Clean management of variables

Fix #2042.

tests/test_variables.py

@@ -110,6 +110,22 @@ def test_variable_chain_root():
     assert html.width == 10
 
 
+def test_variable_self():
+    page, = render_pages('''
+      <style>
+        html { --var1: var(--var1) }
+      </style>
+    ''')
+
+
+def test_variable_loop():
+    page, = render_pages('''
+      <style>
+        html { --var1: var(--var2); --var2: var(--var1) }
+      </style>
+    ''')
+
+
 def test_variable_chain_root_missing():
     # Regression test for https://github.com/Kozea/WeasyPrint/issues/1656
     page, = render_pages('''
@@ -479,3 +495,29 @@ def test_variable_in_function_missing():
     h11, div1, h12, div2 = section.children
     assert not div1.children
     assert not div2.children
+
+
+@assert_no_logs
+def test_variable_in_function_in_variable():
+    page, = render_pages('''
+      <style>
+        html { --name: title; --counter: counter(var(--name), upper-roman) }
+        h1 { counter-increment: var(--name) }
+        div::before { content: var(--counter) }
+      </style>
+      <section>
+        <h1></h1>
+        <div></div>
+        <h1></h1>
+        <div></div>
+        <h1></h1>
+        <div style="--counter: counter(var(--name), lower-roman)"></div>
+      </section>
+    ''')
+    html, = page.children
+    body, = html.children
+    section, = body.children
+    h11, div1, h12, div2, h13, div3 = section.children
+    assert div1.children[0].children[0].children[0].text == 'I'
+    assert div2.children[0].children[0].children[0].text == 'II'
+    assert div3.children[0].children[0].children[0].text == 'iii'

weasyprint/css/__init__.py

@@ -609,32 +609,17 @@ def resolve_var(computed, token, parent_style):
             token.source_line, token.source_column, token.name, arguments)
         return resolve_var(computed, token, parent_style) or (token,)
 
-    default = None  # just for the linter
-    known_variable_names = set()
-    computed_value = (token,)
-    while (computed_value and
-            isinstance(computed_value, tuple)
-            and len(computed_value) == 1):
-        value = computed_value[0]
-        if value.type == 'ident' and value.value == 'initial':
+    args = parse_function(token)[1]
+    variable_name = args.pop(0).value.replace('-', '_')  # first arg is name
+    default = args  # next args are default value
+    computed_value = []
+    for value in computed[variable_name]:
+        resolved = resolve_var(computed, value, parent_style)
+        computed_value.extend((value,) if resolved is None else resolved)
+    if len(computed_value) == 1:
+        token, = computed_value
+        if token.type == 'ident' and token.value == 'initial':
             return default
-        if check_var_function(value):
-            args = parse_function(value)[1]
-            variable_name = args.pop(0).value.replace('-', '_')
-            if variable_name in known_variable_names:
-                computed_value = default
-                break
-            known_variable_names.add(variable_name)
-            default = args
-            computed_value = computed[variable_name]
-            if computed_value is not None:
-                continue
-            if parent_style is None:
-                computed_value = default
-            else:
-                computed_value = parent_style[variable_name] or default
-        else:
-            break
     return computed_value