Fix Dart formatting in JSON strings, standardized strings, etc

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## 0.2.2
 
 * Enable support for `enum` values.
+* Added `asConst` to `JsonLiteral`.
+* Improved the handling of Dart-specific characters in JSON strings.
 
 ## 0.2.1
 

analysis_options.yaml

@@ -35,7 +35,6 @@ linter:
     - only_throw_errors
     - prefer_final_fields
     - prefer_is_not_empty
-    # Waiting for linter 0.1.33 to land in SDK
-    #- prefer_single_quotes
+    - prefer_single_quotes
     - slash_for_doc_comments
     - type_init_formals

lib/src/json_literal.dart

@@ -2,9 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// TODO: option to make the literal a const
 class JsonLiteral {
+  /// The relative path from the Dart file with the annotation to the file
+  /// containing the source JSON.
   final String path;
 
-  const JsonLiteral(this.path);
+  /// `true` if the JSON literal should be written as a constant.
+  final bool asConst;
+
+  const JsonLiteral(this.path, {bool asConst: false})
+      : this.asConst = asConst ?? false;
 }

lib/src/json_literal_generator.dart

@@ -28,14 +28,89 @@ class JsonLiteralGenerator extends GeneratorForAnnotation<JsonLiteral> {
         p.join(sourcePathDir, annotation.read('path').stringValue));
     var content = JSON.decode(await buildStep.readAsString(fileId));
 
-    var thing = JSON.encode(content);
+    var asConst = annotation.read('asConst').boolValue;
 
-    var marked = _isConstType(content) ? 'const' : 'final';
+    var thing = _jsonLiteralAsDart(content, asConst).toString();
+    var marked = asConst ? 'const' : 'final';
 
     return '$marked _\$${element.displayName}JsonLiteral = $thing;';
   }
 }
 
-bool _isConstType(value) {
-  return value == null || value is String || value is num || value is bool;
+/// Returns a [String] representing a valid Dart literal for [value].
+///
+/// If [asConst] is `true`, the returned [String] is encoded as a `const`
+/// literal.
+String _jsonLiteralAsDart(dynamic value, bool asConst) {
+  if (value == null) return 'null';
+
+  if (value is String) return _jsonStringAsDart(value);
+
+  if (value is bool || value is num) return value.toString();
+
+  if (value is List) {
+    var listItems =
+        value.map((v) => _jsonLiteralAsDart(v, asConst)).join(',\n');
+    return '${asConst ? 'const' : ''}[$listItems]';
+  }
+
+  if (value is Map) return _jsonMapAsDart(value, asConst);
+
+  throw new StateError(
+      'Should never get here – with ${value.runtimeType} - `$value`.');
+}
+
+String _jsonMapAsDart(Map value, bool asConst) {
+  var buffer = new StringBuffer();
+  if (asConst) {
+    buffer.write('const ');
+  }
+  buffer.write('{');
+
+  var first = true;
+  value.forEach((String k, v) {
+    if (first) {
+      first = false;
+    } else {
+      buffer.writeln(',');
+    }
+    buffer.write(_jsonStringAsDart(k));
+    buffer.write(':');
+    buffer.write(_jsonLiteralAsDart(v, asConst));
+  });
+
+  buffer.write('}');
+
+  return buffer.toString();
+}
+
+String _jsonStringAsDart(String value) {
+  var containsSingleQuote = value.contains("'");
+  var contains$ = value.contains(r'$');
+
+  if (containsSingleQuote) {
+    if (value.contains('"')) {
+      // `value` contains both single and double quotes as well as `$`.
+      // The only safe way to wrap the content is to escape all of the
+      // problematic characters.
+      var string = value
+          .replaceAll('\$', '\\\$')
+          .replaceAll('"', '\\"')
+          .replaceAll("'", "\\'");
+      return "'$string'";
+    } else if (contains$) {
+      // `value` contains "'" and "$", but not '"'.
+      // Safely wrap it in a raw string within double-quotes.
+      return 'r"$value"';
+    }
+    return '"$value"';
+  } else if (contains$) {
+    // `value` contains "$", but no "'"
+    // wrap it in a raw string using single quotes
+    return "r'$value'";
+  }
+
+  // `value` contains no problematic characters - except for '"' maybe.
+  // Wrap it in standard single-quotes.
+  return "'$value'";
 }

