Smarter splitting around named collection arguments.

lib/src/source_visitor.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library dart_style.src.source_visitor;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 
@@ skipping 819 matching lines @@
         if (param != node.parameters.last) token(param.endToken.next);
 
         if (param != requiredParams.last) rule.beforeArgument(split());
       }
 
       builder.endSpan();
       builder.endRule();
     }
 
     if (optionalParams.isNotEmpty) {
-      var namedRule = new NamedRule();
+      var namedRule = new NamedRule(null, 0, 0);
       if (rule != null) rule.setNamedArgsRule(namedRule);
 
       _metadataRules.last.bindNamedRule(namedRule);
 
       builder.startRule(namedRule);
 
       // Make sure multi-line default values are indented.
       builder.startBlockArgumentNesting();
 
-      namedRule
-          .beforeArguments(builder.split(space: requiredParams.isNotEmpty));
+      namedRule.beforeArgument(builder.split(space: requiredParams.isNotEmpty));
 
       // "[" or "{" for optional parameters.
       token(node.leftDelimiter);
 
       for (var param in optionalParams) {
         visit(param);
 
         // Write the trailing comma.
         if (param != node.parameters.last) token(param.endToken.next);
-        if (param != optionalParams.last) split();
+        if (param != optionalParams.last) namedRule.beforeArgument(split());
       }
 
       builder.endBlockArgumentNesting();
       builder.endRule();
 
       // "]" or "}" for optional parameters.
       token(node.rightDelimiter);
     }
 
     _metadataRules.removeLast();
@@ skipping 325 matching lines @@
       return;
     }
 
     new CallChainVisitor(this, node).visit();
   }
 
   visitNamedExpression(NamedExpression node) {
     builder.nestExpression();
     builder.startSpan();
     visit(node.name);
-    visit(node.expression, before: soloSplit);
+
+    // Don't allow a split between a name and a collection. Instead, we want
+    // the collection itself to split, or to split before the argument.
+    if (node.expression is ListLiteral || node.expression is MapLiteral) {
+      space();
+    } else {
+      soloSplit();
+    }
+
+    visit(node.expression);
     builder.endSpan();
     builder.unnest();
   }
 
   visitNativeClause(NativeClause node) {
     token(node.nativeKeyword);
     space();
     visit(node.name);
   }
 
@@ skipping 1114 matching lines @@
   /// Gets the 1-based line number that the beginning of [token] lies on.
   int _startLine(Token token) => _lineInfo.getLocation(token.offset).lineNumber;
 
   /// Gets the 1-based line number that the end of [token] lies on.
   int _endLine(Token token) => _lineInfo.getLocation(token.end).lineNumber;
 
   /// Gets the 1-based column number that the beginning of [token] lies on.
   int _startColumn(Token token) =>
       _lineInfo.getLocation(token.offset).columnNumber;
 }