Add assist to convert child: to children: in Flutter new-exprs

pkg/analysis_server/lib/src/services/correction/assist_internal.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 services.src.correction.assist;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/plugin/edit/assist/assist_core.dart';
@@ skipping 103 matching lines @@
     _addProposal_addTypeAnnotation_DeclaredIdentifier();
     _addProposal_addTypeAnnotation_SimpleFormalParameter();
     _addProposal_addTypeAnnotation_VariableDeclaration();
     _addProposal_assignToLocalVariable();
     _addProposal_convertIntoFinalField();
     _addProposal_convertIntoGetter();
     _addProposal_convertDocumentationIntoBlock();
     _addProposal_convertDocumentationIntoLine();
     _addProposal_convertToBlockFunctionBody();
     _addProposal_convertToExpressionFunctionBody();
+    _addProposal_convertFlutterChild();
     _addProposal_convertToForIndexLoop();
     _addProposal_convertToIsNot_onIs();
     _addProposal_convertToIsNot_onNot();
     _addProposal_convertToIsNotEmpty();
     _addProposal_convertToFieldParameter();
     _addProposal_convertToNormalParameter();
     _addProposal_encapsulateField();
     _addProposal_exchangeOperands();
     _addProposal_importAddShow();
     _addProposal_introduceLocalTestedType();
@@ skipping 364 matching lines @@
             }
           }
           _insertBuilder(sb, comment.length);
         }
       }
     }
     // add proposal
     _addAssist(DartAssistKind.CONVERT_DOCUMENTATION_INTO_LINE, []);
   }
 
+  void _addProposal_convertFlutterChild() {
+    NamedExpression namedExp;
+    // Allow assist to activate from either the new-expr or the child: arg.
+    if (node is SimpleIdentifier &&
+        node.parent is Label &&
+        node.parent.parent is NamedExpression) {
+      namedExp = node.parent.parent as NamedExpression;
+      if ((node as SimpleIdentifier).name != 'child' ||
+          namedExp.expression == null) {
+        return;
+      }
+      if (namedExp.parent?.parent is! InstanceCreationExpression) {
+        return;
+      }
+      InstanceCreationExpression newExpr = namedExp.parent.parent;
+      if (newExpr == null || !_isFlutterInstanceCreationExpression(newExpr)) {
+        return;
+      }
+    } else {
+      InstanceCreationExpression newExpr = _identifyNewExpression();
+      if (newExpr == null || !_isFlutterInstanceCreationExpression(newExpr)) {
+        _coverageMarker();
+        return;
+      }
+      namedExp = _findChildArgument(newExpr);
+      if (namedExp == null || namedExp.expression == null) {
+        _coverageMarker();
+        return;
+      }
+    }
+    InstanceCreationExpression childArg = _getChildWidget(namedExp, false);
+    if (childArg == null) {
+      _coverageMarker();
+      return;
+    }
+    int childLoc = namedExp.offset + 'child'.length;
+    _addInsertEdit(childLoc, 'ren');
+    int listLoc = childArg.offset;
+    String childArgSrc = utils.getNodeText(childArg);
+    if (!childArgSrc.contains(eol)) {
+      _addInsertEdit(listLoc, '<Widget>[');
+      _addInsertEdit(listLoc + childArg.length, ']');
+    } else {
+      int newlineLoc = childArgSrc.lastIndexOf(eol);
+      if (newlineLoc == childArgSrc.length) {
+        newlineLoc -= 1;
+      }
+      String indentOld = utils.getLinePrefix(childArg.offset + 1 + newlineLoc);
+      String indentNew = '$indentOld${utils.getIndent(1)}';
+      // The separator includes 'child:' but that has no newlines.
+      String separator =
+          utils.getText(namedExp.offset, childArg.offset - namedExp.offset);
+      String prefix = separator.contains(eol) ? "" : "$eol$indentNew";
+      if (prefix.isEmpty) {
+        _addInsertEdit(namedExp.offset + 'child:'.length, ' <Widget>[');
+        _addRemoveEdit(rangeStartLength(childArg.offset - 2, 2));
+      } else {
+        _addInsertEdit(listLoc, '<Widget>[');
+      }
+      String newChildArgSrc = childArgSrc.replaceAll(
+          new RegExp("^$indentOld", multiLine: true), "$indentNew");
+      newChildArgSrc = "$prefix$newChildArgSrc,$eol$indentOld]";
+      _addReplaceEdit(rangeNode(childArg), newChildArgSrc);
+    }
+    _addAssist(DartAssistKind.CONVERT_FLUTTER_CHILD, []);
+  }
+
   void _addProposal_convertIntoFinalField() {
     // Find the enclosing getter.
     MethodDeclaration getter;
     for (AstNode n = node; n != null; n = n.parent) {
       if (n is MethodDeclaration) {
         getter = n;
         break;
       }
       if (n is SimpleIdentifier ||
           n is TypeAnnotation ||
@@ skipping 1786 matching lines @@
       newExpr.argumentList.arguments.firstWhere(
           (arg) => arg is NamedExpression && arg.name.label.name == 'child',
           orElse: () => null);
 
   InstanceCreationExpression _findChildWidget(
       InstanceCreationExpression newExpr) {
     NamedExpression child = _findChildArgument(newExpr);
     return _getChildWidget(child);
   }
 
-  InstanceCreationExpression _getChildWidget(NamedExpression child) {
+  InstanceCreationExpression _getChildWidget(NamedExpression child,
+      [bool strict = false]) {
     if (child?.expression is InstanceCreationExpression) {
       InstanceCreationExpression childNewExpr = child.expression;
       if (_isFlutterInstanceCreationExpression(childNewExpr)) {
-        if (_findChildArgument(childNewExpr) != null) {
+        if (!strict || (_findChildArgument(childNewExpr) != null)) {
           return childNewExpr;
         }
       }
     }
     return null;
   }
 
   /**
    * Returns an existing or just added [LinkedEditGroup] with [groupId].
    */
@@ skipping 237 matching lines @@
 class _SimpleIdentifierRecursiveAstVisitor extends RecursiveAstVisitor {
   final _SimpleIdentifierVisitor visitor;
 
   _SimpleIdentifierRecursiveAstVisitor(this.visitor);
 
   @override
   visitSimpleIdentifier(SimpleIdentifier node) {
     visitor(node);
   }
 }