Avoid generating the same Stylizer rules again

src/calibre/ebooks/oeb/stylizer.py

@@ -95,6 +95,77 @@ def test_media_ok():
     assert media_ok('screen, (device-width:10px)')
     assert not media_ok('screen and (device-width:10px)')
 
+class StylizerRules(object):
+
+    def __init__(self, opts, profile, stylesheets):
+        self.opts, self.profile, self.stylesheets = opts, profile, stylesheets
+
+        index = 0
+        self.rules = []
+        self.page_rule = {}
+        self.font_face_rules = []
+        for sheet_index, stylesheet in enumerate(stylesheets):
+            href = stylesheet.href
+            for rule in stylesheet.cssRules:
+                if rule.type == rule.MEDIA_RULE:
+                    if media_ok(rule.media.mediaText):
+                        for subrule in rule.cssRules:
+                            self.rules.extend(self.flatten_rule(subrule, href, index, is_user_agent_sheet=sheet_index==0))
+                            index += 1
+                else:
+                    self.rules.extend(self.flatten_rule(rule, href, index, is_user_agent_sheet=sheet_index==0))
+                    index = index + 1
+        self.rules.sort(key=itemgetter(0))  # sort by specificity
+
+    def flatten_rule(self, rule, href, index, is_user_agent_sheet=False):
+        results = []
+        sheet_index = 0 if is_user_agent_sheet else 1
+        if isinstance(rule, CSSStyleRule):
+            style = self.flatten_style(rule.style)
+            for selector in rule.selectorList:
+                specificity = (sheet_index,) + selector.specificity + (index,)
+                text = selector.selectorText
+                selector = list(selector.seq)
+                results.append((specificity, selector, style, text, href))
+        elif isinstance(rule, CSSPageRule):
+            style = self.flatten_style(rule.style)
+            self.page_rule.update(style)
+        elif isinstance(rule, CSSFontFaceRule):
+            if rule.style.length > 1:
+                # Ignore the meaningless font face rules generated by the
+                # benighted MS Word that contain only a font-family declaration
+                # and nothing else
+                self.font_face_rules.append(rule)
+        return results
+
+    def flatten_style(self, cssstyle):
+        style = {}
+        for prop in cssstyle:
+            name = prop.name
+            normalizer = normalizers.get(name, None)
+            if normalizer is not None:
+                style.update(normalizer(name, prop.cssValue))
+            elif name == 'text-align':
+                style['text-align'] = self._apply_text_align(prop.value)
+            else:
+                style[name] = prop.value
+        if 'font-size' in style:
+            size = style['font-size']
+            if size == 'normal':
+                size = 'medium'
+            if size == 'smallest':
+                size = 'xx-small'
+            if size in FONT_SIZE_NAMES:
+                style['font-size'] = "%.1frem" % (self.profile.fnames[size] / float(self.profile.fbase))
+        if '-epub-writing-mode' in style:
+            for x in ('-webkit-writing-mode', 'writing-mode'):
+                style[x] = style.get(x, style['-epub-writing-mode'])
+        return style
+
+    def _apply_text_align(self, text):
+        if text in ('left', 'justify') and self.opts.change_justification in ('left', 'justify'):
+            text = self.opts.change_justification
+        return text
 
 class Stylizer(object):
     STYLESHEETS = WeakKeyDictionary()
@@ -133,7 +204,6 @@ class Stylizer(object):
 
