feat: Easily un-parenthesize selected math

.gitignore

@@ -1,2 +1,6 @@
 /node_modules
 /build
+
+.idea/
+.vscode/
+

src/commands/math/commands.ts

@@ -1325,6 +1325,8 @@ class Bracket extends DelimsNode {
     [L]: { ch: string; ctrlSeq: string };
     [R]: { ch: string; ctrlSeq: string };
   };
+  // Skip mathspeak and instead emit an empty string.
+  skipMathspeak = false;
   constructor(
     side: BracketSide,
     open: string,
@@ -1404,6 +1406,7 @@ class Bracket extends DelimsNode {
     this.checkCursorContextClose(ctx);
   }
   mathspeak(opts?: MathspeakOptions) {
+    if (this.skipMathspeak) return '';
     var open = this.sides[L].ch,
       close = this.sides[R].ch;
     if (open === '|' && close === '|') {
@@ -1454,7 +1457,57 @@ class Bracket extends DelimsNode {
       .removeClass('mq-ghost');
     this.replaceBracket(brackFrag, this.side);
   }
+
+  // Returns true iff handled the insertion.
+  unwrapSelectedBracket(cursor: Cursor) {
+    var seln = this.replacedFragment;
+    if (!seln) return false;
+
+    var inner = seln.getEnd(L);
+    if ( // do we have a matching bracket pair?
+      !(inner instanceof Bracket) ||
+      inner !== seln.getEnd(R) ||
+      inner.sides[L].ch !== this.sides[L].ch ||
+      inner.sides[R].ch !== this.sides[R].ch
+    ) {
+      return false;
+    }
+
+    var innerBlock = inner.getEnd(L);
+    // Nothing to unwrap if the bracket is empty; fall back to wrapping.
+    if (innerBlock.isEmpty()) return false;
+
+    var innerR = innerBlock.getEnd(R) as MQNode;
+
+    // Move the bracket's children to where the selection was
+    // and drop the bracket that was there
+    var children = innerBlock.children();
+    var brackFrag = seln.domFrag();
+    children.disown().adopt(cursor.parent, cursor[L], cursor[R]);
+    children.domFrag().insertBefore(brackFrag);
+    brackFrag.remove();
+
+    cursor.parent.bubble(function (node) {
+      node.reflow();
+      return undefined;
+    });
+    // remove the selection
+    cursor.insRightOf(innerR);
+
+    // Skip the announcement for the otherwise to-be created bracket and
+    // instead announce the unwrapped contents.
+    this.skipMathspeak = true;
+    cursor.controller.aria.queue(
+      children
+        .fold('', function (speech, child) {
+          return speech + ' ' + child.mathspeak();
+        })
+        .trim()
+    );
+    return true;
+  }
   createLeftOf(cursor: Cursor) {
+    if (this.unwrapSelectedBracket(cursor)) return;
     var brack;
     if (!this.replacedFragment) {
       // unless wrapping seln in brackets,

test/unit/typing.test.js

@@ -766,6 +766,45 @@ suite('typing with auto-replaces', function () {
         assertLatex('1+2+3+4');
       });
 
+      test('wrapping a bracketed selection in the same bracket unwraps it', function () {
+        mq.typedText('(ab)');
+        assertLatex('\\left(ab\\right)');
+        mq.keystroke('Shift-Home').typedText('(');
+        assertLatex('ab');
+        // cursor should go after contents
+        // so typing "(" inserts a new bracket
+        mq.typedText('(');
+        assertLatex('ab\\left(\\right)');
+      });
+
+      test('unwrapping only happens when the selection is exactly one bracket', function () {
+        mq.typedText('(a)(b)');
+        assertLatex('\\left(a\\right)\\left(b\\right)');
+        mq.keystroke('Shift-Home').typedText('(');
+        assertLatex('\\left(\\left(a\\right)\\left(b\\right)\\right)');
+      });
+
+      test('unwrapping only happens when the bracket type matches', function () {
+        mq.typedText('(ab)');
+        assertLatex('\\left(ab\\right)');
+        mq.keystroke('Shift-Home').typedText('[');
+        assertLatex('\\left[\\left(ab\\right)\\right]');
+      });
+
+      test('does not unwrap a mismatched bracket', function () {
+        mq.typedText('(ab]');
+        assertLatex('\\left(ab\\right]');
+        mq.keystroke('Shift-Home').typedText('(');
+        assertLatex('\\left(\\left(ab\\right]\\right)');
+      });
+
+      test('wrapping an empty bracket in the same bracket wraps rather than unwraps', function () {
+        mq.typedText('()');
+        assertLatex('\\left(\\right)');
+        mq.keystroke('Shift-Home').typedText('(');
+        assertLatex('\\left(\\left(\\right)\\right)');
+      });
+
       test('backspacing close-bracket of 1+(2+3] (nothing after) then typing', function () {
         mq.typedText('1+(2+3]');
         assertLatex('1+\\left(2+3\\right]');