Add DartType.getDisplayString()

[email protected], [email protected]

Change-Id: I3849ccb4d2359fddf470b42280e3ea21e38f3664
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127344
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analysis_server/test/analysis/get_hover_test.dart

@@ -54,7 +54,7 @@ class B<T> extends A<T> with M1, M2<int> implements I1<int, String>, I2 {}
     expect(
         hover.elementDescription,
         'class B<T> extends A<T> with M1, M2<int> '
-        'implements I1<int, String>, I2');
+        'implements I1<int, String>, I2<dynamic>');
     expect(hover.staticType, isNull);
     expect(hover.propagatedType, isNull);
   }

pkg/analyzer/lib/dart/element/type.dart

@@ -115,6 +115,20 @@ abstract class DartType {
   /// Return the nullability suffix of this type.
   NullabilitySuffix get nullabilitySuffix;
 
+  /// Return the presentation of this type as it should appear when presented
+  /// to users in contexts such as error messages.
+  ///
+  /// If [withNullability] is `true`, then [NullabilitySuffix.question] and
+  /// [NullabilitySuffix.star] will be be represented as `?` and `*`.
+  /// [NullabilitySuffix.none] does not have any explicit presentation.
+  ///
+  /// If [withNullability] is `false`, nullability suffixes will not be
+  /// included into the presentation.
+  ///
+  /// Clients should not depend on the content of the returned value as it will
+  /// be changed if doing so would improve the UX.
+  String getDisplayString({bool withNullability = false});
+
   /// If this type is a [TypeParameterType], returns its bound if it has one, or
   /// [objectType] otherwise.
   ///

pkg/analyzer/lib/error/listener.dart

@@ -202,7 +202,7 @@ class ErrorReporter {
         if (name != null && name.isNotEmpty) {
           StringBuffer buffer = new StringBuffer();
           buffer.write(name);
-          (type as TypeImpl).appendTo(buffer);
+          (type as TypeImpl).appendTo(buffer, withNullability: false);
           return buffer.toString();
         }
       }

pkg/analyzer/lib/src/dart/element/element.dart

@@ -4610,7 +4610,7 @@ class GenericFunctionTypeElementImpl extends ElementImpl
   void appendTo(StringBuffer buffer) {
     DartType type = returnType;
     if (type is TypeImpl) {
-      type.appendTo(buffer);
+      type.appendTo(buffer, withNullability: false);
       buffer.write(' Function');
     } else {
       buffer.write('Function');

pkg/analyzer/lib/src/dart/element/type.dart

@@ -64,6 +64,11 @@ class DynamicTypeImpl extends TypeImpl {
   @override
   bool operator ==(Object object) => identical(object, this);
 
+  @override
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
+    buffer.write('dynamic');
+  }
+
   @override
   DartType replaceTopAndBottom(TypeProvider typeProvider,
       {bool isCovariant = true}) {
@@ -142,50 +147,6 @@ class FunctionTypeImpl extends TypeImpl implements FunctionType {
   @override
   List<TypeParameterElement> get boundTypeParameters => typeFormals;
 
-  @override
-  String get displayName {
-    if (name == null || name.isEmpty) {
-      // Function types have an empty name when they are defined implicitly by
-      // either a closure or as part of a parameter declaration.
-      StringBuffer buffer = new StringBuffer();
-      appendTo(buffer);
-      if (nullabilitySuffix == NullabilitySuffix.question) {
-        buffer.write('?');
-      }
-      return buffer.toString();
-    }
-
-    List<DartType> typeArguments = this.typeArguments;
-
-    bool allTypeArgumentsAreDynamic() {
-      for (DartType type in typeArguments) {
-        if (type != null && !type.isDynamic) {
-          return false;
-        }
-      }
-      return true;
-    }
-
-    StringBuffer buffer = new StringBuffer();
-    buffer.write(name);
-    // If there is at least one non-dynamic type, then list them out.
-    if (!allTypeArgumentsAreDynamic()) {
-      buffer.write("<");
-      for (int i = 0; i < typeArguments.length; i++) {
-        if (i != 0) {
-          buffer.write(", ");
-        }
-        DartType typeArg = typeArguments[i];
-        buffer.write(typeArg.displayName);
-      }
-      buffer.write(">");
-    }
-    if (nullabilitySuffix == NullabilitySuffix.question) {
-      buffer.write('?');
-    }
-    return buffer.toString();
-  }
-
   @override
   FunctionTypedElement get element {
     var element = super.element;
@@ -294,7 +255,7 @@ class FunctionTypeImpl extends TypeImpl implements FunctionType {
   }
 
