New Quick Assist - 'Convert to field formal parameter'.

pkg/analysis_server/lib/src/services/correction/assist_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/assist_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
index d9eb0a494c8f0e14e965c2b2656e97ebb63c8054..9c5e9ba5d5bb7fca3270ad7e74d6cbe2b25b335d 100644
--- a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
@@ -87,6 +87,7 @@ class AssistProcessor {
     _addProposal_convertToIsNot_onIs();
     _addProposal_convertToIsNot_onNot();
     _addProposal_convertToIsNotEmpty();
+    _addProposal_convertToFieldParameter();
     _addProposal_convertToNormalParameter();
     _addProposal_encapsulateField();
     _addProposal_exchangeOperands();
@@ -444,6 +445,93 @@ class AssistProcessor {
     _addAssist(DartAssistKind.CONVERT_INTO_EXPRESSION_BODY, []);
   }
 
+  void _addProposal_convertToFieldParameter() {
+    if (node == null) {
+      return;
+    }
+    // prepare ConstructorDeclaration
+    ConstructorDeclaration constructor =
+        node.getAncestor((node) => node is ConstructorDeclaration);
+    if (constructor == null) {
+      return;
+    }
+    FormalParameterList parameterList = constructor.parameters;
+    List<ConstructorInitializer> initializers = constructor.initializers;
+    // prepare parameter
+    SimpleFormalParameter parameter;
+    if (node.parent is SimpleFormalParameter &&
+        node.parent.parent is FormalParameterList &&
+        node.parent.parent.parent is ConstructorDeclaration) {
+      parameter = node.parent;
+    }
+    if (node is SimpleIdentifier &&
+        node.parent is ConstructorFieldInitializer) {
+      String name = (node as SimpleIdentifier).name;
+      ConstructorFieldInitializer initializer = node.parent;
+      if (initializer.expression == node) {
+        for (FormalParameter formalParameter in parameterList.parameters) {
+          if (formalParameter is SimpleFormalParameter &&
+              formalParameter.identifier.name == name) {
+            parameter = formalParameter;
+          }
+        }
+      }
+    }
+    // analyze parameter
+    if (parameter != null) {
+      String parameterName = parameter.identifier.name;
+      ParameterElement parameterElement = parameter.element;
+      // check number of references
+      {
+        int numOfReferences = 0;
+        AstVisitor visitor = new _SimpleIdentifierRecursiveAstVisitor(
+            (SimpleIdentifier node) {
+          if (node.staticElement == parameterElement) {
+            numOfReferences++;
+          }
+        });
+        for (ConstructorInitializer initializer in initializers) {
+          initializer.accept(visitor);
+        }
+        if (numOfReferences != 1) {
+          return;
+        }
+      }
+      // find the field initializer
+      ConstructorFieldInitializer parameterInitializer;
+      for (ConstructorInitializer initializer in initializers) {
+        if (initializer is ConstructorFieldInitializer) {
+          Expression expression = initializer.expression;
+          if (expression is SimpleIdentifier &&
+              expression.name == parameterName) {
+            parameterInitializer = initializer;
+          }
+        }
+      }
+      if (parameterInitializer == null) {
+        return;
+      }
+      String fieldName = parameterInitializer.fieldName.name;
+      // replace parameter
+      _addReplaceEdit(rangeNode(parameter), 'this.$fieldName');
+      // remove initializer
+      int initializerIndex = initializers.indexOf(parameterInitializer);
+      if (initializers.length == 1) {
+        _addRemoveEdit(rangeEndEnd(parameterList, parameterInitializer));
+      } else {
+        if (initializerIndex == 0) {
+          ConstructorInitializer next = initializers[initializerIndex + 1];
+          _addRemoveEdit(rangeStartStart(parameterInitializer, next));
+        } else {
+          ConstructorInitializer prev = initializers[initializerIndex - 1];
+          _addRemoveEdit(rangeEndEnd(prev, parameterInitializer));
+        }
+      }
+      // add proposal
+      _addAssist(DartAssistKind.CONVERT_TO_FIELD_PARAMETER, []);
+    }
+  }
+
   void _addProposal_convertToForIndexLoop() {
     // find enclosing ForEachStatement
     ForEachStatement forEachStatement =