feat(math): implement m:bar overbar/underbar converter by Muhammad-Nur-Alamsyah-Anwar · Pull Request #2619 · superdoc-dev/superdoc

Muhammad-Nur-Alamsyah-Anwar · 2026-03-28T06:25:12Z

Implemented the m:bar (overbar/underbar) OMML → MathML converter.

OMML: m:bar → m:barPr (pos: top/bot) + m:e
MathML: <mover> (top) or <munder> (bottom) with stretchy <mo>

Added converters/bar.ts with proper Unicode (U+203E overline, U+0332 low line)
Registered in MATH_OBJECT_REGISTRY
Added 3 unit tests in omml-to-mathml.test.ts (overbar, underbar, default)
Follows existing patterns (see fraction.ts)

Fixes #2610.

Closes superdoc-dev#2610 - Add convertBar() in converters/bar.ts: - Reads m:barPr/m:pos@m:val to determine position - 'top' (default) → <mover> with U+203E (overline) - 'bot' → <munder> with U+0332 (combining low line) - stretchy='true' so the bar stretches over the base expression - Register 'm:bar': convertBar in MATH_OBJECT_REGISTRY - Export convertBar from converters/index.ts - Add 3 unit tests: overbar, underbar, missing barPr fallback

Copilot

Pull request overview

Implements support for converting OMML m:bar (overbar/underbar) nodes into MathML, extending the OMML→MathML converter’s registry-based coverage.

Changes:

Added a new convertBar converter (m:bar → <mover>/<munder> with a stretchy <mo>).
Registered m:bar in the math object registry and re-exported the converter.
Added unit tests covering overbar, underbar, and default behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.ts	Registers `m:bar` converter in the OMML→MathML registry.
packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.test.ts	Adds unit tests for `m:bar` conversion behavior.
packages/layout-engine/painters/dom/src/features/math/converters/index.ts	Exports the new `convertBar` converter.
packages/layout-engine/painters/dom/src/features/math/converters/bar.ts	Implements `m:bar` → MathML conversion logic.

Copilot · 2026-03-28T06:27:53Z

packages/layout-engine/painters/dom/src/features/math/converters/bar.ts

+  const barPr = elements.find((e) => e.name === 'm:barPr');
+  const pos = barPr?.elements?.find((e) => e.name === 'm:pos');
+  const posVal = pos?.attributes?.['m:val'];
+  const isUnder = posVal === 'bot';
+


m:bar default position appears to be inverted. The implementation defaults to <mover> when m:barPr/m:pos is missing (since isUnder is only true for m:val === 'bot'), but the spec/issue description indicates 'bot' is the default. Consider treating missing/unknown m:pos@m:val as underbar and only using overbar when m:val === 'top', and update the doc comment accordingly.

@Muhammad-Nur-Alamsyah-Anwar this is right — we tested in Word, default is underbar.

Copilot · 2026-03-28T06:27:54Z

packages/layout-engine/painters/dom/src/features/math/converters/bar.ts

+  const base = elements.find((e) => e.name === 'm:e');
+
+  const wrapper = doc.createElementNS(MATHML_NS, isUnder ? 'munder' : 'mover');
+  wrapper.appendChild(convertChildren(base?.elements ?? []));


wrapper.appendChild(convertChildren(base?.elements ?? [])) can expand to multiple nodes (e.g., x+1 becomes <mi/><mo/><mn/>), which would make <mover>/<munder> have more than two children and produce invalid MathML. Consider converting the m:e container itself (so it can wrap multiple children into a single <mrow>), or otherwise ensure the base is a single node before appending the accent.

