Support [@pxxxx]{.title} as a way to inject a title of the paper into the citation.

Author: mpark

README.md

@@ -424,6 +424,10 @@ In-text citations look like this: `[@id]`
 
 ![](img/citation.png)
 
+You may also include the title of the paper like `[@P1240R2]{.title}` which generates:
+
+![](img/citetitle.png)
+
 ### References
 
 #### Automatic References

TEST.md

@@ -396,9 +396,12 @@ There are three supported styles of note:
 Automatic references are written as `[@N4762]` and renders as [@N4762].
 Anything in <https://wg21.link/index.yaml> are linked automatically.
 
-  - `N` Papers (e.g., `[@N3887]` [@N3887])
-  - `P` Papers (e.g., `[@P1371R1]` [@P1371R1])
-  - CWG Issues (e.g., `[@CWG1234]` [@CWG1234])
-  - LWG Issues (e.g., `[@LWG1234]` [@LWG1234])
-  - Github Edits (e.g, `[@EDIT1234]` [@EDIT1234])
-  - Standing Documents (e.g., `[@SD6]` [@SD6])
+  - `N` Papers (e.g., `[@N3887]` → [@N3887])
+  - `P` Papers (e.g., `[@P1371R1]` → [@P1371R1])
+  - CWG Issues (e.g., `[@CWG1234]` → [@CWG1234])
+  - LWG Issues (e.g., `[@LWG1234]` → [@LWG1234])
+  - Github Edits (e.g, `[@EDIT1234]` → [@EDIT1234])
+  - Standing Documents (e.g., `[@SD6]` → [@SD6])
+
+You may also write `[@P2996R8]{.title}`{.default} to include the title of the paper,
+and renders as: [@P2996R8]{.title}.

data/csl/wg21.csl

@@ -101,10 +101,14 @@
     <sort>
       <key variable="citation-label"/>
     </sort>
-    <layout prefix="[" suffix="]" delimiter=",">
-      <group delimiter=":">
-        <text variable="citation-label"/>
-        <text variable="locator"/>
+    <layout delimiter=",">
+      <group delimiter=" ">
+        <text variable="citation-label" prefix="[" suffix="]"/>
+        <choose>
+          <if variable="locator">
+            <text macro="title" prefix="(" suffix=")"/>
+          </if>
+        </choose>
       </group>
     </layout>
   </citation>

data/defaults.sh

@@ -17,6 +17,7 @@ self-contained: true
 data-dir: ${DATADIR}
 
 filters:
+  - citetitle.py
   - citeproc
   - wg21.py
 

data/filters/citetitle.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python3
+
+# MPark.WG21
+#
+# Copyright Michael Park, 2025
+#
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+import panflute as pf
+
+"""
+This filter is separate from `wg21.py` because it needs to run before `citeproc`.
+`wg21.py` currently needs to run after `citeproc` due to `citation_link` (may be others too).
+
+The mechanism is a bit convoluted, but basically... `wg21.csl` is the CSL definition
+that determines how references are handled and rendered. The logic there is to optionally
+display the title of the reference if a "locator" is present. I don't currently know of
+another way to inject a cite-specific thing into the citation.
+
+So, for example `[@Pxxxx]` is a citation without a locator, whereas `[@Pxxxx{}]` is
+a citation with a locator. Note the "{}" suffix. This is sufficient to inject the title.
+However, since this syntax is rather unfamiliar and cryptic, we offer `[@Pxxxx]{.title}`
+instead. This filter transforms `[@Pxxxx]{.title}` into `[@Pxxxx{}]`.
+"""
+
+def citetitle(elem, doc):
+    if not (
+        isinstance(elem, pf.Span) and
+        elem.classes == ['title'] and
+        len(elem.content) == 1 and
+        isinstance(elem.content[0], pf.Cite)
+    ):
+        return None
+
+    for citation in elem.content[0].citations:
+        citation.suffix.append(pf.Str('{}'))
+
+    return elem
+
+if __name__ == '__main__':
+    pf.run_filter(citetitle)

