Implement StaticRange (#31809)

* Add DOM interface for AbstractRange

* Add DOM interface for StaticRange

* Update WPT tests for StaticRange-constructor.html

* Fix formatting

* Add AbstractRange & StaticRange in interfaces.html

* rebased the code and fixed the failures

Signed-off-by: Cathie Chen <cathiechen@igalia.com>

* update the expected result in idlharness.window.js.ini file

* Addressed the code review comments

* updae the test result of legacy layout

---------

Signed-off-by: Cathie Chen <cathiechen@igalia.com>
Co-authored-by: Nipun Garg <nipung271@gmail.com>

components/script/dom/abstractrange.rs

@@ -0,0 +1,177 @@
+/* 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 std::cell::Cell;
+use std::cmp::{Ord, Ordering, PartialEq, PartialOrd};
+
+use deny_public_fields::DenyPublicFields;
+use dom_struct::dom_struct;
+
+use crate::dom::bindings::codegen::Bindings::AbstractRangeBinding::AbstractRangeMethods;
+use crate::dom::bindings::codegen::Bindings::NodeBinding::{NodeConstants, NodeMethods};
+use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
+use crate::dom::bindings::root::{DomRoot, MutDom};
+use crate::dom::document::Document;
+use crate::dom::node::{Node, ShadowIncluding};
+
+#[dom_struct]
+pub struct AbstractRange {
+    reflector_: Reflector,
+    start: BoundaryPoint,
+    end: BoundaryPoint,
+}
+
+impl AbstractRange {
+    pub fn new_inherited(
+        start_container: &Node,
+        start_offset: u32,
+        end_container: &Node,
+        end_offset: u32,
+    ) -> AbstractRange {
+        AbstractRange {
+            reflector_: Reflector::new(),
+            start: BoundaryPoint::new(start_container, start_offset),
+            end: BoundaryPoint::new(end_container, end_offset),
+        }
+    }
+
+    pub fn new(
+        document: &Document,
+        start_container: &Node,
+        start_offset: u32,
+        end_container: &Node,
+        end_offset: u32,
+    ) -> DomRoot<AbstractRange> {
+        let abstractrange = reflect_dom_object(
+            Box::new(AbstractRange::new_inherited(
+                start_container,
+                start_offset,
+                end_container,
+                end_offset,
+            )),
+            document.window(),
+        );
+        abstractrange
+    }
+
+    pub fn start(&self) -> &BoundaryPoint {
+        &self.start
+    }
+
+    pub fn end(&self) -> &BoundaryPoint {
+        &self.end
+    }
+}
+
+impl AbstractRangeMethods for AbstractRange {
+    /// <https://dom.spec.whatwg.org/#dom-range-startcontainer>
+    fn StartContainer(&self) -> DomRoot<Node> {
+        self.start.node.get()
+    }
+
+    /// <https://dom.spec.whatwg.org/#dom-range-startoffset>
+    fn StartOffset(&self) -> u32 {
+        self.start.offset.get()
+    }
+
+    /// <https://dom.spec.whatwg.org/#dom-range-endcontainer>
+    fn EndContainer(&self) -> DomRoot<Node> {
+        self.end.node.get()
+    }
+
+    /// <https://dom.spec.whatwg.org/#dom-range-endoffset>
+    fn EndOffset(&self) -> u32 {
+        self.end.offset.get()
+    }
+
+    /// <https://dom.spec.whatwg.org/#dom-range-collapsed>
+    fn Collapsed(&self) -> bool {
+        self.start == self.end
+    }
+}
+
+#[derive(DenyPublicFields, JSTraceable, MallocSizeOf)]
+#[crown::unrooted_must_root_lint::must_root]
+pub struct BoundaryPoint {
+    node: MutDom<Node>,
+    offset: Cell<u32>,
+}
+
+impl BoundaryPoint {
+    fn new(node: &Node, offset: u32) -> BoundaryPoint {
+        debug_assert!(!node.is_doctype());
+        BoundaryPoint {
+            node: MutDom::new(node),
+            offset: Cell::new(offset),
+        }
+    }
+
+    pub fn set(&self, node: &Node, offset: u32) {
+        self.node.set(node);
+        self.set_offset(offset);
+    }
+
+    pub fn set_offset(&self, offset: u32) {
+        self.offset.set(offset);
+    }
+
+    pub fn node(&self) -> &MutDom<Node> {
+        &self.node
+    }
+}
+
+#[allow(crown::unrooted_must_root)]
+impl PartialOrd for BoundaryPoint {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        bp_position(
+            &self.node.get(),
+            self.offset.get(),
+            &other.node.get(),
+            other.offset.get(),
+        )
+    }
+}
+
+#[allow(crown::unrooted_must_root)]
+impl PartialEq for BoundaryPoint {
+    fn eq(&self, other: &Self) -> bool {
+        self.node.get() == other.node.get() && self.offset.get() == other.offset.get()
+    }
+}
+
+/// <https://dom.spec.whatwg.org/#concept-range-bp-position>
+pub fn bp_position(a_node: &Node, a_offset: u32, b_node: &Node, b_offset: u32) -> Option<Ordering> {
+    if a_node as *const Node == b_node as *const Node {
+        // Step 1.
+        return Some(a_offset.cmp(&b_offset));
+    }
+    let position = b_node.CompareDocumentPosition(a_node);
+    if position & NodeConstants::DOCUMENT_POSITION_DISCONNECTED != 0 {
+        // No order is defined for nodes not in the same tree.
+        None
+    } else if position & NodeConstants::DOCUMENT_POSITION_FOLLOWING != 0 {
+        // Step 2.
+        match bp_position(b_node, b_offset, a_node, a_offset).unwrap() {
+            Ordering::Less => Some(Ordering::Greater),
+            Ordering::Greater => Some(Ordering::Less),
+            Ordering::Equal => unreachable!(),
+        }
+    } else if position & NodeConstants::DOCUMENT_POSITION_CONTAINS != 0 {
+        // Step 3-1, 3-2.
+        let mut b_ancestors = b_node.inclusive_ancestors(ShadowIncluding::No);
+        let child = b_ancestors
+            .find(|child| &*child.GetParentNode().unwrap() == a_node)
+            .unwrap();
+        // Step 3-3.
+        if child.index() < a_offset {
+            Some(Ordering::Greater)
+        } else {
+            // Step 4.
+            Some(Ordering::Less)
+        }
+    } else {
+        // Step 4.
+        Some(Ordering::Less)
+    }
+}