Support counter-set

Code was sleeping commented since December 2011 and could have been working in
WeasyPrint 0.3. Easiest feature ever thanks to @SimonSapin.

Fix #1019.

weasyprint/css/properties.py

@@ -23,12 +23,6 @@ INITIAL_VALUES = {
     'clear': 'none',
     'clip': (),  # computed value for 'auto'
     'color': parse_color('black'),  # chosen by the user agent
-    # Means 'none', but allow `display: list-item` to increment the
-    # list-item counter. If we ever have a way for authors to query
-    # computed values (JavaScript?), this value should serialize to 'none'.
-    'counter_increment': 'auto',
-    'counter_reset': (),  # parsed value for 'none'
-    # 'counter_set': (),  # parsed value for 'none'
     'direction': 'ltr',
     'display': 'inline',
     'empty_cells': 'show',
@@ -36,9 +30,6 @@ INITIAL_VALUES = {
     'height': 'auto',
     'left': 'auto',
     'line_height': 'normal',
-    'list_style_image': ('none', None),
-    'list_style_position': 'outside',
-    'list_style_type': 'disc',
     'margin_top': Dimension(0, 'px'),
     'margin_right': Dimension(0, 'px'),
     'margin_bottom': Dimension(0, 'px'),
@@ -199,6 +190,17 @@ INITIAL_VALUES = {
     'overflow': 'visible',
     'text_overflow': 'clip',
 
+    # Lists Module 3 (WD): https://drafts.csswg.org/css-lists-3/
+    # Means 'none', but allow `display: list-item` to increment the
+    # list-item counter. If we ever have a way for authors to query
+    # computed values (JavaScript?), this value should serialize to 'none'.
+    'counter_increment': 'auto',
+    'counter_reset': (),  # parsed value for 'none'
+    'counter_set': (),  # parsed value for 'none'
+    'list_style_image': ('none', None),
+    'list_style_position': 'outside',
+    'list_style_type': 'disc',
+
     # Proprietary
     'anchor': None,  # computed value of 'none'
     'link': None,  # computed value of 'none'
@@ -297,6 +299,7 @@ TABLE_WRAPPER_BOX_PROPERTIES = {
     'clear',
     'counter_increment',
     'counter_reset',
+    'counter_set',
     'float',
     'left',
     'margin_top',

weasyprint/css/validation/properties.py

@@ -499,6 +499,12 @@ def counter_reset(tokens):
     return counter(tokens, default_integer=0)
 
 
+@property()
+def counter_set(tokens):
+    """``counter-set`` property validation."""
+    return counter(tokens, default_integer=0)
+
+
 def counter(tokens, default_integer):
     """``counter-increment`` and ``counter-reset`` properties validation."""
     if get_single_keyword(tokens) == 'none':

weasyprint/formatting_structure/build.py

@@ -671,14 +671,13 @@ def update_counters(state, style):
             sibling_scopes.add(name)
         counter_values.setdefault(name, []).append(value)
 
-    # XXX Disabled for now, only exists in Lists3’s editor’s draft.
-#    for name, value in style['counter_set']:
-#        values = counter_values.setdefault(name, [])
-#        if not values:
-#            assert name not in sibling_scopes
-#            sibling_scopes.add(name)
-#            values.append(0)
-#        values[-1] = value
+    for name, value in style['counter_set']:
+        values = counter_values.setdefault(name, [])
+        if not values:
+            assert name not in sibling_scopes
+            sibling_scopes.add(name)
+            values.append(0)
+        values[-1] = value
 
     counter_increment = style['counter_increment']
     if counter_increment == 'auto':

weasyprint/layout/pages.py

@@ -284,8 +284,7 @@ def _standardize_page_based_counters(style, pseudo_type):
 
     """
     page_counter_touched = False
-    # XXX 'counter-set` not yet supported
-    for propname in ('counter_reset', 'counter_increment'):
+    for propname in ('counter_set', 'counter_reset', 'counter_increment'):
         if style[propname] == 'auto':
             style[propname] = ()
             continue

weasyprint/tests/test_counters.py

@@ -503,6 +503,68 @@ def test_list_style_types(style_type, values):
     assert li_4.children[0].children[0].children[0].text == values[3]
 
 
+def test_counter_set():
+    page, = render_pages('''
+      <style>
+        body { counter-reset: h2 0 h3 4; font-size: 1px }
+        article { counter-reset: h2 2 }
+        h1 { counter-increment: h1 }
+        h1::before { content: counter(h1) }
+        h2 { counter-increment: h2; counter-set: h3 3 }
+        h2::before { content: counter(h2) }
+        h3 { counter-increment: h3 }
+        h3::before { content: counter(h3) }
+      </style>
+      <article>
+        <h1></h1>
+      </article>
+      <article>
+        <h2></h2>
+        <h3></h3>
+      </article>
+      <article>
+        <h3></h3>
+      </article>
+      <article>
+        <h2></h2>
+      </article>
+      <article>
+        <h3></h3>
+        <h3></h3>
+      </article>
+      <article>
+        <h1></h1>
+        <h2></h2>
+        <h3></h3>
+      </article>
+    ''')
+    html, = page.children
+    body, = html.children
+    art_1, art_2, art_3, art_4, art_5, art_6 = body.children
+
+    h1, = art_1.children
+    assert h1.children[0].children[0].children[0].text == '1'
+
+    h2, h3, = art_2.children
+    assert h2.children[0].children[0].children[0].text == '3'
+    assert h3.children[0].children[0].children[0].text == '4'
+
+    h3, = art_3.children
+    assert h3.children[0].children[0].children[0].text == '5'
+
+    h2, = art_4.children
+    assert h2.children[0].children[0].children[0].text == '3'
+
+    h3_1, h3_2 = art_5.children
+    assert h3_1.children[0].children[0].children[0].text == '4'
+    assert h3_2.children[0].children[0].children[0].text == '5'
+
+    h1, h2, h3 = art_6.children
+    assert h1.children[0].children[0].children[0].text == '1'
+    assert h2.children[0].children[0].children[0].text == '3'
+    assert h3.children[0].children[0].children[0].text == '4'
+
+
 def test_counter_multiple_extends():
     # Inspired by W3C failing test system-extends-invalid
     page, = render_pages('''

weasyprint/tests/test_css_validation.py

@@ -77,7 +77,7 @@ def test_function_invalid(rule):
     ('counter-increment: foo bar 2 baz', {
         'counter_increment': (('foo', 1), ('bar', 2), ('baz', 1))}),
     ('counter-reset: foo', {'counter_reset': (('foo', 0),)}),
-    ('counter-reset: FoO', {'counter_reset': (('FoO', 0),)}),
+    ('counter-set: FoO', {'counter_set': (('FoO', 0),)}),
     ('counter-increment: foo bAr 2 Bar', {
         'counter_increment': (('foo', 1), ('bAr', 2), ('Bar', 1))}),
     ('counter-reset: none', {'counter_reset': ()}),