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fix(html): preserve the document around the rustmotion element #255

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Merged
LeadcodeDev merged 1 commit into from
Sep 22, 2026
Merged

fix(html): preserve the document around the rustmotion element #255

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41 changes: 34 additions & 7 deletions crates/rustmotion-html/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -401,7 +401,7 @@ pub fn set_inline_style(html: &str, pointer: &str, prop: &str, value: &str) -> O
let root = find_element(&dom.document, "rustmotion")?;
let target = resolve_pointer(&root, pointer)?;
set_style_attr(&target, prop, value)?;
Some(serialize_element(&root))
splice_rustmotion_subtree(html, &root)
}

/// Replace the text content of the element addressed by the JSON pointer with
Expand All @@ -413,7 +413,7 @@ pub fn set_text_content(html: &str, pointer: &str, text: &str) -> Option<String>
let root = find_element(&dom.document, "rustmotion")?;
let target = resolve_pointer(&root, pointer)?;
set_text(&target, text)?;
Some(serialize_element(&root))
splice_rustmotion_subtree(html, &root)
}

/// Set or replace a plain attribute on the element addressed by the JSON
Expand All @@ -429,7 +429,7 @@ pub fn set_attribute(html: &str, pointer: &str, name: &str, value: &str) -> Opti
let root = find_element(&dom.document, "rustmotion")?;
let target = resolve_pointer(&root, pointer)?;
set_attr(&target, name, value)?;
Some(serialize_element(&root))
splice_rustmotion_subtree(html, &root)
}

/// Remove one inline `style` property from the element addressed by the JSON
Expand All @@ -441,7 +441,7 @@ pub fn remove_inline_style(html: &str, pointer: &str, prop: &str) -> Option<Stri
let root = find_element(&dom.document, "rustmotion")?;
let target = resolve_pointer(&root, pointer)?;
remove_style_decl(&target, prop)?;
Some(serialize_element(&root))
splice_rustmotion_subtree(html, &root)
}

/// Upsert (or, for an empty value, remove) a plain attribute on an element.
Expand Down Expand Up @@ -600,15 +600,42 @@ fn upsert_decl(decls: &str, prop: &str, value: &str) -> String {
.join("; ")
}

fn serialize_element(handle: &Handle) -> String {
/// Re-serialize `root` (the mutated `<rustmotion>` subtree) and splice it
/// back into `original` at the exact byte span its `<rustmotion>...
/// </rustmotion>` element occupies there, leaving everything before and
/// after — doctype, `<head>`, comments, anything else the author wrote —
/// byte-for-byte untouched. `original` is used as the source of truth for
/// that surrounding content rather than `root`'s own parsed document,
/// because `parse_fragment_dom` parses in a body-fragment context, which
/// does not retain a doctype at all and does not guarantee round-tripping
/// `<html>`/`<head>`/`<body>` the way the author wrote them. Refuses
/// (`None`) rather than write a corrupted file when the span can't be
/// located (no `<rustmotion>`/`</rustmotion>` literal in `original`, e.g. an
/// unclosed root) or the serializer itself fails.
fn splice_rustmotion_subtree(original: &str, root: &Handle) -> Option<String> {
let open_start = original.find("<rustmotion")?;
let close_start = original.rfind("</rustmotion")?;
let close_end = close_start + original[close_start..].find('>')? + 1;
if close_end <= open_start {
return None;
}
let serialized = serialize_element(root).ok()?;
let mut out = String::with_capacity(original.len() + serialized.len());
out.push_str(&original[..open_start]);
out.push_str(&serialized);
out.push_str(&original[close_end..]);
Some(out)
}

fn serialize_element(handle: &Handle) -> Result<String, HtmlError> {
let mut buf = Vec::new();
let node: SerializableHandle = handle.clone().into();
let opts = SerializeOpts {
traversal_scope: TraversalScope::IncludeNode,
..Default::default()
};
let _ = serialize(&mut buf, &node, opts);
String::from_utf8(buf).unwrap_or_default()
serialize(&mut buf, &node, opts).map_err(|e| HtmlError::SerializeFailed(e.to_string()))?;
String::from_utf8(buf).map_err(|e| HtmlError::SerializeFailed(e.to_string()))
}

#[cfg(test)]
Expand Down
76 changes: 76 additions & 0 deletions crates/rustmotion-html/tests/audit_ws_f.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -263,3 +263,79 @@ fn inline_formatting_tags_still_flatten_into_the_parent_text() {
json!("Real bold text")
);
}

// ---------------------------------------------------------------------------
// studio HTML write-back silently deletes everything outside
// <rustmotion> in the author's file.
// ---------------------------------------------------------------------------

#[test]
fn write_back_preserves_doctype_head_and_surrounding_comments() {
let html = concat!(
"<!DOCTYPE html>\n",
"<html><head><meta charset=\"utf-8\"></head><body>\n",
"<!-- authored by hand -->\n",
"<rustmotion width=\"100\" height=\"100\"><scene duration=\"2\">",
"<h1 style=\"font-size:96\">Hi</h1></scene></rustmotion>\n",
"<!-- trailing note -->\n",
"</body></html>\n",
);
let out = rustmotion_html::set_inline_style(html, "/scenes/0/children/0", "font-size", "120")
.expect("pointer resolves");
assert!(
out.contains("<!DOCTYPE html>"),
"doctype must survive: {out}"
);
assert!(
out.contains("<meta charset=\"utf-8\">"),
"head must survive: {out}"
);
assert!(
out.contains("<!-- authored by hand -->"),
"leading comment must survive: {out}"
);
assert!(
out.contains("<!-- trailing note -->"),
"trailing comment must survive: {out}"
);
assert!(
out.contains("font-size:120"),
"the edit itself must still apply: {out}"
);
let v = html_to_scenario_value(&out).expect("round-trips through the transpiler");
assert_eq!(
v["scenes"][0]["children"][0]["style"]["font-size"],
json!(120)
);
}

#[test]
fn write_back_via_set_text_content_also_preserves_surrounding_document() {
let html = concat!(
"<!DOCTYPE html>\n",
"<!-- keep me -->\n",
"<rustmotion width=\"100\" height=\"100\"><scene duration=\"2\">",
"<h1>Hi</h1></scene></rustmotion>\n",
"<!-- keep me too -->\n",
);
let out = rustmotion_html::set_text_content(html, "/scenes/0/children/0", "Bonjour")
.expect("pointer resolves");
assert!(
out.contains("<!DOCTYPE html>"),
"doctype must survive: {out}"
);
assert!(out.contains("<!-- keep me -->"), "got: {out}");
assert!(out.contains("<!-- keep me too -->"), "got: {out}");
let v = html_to_scenario_value(&out).expect("round-trips through the transpiler");
assert_eq!(v["scenes"][0]["children"][0]["content"], json!("Bonjour"));
}

#[test]
fn write_back_refuses_when_the_closing_tag_cannot_be_located_in_source() {
let html = r##"<rustmotion width="100" height="100"><scene duration="2"><h1 style="font-size:96">Hi</h1></scene>"##;
let out = rustmotion_html::set_inline_style(html, "/scenes/0/children/0", "font-size", "120");
assert!(
out.is_none(),
"must refuse rather than write a file it cannot faithfully reconstruct"
);
}
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