generated/TEST.html

@@ -932,23 +932,27 @@ <h1 data-number="7" id="notes"><span class="header-section-number">7</span> Note
 </ul>
 <h1 data-number="8" id="citation"><span class="header-section-number">8</span> Citation<a href="#citation" class="self-link"></a></h1>
 <p>Automatic references are written as <code class="sourceCode cpp"><span class="op">[@</span>N4762<span class="op">]</span></code>
-and renders as <span class="citation" data-cites="N4762">[<a href="https://wg21.link/n4762" role="doc-biblioref">N4762</a>]</span>.
+and renders as <span class="citation" data-cites="N4762"><a href="https://wg21.link/n4762" role="doc-biblioref">[N4762]</a></span>.
 Anything in <a href="https://wg21.link/index.yaml" class="uri">https://wg21.link/index.yaml</a> are linked
 automatically.</p>
 <ul>
 <li><code class="sourceCode cpp">N</code> Papers (e.g., <code class="sourceCode cpp"><span class="op">[@</span>N3887<span class="op">]</span></code>
-<span class="citation" data-cites="N3887">[<a href="https://wg21.link/n3887" role="doc-biblioref">N3887</a>]</span>)</li>
+→ <span class="citation" data-cites="N3887"><a href="https://wg21.link/n3887" role="doc-biblioref">[N3887]</a></span>)</li>
 <li><code class="sourceCode cpp">P</code> Papers (e.g., <code class="sourceCode cpp"><span class="op">[@</span>P1371R1<span class="op">]</span></code>
-<span class="citation" data-cites="P1371R1">[<a href="https://wg21.link/p1371r1" role="doc-biblioref">P1371R1</a>]</span>)</li>
+→ <span class="citation" data-cites="P1371R1"><a href="https://wg21.link/p1371r1" role="doc-biblioref">[P1371R1]</a></span>)</li>
 <li>CWG Issues (e.g., <code class="sourceCode cpp"><span class="op">[@</span>CWG1234<span class="op">]</span></code>
-<span class="citation" data-cites="CWG1234">[<a href="https://wg21.link/cwg1234" role="doc-biblioref">CWG1234</a>]</span>)</li>
+→ <span class="citation" data-cites="CWG1234"><a href="https://wg21.link/cwg1234" role="doc-biblioref">[CWG1234]</a></span>)</li>
 <li>LWG Issues (e.g., <code class="sourceCode cpp"><span class="op">[@</span>LWG1234<span class="op">]</span></code>
-<span class="citation" data-cites="LWG1234">[<a href="https://wg21.link/lwg1234" role="doc-biblioref">LWG1234</a>]</span>)</li>
+→ <span class="citation" data-cites="LWG1234"><a href="https://wg21.link/lwg1234" role="doc-biblioref">[LWG1234]</a></span>)</li>
 <li>Github Edits (e.g, <code class="sourceCode cpp"><span class="op">[@</span>EDIT1234<span class="op">]</span></code>
-<span class="citation" data-cites="EDIT1234">[<a href="https://wg21.link/edit1234" role="doc-biblioref">EDIT1234</a>]</span>)</li>
+→ <span class="citation" data-cites="EDIT1234"><a href="https://wg21.link/edit1234" role="doc-biblioref">[EDIT1234]</a></span>)</li>
 <li>Standing Documents (e.g., <code class="sourceCode cpp"><span class="op">[@</span>SD6<span class="op">]</span></code>
-<span class="citation" data-cites="SD6">[<a href="https://wg21.link/sd6" role="doc-biblioref">SD6</a>]</span>)</li>
+→ <span class="citation" data-cites="SD6"><a href="https://wg21.link/sd6" role="doc-biblioref">[SD6]</a></span>)</li>
 </ul>
+<p>You may also write
+<code class="sourceCode default">[@P2996R8]{.title}</code> to include
+the title of the paper, and renders as: <span class="title"><span class="citation" data-cites="P2996R8"><a href="https://wg21.link/p2996r8" role="doc-biblioref">[P2996R8]
+(Reflection for C++26)</a></span></span>.</p>
 <h1 data-number="9" id="bibliography"><span class="header-section-number">9</span> References<a href="#bibliography" class="self-link"></a></h1>
 <div id="refs" class="references csl-bib-body hanging-indent" data-entry-spacing="1" role="doc-bibliography">
 <div id="ref-CWG1234" class="csl-entry" role="doc-biblioentry">
@@ -973,6 +977,11 @@ <h1 data-number="9" id="bibliography"><span class="header-section-number">9</spa
 [P1371R1] Sergei Murzin, Michael Park, David Sankel, Dan Sarginson.
 2019-06-17. Pattern Matching. <a href="https://wg21.link/p1371r1"><div class="csl-block">https://wg21.link/p1371r1</div></a>
 </div>
+<div id="ref-P2996R8" class="csl-entry" role="doc-biblioentry">
+[P2996R8] Barry Revzin, Wyatt Childers, Peter Dimov, Andrew Sutton,
+Faisal Vali, Daveed Vandevoorde, Dan Katz. 2024-12-17. Reflection for
+C++26. <a href="https://wg21.link/p2996r8"><div class="csl-block">https://wg21.link/p2996r8</div></a>
+</div>
 <div id="ref-SD6" class="csl-entry" role="doc-biblioentry">
 [SD6] SG10 Feature Test Recommendations. <a href="https://wg21.link/sd6"><div class="csl-block">https://wg21.link/sd6</div></a>
 </div>