Suggested change

wrapper.appendChild(convertChildren(base?.elements ?? []));

// Convert the m:e container itself so that the base becomes a single MathML node.

wrapper.appendChild(convertChildren(base ? [base] : []));

@Muhammad-Nur-Alamsyah-Anwar correct — bar breaks on multi-letter expressions. see our review comment.

packages/layout-engine/painters/dom/src/features/math/converters/bar.ts

Copilot · 2026-03-28T06:27:54Z

packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.test.ts

+  it('defaults to overbar when m:barPr is missing', () => {
+    const omml = {
+      name: 'm:oMath',
+      elements: [{
+        name: 'm:bar',
+        elements: [
+          { name: 'm:e', elements: [{ name: 'm:r', elements: [{ name: 'm:t', elements: [{ type: 'text', text: 'z' }] }] }] },
+        ],
+      }],
+    };
+    const result = convertOmmlToMathml(omml, doc);
+    expect(result).not.toBeNull();
+    const mover = result!.querySelector('mover');
+    expect(mover).not.toBeNull();
+  });


This test asserts the default behavior is an overbar (<mover>) when m:barPr is missing, but the issue/PR description states 'bot' is the default (i.e., <munder>). Update the expectation (and the converter) so the default matches the intended OMML behavior.

@Muhammad-Nur-Alamsyah-Anwar yes, test expectation needs to flip to underbar.

packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.test.ts

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chatgpt-codex-connector · 2026-03-28T06:27:58Z

packages/layout-engine/painters/dom/src/features/math/converters/bar.ts

+  const base = elements.find((e) => e.name === 'm:e');
+
+  const wrapper = doc.createElementNS(MATHML_NS, isUnder ? 'munder' : 'mover');
+  wrapper.appendChild(convertChildren(base?.elements ?? []));


Wrap m:bar base in one node before adding accent

mover/munder are 2-argument MathML elements (base + script), but this line appends the converted children of m:e as a fragment, so expressions like x+1 under a bar become multiple base siblings plus the accent. In that case the bar is applied incorrectly (typically only to the first child) or the MathML tree is invalid for consumers. Wrap the converted base in a single container (e.g., <mrow>) before appending the accent so the bar applies to the full expression.

Useful? React with 👍 / 👎.

same as #2 — covered in our review.

caio-pizzol

@Muhammad-Nur-Alamsyah-Anwar nice contribution! two things to fix: the default position should be underbar (verified against Word), and bars over multi-part expressions (like x + y) need the base grouped so the bar stretches across. left inline comments.

packages/layout-engine/painters/dom/src/features/math/converters/bar.ts

packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.ts

packages/layout-engine/painters/dom/src/features/math/omml-to-mathml.test.ts

- Default to munder (underbar) when no position is specified, matching Word's rendering behavior (posVal !== 'top') - Wrap base content in <mrow> to correctly group multi-token expressions like 'x + y' as a single MathML child - Move m:bar entry from 'Not yet implemented' to 'Implemented' section in the registry - Strengthen tests: assert base content text and <mo> character for all three cases (top, bot, default)

caio-pizzol

@Muhammad-Nur-Alamsyah-Anwar all four points from last round are fixed — default position, mrow wrapping, registry section, and test assertions. lgtm, approving.

superdoc-bot · 2026-03-28T11:54:15Z

🎉 This PR is included in vscode-ext v1.1.0-next.36

superdoc-bot · 2026-03-28T11:55:32Z

🎉 This PR is included in superdoc v1.24.0-next.35

The release is available on GitHub release

superdoc-bot · 2026-03-28T11:56:01Z

🎉 This PR is included in superdoc-cli v0.5.0-next.35

The release is available on GitHub release

superdoc-bot · 2026-03-28T11:57:43Z

🎉 This PR is included in superdoc-sdk v1.3.0-next.35

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Muhammad-Nur-Alamsyah-Anwar force-pushed the feat/math-m-bar-converter branch from a89b98c to 7ab09f9 Compare March 28, 2026 10:20

Merge branch 'main' into feat/math-m-bar-converter

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Merge branch 'main' into feat/math-m-bar-converter

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caio-pizzol enabled auto-merge (squash) March 28, 2026 11:46

caio-pizzol merged commit db0853d into superdoc-dev:main Mar 28, 2026
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caio-pizzol mentioned this pull request Mar 28, 2026

fix(math): use U+2015 for underbar accent instead of U+0332 (SD-2403) #2621

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Muhammad-Nur-Alamsyah-Anwar deleted the feat/math-m-bar-converter branch March 29, 2026 02:54

	wrapper.appendChild(convertChildren(base?.elements ?? []));
	// Convert the m:e container itself so that the base becomes a single MathML node.
	wrapper.appendChild(convertChildren(base ? [base] : []));

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