Remove non-idiomatic ShapeVisitor builder

CHANGELOG.md

@@ -147,6 +147,9 @@ reference lookups. ([#287](https://github.com/awslabs/smithy/pull/287))
 `Pattern` class. ([#315](https://github.com/awslabs/smithy/pull/315))
 * Removed the `Triple` class from `smithy-utils`. ([#313](https://github.com/awslabs/smithy/pull/313))
 * Normalized class names for OpenAPI `SecurityScemeConverter` implementations. ([#291](https://github.com/awslabs/smithy/pull/291))
+* Removed `software.amazon.smithy.model.shapes.Shape#visitor` and
+  `software.amazon.smithy.model.shapes.ShapeVisitor$Builder`. Use
+  `software.amazon.smithy.model.shapes.ShapeVisitor$Default` instead [BC].
 
 #### Deprecation cleanup
 

smithy-linters/src/main/java/software/amazon/smithy/linters/ShouldHaveUsedTimestampValidator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
@@ -16,22 +16,19 @@
 package software.amazon.smithy.linters;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.node.NodeMapper;
-import software.amazon.smithy.model.shapes.FloatShape;
-import software.amazon.smithy.model.shapes.IntegerShape;
-import software.amazon.smithy.model.shapes.LongShape;
 import software.amazon.smithy.model.shapes.MemberShape;
+import software.amazon.smithy.model.shapes.NumberShape;
 import software.amazon.smithy.model.shapes.Shape;
 import software.amazon.smithy.model.shapes.ShapeType;
 import software.amazon.smithy.model.shapes.ShapeVisitor;
-import software.amazon.smithy.model.shapes.ShortShape;
-import software.amazon.smithy.model.shapes.StringShape;
 import software.amazon.smithy.model.shapes.StructureShape;
 import software.amazon.smithy.model.shapes.UnionShape;
 import software.amazon.smithy.model.validation.AbstractValidator;
@@ -111,15 +108,27 @@ private ShouldHaveUsedTimestampValidator(Config config) {
 
     @Override
     public List<ValidationEvent> validate(Model model) {
-        ShapeVisitor<List<ValidationEvent>> visitor = Shape.<List<ValidationEvent>>visitor()
-                .when(StringShape.class, s -> validateSimpleShape(s, patterns))
-                .when(ShortShape.class, s -> validateSimpleShape(s, patterns))
-                .when(IntegerShape.class, s -> validateSimpleShape(s, patterns))
-                .when(LongShape.class, s -> validateSimpleShape(s, patterns))
-                .when(FloatShape.class, s -> validateSimpleShape(s, patterns))
-                .when(StructureShape.class, shape -> validateStructure(shape, model, patterns))
-                .when(UnionShape.class, shape -> validateUnion(shape, model, patterns))
-                .orElse(ListUtils.of());
+        ShapeVisitor<List<ValidationEvent>> visitor = new ShapeVisitor.Default<List<ValidationEvent>>() {
+            @Override
+            protected List<ValidationEvent> getDefault(Shape shape) {
+                if (shape.isStringShape() || shape instanceof NumberShape) {
+                    return validateSimpleShape(shape, patterns);
+                } else {
+                    return Collections.emptyList();
+                }
+            }
+
+            @Override
+            public List<ValidationEvent> structureShape(StructureShape shape) {
+                return validateStructure(shape, model, patterns);
+            }
+
+            @Override
+            public List<ValidationEvent> unionShape(UnionShape shape) {
+                return validateUnion(shape, model, patterns);
+            }
+        };
+
         return model.shapes().flatMap(shape -> shape.accept(visitor).stream()).collect(Collectors.toList());
     }
 

smithy-linters/src/main/java/software/amazon/smithy/linters/StutteredShapeNameValidator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
@@ -15,14 +15,13 @@
 
 package software.amazon.smithy.linters;
 
+import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.shapes.Shape;
-import software.amazon.smithy.model.shapes.ShapeVisitor;
 import software.amazon.smithy.model.shapes.StructureShape;
 import software.amazon.smithy.model.shapes.UnionShape;
 import software.amazon.smithy.model.validation.AbstractValidator;
@@ -43,11 +42,12 @@ public Provider() {
 
     @Override
     public List<ValidationEvent> validate(Model model) {
-        ShapeVisitor<List<ValidationEvent>> visitor = Shape.<List<ValidationEvent>>visitor()
-                .when(UnionShape.class, shape -> validateNames(model, shape, shape.getMemberNames()))
-                .when(StructureShape.class, shape -> validateNames(model, shape, shape.getMemberNames()))
-                .orElseGet(Collections::emptyList);
-        return model.shapes().flatMap(shape -> shape.accept(visitor).stream()).collect(Collectors.toList());
+        List<ValidationEvent> events = new ArrayList<>();
+        model.shapes(StructureShape.class)
+                .forEach(shape -> events.addAll(validateNames(model, shape, shape.getMemberNames())));
+        model.shapes(UnionShape.class)
+                .forEach(shape -> events.addAll(validateNames(model, shape, shape.getMemberNames())));
+        return events;
     }
 
     private List<ValidationEvent> validateNames(Model model, Shape shape, Collection<String> memberNames) {

smithy-model/src/main/java/software/amazon/smithy/model/shapes/Shape.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
@@ -42,6 +42,7 @@
  * compared in the context of a Model that forbids shape ID conflicts.
  */
 public abstract class Shape implements FromSourceLocation, Tagged, ToShapeId, Comparable<Shape> {
+
     private final ShapeId id;
     private final Map<ShapeId, Trait> traits;
     private final transient SourceLocation source;
@@ -115,16 +116,6 @@ public final ShapeType getType() {
      */
     public abstract <R> R accept(ShapeVisitor<R> cases);
 
