Allow @page inside @media

Author: SimonSapin

tinycss/css21.py

@@ -482,6 +482,8 @@ def read_at_rule(self, at_keyword_token, tokens):
         return AtRule(at_keyword, head, body,
                       at_keyword_token.line, at_keyword_token.column)
 
+    at_page_allowed_contexts = ['stylesheet']
+
     def parse_at_rule(self, rule, previous_rules, errors, context):
         """Parse an at-rule.
 
@@ -508,7 +510,7 @@ def parse_at_rule(self, rule, previous_rules, errors, context):
 
         """
         if rule.at_keyword == '@page':
-            if context != 'stylesheet':
+            if context not in self.at_page_allowed_contexts:
                 raise ParseError(rule, '@page rule not allowed in ' + context)
             selector, specificity = self.parse_page_selector(rule.head)
             if rule.body is None:

tinycss/page3.py

@@ -107,6 +107,8 @@ class CSSPage3Parser(CSS21Parser):
         '@right-bottom',
     ]
 
+    at_page_allowed_contexts = ['stylesheet', '@media']
+
     def parse_at_rule(self, rule, previous_rules, errors, context):
         if rule.at_keyword in self.PAGE_MARGIN_AT_KEYWORDS:
             if context != '@page':
@@ -150,6 +152,8 @@ def parse_page_selector(self, head):
         if (len(head) == 2 and head[0].type == ':'
                 and head[1].type == 'IDENT'):
             pseudo_class = head[1].value
+            # :blank is defined in GCPM:
+            # http://dev.w3.org/csswg/css3-gcpm/#styling-blank-pages
             specificity = {
                 'first': (1, 0), 'blank': (1, 0),
                 'left': (0, 1), 'right': (0, 1),

tinycss/tests/test_page3.py

@@ -12,6 +12,7 @@
 
 import pytest
 
+from tinycss.css21 import CSS21Parser
 from tinycss.page3 import CSSPage3Parser
 from .test_tokenizer import jsonify
 from . import assert_errors
@@ -99,3 +100,21 @@ def declarations(rule):
     rules = [(margin_rule.at_keyword, declarations(margin_rule))
              for margin_rule in rule.at_rules]
     assert rules == expected_rules
+
+
+def test_in_at_media():
+    css = '@media print { @page { size: A4 } }'
+
+    stylesheet = CSS21Parser().parse_stylesheet(css)
+    assert_errors(stylesheet.errors, ['@page rule not allowed in @media'])
+    at_media_rule, = stylesheet.rules
+    assert at_media_rule.at_keyword == '@media'
+    assert at_media_rule.rules == []
+
+    stylesheet = CSSPage3Parser().parse_stylesheet(css)
+    assert stylesheet.errors == []
+    at_media_rule, = stylesheet.rules
+    at_page_rule, = at_media_rule.rules
+    assert at_media_rule.at_keyword == '@media'
+    assert at_page_rule.at_keyword == '@page'
+    assert len(at_page_rule.declarations) == 1