style: Support resolving variables pointing to variables

robinlinden · Nov 19, 2024 · 644c54d · 644c54d
1 parent a8680ab
commit 644c54d
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Showing 2 changed files with 25 additions and 9 deletions.
diff --git a/style/styled_node.cpp b/style/styled_node.cpp
@@ -22,6 +22,7 @@
 #include <cstring>
 #include <iterator>
 #include <optional>
+#include <set>
 #include <sstream>
 #include <string>
 #include <string_view>
@@ -266,9 +267,9 @@ std::string_view StyledNode::get_raw_property(css::PropertyId property) const {
     }
 
     // If this is a var() we can easily expand here, do so.
-    if (it->second.starts_with("var(") && (it->second.find(')') != std::string::npos)) {
-        auto value = std::string_view{it->second};
-
+    auto value = std::string_view{it->second};
+    std::set<std::string_view> seen_variables{};
+    while (value.starts_with("var(") && (value.find(')') != std::string::npos)) {
         // Remove "var(" from the start and ")" from the end. 5 characters in total.
         auto var = value.substr(4, value.size() - 5);
         auto [var_name, fallback] = util::split_once(var, ",");
@@ -283,10 +284,20 @@ std::string_view StyledNode::get_raw_property(css::PropertyId property) const {
             return css::initial_value(property);
         }
 
-        return *prop;
+        if (!prop->starts_with("var(")) {
+            return *prop;
+        }
+
+        seen_variables.insert(value);
+        if (seen_variables.contains(*prop)) {
+            spdlog::warn("Circular variable reference '{}'", *prop);
+            return css::initial_value(property);
+        }
+
+        value = *prop;
     }
 
-    return it->second;
+    return value;
 }
 
 // NOLINTNEXTLINE(misc-no-recursion)

diff --git a/style/styled_node_test.cpp b/style/styled_node_test.cpp
@@ -508,11 +508,16 @@ int main() {
                 },
         };
 
-        // TODO(robinlinden)
-        // expect_eq(styled_node.get_property<css::PropertyId::FontWeight>(), //
-        //         style::FontWeight::bold());
         expect_eq(styled_node.get_property<css::PropertyId::FontWeight>(), //
-                std::nullopt);
+                style::FontWeight::bold());
+
+        // Circular references are bad.
+        styled_node.custom_properties = {
+                {"--a", "var(--b)"},
+                {"--b", "var(--a)"},
+        };
+        expect_eq(styled_node.get_property<css::PropertyId::FontWeight>(), //
+                style::FontWeight::normal());
     });
 
     etest::test("var() with fallback, var exists", [] {