From e873370e16943dbbadb70222e272eff6c7c7da33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=BAnar=20Berg?= <runarberg@zoho.com>
Date: Thu, 13 Mar 2025 07:43:49 -0700
Subject: [PATCH] Ease restrictions on when infix base becomes double pipe
 fenced

fixes #142
---
 demo/test-cases.html                  |   1 +
 src/compiler/parser/handlers/infix.js |   9 +++++----
 test/snapshots/sub-supscripts.js.md   |   6 ++++++
 test/snapshots/sub-supscripts.js.snap | Bin 800 -> 842 bytes
 test/sub-supscripts.js                |   4 ++++
 5 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/demo/test-cases.html b/demo/test-cases.html
index 67a25c3..4348358 100644
--- a/demo/test-cases.html
+++ b/demo/test-cases.html
@@ -283,6 +283,7 @@ <h2>Super and Subscripts</h2>
         <test-case display="block">(X^T)_ i.,j = X_ j.,i</test-case>
         <test-case display="block">||bf a||^2</test-case>
         <test-case display="block">|bf b|_i</test-case>
+        <test-case display="block">||a*b||^2</test-case>
 
         <test-case display="block">
           ln x = int_1^x 1/t dt
diff --git a/src/compiler/parser/handlers/infix.js b/src/compiler/parser/handlers/infix.js
index dc23403..8a5cccb 100644
--- a/src/compiler/parser/handlers/infix.js
+++ b/src/compiler/parser/handlers/infix.js
@@ -210,15 +210,16 @@ function rightAssociate(op, [left, right]) {
  * @returns {boolean}
  */
 function isPipeDelimited(nodes) {
-  if (nodes.length !== 3) {
+  if (nodes.length < 3) {
     return false;
   }
 
-  const [open, , close] = nodes;
+  const open = nodes.at(0);
+  const close = nodes.at(-1);
 
   return (
-    open.type === "OperatorLiteral" &&
-    close.type === "OperatorLiteral" &&
+    open?.type === "OperatorLiteral" &&
+    close?.type === "OperatorLiteral" &&
     (open.value === "|" || open.value === "∥" || open.value === "‖") &&
     open.value === close.value
   );
diff --git a/test/snapshots/sub-supscripts.js.md b/test/snapshots/sub-supscripts.js.md
index 81db9b3..6f94c99 100644
--- a/test/snapshots/sub-supscripts.js.md
+++ b/test/snapshots/sub-supscripts.js.md
@@ -99,3 +99,9 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 1
 
