelines = None
         errors = []
         for i, pat in enumerate(pats):
             if len(pat) == 3:
                 p, msg, ignore = pat
             else:
                 p, msg = pat
                 ignore = None
             if i >= nerrs:
                 msg = "warning: " + msg
 
             pos = 0
             n = 0
             for m in p.finditer(post):
                 if prelines is None:
                     prelines = pre.splitlines()
                     postlines = post.splitlines(True)
 
                 start = m.start()
                 while n < len(postlines):
                     step = len(postlines[n])
                     if pos + step > start:
                         break
                     pos += step
                     n += 1
                 l = prelines[n]
 
                 if ignore and re.search(ignore, l, re.MULTILINE):
                     if debug:
                         print("Skipping %s for %s:%s (ignore pattern)" % (
                             name, f, n))
                     continue
                 bd = ""
                 if blame:
                     bd = 'working directory'
-                    if not blamecache:
+                    if blamecache is None:
                         blamecache = getblame(f)
+                        context['blamecache'] = blamecache
                     if n < len(blamecache):
                         bl, bu, br = blamecache[n]
                         if bl == l:
                             bd = '%s@%s' % (bu, br)
 
                 errors.append((f, lineno and n + 1, l, msg, bd))
                 result = False
 
         errors.sort()
         for e in errors:
             logfunc(*e)
             fc += 1
             if maxerr and fc >= maxerr:
                 print(" (too many errors, giving up)")
                 break
 
     return result
 
 def main():
     parser = optparse.OptionParser("%prog [options] [files | -]")
     parser.add_option("-w", "--warnings", action="store_true",
                       help="include warning-level checks")
     parser.add_option("-p", "--per-file", type="int",
                       help="max warnings per file")
     parser.add_option("-b", "--blame", action="store_true",
                       help="use annotate to generate blame info")
     parser.add_option("", "--debug", action="store_true",
                       help="show debug information")
     parser.add_option("", "--nolineno", action="store_false",
                       dest='lineno', help="don't show line numbers")
 
     parser.set_defaults(per_file=15, warnings=False, blame=False, debug=False,
                         lineno=True)
     (options, args) = parser.parse_args()
 
     if len(args) == 0:
         check = glob.glob("*")
     elif args == ['-']:
         # read file list from stdin
         check = sys.stdin.read().splitlines()
     else:
         check = args
 
     _preparepats()
 
     ret = 0
     for f in check:
         if not checkfile(f, maxerr=options.per_file, warnings=options.warnings,
                          blame=options.blame, debug=options.debug,
                          lineno=options.lineno):
             ret = 1
     return ret
 
 if __name__ == "__main__":
     sys.exit(main())