lib/src/json_serializable_generator.dart

@@ -74,7 +74,7 @@ class JsonSerializableGenerator
         fieldsList.where((fe) => fe.type.isUndefined).toList();
     if (undefinedFields.isNotEmpty) {
       var description =
-          undefinedFields.map((fe) => "`${fe.displayName}`").join(', ');
+          undefinedFields.map((fe) => '`${fe.displayName}`').join(', ');
 
       throw new InvalidGenerationSourceError(
           'At least one field has an invalid type: $description.',
@@ -153,13 +153,13 @@ class JsonSerializableGenerator
 
     // TODO(kevmoo) We could write all values up to the null-excluded value
     //   directly in this literal.
-    buffer.writeln("var $toJsonMapVarName = <String, dynamic>{};");
+    buffer.writeln('var $toJsonMapVarName = <String, dynamic>{};');
 
-    buffer.writeln("""void $toJsonMapHelperName(String key, dynamic value) {
+    buffer.writeln('''void $toJsonMapHelperName(String key, dynamic value) {
     if (value != null) {
       $toJsonMapVarName[key] = value;
     }
-    }""");
+    }''');
 
     fields.forEach((fieldName, field) {
       try {
@@ -173,21 +173,21 @@ class JsonSerializableGenerator
         }
 
         if (_includeIfNull(field, includeIfNull)) {
-          buffer.writeln("$toJsonMapVarName[$safeJsonKeyString] = "
-              "${_serialize(field.type, fieldName,  _nullable(field))};");
+          buffer.writeln('$toJsonMapVarName[$safeJsonKeyString] = '
+              '${_serialize(field.type, fieldName,  _nullable(field))};');
         } else {
-          buffer.writeln("$toJsonMapHelperName($safeJsonKeyString, "
-              "${_serialize(field.type, fieldName, _nullable(field))});");
+          buffer.writeln('$toJsonMapHelperName($safeJsonKeyString, '
+              '${_serialize(field.type, fieldName, _nullable(field))});');
         }
       } on UnsupportedTypeError {
         throw new InvalidGenerationSourceError(
-            "Could not generate `toJson` code for `${friendlyNameForElement(
-                field)}`.",
-            todo: "Make sure all of the types are serializable.");
+            'Could not generate `toJson` code for `${friendlyNameForElement(
+                field)}`.',
+            todo: 'Make sure all of the types are serializable.');
       }
     });
 
-    buffer.writeln(r"return $map;");
+    buffer.writeln(r'return $map;');
 
     buffer.writeln('}');
   }
@@ -200,12 +200,11 @@ class JsonSerializableGenerator
     fields.forEach((fieldName, field) {
       try {
         pairs.add("'${_fieldToJsonMapKey(field, fieldName)}': "
-            "${_serialize(field.type, fieldName, _nullable(field))}");
+            '${_serialize(field.type, fieldName, _nullable(field))}');
       } on UnsupportedTypeError {
         throw new InvalidGenerationSourceError(
-            "Could not generate `toJson` code for `${friendlyNameForElement(
-              field)}`.",
-            todo: "Make sure all of the types are serializable.");
+            'Could not generate `toJson` code for `${friendlyNameForElement(field)}`.',
+            todo: 'Make sure all of the types are serializable.');
       }
     });
     buffer.writeAll(pairs, ', ');
@@ -257,7 +256,7 @@ class JsonSerializableGenerator
         .toList();
     if (undefinedArgs.isNotEmpty) {
       var description =
-          undefinedArgs.map((fe) => "`${fe.displayName}`").join(', ');
+          undefinedArgs.map((fe) => '`${fe.displayName}`').join(', ');
 
       throw new InvalidGenerationSourceError(
           'At least one constructor argument has an invalid type: $description.',
@@ -301,7 +300,7 @@ class JsonSerializableGenerator
     } else {
       fieldsToSet.forEach((name, field) {
         buffer.writeln();
-        buffer.write("      ..${name} = ");
+        buffer.write('      ..${name} = ');
         buffer.write(_deserializeForField(name, field));
       });
       buffer.writeln(';');
@@ -331,11 +330,11 @@ class JsonSerializableGenerator
 
     try {
       var safeName = _safeNameAccess(name);
-      return _deserialize(targetType, "json[$safeName]", _nullable(field));
+      return _deserialize(targetType, 'json[$safeName]', _nullable(field));
     } on UnsupportedTypeError {
       throw new InvalidGenerationSourceError(
-          "Could not generate fromJson code for `${friendlyNameForElement(field)}`.",
-          todo: "Make sure all of the types are serializable.");
+          'Could not generate fromJson code for `${friendlyNameForElement(field)}`.',
+          todo: 'Make sure all of the types are serializable.');
     }
   }
 
