Mustachio: add SimpleRenderer and demote many classes from using full renderers (#2458)

Author: srawlins

lib/src/generator/templates.renderers.dart

@@ -7,7 +7,14 @@ class Renderer {
   /// The type of the context type, specified as the [Context] type argument.
   final Context context;
 
-  const Renderer(this.name, this.context);
+  /// A set of types which are "visible" to Mustache. Mustache rendering has
+  /// access to all of a type's public getters if it is visible to Mustache.
+  ///
+  /// Note that all subtypes and supertypes of a "visible" type are also visible
+  /// to Mustache.
+  final Set<Type> visibleTypes;
+
+  const Renderer(this.name, this.context, {this.visibleTypes = const {}});
 }
 
 /// A container for a type, [T], which is the type of a context object,

lib/src/mustachio/annotations.dart

@@ -20,6 +20,9 @@ abstract class RendererBase<T> {
 
   void write(String text) => buffer.write(text);
 
+  String get contextChainString =>
+      parent == null ? '$T' : '${parent.contextChainString} > $T';
+
   /// Returns the [Property] on this renderer named [name].
   ///
   /// If no property named [name] exists for this renderer, `null` is returned.
@@ -39,19 +42,21 @@ abstract class RendererBase<T> {
     if (property != null) {
       try {
         return property.renderVariable(context, property, [...names.skip(1)]);
-      } on MustachioResolutionError {
+      } on PartialMustachioResolutionError catch (e) {
         // The error thrown by [Property.renderVariable] does not have all of
         // the names required for a decent error. We throw a new error here.
         throw MustachioResolutionError(
-            'Failed to resolve $names as a property chain on any types in the '
-            'current context');
+            "Failed to resolve '${e.name}' on ${e.contextType} while resolving "
+            '${names.skip(1)} as a property chain on any types in the context '
+            "chain: $contextChainString, after first resolving '${names.first}'"
+            'to a property on $T');
       }
     } else if (parent != null) {
       return parent.getFields(names);
     } else {
       throw MustachioResolutionError(
           'Failed to resolve ${names.first} as a property on any types in the '
-          'current context');
+          'context chain: $contextChainString');
     }
   }
 
@@ -117,6 +122,33 @@ abstract class RendererBase<T> {
   }
 }
 
+String renderSimple(Object context, List<MustachioNode> ast,
+    {RendererBase parent}) {
+  var renderer = SimpleRenderer(context, parent);
+  renderer.renderBlock(ast);
+  return renderer.buffer.toString();
+}
+
+class SimpleRenderer extends RendererBase<Object> {
+  SimpleRenderer(Object context, RendererBase<Object> parent)
+      : super(context, parent);
+
+  @override
+  Property<Object> getProperty(String key) => null;
+
+  @override
+  String getFields(List<String> keyParts) {
+    if (keyParts.length == 1 && keyParts.single == '.') {
+      return context.toString();
+    }
+    if (parent != null) {
+      return parent.getFields(keyParts);
+    } else {
+      return 'null';
+    }
+  }
+}
+
 /// An individual property of objects of type [T], including functions for
 /// rendering various types of Mustache nodes.
 class Property<T> {
@@ -156,4 +188,17 @@ class MustachioResolutionError extends Error {
   String message;
 
   MustachioResolutionError([this.message]);
+
+  @override
+  String toString() => 'MustachioResolutionError: $message';
+}
+
+/// An error indicating that a renderer failed to resolve a follow-on name in a
+/// multi-name key.
+class PartialMustachioResolutionError extends Error {
+  String name;
+
+  Type contextType;
+
+  PartialMustachioResolutionError(this.name, this.contextType);
 }

lib/src/mustachio/renderer_base.dart

@@ -13,7 +13,9 @@ class Renderer {
 
   final Context context;
 
-  const Renderer(this.name, this.context);
+  final Set<Type> visibleTypes;
+
+  const Renderer(this.name, this.context, {this.visibleTypes = const {}});
 }
 
 class Context<T> {
@@ -23,7 +25,7 @@ class Context<T> {
 };
 