-    /**
-     * Creates a {@link ShapeVisitor.Builder}.
-     *
-     * @param <R> Return type of the visitor.
-     * @return Shape visitor builder.
-     */
-    public static <R> ShapeVisitor.Builder<R> visitor() {
-        return new ShapeVisitor.Builder<>();
-    }
-
     /**
      * Get the {@link ShapeId} of the shape.
      *

smithy-model/src/main/java/software/amazon/smithy/model/shapes/ShapeVisitor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
@@ -15,20 +15,11 @@
 
 package software.amazon.smithy.model.shapes;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Objects;
-import java.util.function.Function;
-import java.util.function.Supplier;
-import software.amazon.smithy.utils.SmithyBuilder;
-
 /**
  * Shape visitor pattern.
  *
  * @param <R> Return type of the visitor.
  * @see Default
- * @see Shape#visitor()
- * @see Builder
  */
 public interface ShapeVisitor<R> {
 
@@ -76,89 +67,6 @@ public interface ShapeVisitor<R> {
 
     R timestampShape(TimestampShape shape);
 
-    /**
-     * Creates a {@link ShapeVisitor} used to dispatch to functions based
-     * on a model type.
-     *
-     * @param <R> Return value from each case.
-     */
-    final class Builder<R> implements SmithyBuilder<ShapeVisitor<R>> {
-
-        private Map<Class<? extends Shape>, Function<? extends Shape, R>> functions = new HashMap<>();
-        private Function<Shape, R> orElse = shape -> {
-            throw new IllegalStateException("Unexpected shape: " + shape.getClass().getCanonicalName());
-        };
-
-        Builder() {}
-
-        @Override
-        @SuppressWarnings("unchecked")
-        public ShapeVisitor<R> build() {
-            return new Default<R>() {
-                protected R getDefault(Shape shape) {
-                    Function<Shape, R> f = (Function<Shape, R>) functions.get(shape.getClass());
-                    return f != null ? f.apply(shape) : orElse.apply(shape);
-                }
-            };
-        }
-
-        /**
-         * Register a case for unhandled shapes and builds the Cases.
-         *
-         * @param f Function to use for unhandled visitor.
-         * @return Returns the built {@link ShapeVisitor}
-         */
-        public ShapeVisitor<R> orElseGet(Function<Shape, R> f) {
-            orElse = Objects.requireNonNull(f);
-            return build();
-        }
-
-        /**
-         * Register a case for unhandled shapes and builds the Cases.
-         *
-         * @param f Supplier to use for unhandled visitor.
-         * @return Returns the built {@link ShapeVisitor}
-         */
-        public ShapeVisitor<R> orElseGet(Supplier<R> f) {
-            return orElseGet(shape -> f.get());
-        }
-
-        /**
-         * Return a value for all unhandled nodes.
-         *
-         * @param defaultValue Default value to return for unhandled visitor.
-         * @return Returns the built {@link ShapeVisitor}
-         */
-        public ShapeVisitor<R> orElse(R defaultValue) {
-            return orElseGet(shape -> defaultValue);
-        }
-
-        /**
-         * Register a case for unhandled shapes that throws an exception.
-         *
-         * @param e Exception to throw if an unhandled case is encountered.
-         * @return Returns the built {@link ShapeVisitor}
-         */
-        public ShapeVisitor<R> orElseThrow(RuntimeException e) {
-            return orElseGet(shape -> {
-                throw e;
-            });
-        }
-
-        /**
-         * Invoked when a specific shape type is encountered.
-         *
-         * @param type Shape type to handle.
-         * @param f Function that accepts the shape and returns R.
-         * @param <T> The shape type being handled.
-         * @return Returns the visitor builder.
-         */
-        public <T extends Shape> Builder<R> when(Class<T> type, Function<T, R> f) {
-            functions.put(type, Objects.requireNonNull(f));
-            return this;
-        }
-    }
-
     /**
      * Creates {@link ShapeVisitor} that return a value when necessary
      * when visiting shapes.

smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/ReferencesTraitValidator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -87,10 +88,13 @@ private List<ValidationEvent> validateSingleReference(
             ReferencesTrait trait,
             ResourceShape target
     ) {
-        return shape.accept(Shape.<List<ValidationEvent>>visitor()
-                .when(StructureShape.class, s -> validateStructureRef(model, reference, s, trait, target))
-                .when(StringShape.class, s -> validateStringShapeRef(reference, s, trait, target))
-                .orElse(ListUtils.of()));
+        if (shape.asStructureShape().isPresent()) {
+            return validateStructureRef(model, reference, shape.asStructureShape().get(), trait, target);
+        } else if (shape.asStringShape().isPresent()) {
+            return validateStringShapeRef(reference, shape.asStringShape().get(), trait, target);
+        } else {
+            return Collections.emptyList();
+        }
     }
 
     private List<ValidationEvent> validateStringShapeRef(