         parser = CSSParser(fetcher=self._fetch_css_file,
                 log=logging.getLogger('calibre.css'))
-        self.font_face_rules = []
         for elem in style_tags:
             if (elem.tag == XHTML('style') and elem.get('type', CSS_MIME) in OEB_STYLES and media_ok(elem.get('media'))):
                 text = elem.text if elem.text else u''
@@ -200,29 +270,20 @@ class Stylizer(object):
                     self.logger.exception('Failed to parse %s, ignoring.'%w)
                     self.logger.debug('Bad css: ')
                     self.logger.debug(x)
-        rules = []
+
-        index = 0
+        # using the profile to store the rules, page rule and font face rules
-        self.stylesheets = set()
+        # and generating them again if stylesheets are different
-        self.page_rule = {}
+        # they should depend on opts too, but opts shouldn't change during
-        for sheet_index, stylesheet in enumerate(stylesheets):
+        # a conversion process, so it should be safe...
-            href = stylesheet.href
+        if (not hasattr(self.profile, 'stylizer_rules')) \
-            self.stylesheets.add(href)
+            or set(self.profile.stylizer_rules.stylesheets) != set(stylesheets):
-            for rule in stylesheet.cssRules:
+            self.profile.stylizer_rules = StylizerRules(self.opts, self.profile, stylesheets)
-                if rule.type == rule.MEDIA_RULE:
+
-                    if media_ok(rule.media.mediaText):
-                        for subrule in rule.cssRules:
-                            rules.extend(self.flatten_rule(subrule, href, index, is_user_agent_sheet=sheet_index==0))
-                            index += 1
-                else:
-                    rules.extend(self.flatten_rule(rule, href, index, is_user_agent_sheet=sheet_index==0))
-                    index = index + 1
-        rules.sort(key=itemgetter(0))  # sort by specificity
-        self.rules = rules
         self._styles = {}
         pseudo_pat = re.compile(u':{1,2}(%s)' % ('|'.join(INAPPROPRIATE_PSEUDO_CLASSES)), re.I)
         select = Select(tree, ignore_inappropriate_pseudo_classes=True)
 
-        for _, _, cssdict, text, _ in rules:
+        for _, _, cssdict, text, _ in self.rules:
             fl = pseudo_pat.search(text)
             try:
                 matches = tuple(select(text))
@@ -287,6 +348,21 @@ class Stylizer(object):
                 if upd:
                     style._update_cssdict(upd)
 
+    @property
+    def rules(self):
+        return self.profile.stylizer_rules.rules
+
+    @property
+    def page_rule(self):
+        return self.profile.stylizer_rules.page_rule
+
+    @property
+    def font_face_rules(self):
+        return self.profile.stylizer_rules.font_face_rules
+
+    def flatten_style(self, cssstyle):
+        return self.profile.stylizer_rules.flatten_style(cssstyle)
+
     def _fetch_css_file(self, path):
         hrefs = self.oeb.manifest.hrefs
         if path not in hrefs:
@@ -301,56 +377,6 @@ class Stylizer(object):
             data = data.encode('utf-8')
         return ('utf-8', data)
 
-    def flatten_rule(self, rule, href, index, is_user_agent_sheet=False):
-        results = []
-        sheet_index = 0 if is_user_agent_sheet else 1
-        if isinstance(rule, CSSStyleRule):
-            style = self.flatten_style(rule.style)
-            for selector in rule.selectorList:
-                specificity = (sheet_index,) + selector.specificity + (index,)
-                text = selector.selectorText
-                selector = list(selector.seq)
-                results.append((specificity, selector, style, text, href))
-        elif isinstance(rule, CSSPageRule):
-            style = self.flatten_style(rule.style)
-            self.page_rule.update(style)
-        elif isinstance(rule, CSSFontFaceRule):
-            if rule.style.length > 1:
-                # Ignore the meaningless font face rules generated by the
-                # benighted MS Word that contain only a font-family declaration
-                # and nothing else
-                self.font_face_rules.append(rule)
-        return results
-
-    def flatten_style(self, cssstyle):
-        style = {}
-        for prop in cssstyle:
-            name = prop.name
-            normalizer = normalizers.get(name, None)
-            if normalizer is not None:
-                style.update(normalizer(name, prop.cssValue))
-            elif name == 'text-align':
-                style['text-align'] = self._apply_text_align(prop.value)
-            else:
-                style[name] = prop.value
-        if 'font-size' in style:
-            size = style['font-size']
-            if size == 'normal':
-                size = 'medium'
-            if size == 'smallest':
-                size = 'xx-small'
-            if size in FONT_SIZE_NAMES:
-                style['font-size'] = "%.1frem" % (self.profile.fnames[size] / float(self.profile.fbase))
-        if '-epub-writing-mode' in style:
-            for x in ('-webkit-writing-mode', 'writing-mode'):
-                style[x] = style.get(x, style['-epub-writing-mode'])
-        return style
-
-    def _apply_text_align(self, text):
-        if text in ('left', 'justify') and self.opts.change_justification in ('left', 'justify'):
-            text = self.opts.change_justification
-        return text
-
     def style(self, element):
         try:
             return self._styles[element]