     '<math><msub><mrow><mo>|</mo><mi>𝐛</mi><mo>|</mo></mrow><mi>i</mi></msub></math>'
+
+## Norm of the dot product square
+
+> Snapshot 1
+
+    '<math><msup><mrow><mo>‖</mo><mi>a</mi><mo>·</mo><mi>b</mi><mo>‖</mo></mrow><mn>2</mn></msup></math>'
diff --git a/test/snapshots/sub-supscripts.js.snap b/test/snapshots/sub-supscripts.js.snap
index eea6a892c59436185c65cfd3b3389f8f31c69591..7a1e061c0fcac26ce54e7bb0ddbadfb31391bef2 100644
GIT binary patch
literal 842
zcmV-Q1GW4?RzV<BZeeh9Xm4~Nb~6eC01+Ul6{5vlv|*FN_>2Z~$r=NW$*`dYYxM-D
z2Dxz}YafdU00000000BMmCbI`KoG|h5aP^{185aE@D)P2AR*VN5<(#HQMDB+5^A!x
zH}MvGci9~`sni2S9IAo@6%q$f4+S9(JOFoIfH&ZfC+H&}$M(i+J0#^mF1F+G{D1r3
znc0J`6L9yLdi$9Gg@CBrREYp@Dx@MuxsnP{R52`+&p~Y;cpe74Y8|hgti`|jiQ1|9
zRV&2c+g7L|$F@RhW2+U?(H%|hTFI-{C@xisa!P{8qiYF6i`mz$R>%@9QP3Kk&M&L^
zcftFHpq*P>QB$waRCg)>t}GGe5n0wplp#XFClYy75*H|E|B30`LJ;u2LLe~>DC@;+
zh|3B4@iIlZWuVMW+7HS5v0i$~sZUFjl#nwaO|gmwXDSvE8=UZ$@gEtw3o|)cf+#O%
z_O$tA)A#87vd^QyLyQ9gNid+!+FA!;qif3ba@WAQnc*a&V-{`?cfMJzkeeteVxHqt
znWNqA#MRPiZ>2oWB+qB3+5MW*<VHu1Ce6o;d>u0%M_s~PGT#6hk%m2dv#V2Tp<>AE
zB&4O0w0O<~wYUjB?r}*lL*NrGNmzFNeV*;utJ<vdD&+R%6f_HUCWp=!Lfu)Wpm=~m
z(m~uRObM<?iT+9bj)8xpZuVuR!xsuHtGa(y#?xPvzq@FfUa&so$PKVk^NpAw5>3iB
zsG?3lnu-W4F>u+ihudHD?yeUKCPB`7<rsXK;QGG`7Av&kj9c*uVi+Qc0~GKcmK6Mo
zqWNvO{!14PEg*FxHaZ}h)FTWUcEGgP1KmWq^=9QV-1)A%d@d=F@h9Wa6Luwb3qg<t
zrSGy5kV@cqFRwN1!~MNIZ3<MhZR$pUk@w>xkav;LchKi$Kh})~e`@xSuJNhQ<!&%9
z`QBK59$`shB8(W96`SN4P>)Th)E0aA;)Ay0aR1%M@o39lRF3{44%}lN86-3z?lB4x
zl-qT+V<0V6Hmkjr2l}LewkFQJic|LNLoUP7cKHN(9FUOQi(EizWLueR!yxmgn>9WJ
Ue*VyZI!Cqd4?ieAYtIS*0O;V6f&c&j

literal 800
zcmV+*1K<2XRzV<BZeeh9Xm4~Nb~6eC00JjGcJ*s(;hQ9pLg`@Wg~oje;FT9@qU5sa
zJFZ0?kROW(00000000BMmCtL`KorM!74huRgD|Wf{I#z2B1k$?5K&MpZIKnE-AOXL
znVQVRnHP5pJy`Kjs)$AKp!85hJov}>A9&cmpnrm7lg!Q}S-X00FUc}5@B5kWy!Ym?
z?}oyArrv#_z#ydR4pVVRwiHr{t31hKP)u<Wt3ZI-IrM!3r0bk)oNlDQ=BdV+<~1iG
z5MU=#iHn_xVd8WmHhE*&TPIuUOyY8-#88T<{Clm~(&G4r(}{Sd6_>O|XU%Q3|19{x
z62!*l%9?tAwz^vbaCL=ppUSE}VjNKh0hP#Sl6t@d|4&Tkm%>mC6#_|E$oL>-Lqg6t
zk5@U$Z3|^#)_F)VO!e}Ip?+MNtc2VdY06bJI#;ua)ZmQ2ivP&cU7E|u3Pg1~^QSeF
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z{iiM(Rzm70d~!jwnNK;iaLBdSBi%&Cev5J$@BYwTzK|8j^pol6iTaXwr64GR^0lG_
zq>4#;me*VO=wN?en*ud$o4YYw7Q^%k6nzxyHyDblADdQ#Kec;E*Z8sjtKDEf%-&di
zo)Ae>B7(S(HHYL|P>*e>+!j23`B7VObnyPubhH%<wWGg`1NXU4M;T2-2An|x)pqUn
eETom%X2shk&}R*_J#*$6b^IHZ7UiKI3IG6iafA>6

diff --git a/test/sub-supscripts.js b/test/sub-supscripts.js
index 3c276cb..fd4aa4e 100644
--- a/test/sub-supscripts.js
+++ b/test/sub-supscripts.js
@@ -68,3 +68,7 @@ test("Square of a norm", (t) => {
 test("Index of a magnitute", (t) => {
   t.snapshot(render("|bf b|_i"));
 });
+
+test("Norm of the dot product square", (t) => {
+  t.snapshot(render("||a*b||^2"));
+});