@@ -369,7 +368,7 @@ JsonKey _jsonKeyFor(FieldElement element) {
   var key = _jsonKeyExpando[element];
 
   if (key == null) {
-    // If an annotation exists on `element` the source is a "real" field.
+    // If an annotation exists on `element` the source is a 'real' field.
     // If the result is `null`, check the getter – it is a property.
     // TODO(kevmoo) setters: github.com/dart-lang/json_serializable/issues/24
     var obj = _jsonKeyChecker.firstAnnotationOfExact(element) ??

lib/src/type_helpers/date_time_helper.dart

@@ -18,7 +18,7 @@ class DateTimeHelper extends TypeHelper {
       buffer.write('?');
     }
 
-    buffer.write(".toIso8601String()");
+    buffer.write('.toIso8601String()');
 
     return buffer.toString();
   }
@@ -30,7 +30,7 @@ class DateTimeHelper extends TypeHelper {
     }
 
     return commonNullPrefix(
-        nullable, expression, "DateTime.parse($expression as String)");
+        nullable, expression, 'DateTime.parse($expression as String)');
   }
 }
 

lib/src/type_helpers/enum_helper.dart

@@ -10,7 +10,7 @@ class EnumHelper extends TypeHelper {
       TypeHelperGenerator serializeNested) {
     if (targetType is InterfaceType && targetType.element.isEnum) {
       return commonNullPrefix(
-          nullable, expression, '$expression.toString().split(".")[1]');
+          nullable, expression, "$expression.toString().split('.')[1]");
     }
 
     return null;

lib/src/type_helpers/iterable_helper.dart

@@ -3,7 +3,7 @@ import 'package:source_gen/source_gen.dart' show TypeChecker;
 import '../type_helper.dart';
 
 /// Name used for closure argument when generating calls to `map`.
-final _closureArg = "e";
+final _closureArg = 'e';
 
 class IterableHelper extends TypeHelper {
   const IterableHelper();
@@ -30,7 +30,7 @@ class IterableHelper extends TypeHelper {
     if (subFieldValue != _closureArg) {
       // TODO: the type could be imported from a library with a prefix!
       expression =
-          "${expression}${optionalQuestion}.map(($_closureArg) => $subFieldValue)";
+          '${expression}${optionalQuestion}.map(($_closureArg) => $subFieldValue)';
 
       // expression now represents an Iterable (even if it started as a List
       // ...resetting `isList` to `false`.
@@ -39,7 +39,7 @@ class IterableHelper extends TypeHelper {
 
     if (!isList) {
       // If the static type is not a List, generate one.
-      expression += "${optionalQuestion}.toList()";
+      expression += '${optionalQuestion}.toList()';
     }
 
     return expression;
@@ -65,10 +65,10 @@ class IterableHelper extends TypeHelper {
     var optionalQuestion = nullable ? '?' : '';
 
     var output =
-        "($expression as List)${optionalQuestion}.map(($_closureArg) => $itemSubVal)";
+        '($expression as List)${optionalQuestion}.map(($_closureArg) => $itemSubVal)';
 
     if (_coreListChecker.isAssignableFromType(targetType)) {
-      output += "${optionalQuestion}.toList()";
+      output += '${optionalQuestion}.toList()';
     }
 
     return output;

lib/src/type_helpers/json_helper.dart

@@ -42,7 +42,7 @@ class JsonHelper extends TypeHelper {
 
     // TODO: the type could be imported from a library with a prefix!
     // github.com/dart-lang/json_serializable/issues/19
-    var result = "new ${targetType.name}.fromJson($expression$asCast)";
+    var result = 'new ${targetType.name}.fromJson($expression$asCast)';
 
     return commonNullPrefix(nullable, expression, result);
   }