feat(html): SVG HTML integration points switch back to HTML namespace (#83)

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- HTML5 integration points (#83, stage 7): HTML content inside an SVG integration point (`foreignObject`, `desc`, `title`) is now parsed in the HTML namespace rather than SVG, so `<svg><foreignObject><div>` puts the `div` (and its descendants) back in HTML; re-entering `<svg>` inside an integration point switches back to the SVG namespace.
 - HTML5 table foster-parenting (#83, stage 6): stray flow content inside a table is now moved out rather than nested in the table structure, matching the HTML standard. A non-table element or character data appearing while a `table`/`tbody`/`thead`/`tfoot`/`tr` is the open node is inserted immediately before the table (`<table><b>x</table>` -> `<b>x</b><table></table>`), while well-formed cell content is untouched.
 - HTML5 SVG attribute-name case adjustment (#83, stage 5): an SVG attribute written in mixed case is restored to its canonical camel case in the tree (`viewbox` -> `viewBox`, `gradienttransform` -> `gradientTransform`, and the rest), applying only to elements in the SVG namespace. HTML attribute names are left as the tokenizer lowercased them. With this, SVG/MathML foreign content carries correct element and attribute names.
 - HTML5 adoption agency algorithm and active formatting elements (#83, stage 4): misnested formatting tags are now recovered exactly as the HTML standard prescribes. Overlapping tags nest (`<b><i></b></i>` -> `<b><i></i></b>`), content after an out-of-order close is re-wrapped by reconstructing the active formatting elements (`<b><i></b>X</i>` -> `<b><i></i></b><i>X</i>`), and a block inside a formatting element reparents through the furthest-block path, including the canonical `<p>1<b>2<i>3</b>4</i>5</p>` -> `<p>1<b>2<i>3</i></b><i>4</i>5</p>`.

README.md

@@ -89,7 +89,7 @@ flowchart TB
 
 PureXML is a working, dependency-free XML library today: parse, emit, validate,
 query, and stream documents on macOS, Linux, Windows, and WASM. The test suite
-currently runs **738 tests in 115 suites** (`swift test`).
+currently runs **740 tests in 115 suites** (`swift test`).
 
 ### Shipped (libxml2-aligned surface)
 

Sources/HTML/HTMLDocumentBuilder.swift

@@ -250,13 +250,23 @@ final class HTMLDocument {
         }
     }
 
-    /// The foreign-content namespace for a body element: SVG/MathML on entry, or
-    /// the nearest open foreign ancestor's namespace inside one.
+    /// The foreign-content namespace for a body element: SVG/MathML on entry, the
+    /// nearest open foreign ancestor's namespace inside one, or HTML (nil) when
+    /// that ancestor is an HTML integration point (`foreignObject`/`desc`/`title`),
+    /// whose content is parsed as ordinary HTML.
     private func bodyForeignNamespace(for name: String) -> String? {
         if name == "svg" { return ForeignNamespace.svg }
         if name == "math" { return ForeignNamespace.mathml }
-        return openBody.reversed().compactMap { $0.name?.namespaceURI }.first
+        for node in openBody.reversed() {
+            guard let namespace = node.name?.namespaceURI else { continue }
+            if Self.svgIntegrationPoints.contains(tagName(node)) { return nil }
+            return namespace
+        }
+        return nil
     }
+
+    /// The SVG elements that are HTML integration points: their content is HTML.
+    private static let svgIntegrationPoints: Set<String> = ["foreignobject", "desc", "title"]
 }
 
 /// The head's open-element stack still uses the pop-on-close `DocFrame` model (it

Tests/HTMLForeignContentTests.swift

@@ -79,4 +79,18 @@ struct HTMLForeignContentTests {
         let element = find("p", in: "<p viewbox=\"x\"></p>")
         #expect(element?.attributes.contains { $0.name.description == "viewbox" } == true)
     }
+
+    @Test("HTML content inside an SVG integration point is back in the HTML namespace")
+    func test_integrationPoint() {
+        let html = "<svg><foreignObject><div><span>x</span></div></foreignObject></svg>"
+        #expect(find("foreignObject", in: html)?.name.namespaceURI == svg)
+        #expect(find("div", in: html)?.name.namespaceURI == nil)
+        #expect(find("span", in: html)?.name.namespaceURI == nil)
+    }
+
+    @Test("Re-entering svg inside an integration point switches back to SVG")
+    func test_reentrantForeign() {
+        let html = "<svg><foreignObject><svg><rect></rect></svg></foreignObject></svg>"
+        #expect(find("rect", in: html)?.name.namespaceURI == svg)
+    }
 }