Layout 2020 skeleton for display: flex, behind a pref

components/layout_2020/flexbox.rs

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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::context::LayoutContext;
+use crate::dom_traversal::{NodeExt, NonReplacedContents};
+use crate::formatting_contexts::IndependentLayout;
+use crate::positioned::PositioningContext;
+use crate::sizing::{BoxContentSizes, ContentSizesRequest};
+use crate::ContainingBlock;
+use servo_arc::Arc;
+use style::properties::ComputedValues;
+use style::values::specified::text::TextDecorationLine;
+
+// FIXME: `min-width: auto` is not zero: https://drafts.csswg.org/css-flexbox/#min-size-auto
+
+#[derive(Debug, Serialize)]
+pub(crate) struct FlexContainer {
+    unimplemented_fallback: crate::flow::BlockFormattingContext,
+}
+
+impl FlexContainer {
+    pub fn construct<'dom>(
+        context: &LayoutContext,
+        node: impl NodeExt<'dom>,
+        style: &Arc<ComputedValues>,
+        contents: NonReplacedContents,
+        content_sizes: ContentSizesRequest,
+        propagated_text_decoration_line: TextDecorationLine,
+    ) -> (Self, BoxContentSizes) {
+        let (unimplemented_fallback, content_sizes) =
+            crate::flow::BlockFormattingContext::construct(
+                context,
+                node,
+                style,
+                contents,
+                content_sizes,
+                propagated_text_decoration_line,
+            );
+        (
+            Self {
+                unimplemented_fallback,
+            },
+            content_sizes,
+        )
+    }
+
+    pub(crate) fn layout(
+        &self,
+        layout_context: &LayoutContext,
+        positioning_context: &mut PositioningContext,
+        containing_block: &ContainingBlock,
+        tree_rank: usize,
+    ) -> IndependentLayout {
+        self.unimplemented_fallback.layout(
+            layout_context,
+            positioning_context,
+            containing_block,
+            tree_rank,
+        )
+    }
+}