calibre/src/cssutils/parse.py

#!/usr/bin/env python
"""A validating CSSParser"""
__all__ = ['CSSParser']
__docformat__ = 'restructuredtext'
__version__ = '$Id: parse.py 1754 2009-05-30 14:50:13Z cthedot $'

from helper import Deprecated, path2url
import codecs
import cssutils
import os
import tokenize2
import urllib

class CSSParser(object):
    """Parse a CSS StyleSheet from URL, string or file and return a DOM Level 2
    CSS StyleSheet object.

    Usage::

        parser = CSSParser()
        # optionally
        parser.setFetcher(fetcher)
        sheet = parser.parseFile('test1.css', 'ascii')
        print sheet.cssText
    """
    def __init__(self, log=None, loglevel=None, raiseExceptions=None,
                 fetcher=None):
        """
        log
            logging object
        loglevel
            logging loglevel
        raiseExceptions
            if log should simply log (default) or raise errors during
            parsing. Later while working with the resulting sheets
            the setting used in cssutils.log.raiseExeptions is used
        fetcher
            see ``setFetcher(fetcher)``
        """
        if log is not None:
            cssutils.log.setLog(log)
        if loglevel is not None:
            cssutils.log.setLevel(loglevel)

        # remember global setting
        self.__globalRaising = cssutils.log.raiseExceptions
        if raiseExceptions:
            self.__parseRaising = raiseExceptions
        else:
            # DEFAULT during parse
            self.__parseRaising = False

        self.__tokenizer = tokenize2.Tokenizer()
        self.setFetcher(fetcher)

    def __parseSetting(self, parse):
        """during parse exceptions may be handled differently depending on
        init parameter ``raiseExceptions``
        """
        if parse:
            cssutils.log.raiseExceptions = self.__parseRaising
        else:
            cssutils.log.raiseExceptions = self.__globalRaising

    def parseString(self, cssText, encoding=None, href=None, media=None,
                    title=None):
        """Parse `cssText` as :class:`~cssutils.css.CSSStyleSheet`.
        Errors may be raised (e.g. UnicodeDecodeError).

        :param cssText:
            CSS string to parse
        :param encoding:
            If ``None`` the encoding will be read from BOM or an @charset
            rule or defaults to UTF-8.
            If given overrides any found encoding including the ones for
            imported sheets.
            It also will be used to decode `cssText` if given as a (byte)
            string.
        :param href:
            The ``href`` attribute to assign to the parsed style sheet.
            Used to resolve other urls in the parsed sheet like @import hrefs.
        :param media:
            The ``media`` attribute to assign to the parsed style sheet
            (may be a MediaList, list or a string).
        :param title:
            The ``title`` attribute to assign to the parsed style sheet.
        :returns:
            :class:`~cssutils.css.CSSStyleSheet`.
        """
        self.__parseSetting(True)
        if isinstance(cssText, str):
            cssText = codecs.getdecoder('css')(cssText, encoding=encoding)[0]

        sheet = cssutils.css.CSSStyleSheet(href=href,
                                           media=cssutils.stylesheets.MediaList(media),
                                           title=title)
        sheet._setFetcher(self.__fetcher)
        # tokenizing this ways closes open constructs and adds EOF
        sheet._setCssTextWithEncodingOverride(self.__tokenizer.tokenize(cssText,
                                                                        fullsheet=True),
                                              encodingOverride=encoding)
        self.__parseSetting(False)
        return sheet

    def parseFile(self, filename, encoding=None,
                  href=None, media=None, title=None):
        """Retrieve content from `filename` and parse it. Errors may be raised
        (e.g. IOError).
        
        :param filename:
            of the CSS file to parse, if no `href` is given filename is
            converted to a (file:) URL and set as ``href`` of resulting
            stylesheet.
            If `href` is given it is set as ``sheet.href``. Either way
            ``sheet.href`` is used to resolve e.g. stylesheet imports via
            @import rules.
        :param encoding:
            Value ``None`` defaults to encoding detection via BOM or an
            @charset rule.
            Other values override detected encoding for the sheet at
            `filename` including any imported sheets.
        :returns:
            :class:`~cssutils.css.CSSStyleSheet`.
        """
        if not href:
            # prepend // for file URL, urllib does not do this?
            #href = u'file:' + urllib.pathname2url(os.path.abspath(filename))          
            href = path2url(filename)

        return self.parseString(open(filename, 'rb').read(),
                                encoding=encoding, # read returns a str
                                href=href, media=media, title=title)

    def parseUrl(self, href, encoding=None, media=None, title=None):
        """Retrieve content from URL `href` and parse it. Errors may be raised
        (e.g. URLError).
        
        :param href:
            URL of the CSS file to parse, will also be set as ``href`` of
            resulting stylesheet
        :param encoding:
            Value ``None`` defaults to encoding detection via HTTP, BOM or an
            @charset rule.
            A value overrides detected encoding for the sheet at ``href``
            including any imported sheets.
        :returns:
            :class:`~cssutils.css.CSSStyleSheet`.
        """
        encoding, enctype, text = cssutils.util._readUrl(href,
                                                         overrideEncoding=encoding)
        if enctype == 5:
            # do not used if defaulting to UTF-8
            encoding = None
            
        if text is not None:
            return self.parseString(text, encoding=encoding,
                                    href=href, media=media, title=title)

    def setFetcher(self, fetcher=None):
        """Replace the default URL fetch function with a custom one.
        
        :param fetcher:
            A function which gets a single parameter

            ``url``
                the URL to read

            and must return ``(encoding, content)`` where ``encoding`` is the 
            HTTP charset normally given via the Content-Type header (which may
            simply omit the charset in which case ``encoding`` would be 
            ``None``) and ``content`` being the string (or unicode) content.
            
            The Mimetype should be 'text/css' but this has to be checked by the
            fetcher itself (the default fetcher emits a warning if encountering
            a different mimetype).

            Calling ``setFetcher`` with ``fetcher=None`` resets cssutils
            to use its default function.
        """
        self.__fetcher = fetcher

    @Deprecated('Use cssutils.CSSParser().parseFile() instead.')
    def parse(self, filename, encoding=None,
              href=None, media=None, title=None):
        self.parseFile(filename, encoding, href, media, title)