fix(generator): escape control characters in generated string literals

packages/ack_generator/CHANGELOG.md

@@ -37,6 +37,12 @@
 * `inference.dart` exports shared type and constraint inference for other
   generators. The class-first generator uses this library.
 
+### Fixed
+
+* Escape line terminators and other control characters in every generated
+  string literal. `@Pattern`, discriminator, and key values containing a
+  newline or carriage return now produce valid Dart source.
+
 ## 1.6.2
 
 ### Changed

packages/ack_generator/lib/src/analyzer/class_model_graph_builder.dart

@@ -14,6 +14,7 @@ import '../json/helper_names.dart';
 import '../models/schema_model_graph.dart';
 import '../inference/schema_inference.dart';
 import 'generated_companion_visibility.dart';
+import '../utils/string_literal.dart';
 
 typedef _ModelOptions = ({
   String? schemaName,
@@ -614,7 +615,7 @@ final class ClassModelGraphBuilder {
         isDiscriminator: isDiscriminator,
       );
       var schema = isDiscriminator && discriminatorValue != null
-          ? '${_ack('Ack')}.literal(${_literal(discriminatorValue)})'
+          ? '${_ack('Ack')}.literal(${dartStringLiteral(discriminatorValue)})'
           : await _fieldSchema(field, futureType: futureType);
       schema = _inference.applyDescription(schema, field);
       schema = _applyPresence(
@@ -1940,14 +1941,6 @@ final class ClassModelGraphBuilder {
     return prefix == null || prefix.isEmpty ? symbol : '$prefix.$symbol';
   }
 
-  String _literal(String value) {
-    final escaped = value
-        .replaceAll(r'\', r'\\')
-        .replaceAll("'", r"\'")
-        .replaceAll(r'$', r'\$');
-    return "'$escaped'";
-  }
-
   AckSchemaId _id(ClassElement element) => AckSchemaId(
     libraryUri: library.element.uri,
     declarationName: element.name!,

packages/ack_generator/lib/src/builders/class_model_emitter.dart

@@ -1,6 +1,7 @@
 import '../json/helper_names.dart';
 import '../models/schema_model_graph.dart';
 import 'data_class_emitter.dart';
+import '../utils/string_literal.dart';
 
 /// Emits class-first schema codecs and top-level JSON/runtime glue.
 final class AckClassModelEmitter {
@@ -106,10 +107,10 @@ final class AckClassModelEmitter {
     for (final entry in node.branches.entries) {
       final branch = nodes[entry.value]!;
       schemaEntries.add(
-        '${_literal(entry.key)}: ${ackClassRawObjectName(branch.className)}',
+        '${dartStringLiteral(entry.key)}: ${ackClassRawObjectName(branch.className)}',
       );
       decodeCases.add(
-        '${_literal(entry.key)} => '
+        '${dartStringLiteral(entry.key)} => '
         '${ackClassFromRuntimeName(branch.className)}(value)',
       );
     }
@@ -146,14 +147,14 @@ final class AckClassModelEmitter {
     output
       ..writeln('''
 final $rawName = ${_ack('Ack')}.discriminated(
-  discriminatorKey: ${_literal(node.discriminatorKey)},
+  discriminatorKey: ${dartStringLiteral(node.discriminatorKey)},
   schemas: {${schemaEntries.join(', ')}},
 );
 
 final $wireName = ${_ack('Ack')}.preserveBoundary($rawName);
 
 final ${metadata.backingName} = $rawName.codec<${node.className}>(
-  decode: (value) => switch (value[${_literal(node.discriminatorKey)}]) {
+  decode: (value) => switch (value[${dartStringLiteral(node.discriminatorKey)}]) {
     ${decodeCases.join(',\n    ')},
     final unknown => throw StateError(
       'Unknown ${node.discriminatorKey}: \$unknown',
@@ -253,9 +254,9 @@ abstract final class ${metadata.facadeName} {
       if (node.discriminatorKey case final key?)
         if (node.discriminatorValue case final value?)
           if (!node.fields.any((field) => field.jsonKey == key))
-            '${_literal(key)}: ${_ack('Ack')}.literal(${_literal(value)}).optional()',
+            '${dartStringLiteral(key)}: ${_ack('Ack')}.literal(${dartStringLiteral(value)}).optional()',
       for (final field in node.fields)
-        '${_literal(field.jsonKey)}: ${field.schemaExpression}',
+        '${dartStringLiteral(field.jsonKey)}: ${field.schemaExpression}',
     ];
     final additional = node.allowsUnknownProperties
         ? ', additionalProperties: true'
@@ -279,7 +280,7 @@ ${node.className} $function(Map<String, Object?> value) {
   const declared = ${_keySet(declared)};
   return $helper(<String, dynamic>{
     ...value,
-    ${_literal(captureJsonKey)}: Map<String, Object?>.fromEntries(
+    ${dartStringLiteral(captureJsonKey)}: Map<String, Object?>.fromEntries(
       value.entries.where((entry) => !declared.contains(entry.key)),
     ),
   });
@@ -313,10 +314,10 @@ Map<String, Object?> $function(${node.className} model) =>
       ..add('final result = <String, Object?>{...$jsonHelper(model)};')
       ..addAll([
         if (captureJsonKey != null)
-          'result.remove(${_literal(captureJsonKey)});',
+          'result.remove(${dartStringLiteral(captureJsonKey)});',
         for (final field in requiredNulls)
           'if (model.${field.dartName} == null) { '
-              'result[${_literal(field.jsonKey)}] = null; }',
+              'result[${dartStringLiteral(field.jsonKey)}] = null; }',
       ]);
 
