Format records and record type annotations. (#1158)

* Format records and record type annotations.

In the process of working on this, I discovered that multi-line
function types with trailing commas are pretty busted looking. (I guess
no one puts trailing commas there.) I fixed those too, since they are
structurally similar to record types in many ways.

* Update lib/src/source_visitor.dart

Co-authored-by: Nate Bosch <[email protected]>

Co-authored-by: Nate Bosch <[email protected]>

Author: munificent

CHANGELOG.md

@@ -1,5 +1,7 @@
 # 2.2.5-dev
 
+* Format record expressions and record type annotations.
+* Better indentation of multiline function types inside type argument lists. 
 * Require `package:analyzer` `^5.1.0`.
 * Format unnamed libraries.
 * Require Dart 2.18.

lib/src/argument_list_visitor.dart

@@ -453,13 +453,18 @@ class ArgumentSublist {
 
       // Tell it to use the rule we've already created.
       visitor.beforeBlock(argumentBlock, blockRule, previousSplit);
-    } else if (_allArguments.length > 1) {
+    } else if (_allArguments.length > 1 ||
+        _allArguments.first is RecordLiteral) {
       // Edge case: Only bump the nesting if there are multiple arguments. This
       // lets us avoid spurious indentation in cases like:
       //
       //     function(function(() {
       //       body;
       //     }));
+      //
+      // Do bump the nesting if the single argument is a record because records
+      // are formatted like regular values when they appear in argument lists
+      // even though they internally get block-like formatting.
       visitor.builder.startBlockArgumentNesting();
     } else if (argument is! NamedExpression) {
       // Edge case: Likewise, don't force the argument to split if there is
@@ -478,7 +483,8 @@ class ArgumentSublist {
 
     if (argumentBlock != null) {
       rule.enableSplitOnInnerRules();
-    } else if (_allArguments.length > 1) {
+    } else if (_allArguments.length > 1 ||
+        _allArguments.first is RecordLiteral) {
       visitor.builder.endBlockArgumentNesting();
     } else if (argument is! NamedExpression) {
       rule.enableSplitOnInnerRules();

lib/src/ast_extensions.dart

@@ -100,8 +100,8 @@ extension ExpressionExtensions on Expression {
   ///     ]..addAll(numbers);
   bool get isCollectionLike {
     var expression = this;
-    if (expression is ListLiteral) return false;
-    if (expression is SetOrMapLiteral) return false;
+    if (expression is ListLiteral) return true;
+    if (expression is SetOrMapLiteral) return true;
 
     // If the target is a call with a trailing comma in the argument list,
     // treat it like a collection literal.
@@ -119,7 +119,7 @@ extension ExpressionExtensions on Expression {
     //       element
     //     ])..cascade();
 
-    return arguments == null || !arguments.arguments.hasCommaAfter;
+    return arguments != null && arguments.arguments.hasCommaAfter;
   }
 
   /// Whether this is an argument in an argument list with a trailing comma.

lib/src/dart_formatter.dart

@@ -90,6 +90,7 @@ class DartFormatter {
     var featureSet = FeatureSet.fromEnableFlags2(
       sdkLanguageVersion: Version(2, 19, 0),
       flags: [
+        'records',
         'unnamed-libraries',
       ],
     );

lib/src/line_writer.dart

@@ -180,10 +180,11 @@ class LineWriter {
   void _writeChunksUnsplit(BlockChunk block) {
     for (var chunk in block.children) {
       if (chunk.spaceWhenUnsplit) _buffer.write(' ');
-      _writeChunk(chunk);
 
       // Recurse into the block.
       if (chunk is BlockChunk) _writeChunksUnsplit(chunk);
+
+      _writeChunk(chunk);
     }
   }