fix: \sout in text mode (#4173)

Co-authored-by: Erik Demaine <edemaine@mit.edu>

Author: ronkok

contrib/render-a11y-string/test/render-a11y-string-spec.ts

@@ -143,9 +143,9 @@ describe("renderA11yString", () => {
         });
 
         test("\\sout", () => {
-            const result = renderA11yString("\\sout{a}");
+            const result = renderA11yString("\\text{\\sout{a}}");
             expect(result).toMatchInlineSnapshot(
-                `"start strikeout, a, end strikeout"`,
+                `"start text, start strikeout, a, end strikeout, end text"`,
             );
         });
     });

docs/support_table.md

@@ -989,7 +989,7 @@ use `\ce` instead|
 |\smash|$\left(x^{\smash{2}}\right)$|`\left(x^{\smash{2}}\right)`|
 |\smile|$\smile$||
 |\smiley|<span style="color:firebrick;">Not supported</span>||
-|\sout|$\sout{abc}$|`\sout{abc}`|
+|\sout|$\text{\sout{abc}}$|`\text{\sout{abc}}`|
 |\Space|<span style="color:firebrick;">Not supported</span>|see `\space`
 |\space|$a\space b$|`a\space b`|
 |\spades|$\spades$||

docs/supported.md

@@ -237,7 +237,7 @@ Any character can be written with the `\char` function and the Unicode code in h
 |$\cancel{5}$ `\cancel{5}`|$\overbrace{a+b+c}^{\text{note}}$ `\overbrace{a+b+c}^{\text{note}}`
 |$\bcancel{5}$ `\bcancel{5}` |$\underbrace{a+b+c}_{\text{note}}$ `\underbrace{a+b+c}_{\text{note}}`
 |$\xcancel{ABC}$ `\xcancel{ABC}`|$\not =$ `\not =`
-|$\sout{abc}$ `\sout{abc}`|$\boxed{\pi=\frac c d}$ `\boxed{\pi=\frac c d}`
+|$\text{\sout{abc}}$ `\text{\sout{abc}}`|$\boxed{\pi=\frac c d}$ `\boxed{\pi=\frac c d}`
 |$a_{\angl n}$ `$a_{\angl n}`|$a_\angln$ `a_\angln`
 |$\phase{-78^\circ}$`\phase{-78^\circ}` |
 

src/functions/enclose.ts

@@ -286,7 +286,7 @@ defineFunction({
 
 defineFunction({
     type: "enclose",
-    names: ["\\cancel", "\\bcancel", "\\xcancel", "\\sout", "\\phase"],
+    names: ["\\cancel", "\\bcancel", "\\xcancel", "\\phase"],
     props: {
         numArgs: 1,
     },
@@ -303,6 +303,30 @@ defineFunction({
     mathmlBuilder,
 });
 
+defineFunction({
+    type: "enclose",
+    names: ["\\sout"],
+    props: {
+        numArgs: 1,
+        allowedInText: true,
+    },
+    handler({parser, funcName}, args) {
+        if (parser.mode === "math") {
+            parser.settings.reportNonstrict("mathVsSout",
+                `LaTeX's \\sout works only in text mode`);
+        }
+        const body = args[0];
+        return {
+            type: "enclose",
+            mode: parser.mode,
+            label: funcName,
+            body,
+        };
+    },
+    htmlBuilder,
+    mathmlBuilder,
+});
+
 defineFunction({
     type: "enclose",
     names: ["\\angl"],

test/katex-spec.ts

@@ -2773,10 +2773,11 @@ describe("A strike-through builder", function() {
         expect`\cancel{x}^2`.toBuild();
         expect`\cancel{x}_2`.toBuild();
         expect`\cancel{x}_2^2`.toBuild();
-        expect`\sout{x}`.toBuild();
-        expect`\sout{x}^2`.toBuild();
-        expect`\sout{x}_2`.toBuild();
-        expect`\sout{x}_2^2`.toBuild();
+        expect`\sout{x}`.toBuild(nonstrictSettings);
+        expect`\sout{x}^2`.toBuild(nonstrictSettings);
+        expect`\sout{x}_2`.toBuild(nonstrictSettings);
+        expect`\sout{x}_2^2`.toBuild(nonstrictSettings);
+        expect`\text{\sout{abc}}`.toBuild();
     });
 
     it("should produce mords", function() {
@@ -2788,6 +2789,16 @@ describe("A strike-through builder", function() {
     });
 });
 
+describe("A \\sout parser", function() {
+    it("should work in text mode", function() {
+        expect`\text{\sout{abc}}`.toParse();
+    });
+
+    it("should fail in math mode with strict settings", function() {
+        expect`\sout{x}`.not.toParse(strictSettings);
+    });
+});
+
 describe("A actuarial angle parser", function() {
     it("should not fail in math mode", function() {
         expect`a_{\angl{n}}`.toParse();