Avoid triggering dart-lang/sdk#34775 (#10)

Author: nex3

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 0.2.2
+
+- Avoid triggering https://github.com/dart-lang/sdk/issue/34775.
+
+* Explicitly declare `Repl.exit()`'s type as `FutureOr<void>`.
+
 ## 0.2.1
 
 - Migrate to null-safety

example/example.dart

@@ -8,6 +8,7 @@ main(args) async {
   var repl = new Repl(prompt: '>>> ', continuation: '... ', validator: v);
   await for (var x in repl.runAsync()) {
     if (x.trim().isEmpty) continue;
+    if (x == 'throw;') throw "oh no!";
     print(x);
   }
 }

lib/cli_repl.dart

@@ -1,5 +1,7 @@
 library cli_repl;
 
+import 'dart:async';
+
 import 'src/repl_adapter.dart';
 
 class Repl {
@@ -34,7 +36,7 @@ class Repl {
   Stream<String> runAsync() => _adapter.runAsync();
 
   /// Kills and cleans up the REPL.
-  Future exit() => _adapter.exit();
+  FutureOr<void> exit() => _adapter.exit();
 
   /// History is by line, not by statement.
   ///

lib/src/repl_adapter/interface.dart

@@ -11,5 +11,5 @@ class ReplAdapter {
 
   Stream<String> runAsync() async* {}
 
-  exit() {}
+  FutureOr<void> exit() {}
 }

lib/src/repl_adapter/node.dart

@@ -16,37 +16,52 @@ class ReplAdapter {
 
   ReadlineInterface? rl;
 
-  Stream<String> runAsync() async* {
+  Stream<String> runAsync() {
     var output = stdinIsTTY ? stdout : null;
-    rl = readline.createInterface(
+    var rl = this.rl = readline.createInterface(
         new ReadlineOptions(input: stdin, output: output, prompt: repl.prompt));
-    String statement = "";
-    String prompt = repl.prompt;
-    var controller = new StreamController<String>();
-    var queue = new StreamQueue<String>(controller.stream);
-    rl!.on('line', allowInterop((value) {
-      controller.add(value);
-    }));
-    while (true) {
-      if (stdinIsTTY) stdout.write(prompt);
-      var line = await queue.next;
-      if (!stdinIsTTY) print('$prompt$line');
-      statement += line;
-      if (repl.validator(statement)) {
-        yield statement;
-        statement = "";
-        prompt = repl.prompt;
-        rl!.setPrompt(repl.prompt);
-      } else {
-        statement += '\n';
-        prompt = repl.continuation;
-        rl!.setPrompt(repl.continuation);
-      }
-    }
+    var statement = "";
+    var prompt = repl.prompt;
+
+    late StreamController<String> runController;
+    runController = StreamController<String>(
+        onListen: () async {
+          try {
+            var lineController = StreamController<String>();
+            var lineQueue = StreamQueue<String>(lineController.stream);
+            rl.on('line',
+                allowInterop((value) => lineController.add(value as String)));
+
+            while (true) {
+              if (stdinIsTTY) stdout.write(prompt);
+              var line = await lineQueue.next;
+              if (!stdinIsTTY) print('$prompt$line');
+              statement += line;
+              if (repl.validator(statement)) {
+                runController.add(statement);
+                statement = "";
+                prompt = repl.prompt;
+                rl.setPrompt(repl.prompt);
+              } else {
+                statement += '\n';
+                prompt = repl.continuation;
+                rl.setPrompt(repl.continuation);
+              }
+            }
+          } catch (error, stackTrace) {
+            runController.addError(error, stackTrace);
+            await exit();
+            runController.close();
+          }
+        },
+        onCancel: exit);
+
+    return runController.stream;
   }
 
