view hgext/highlight/highlight.py @ 20742:3681de20b0a7

parsers: fail fast if Python has wrong minor version (issue4110) This change causes an informative ImportError to be raised when importing the parsers extension module if the minor version of the currently-running Python interpreter doesn't match that of the Python used when compiling the extension module. This change also exposes a parsers.versionerrortext constant in the C implementation of the module. Its presence can be used to determine whether this behavior is present in a version of the module. The value of the constant is the leading text of the ImportError raised and is set to "Python minor version mismatch". Here is an example of what the new error looks like: Traceback (most recent call last): File "test.py", line 1, in <module> import mercurial.parsers ImportError: Python minor version mismatch: The Mercurial extension modules were compiled with Python 2.7.6, but Mercurial is currently using Python with sys.hexversion=33883888: Python 2.5.6 (r256:88840, Nov 18 2012, 05:37:10) [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] at: /opt/local/Library/Frameworks/Python.framework/Versions/2.5/Resources/ Python.app/Contents/MacOS/Python The reason for raising an error in this scenario is that Python's C API is known not to be compatible from minor version to minor version, even if sys.api_version is the same. See for example this Python bug report about incompatibilities between 2.5 and 2.6+: http://bugs.python.org/issue8118 These incompatibilities can cause Mercurial to break in mysterious, unforeseen ways. For example, when Mercurial compiled with Python 2.7 was run with 2.5, the following crash occurred when running "hg status": http://bz.selenic.com/show_bug.cgi?id=4110 After this crash was fixed, running with Python 2.5 no longer crashes, but the following puzzling behavior still occurs: $ hg status ... File ".../mercurial/changelog.py", line 123, in __init__ revlog.revlog.__init__(self, opener, "00changelog.i") File ".../mercurial/revlog.py", line 251, in __init__ d = self._io.parseindex(i, self._inline) File ".../mercurial/revlog.py", line 158, in parseindex index, cache = parsers.parse_index2(data, inline) TypeError: data is not a string which can be reproduced more simply with: import mercurial.parsers as parsers parsers.parse_index2("", True) Both the crash and the TypeError occurred because the Python C API's PyString_Check() returns the wrong value when the C header files from Python 2.7 are run with Python 2.5. This is an example of an incompatibility of the sort mentioned in the Python bug report above. Failing fast with an informative error message results in a better user experience in cases like the above. The information in the ImportError also simplifies troubleshooting for those on Mercurial mailing lists, the bug tracker, etc. This patch only adds the version check to parsers.c, which is sufficient to affect command-line commands like "hg status" and "hg summary". An idea for a future improvement is to move the version-checking C code to a more central location, and have it run when importing all Mercurial extension modules and not just parsers.c.
author Chris Jerdonek <chris.jerdonek@gmail.com>
date Wed, 04 Dec 2013 20:38:27 -0800
parents bcdfb6078b9f
children 7b8ff3fd11d3
line wrap: on
line source

# highlight.py - highlight extension implementation file
#
#  Copyright 2007-2009 Adam Hupp <adam@hupp.org> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
#
# The original module was split in an interface and an implementation
# file to defer pygments loading and speedup extension setup.

from mercurial import demandimport
demandimport.ignore.extend(['pkgutil', 'pkg_resources', '__main__'])
from mercurial import util, encoding

from pygments import highlight
from pygments.util import ClassNotFound
from pygments.lexers import guess_lexer, guess_lexer_for_filename, TextLexer
from pygments.formatters import HtmlFormatter

SYNTAX_CSS = ('\n<link rel="stylesheet" href="{url}highlightcss" '
              'type="text/css" />')

def pygmentize(field, fctx, style, tmpl):

    # append a <link ...> to the syntax highlighting css
    old_header = tmpl.load('header')
    if SYNTAX_CSS not in old_header:
        new_header =  old_header + SYNTAX_CSS
        tmpl.cache['header'] = new_header

    text = fctx.data()
    if util.binary(text):
        return

    # Pygments is best used with Unicode strings:
    # <http://pygments.org/docs/unicode/>
    text = text.decode(encoding.encoding, 'replace')

    # To get multi-line strings right, we can't format line-by-line
    try:
        lexer = guess_lexer_for_filename(fctx.path(), text[:1024],
                                         stripnl=False)
    except (ClassNotFound, ValueError):
        try:
            lexer = guess_lexer(text[:1024], stripnl=False)
        except (ClassNotFound, ValueError):
            lexer = TextLexer(stripnl=False)

    formatter = HtmlFormatter(style=style)

    colorized = highlight(text, lexer, formatter)
    # strip wrapping div
    colorized = colorized[:colorized.find('\n</pre>')]
    colorized = colorized[colorized.find('<pre>') + 5:]
    coloriter = (s.encode(encoding.encoding, 'replace')
                 for s in colorized.splitlines())

    tmpl.filters['colorize'] = lambda x: coloriter.next()

    oldl = tmpl.cache[field]
    newl = oldl.replace('line|escape', 'line|colorize')
    tmpl.cache[field] = newl