Use the real constants module.

This is progressing refactor of the calibre code to make it more
readable, and transform it to something more coherent.

In this patch, there are changes regarding imports for some modules,
instead of polluting namespace of each module with some other modules
symbols, which often were imported from other modules. Yuck.

ebook_converter/ebooks/htmlz/oeb2html.py

@@ -9,8 +9,9 @@ from functools import partial
 from lxml import html
 
 from ebook_converter import prepare_string_for_xml
-from ebook_converter.ebooks.oeb.base import (
-    XHTML, XHTML_NS, SVG_NS, barename, namespace, OEB_IMAGES, XLINK, rewrite_links, urlnormalize)
+from ebook_converter import constants as const
+from ebook_converter.ebooks.oeb import base
+from ebook_converter.ebooks.oeb import parse_utils
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
 from ebook_converter.utils.logging import default_log
 from ebook_converter.polyglot.builtins import as_bytes
@@ -61,9 +62,9 @@ class OEB2HTML(object):
         for item in oeb_book.spine:
             self.log.debug('Converting %s to HTML...' % item.href)
             self.rewrite_ids(item.data, item)
-            rewrite_links(item.data, partial(self.rewrite_link, page=item))
+            base.rewrite_links(item.data, partial(self.rewrite_link, page=item))
             stylizer = Stylizer(item.data, item.href, oeb_book, self.opts)
-            output += self.dump_text(item.data.find(XHTML('body')), stylizer, item)
+            output += self.dump_text(item.data.find(base.tag('xhtml', 'body')), stylizer, item)
             output.append('\n\n')
         output.append('</body></html>')
         return ''.join(output)
@@ -80,7 +81,7 @@ class OEB2HTML(object):
 
     def map_resources(self, oeb_book):
         for item in oeb_book.manifest:
-            if item.media_type in OEB_IMAGES:
+            if item.media_type in base.OEB_IMAGES:
                 if item.href not in self.images:
                     ext = os.path.splitext(item.href)[1]
                     fname = '%s%s' % (len(self.images), ext)
@@ -88,9 +89,9 @@ class OEB2HTML(object):
                     self.images[item.href] = fname
             if item in oeb_book.spine:
                 self.get_link_id(item.href)
-                root = item.data.find(XHTML('body'))
+                root = item.data.find(base.tag('xhtml', 'body'))
                 link_attrs = set(html.defs.link_attrs)
-                link_attrs.add(XLINK('href'))
+                link_attrs.add(base.tag('xlink', 'href'))
                 for el in root.iter():
                     attribs = el.attrib
                     try:
@@ -108,7 +109,7 @@ class OEB2HTML(object):
     def rewrite_link(self, url, page=None):
         if not page:
             return url
-        abs_url = page.abshref(urlnormalize(url))
+        abs_url = page.abshref(base.urlnormalize(url))
         if abs_url in self.images:
             return 'images/%s' % self.images[abs_url]
         if abs_url in self.links:
@@ -121,7 +122,7 @@ class OEB2HTML(object):
                 tag = el.tag
             except UnicodeDecodeError:
                 continue
-            if tag == XHTML('body'):
+            if tag == base.tag('xhtml', 'body'):
                 el.attrib['id'] = self.get_link_id(page.href)[1:]
                 continue
             if 'id' in el.attrib:
@@ -156,9 +157,9 @@ class OEB2HTMLNoCSSizer(OEB2HTML):
 
         # We can only processes tags. If there isn't a tag return any text.
         if not isinstance(elem.tag, (str, bytes)) \
-           or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
+           or parse_utils.namespace(elem.tag) not in (const.XHTML_NS, const.SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and parse_utils.namespace(p.tag) in (const.XHTML_NS, const.SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
@@ -167,7 +168,7 @@ class OEB2HTMLNoCSSizer(OEB2HTML):
         text = ['']
         style = stylizer.style(elem)
         tags = []
-        tag = barename(elem.tag)
+        tag = parse_utils.barename(elem.tag)
         attribs = elem.attrib
 
         if tag == 'body':
@@ -245,9 +246,9 @@ class OEB2HTMLInlineCSSizer(OEB2HTML):
 
         # We can only processes tags. If there isn't a tag return any text.
         if not isinstance(elem.tag, (str, bytes)) \
-           or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
+           or parse_utils.namespace(elem.tag) not in (const.XHTML_NS, const.SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and parse_utils.namespace(p.tag) in (const.XHTML_NS, const.SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
@@ -256,7 +257,7 @@ class OEB2HTMLInlineCSSizer(OEB2HTML):
         text = ['']
         style = stylizer.style(elem)
         tags = []
-        tag = barename(elem.tag)
+        tag = parse_utils.barename(elem.tag)
         attribs = elem.attrib
 
         style_a = '%s' % style
@@ -327,9 +328,9 @@ class OEB2HTMLClassCSSizer(OEB2HTML):
         for item in oeb_book.spine:
             self.log.debug('Converting %s to HTML...' % item.href)
             self.rewrite_ids(item.data, item)
-            rewrite_links(item.data, partial(self.rewrite_link, page=item))
+            base.rewrite_links(item.data, partial(self.rewrite_link, page=item))
             stylizer = Stylizer(item.data, item.href, oeb_book, self.opts)
-            output += self.dump_text(item.data.find(XHTML('body')), stylizer, item)
+            output += self.dump_text(item.data.find(base.tag('xhtml', 'body')), stylizer, item)
             output.append('\n\n')
         if self.opts.htmlz_class_style == 'external':
             css = u'<link href="style.css" rel="stylesheet" type="text/css" />'
@@ -348,9 +349,9 @@ class OEB2HTMLClassCSSizer(OEB2HTML):
 
         # We can only processes tags. If there isn't a tag return any text.
         if not isinstance(elem.tag, (str, bytes)) \
-           or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
+           or parse_utils.namespace(elem.tag) not in (const.XHTML_NS, const.SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and parse_utils.namespace(p.tag) in (const.XHTML_NS, const.SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
@@ -358,7 +359,7 @@ class OEB2HTMLClassCSSizer(OEB2HTML):
         # Setup our variables.
         text = ['']
         tags = []
-        tag = barename(elem.tag)
+        tag = parse_utils.barename(elem.tag)
         attribs = elem.attrib
 
         if tag == 'body':