   @override
-  void appendTo(StringBuffer buffer, {bool withNullability = false}) {
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
     // TODO(paulberry): eliminate code duplication with
     // _ElementWriter.writeType.  See issue #35818.
     if (typeFormals.isNotEmpty) {
@@ -944,39 +905,6 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
     return _constructors;
   }
 
-  @override
-  String get displayName {
-    List<DartType> typeArguments = this.typeArguments;
-
-    bool allTypeArgumentsAreDynamic() {
-      for (DartType type in typeArguments) {
-        if (type != null && !type.isDynamic) {
-          return false;
-        }
-      }
-      return true;
-    }
-
-    StringBuffer buffer = new StringBuffer();
-    buffer.write(name);
-    // If there is at least one non-dynamic type, then list them out.
-    if (!allTypeArgumentsAreDynamic()) {
-      buffer.write("<");
-      for (int i = 0; i < typeArguments.length; i++) {
-        if (i != 0) {
-          buffer.write(", ");
-        }
-        DartType typeArg = typeArguments[i];
-        buffer.write(typeArg.displayName);
-      }
-      buffer.write(">");
-    }
-    if (nullabilitySuffix == NullabilitySuffix.question) {
-      buffer.write('?');
-    }
-    return buffer.toString();
-  }
-
   @override
   ClassElement get element => super.element;
 
@@ -1175,8 +1103,8 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   }
 
   @override
-  void appendTo(StringBuffer buffer, {bool withNullability = false}) {
-    buffer.write(name);
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
+    buffer.write(element.name);
     int argumentCount = typeArguments.length;
     if (argumentCount > 0) {
       buffer.write("<");
@@ -1902,6 +1830,14 @@ class NeverTypeImpl extends TypeImpl {
   @override
   bool operator ==(Object object) => identical(object, this);
 
+  @override
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
+    buffer.write('Never');
+    if (withNullability) {
+      _appendNullability(buffer);
+    }
+  }
+
   @override
   DartType replaceTopAndBottom(TypeProvider typeProvider,
       {bool isCovariant = true}) {
@@ -1963,7 +1899,9 @@ abstract class TypeImpl implements DartType {
   TypeImpl(this._element, this.name);
 
   @override
-  String get displayName => name;
+  String get displayName {
+    return getDisplayString(withNullability: false);
+  }
 
   @override
   Element get element => _element;
@@ -2028,15 +1966,13 @@ abstract class TypeImpl implements DartType {
   /**
    * Append a textual representation of this type to the given [buffer].
    */
-  void appendTo(StringBuffer buffer, {bool withNullability = false}) {
-    if (name == null) {
-      buffer.write("<unnamed type>");
-    } else {
-      buffer.write(name);
-    }
-    if (withNullability) {
-      _appendNullability(buffer);
-    }
+  void appendTo(StringBuffer buffer, {@required bool withNullability});
+
+  @override
+  String getDisplayString({bool withNullability = false}) {
+    var buffer = StringBuffer();
+    appendTo(buffer, withNullability: withNullability);
+    return buffer.toString();
   }
 
   /// Replaces all covariant occurrences of `dynamic`, `Object`, and `void` with
@@ -2061,9 +1997,7 @@ abstract class TypeImpl implements DartType {
 
   @override
   String toString({bool withNullability = false}) {
-    StringBuffer buffer = new StringBuffer();
-    appendTo(buffer, withNullability: withNullability);
-    return buffer.toString();
+    return getDisplayString(withNullability: withNullability);
   }
 
   /**
@@ -2081,11 +2015,6 @@ abstract class TypeImpl implements DartType {
   TypeImpl withNullability(NullabilitySuffix nullabilitySuffix);
 
   void _appendNullability(StringBuffer buffer) {
-    if (isDynamic || isVoid) {
-      // These types don't have nullability variations, so don't append
-      // anything.
-      return;
-    }
     switch (nullabilitySuffix) {
       case NullabilitySuffix.question:
         buffer.write('?');
@@ -2181,6 +2110,14 @@ class TypeParameterTypeImpl extends TypeImpl implements TypeParameterType {
         other.nullabilitySuffix == nullabilitySuffix;
   }
 
+  @override
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
+    buffer.write(element.name);
+    if (withNullability) {
+      _appendNullability(buffer);
+    }
+  }
+
   @override
   DartType replaceTopAndBottom(TypeProvider typeProvider,
       {bool isCovariant = true}) {
@@ -2319,6 +2256,11 @@ class VoidTypeImpl extends TypeImpl implements VoidType {
   @override
   bool operator ==(Object object) => identical(object, this);
 
+  @override
+  void appendTo(StringBuffer buffer, {@required bool withNullability}) {
+    buffer.write('void');
+  }
+
   @override
   DartType replaceTopAndBottom(TypeProvider typeProvider,
       {bool isCovariant = true}) {