-  exit() {
+  FutureOr<void> exit() {
     rl?.close();
+    rl = null;
   }
 }
 

lib/src/repl_adapter/vm.dart

@@ -48,39 +48,56 @@ class ReplAdapter {
     }
   }
 
-  Stream<String> runAsync() async* {
+  Stream<String> runAsync() {
     bool interactive = true;
     try {
       stdin.echoMode = false;
       stdin.lineMode = false;
     } on StdinException {
       interactive = false;
     }
-    charQueue = new StreamQueue<int>(stdin.expand((data) => data));
-    while (true) {
-      try {
-        if (!interactive && !(await charQueue!.hasNext)) {
-          break;
-        }
-        var result = await readStatementAsync();
-        if (result == null) {
-          print("");
-          break;
-        }
-        yield result;
-      } on Exception catch (e) {
-        print(e);
-      }
-    }
-    await exit();
+
+    late StreamController<String> controller;
+    controller = StreamController(
+        onListen: () async {
+          try {
+            var charQueue =
+                this.charQueue = StreamQueue<int>(stdin.expand((data) => data));
+            while (true) {
+              if (!interactive && !(await charQueue.hasNext)) {
+                this.charQueue = null;
+                controller.close();
+                return;
+              }
+
+              var result = await _readStatementAsync(charQueue);
+              if (result == null) {
+                print("");
+                break;
+              }
+              controller.add(result);
+            }
+          } catch (error, stackTrace) {
+            controller.addError(error, stackTrace);
+            await exit();
+            controller.close();
+          }
+        },
+        onCancel: exit,
+        sync: true);
+
+    return controller.stream;
   }
 
-  exit() {
+  FutureOr<void> exit() {
     try {
       stdin.lineMode = true;
       stdin.echoMode = true;
     } on StdinException {}
-    return charQueue?.cancel();
+
+    var future = charQueue?.cancel(immediate: true);
+    charQueue = null;
+    return future;
   }
 
   Iterable<String> linesToStatements(Iterable<String> lines) sync* {
@@ -150,15 +167,15 @@ class ReplAdapter {
     }
   }
 
-  Future<String?> readStatementAsync() async {
+  Future<String?> _readStatementAsync(StreamQueue<int> charQueue) async {
     startReadStatement();
     while (true) {
-      int char = await charQueue!.next;
+      int char = await charQueue.next;
       if (char == eof && buffer.isEmpty) return null;
       if (char == escape) {
-        char = await charQueue!.next;
+        char = await charQueue.next;
         if (char == c('[') || char == c('O')) {
-          var ansi = await charQueue!.next;
+          var ansi = await charQueue.next;
           if (!handleAnsi(ansi)) {
             write('^[');
             input(char);

pubspec.yaml

@@ -1,6 +1,6 @@
 name: cli_repl
 description: A simple library for creating CLI REPLs
-version: 0.2.1
+version: 0.2.2
 homepage: https://github.com/jathak/cli_repl
 author: Jen Thakar <[email protected]>
 

test/repl_test.dart

@@ -4,8 +4,8 @@ import 'package:test/test.dart';
 import 'package:test_process/test_process.dart';
 
 main() {
-  testWith(Platform.executable, 'example/example.dart');
-  testWith('node', 'build/example/example.js');
+  group("VM", () => testWith(Platform.executable, 'example/example.dart'));
+  group("Node.js", () => testWith('node', 'build/example/example.js'));
 }
 
 testWith(String executable, String script) {
@@ -36,4 +36,21 @@ testWith(String executable, String script) {
     expect(process.stdout, emitsDone);
     await process.shouldExit(0);
   });
+
+  // This is a regression test to ensure that the reply code doesn't fall prey
+  // to dart-lang/sdk#34775.
+  test('example repl throws an error', () async {
+    if (!await new File(script).exists()) {
+      fail("$script does not exist");
+    }
+
+    var process = await TestProcess.start(executable, [script]);
+    process.stdin.writeln('throw;');
+    expect(process.stdout, emits(">>> throw;"));
+    expect(process.stdout, emitsDone);
+
+    expect(process.stderr, emitsThrough(contains("oh no!")));
+
+    await process.shouldExit(greaterThan(0));
+  });
 }