repl: align preview with the actual executed code

This adds preview output for input that may not be wrapped.

PR-URL: #32154
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/repl/utils.js

@@ -136,6 +136,8 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
   let previewCompletionCounter = 0;
   let completionPreview = null;
 
+  let wrapped = false;
+
   function getPreviewPos() {
     const displayPos = repl._getDisplayPos(`${repl._prompt}${repl.line}`);
     const cursorPos = repl.line.length !== repl.cursor ?
@@ -244,8 +246,9 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
   function getInputPreview(input, callback) {
     // For similar reasons as `defaultEval`, wrap expressions starting with a
     // curly brace with parenthesis.
-    if (input.startsWith('{') && !input.endsWith(';')) {
+    if (input.startsWith('{') && !input.endsWith(';') && !wrapped) {
       input = `(${input})`;
+      wrapped = true;
     }
     sendInspectorCommand((session) => {
       session.post('Runtime.evaluate', {
@@ -329,13 +332,19 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
       return;
     }
 
-    getInputPreview(line, (error, inspected) => {
+    const inputPreviewCallback = (error, inspected) => {
+      if (inspected === null) {
+        return;
+      }
+
+      wrapped = false;
+
       // Ignore the output if the value is identical to the current line and the
       // former preview is not identical to this preview.
-      if ((line === inspected && lastInputPreview !== inspected) ||
-          inspected === null) {
+      if (line === inspected && lastInputPreview !== inspected) {
         return;
       }
+
       if (error) {
         debug('Error while generating preview', error);
         return;
@@ -386,7 +395,13 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
       repl.output.write(`\n${result}`);
       cursorTo(repl.output, cursorPos.cols);
       moveCursor(repl.output, 0, -rows - 1);
-    });
+    };
+
+    getInputPreview(line, inputPreviewCallback);
+    if (wrapped) {
+      getInputPreview(line, inputPreviewCallback);
+    }
+    wrapped = false;
   };
 
   // -------------------------------------------------------------------------//

test/parallel/test-repl-preview.js

@@ -125,7 +125,13 @@ async function tests(options) {
      '\x1B[90m{ a: true }\x1B[39m\x1B[20G\x1B[1A\x1B[1B\x1B[2K\x1B[1A;',
      '\x1B[90mtrue\x1B[39m\x1B[21G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33mtrue\x1B[39m',
-     '\x1B[1G\x1B[0Jrepl > \x1B[8G']
+     '\x1B[1G\x1B[0Jrepl > \x1B[8G'],
+    ['{};1', [2, 4], '\x1B[33m1\x1B[39m',
+     '{};1',
+     '\x1B[90m1\x1B[39m\x1B[12G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
+     '\x1B[33m1\x1B[39m',
+     '\x1B[1G\x1B[0Jrepl > \x1B[8G'
+    ]
   ];
 
   const hasPreview = repl.terminal &&

test/parallel/test-repl.js

@@ -457,6 +457,28 @@ const errorTests = [
       /'thefourtheye'/
     ]
   },
+  // Check for wrapped objects.
+  {
+    send: '{ a: 1 }.a', // ({ a: 1 }.a);
+    expect: '1'
+  },
+  {
+    send: '{ a: 1 }.a;', // { a: 1 }.a;
+    expect: [
+      kSource,
+      kArrow,
+      '',
+      /^Uncaught SyntaxError: /
+    ]
+  },
+  {
+    send: '{ a: 1 }["a"] === 1', // ({ a: 1 }['a'] === 1);
+    expect: 'true'
+  },
+  {
+    send: '{ a: 1 }["a"] === 1;', // { a: 1 }; ['a'] === 1;
+    expect: 'false'
+  },
   // Empty lines in the REPL should be allowed
   {
     send: '\n\r\n\r\n',