     final entries = <String>[
@@ -325,7 +326,7 @@ Map<String, Object?> $function(${node.className} model) =>
             '    if (!declared.contains(entry.key)) entry.key: entry.value',
       '...result',
       if (discriminatorKey != null && discriminatorValue != null)
-        '${_literal(discriminatorKey)}: ${_literal(discriminatorValue)}',
+        '${dartStringLiteral(discriminatorKey)}: ${dartStringLiteral(discriminatorValue)}',
     ];
     lines.add('return <String, Object?>{${entries.join(',\n  ')}};');
     return '''
@@ -456,7 +457,7 @@ Map<String, Object?> $function(${node.className} model) {
   };
 
   String _keySet(Set<String> keys) =>
-      '<String>{${keys.map(_literal).join(', ')}}';
+      '<String>{${keys.map(dartStringLiteral).join(', ')}}';
 
   AckClassModelMetadata _metadata(AckModelGraph graph, AckModelNode node) {
     final metadata = graph.classMetadataFor(node.id);
@@ -470,12 +471,4 @@ Map<String, Object?> $function(${node.className} model) {
     final prefix = ackPrefix;
     return prefix == null || prefix.isEmpty ? symbol : '$prefix.$symbol';
   }
-
-  String _literal(String value) {
-    final escaped = value
-        .replaceAll(r'\', r'\\')
-        .replaceAll("'", r"\'")
-        .replaceAll(r'$', r'\$');
-    return "'$escaped'";
-  }
 }

packages/ack_generator/lib/src/builders/model_emitter.dart

@@ -3,6 +3,7 @@ import 'package:code_builder/code_builder.dart';
 import '../json/helper_names.dart';
 import '../models/schema_model_graph.dart';
 import 'data_class_emitter.dart';
+import '../utils/string_literal.dart';
 
 /// Emits immutable model declarations solely from a normalized model graph.
 final class AckModelEmitter {
@@ -172,7 +173,7 @@ final class AckModelEmitter {
     for (final entry in node.branches.entries) {
       final branch = nodes[entry.value]!;
       cases.add(
-        '${_literal(entry.key)} => ${branch.className}._fromAckRuntime(value)',
+        '${dartStringLiteral(entry.key)} => ${branch.className}._fromAckRuntime(value)',
       );
     }
     return Class(
@@ -223,7 +224,7 @@ final class AckModelEmitter {
                 ),
               )
               ..body = Code('''
-return switch (value[${_literal(node.discriminatorKey)}]) {
+return switch (value[${dartStringLiteral(node.discriminatorKey)}]) {
   ${cases.join(',\n  ')},
   final unknown => throw StateError(
     'Unknown ${node.discriminatorKey}: \$unknown',
@@ -255,7 +256,7 @@ return switch (value[${_literal(node.discriminatorKey)}]) {
           if (node.additionalProperties) _additionalPropertiesField(),
           _adapter(
             node,
-            '${union.id.declarationName}.effectiveBranch(${_literal(value)})',
+            '${union.id.declarationName}.effectiveBranch(${dartStringLiteral(value)})',
           ),
           if (_exposesSchemaShorthand(
             declarationName: union.id.declarationName,
@@ -278,7 +279,7 @@ return switch (value[${_literal(node.discriminatorKey)}]) {
               ..name = discriminator
               ..returns = refer('String')
               ..lambda = true
-              ..body = Code(_literal(value)),
+              ..body = Code(dartStringLiteral(value)),
           ),
           ..._valueMembers(node.className, _objectDataClass(node)),
           _objectFromRuntime(
@@ -289,7 +290,7 @@ return switch (value[${_literal(node.discriminatorKey)}]) {
           _objectToRuntime(
             node,
             fields: fields,
-            leadingEntries: {discriminator: _literal(value)},
+            leadingEntries: {discriminator: dartStringLiteral(value)},
             isOverride: true,
           ),
           ..._fieldBridges(fields),
@@ -765,7 +766,7 @@ return $helper(<String, dynamic>{
       if (!needsBlock) {
         final entries = <String>[
           for (final entry in leadingEntries.entries)
-            '${_literal(entry.key)}: ${entry.value}',
+            '${dartStringLiteral(entry.key)}: ${entry.value}',
           '...$helper(this)',
         ];
         m
@@ -782,7 +783,7 @@ return $helper(<String, dynamic>{
       for (final field in requiredNulls) {
         lines.add(
           'if (${field.dartName} == null) {'
-          ' result[${_literal(field.jsonKey)}] = null;'
+          ' result[${dartStringLiteral(field.jsonKey)}] = null;'
           ' }',
         );
       }
@@ -791,7 +792,7 @@ return $helper(<String, dynamic>{
           'for (final entry in additionalProperties.entries)\n'
               '    if (!declared.contains(entry.key)) entry.key: entry.value',
         for (final entry in leadingEntries.entries)
-          '${_literal(entry.key)}: ${entry.value}',
+          '${dartStringLiteral(entry.key)}: ${entry.value}',
         '...result',
       ];
       lines.add(
@@ -1022,7 +1023,7 @@ return $helper(<String, dynamic>{
   }) => {...additionalKeys, for (final field in fields) field.jsonKey};
 
