dom: document first element can be null

src/dom/document.zig

@@ -34,9 +34,10 @@ pub const Document = struct {
         return DOMImplementation{};
     }
 
-    pub fn get_documentElement(self: *parser.Document) !ElementUnion {
+    pub fn get_documentElement(self: *parser.Document) !?ElementUnion {
         const e = try parser.documentGetDocumentElement(self);
-        return try Element.toInterface(e);
+        if (e == null) return null;
+        return try Element.toInterface(e.?);
     }
 
     pub fn get_documentURI(self: *parser.Document) ![]const u8 {
@@ -105,13 +106,12 @@ pub const Document = struct {
         alloc: std.mem.Allocator,
         tag_name: []const u8,
     ) !collection.HTMLCollection {
-        const root = try parser.documentGetDocumentElement(self);
-        return try collection.HTMLCollectionByTagName(
-            alloc,
-            parser.elementToNode(root),
-            tag_name,
-            true,
-        );
+        var elt: ?*parser.Node = null;
+        if (try parser.documentGetDocumentElement(self)) |root| {
+            elt = parser.elementToNode(root);
+        }
+
+        return try collection.HTMLCollectionByTagName(alloc, elt, tag_name, true);
     }
 
     pub fn _getElementsByClassName(
@@ -119,13 +119,12 @@ pub const Document = struct {
         alloc: std.mem.Allocator,
         classNames: []const u8,
     ) !collection.HTMLCollection {
-        const root = try parser.documentGetDocumentElement(self);
-        return try collection.HTMLCollectionByClassName(
-            alloc,
-            parser.elementToNode(root),
-            classNames,
-            true,
-        );
+        var elt: ?*parser.Node = null;
+        if (try parser.documentGetDocumentElement(self)) |root| {
+            elt = parser.elementToNode(root);
+        }
+
+        return try collection.HTMLCollectionByClassName(alloc, elt, classNames, true);
     }
 
     pub fn _createDocumentFragment(self: *parser.Document) !*parser.DocumentFragment {
@@ -169,8 +168,11 @@ pub const Document = struct {
     // ParentNode
     // https://dom.spec.whatwg.org/#parentnode
     pub fn get_children(self: *parser.Document) !collection.HTMLCollection {
-        const root = try parser.documentGetDocumentElement(self);
-        return try collection.HTMLCollectionChildren(parser.elementToNode(root), true);
+        var elt: ?*parser.Node = null;
+        if (try parser.documentGetDocumentElement(self)) |root| {
+            elt = parser.elementToNode(root);
+        }
+        return try collection.HTMLCollectionChildren(elt, true);
     }
 
     pub fn deinit(_: *parser.Document, _: std.mem.Allocator) void {}
@@ -188,6 +190,12 @@ pub fn testExecFn(
         .{ .src = "document.__proto__.__proto__.constructor.name", .ex = "Document" },
         .{ .src = "document.__proto__.__proto__.__proto__.constructor.name", .ex = "Node" },
         .{ .src = "document.__proto__.__proto__.__proto__.__proto__.constructor.name", .ex = "EventTarget" },
+
+        .{ .src = "let newdoc = new Document()", .ex = "undefined" },
+        .{ .src = "newdoc.documentElement", .ex = "null" },
+        .{ .src = "newdoc.children.length", .ex = "0" },
+        .{ .src = "newdoc.getElementsByTagName('*').length", .ex = "0" },
+        .{ .src = "newdoc.getElementsByTagName('*').item(0)", .ex = "null" },
     };
     try checkCases(js_env, &constructor);
 

src/dom/html_collection.zig

@@ -57,7 +57,7 @@ pub const MatchByTagName = struct {
 
 pub fn HTMLCollectionByTagName(
     alloc: std.mem.Allocator,
-    root: *parser.Node,
+    root: ?*parser.Node,
     tag_name: []const u8,
     include_root: bool,
 ) !HTMLCollection {
@@ -101,7 +101,7 @@ pub const MatchByClassName = struct {
 
 pub fn HTMLCollectionByClassName(
     alloc: std.mem.Allocator,
-    root: *parser.Node,
+    root: ?*parser.Node,
     classNames: []const u8,
     include_root: bool,
 ) !HTMLCollection {
@@ -116,7 +116,7 @@ pub fn HTMLCollectionByClassName(
 }
 
 pub fn HTMLCollectionChildren(
-    root: *parser.Node,
+    root: ?*parser.Node,
     include_root: bool,
 ) !HTMLCollection {
     return HTMLCollection{
@@ -219,7 +219,7 @@ pub const HTMLCollection = struct {
     matcher: Matcher,
     walker: Walker,
 
-    root: *parser.Node,
+    root: ?*parser.Node,
 
     // By default the HTMLCollection walk on the root's descendant only.
     // But on somes cases, like for dom document, we want to walk over the root
@@ -232,17 +232,21 @@ pub const HTMLCollection = struct {
 
     // start returns the first node to walk on.
     fn start(self: HTMLCollection) !?*parser.Node {
+        if (self.root == null) return null;
+
         if (self.include_root) {
-            return self.root;
+            return self.root.?;
         }
 
-        return try self.walker.get_next(self.root, null);
+        return try self.walker.get_next(self.root.?, null);
     }
 
     /// get_length computes the collection's length dynamically according to
     /// the current root structure.
     // TODO: nodes retrieved must be de-referenced.
     pub fn get_length(self: *HTMLCollection) !u32 {
+        if (self.root == null) return 0;
+
         var len: u32 = 0;
         var node = try self.start() orelse return 0;
 
@@ -253,13 +257,15 @@ pub const HTMLCollection = struct {
                 }
             }
 
-            node = try self.walker.get_next(self.root, node) orelse break;
+            node = try self.walker.get_next(self.root.?, node) orelse break;
         }
 
         return len;
     }
 
     pub fn _item(self: *HTMLCollection, index: u32) !?Union {
+        if (self.root == null) return null;
+
         var i: u32 = 0;
         var node: *parser.Node = undefined;
 
@@ -288,16 +294,15 @@ pub const HTMLCollection = struct {
                 }
             }
 
-            node = try self.walker.get_next(self.root, node) orelse break;
+            node = try self.walker.get_next(self.root.?, node) orelse break;
         }
 
         return null;
     }
 
     pub fn _namedItem(self: *HTMLCollection, name: []const u8) !?Union {
-        if (name.len == 0) {
-            return null;
-        }
+        if (self.root == null) return null;
+        if (name.len == 0) return null;
 
         var node = try self.start() orelse return null;
 
@@ -320,7 +325,7 @@ pub const HTMLCollection = struct {
                 }
             }
 
-            node = try self.walker.get_next(self.root, node) orelse break;
+            node = try self.walker.get_next(self.root.?, node) orelse break;
         }
 
         return null;

src/netsurf.zig

@@ -1150,10 +1150,11 @@ pub inline fn documentGetElementsByTagName(doc: *Document, tagname: []const u8)
 }
 
 // documentGetDocumentElement returns the root document element.
-pub inline fn documentGetDocumentElement(doc: *Document) !*Element {
+pub inline fn documentGetDocumentElement(doc: *Document) !?*Element {
     var elem: ?*Element = undefined;
     const err = documentVtable(doc).dom_document_get_document_element.?(doc, &elem);
     try DOMErr(err);
+    if (elem == null) return null;
     return elem.?;
 }