News download system: Allow use of __future__ in recipes, and do not change line numbers of code in the recipe when compiling it

src/calibre/web/feeds/recipes/__init__.py

@@ -4,20 +4,14 @@ __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 '''
 Builtin recipes.
 '''
-import re, imp, inspect, time, os
-from calibre.web.feeds.news import BasicNewsRecipe, CustomIndexRecipe, \
-    AutomaticNewsRecipe, CalibrePeriodical
+import re, time, io
+from calibre.web.feeds.news import (BasicNewsRecipe, CustomIndexRecipe,
+    AutomaticNewsRecipe, CalibrePeriodical)
 from calibre.ebooks.BeautifulSoup import BeautifulSoup
-from calibre.ptempfile import PersistentTemporaryDirectory
-from calibre import __appname__, english_sort
 from calibre.utils.config import JSONConfig
 
-BeautifulSoup, time, english_sort
-
 basic_recipes = (BasicNewsRecipe, AutomaticNewsRecipe, CustomIndexRecipe,
         CalibrePeriodical)
-_tdir = None
-_crep = 0
 
 custom_recipes = JSONConfig('custom_recipes/index.json')
 
@@ -28,39 +22,33 @@ def custom_recipe_filename(id_, title):
 
 def compile_recipe(src):
     '''
-    Compile the code in src and return the first object that is a recipe or profile.
-    @param src: Python source code
-    @type src: string
-    @return: Recipe class or None, if no such class was found in C{src}
+    Compile the code in src and return a recipe object, if found.
+
+    :param src: Python source code as bytestring or unicode object
+
+    :return: Recipe class or None, if no such class was found in src
     '''
-    global _tdir, _crep
-    if _tdir is None or not os.path.exists(_tdir):
-        _tdir = PersistentTemporaryDirectory('_recipes')
-    temp = os.path.join(_tdir, 'recipe%d.py'%_crep)
-    _crep += 1
     if not isinstance(src, unicode):
         match = re.search(r'coding[:=]\s*([-\w.]+)', src[:200])
         enc = match.group(1) if match else 'utf-8'
         src = src.decode(enc)
-    src = re.sub(r'from __future__.*', '', src)
-    f = open(temp, 'wb')
-    src = 'from %s.web.feeds.news import BasicNewsRecipe, AutomaticNewsRecipe\n'%__appname__ + src
-    src = '# coding: utf-8\n' + src
-    src = 'from __future__ import with_statement\n' + src
+    # Python complains if there is a coding declaration in a unicode string
+    src = re.sub(r'^#.*coding\s*[:=]\s*([-\w.]+)', '#', src, flags=re.MULTILINE)
+    # Translate newlines to \n
+    src = io.StringIO(src, newline=None).getvalue()
 
-    src = src.replace('from libprs500', 'from calibre').encode('utf-8')
-    f.write(src)
-    f.close()
-    module = imp.find_module(os.path.splitext(os.path.basename(temp))[0],
-        [os.path.dirname(temp)])
-    module = imp.load_module(os.path.splitext(os.path.basename(temp))[0], *module)
-    classes = inspect.getmembers(module,
-            lambda x : inspect.isclass(x) and \
-                issubclass(x, (BasicNewsRecipe,)) and \
-                x not in basic_recipes)
-    if not classes:
-        return None
+    namespace = {
+            'BasicNewsRecipe':BasicNewsRecipe,
+            'AutomaticNewsRecipe':AutomaticNewsRecipe,
+            'time':time, 're':re,
+            'BeautifulSoup':BeautifulSoup
+        }
+    exec src in namespace
 
-    return classes[0][1]
+    for x in namespace.itervalues():
+        if (isinstance(x, type) and issubclass(x, BasicNewsRecipe) and x not
+                in basic_recipes):
+            return x
 
+    return None