 const _libraryFrontMatter = '''
-@Renderer(#renderFoo, Context<Foo>())
+@Renderer(#renderFoo, Context<Foo>(), visibleTypes: {Bar})
 library foo;
 import 'package:mustachio/annotations.dart';
 ''';
@@ -137,14 +139,11 @@ class Bar {}
           getValue: (CT_ c) => c.b1,
           renderVariable:
               (CT_ c, Property<CT_> self, List<String> remainingNames) {
-            if (remainingNames.isEmpty) return self.getValue(c).toString();
-            var name = remainingNames.first;
-            if (_Renderer_bool.propertyMap().containsKey(name)) {
-              var nextProperty = _Renderer_bool.propertyMap()[name];
-              return nextProperty.renderVariable(
-                  self.getValue(c), nextProperty, [...remainingNames.skip(1)]);
+            if (remainingNames.isEmpty) {
+              return self.getValue(c).toString();
             } else {
-              throw MustachioResolutionError();
+              throw MustachioResolutionError(
+                  \'Failed to resolve simple renderer use @visibleToMustache\');
             }
           },
           getBool: (CT_ c) => c.b1 == true,
@@ -158,22 +157,19 @@ class Bar {}
           getValue: (CT_ c) => c.l1,
           renderVariable:
               (CT_ c, Property<CT_> self, List<String> remainingNames) {
-            if (remainingNames.isEmpty) return self.getValue(c).toString();
-            var name = remainingNames.first;
-            if (_Renderer_List.propertyMap().containsKey(name)) {
-              var nextProperty = _Renderer_List.propertyMap()[name];
-              return nextProperty.renderVariable(
-                  self.getValue(c), nextProperty, [...remainingNames.skip(1)]);
+            if (remainingNames.isEmpty) {
+              return self.getValue(c).toString();
             } else {
-              throw MustachioResolutionError();
+              throw MustachioResolutionError(
+                  'Failed to resolve simple renderer use @visibleToMustache');
             }
           },
           isEmptyIterable: (CT_ c) => c.l1?.isEmpty ?? true,
           renderIterable:
               (CT_ c, RendererBase<CT_> r, List<MustachioNode> ast) {
             var buffer = StringBuffer();
             for (var e in c.l1) {
-              buffer.write(_render_int(e, ast, parent: r));
+              buffer.write(renderSimple(e, ast, parent: r));
             }
             return buffer.toString();
           },
@@ -187,19 +183,16 @@ class Bar {}
           getValue: (CT_ c) => c.s1,
           renderVariable:
               (CT_ c, Property<CT_> self, List<String> remainingNames) {
-            if (remainingNames.isEmpty) return self.getValue(c).toString();
-            var name = remainingNames.first;
-            if (_Renderer_String.propertyMap().containsKey(name)) {
-              var nextProperty = _Renderer_String.propertyMap()[name];
-              return nextProperty.renderVariable(
-                  self.getValue(c), nextProperty, [...remainingNames.skip(1)]);
+            if (remainingNames.isEmpty) {
+              return self.getValue(c).toString();
             } else {
-              throw MustachioResolutionError();
+              throw MustachioResolutionError(
+                  'Failed to resolve simple renderer use @visibleToMustache');
             }
           },
           isNullValue: (CT_ c) => c.s1 == null,
           renderValue: (CT_ c, RendererBase<CT_> r, List<MustachioNode> ast) {
-            return _render_String(c.s1, ast, parent: r);
+            return renderSimple(c.s1, ast, parent: r);
           },
         ),
 '''));
@@ -276,6 +269,7 @@ import 'package:mustachio/annotations.dart';
   test('builds a renderer for a generic, bounded type', () async {
     await testMustachioBuilder('''
 class Foo<T extends num> {}
+class Bar {}
 ''');
     var renderersLibrary = await resolveGeneratedLibrary(writer);
 
@@ -288,9 +282,6 @@ class Foo<T extends num> {}
     expect(fooRendererClass.typeParameters, hasLength(1));
     var cBound = fooRenderFunction.typeParameters.single.bound;
     expect(cBound.getDisplayString(withNullability: false), equals('num'));
-
-    expect(renderersLibrary.getTopLevelFunction('_render_num'), isNotNull);
-    expect(renderersLibrary.getType('_Renderer_num'), isNotNull);
   });
 
   group('does not generate a renderer', () {
@@ -305,6 +296,7 @@ class Foo {
   void set setter1(Setter s);
   Method method1(Method m);
 }
+class Bar {}
 class Static {}
 class Private {}
 class Setter {}
@@ -332,6 +324,11 @@ class Method {}
       expect(renderersLibrary.getTopLevelFunction('_render_Method'), isNull);
       expect(renderersLibrary.getType('_Renderer_Method'), isNull);
     });
+
+    test('for types not @visibleToMustache', () {
+      expect(renderersLibrary.getTopLevelFunction('_render_String'), isNull);
+      expect(renderersLibrary.getType('_Renderer_String'), isNull);
+    });
   });
 }
 

test/mustachio/builder_test.dart

@@ -1,5 +1,6 @@
 @Renderer(#renderFoo, Context<Foo>())
 @Renderer(#renderBar, Context<Bar>())
+@Renderer(#renderBaz, Context<Baz>())
 library dartdoc.testing.foo;
 
 import 'package:dartdoc/src/mustachio/annotations.dart';
@@ -8,9 +9,14 @@ class Foo {
   String s1;
   bool b1;
   List<int> l1;
+  Baz baz;
 }
 
 class Bar {
   Foo foo;
   String s2;
 }
+
+class Baz {
+  Bar bar;
+}