   String _declaredKeysLiteral(Set<String> keys) =>
-      '<String>{${keys.map(_literal).join(', ')}}';
+      '<String>{${keys.map(dartStringLiteral).join(', ')}}';
 
   AckInferRef _nonNullable(AckInferRef type) => switch (type) {
     AckNullableTypeRef(:final inner) => inner,
@@ -1087,14 +1088,6 @@ return $helper(<String, dynamic>{
     return prefix == null || prefix.isEmpty ? symbol : '$prefix.$symbol';
   }
 
-  String _literal(String value) {
-    final escaped = value
-        .replaceAll(r'\', r'\\')
-        .replaceAll("'", r"\'")
-        .replaceAll(r'$', r'\$');
-    return "'$escaped'";
-  }
-
   static const _runtimeMapType = 'Map<String, Object?>';
   static const _runtimeMapLiteral = '<String, Object?>';
   static const _objectJsonType = 'Map<String, dynamic>';

packages/ack_generator/lib/src/inference/schema_inference.dart

@@ -7,6 +7,7 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:source_gen/source_gen.dart';
 
 import '../utils/doc_comment_utils.dart';
+import '../utils/string_literal.dart';
 
 /// Infers Ack schema expressions from resolved Dart types and annotations.
 ///
@@ -185,7 +186,7 @@ final class AckSchemaInference {
       } else if (_pattern.isExactlyType(valueType)) {
         _require(declaration, type, '@Pattern', isString, 'String field');
         output =
-            '$output.matches(${_literal(value.getField('pattern')!.toStringValue()!)})';
+            '$output.matches(${dartStringLiteral(value.getField('pattern')!.toStringValue()!)})';
       } else if (_email.isExactlyType(valueType)) {
         _require(declaration, type, '@Email', isString, 'String field');
         output = '$output.email()';
@@ -282,7 +283,7 @@ final class AckSchemaInference {
     );
     return description == null
         ? schema
-        : '$schema.describe(${_literal(description)})';
+        : '$schema.describe(${dartStringLiteral(description)})';
   }
 
   String? _scalar(InterfaceType type) {
@@ -319,14 +320,6 @@ final class AckSchemaInference {
     return (number.toIntValue() ?? number.toDoubleValue())!.toString();
   }
 
-  String _literal(String value) {
-    final escaped = value
-        .replaceAll(r'\', r'\\')
-        .replaceAll("'", r"\'")
-        .replaceAll(r'$', r'\$');
-    return "'$escaped'";
-  }
-
   void _require(
     Element declaration,
     DartType type,

packages/ack_generator/lib/src/utils/string_literal.dart

@@ -0,0 +1,16 @@
+/// Returns [value] as a single-quoted Dart string literal.
+///
+/// Escapes backslashes, quotes, and `$`, and writes control characters and
+/// Unicode line separators as `\uXXXX`, so generated source stays valid and
+/// keeps the original string value.
+String dartStringLiteral(String value) {
+  final escaped = value
+      .replaceAll(r'\', r'\\')
+      .replaceAll("'", r"\'")
+      .replaceAll(r'$', r'\$')
+      .replaceAllMapped(RegExp(r'[\x00-\x1f

]'), (match) {
+        final hex = match[0]!.codeUnitAt(0).toRadixString(16).padLeft(4, '0');
+        return '\\u$hex';
+      });
+  return "'$escaped'";
+}