From 04a4450341d372d771248d86dd7f9d1f796fb107 Mon Sep 17 00:00:00 2001
From: Alf Eaton <alf.eaton@overleaf.com>
Date: Wed, 4 Oct 2023 16:11:31 +0100
Subject: [PATCH] Avoid auto-closing $ directly before a TeX command (#15039)

GitOrigin-RevId: e620d6b5c82e179c294930801a95fc4c2c77db57
---
 .../languages/latex/close-bracket-config.ts   | 28 +++++++++++++++++--
 .../codemirror-editor-close-brackets.spec.tsx | 12 ++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/services/web/frontend/js/features/source-editor/languages/latex/close-bracket-config.ts b/services/web/frontend/js/features/source-editor/languages/latex/close-bracket-config.ts
index 1c13487ea8..f86bedbafd 100644
--- a/services/web/frontend/js/features/source-editor/languages/latex/close-bracket-config.ts
+++ b/services/web/frontend/js/features/source-editor/languages/latex/close-bracket-config.ts
@@ -1,5 +1,14 @@
-import { EditorState, SelectionRange, Text } from '@codemirror/state'
-import { CloseBracketConfig, prevChar } from '@codemirror/autocomplete'
+import {
+  CharCategory,
+  EditorState,
+  SelectionRange,
+  Text,
+} from '@codemirror/state'
+import {
+  CloseBracketConfig,
+  nextChar,
+  prevChar,
+} from '@codemirror/autocomplete'
 
 export const closeBracketConfig: CloseBracketConfig = {
   brackets: ['$', '$$', '[', '{', '('],
@@ -22,6 +31,21 @@ export const closeBracketConfig: CloseBracketConfig = {
           // don't auto-close \$
           return open
         }
+
+        const next = nextChar(state.doc, range.head)
+        if (next === '\\') {
+          // avoid auto-closing $ before a TeX command
+          const pos = range.head + prev.length
+          const postnext = nextChar(state.doc, pos)
+
+          if (state.charCategorizer(pos)(postnext) !== CharCategory.Word) {
+            return open + '$'
+          }
+
+          // don't auto-close $\command
+          return open
+        }
+
         // avoid creating an odd number of dollar signs
         const count = countSurroundingCharacters(state.doc, range.from, open)
         if (count % 2 !== 0) {
diff --git a/services/web/test/frontend/features/source-editor/components/codemirror-editor-close-brackets.spec.tsx b/services/web/test/frontend/features/source-editor/components/codemirror-editor-close-brackets.spec.tsx
index a9be4d90db..5b4ef5c647 100644
--- a/services/web/test/frontend/features/source-editor/components/codemirror-editor-close-brackets.spec.tsx
+++ b/services/web/test/frontend/features/source-editor/components/codemirror-editor-close-brackets.spec.tsx
@@ -138,6 +138,18 @@ describe('close brackets', { scrollBehavior: false }, function () {
       cy.get('@active-line').should('have.text', '2$')
     })
 
+    it('does not auto-close a dollar sign before a command', function () {
+      cy.get('@active-line').type('\\nu')
+      cy.get('@active-line').type('{leftArrow}{leftArrow}{leftArrow}$')
+      cy.get('@active-line').should('have.text', '$\\nu')
+    })
+
+    it('does auto-close a dollar sign before a newline', function () {
+      cy.get('@active-line').type('\\\\')
+      cy.get('@active-line').type('{leftArrow}{leftArrow}$')
+      cy.get('@active-line').should('have.text', '$$\\\\')
+    })
+
     it('does auto-close a curly bracket before punctuation', function () {
       cy.get('@active-line').type(':2')
       cy.get('@active-line').type('{leftArrow}{leftArrow}{{}')