test(ie-html): add html5lib tree construction conformance suite — 42.2% pass rate #60

Vendor html5lib-tests tree construction fixtures (56 .dat files, 1578
non-scripted non-fragment tests) with MIT LICENSE attribution.

Conformance harness:
- Parses custom .dat format (#data/#errors/#document sections)
- Skips script-on and fragment tests (not supported)
- Serializes DOM to html5lib expected format with DOCTYPE output
- Per-file and aggregate reporting

Tree builder fixes:
- Initial mode now stores DOCTYPE name/public_id/system_id
- ParseResult exposes doctype fields for serialization
- Recursion guard (depth 20) prevents stack overflow from
  reprocessing loops in table modes

42.2% pass rate (666/1578). Main failure categories:
- Table structure edge cases and foster parenting precision
- Adoption agency corner cases
- Missing: foreign content (SVG/MathML), ruby, button scope
- Missing: InFrameset, template document fragment

Author: thomasnemer

crates/ie-html/src/tree_builder.rs

@@ -11,6 +11,9 @@ pub struct ParseResult {
     pub errors: Vec<String>,
     pub style_elements: Vec<String>,
     pub link_stylesheets: Vec<String>,
+    pub doctype_name: Option<String>,
+    pub doctype_public_id: Option<String>,
+    pub doctype_system_id: Option<String>,
 }
 
 /// Top-level parse function. HTML parsing never fails — errors are collected.
@@ -22,6 +25,9 @@ pub fn parse(html: &str) -> ParseResult {
         errors: tb.errors,
         style_elements: tb.style_elements,
         link_stylesheets: tb.link_stylesheets,
+        doctype_name: tb.doctype_name,
+        doctype_public_id: tb.doctype_public_id,
+        doctype_system_id: tb.doctype_system_id,
     }
 }
 
@@ -41,6 +47,10 @@ struct TreeBuilder<'a> {
     style_elements: Vec<String>,
     link_stylesheets: Vec<String>,
     pending_text: String,
+    reprocess_depth: u32,
+    doctype_name: Option<String>,
+    doctype_public_id: Option<String>,
+    doctype_system_id: Option<String>,
     done: bool,
 }
 
@@ -62,6 +72,10 @@ impl<'a> TreeBuilder<'a> {
             style_elements: Vec::new(),
             link_stylesheets: Vec::new(),
             pending_text: String::new(),
+            reprocess_depth: 0,
+            doctype_name: None,
+            doctype_public_id: None,
+            doctype_system_id: None,
             done: false,
         }
     }
@@ -80,6 +94,12 @@ impl<'a> TreeBuilder<'a> {
     }
 
     fn process_token(&mut self, token: Token) {
+        self.reprocess_depth += 1;
+        if self.reprocess_depth > 20 {
+            // Prevent infinite recursion from reprocessing loops
+            self.reprocess_depth -= 1;
+            return;
+        }
         match self.mode {
             InsertionMode::Initial => self.handle_initial(token),
             InsertionMode::BeforeHtml => self.handle_before_html(token),
@@ -105,6 +125,7 @@ impl<'a> TreeBuilder<'a> {
             InsertionMode::AfterAfterFrameset => self.handle_in_body(token),
             InsertionMode::AfterFrameset => self.handle_in_body(token),
         }
+        self.reprocess_depth -= 1;
     }
 
     // --- Helpers ---
@@ -823,8 +844,16 @@ impl<'a> TreeBuilder<'a> {
             Token::Comment(ref data) => {
                 self.insert_comment_at(data, self.doc.root);
             }
-            Token::Doctype { .. } => {
-                // Accept doctype, always no-quirks mode
+            Token::Doctype {
+                name,
+                public_id,
+                system_id,
+                ..
+            } => {
+                self.doctype_name = name;
+                self.doctype_public_id = public_id;
+                self.doctype_system_id = system_id;
+                self.mode = InsertionMode::BeforeHtml;
             }
             _ => {
                 self.parse_error("unexpected token in Initial mode");

crates/ie-html/tests/html5lib-tree/LICENSE

@@ -0,0 +1,21 @@
+Copyright (c) 2006-2013 James Graham, Geoffrey Sneddon, and
+other contributors
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.