Adds support for integrating client members via plugins

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/OperationGenerator.java

@@ -112,7 +112,7 @@ public void run() {
                     writer.write("if params == nil { params = &$T{} }", inputSymbol);
                     writer.write("");
 
-                    writer.write("result, metadata, err := c.invokeOperation(ctx, $S, params, optFns, $L)",
+                    writer.write("result, metadata, err := c.invokeOperation(ctx, $S, params, optFns, c.$L)",
                             operationSymbol.getName(), getAddOperationMiddlewareFuncName(operationSymbol));
                     writer.write("if err != nil { return nil, err }");
                     writer.write("");
@@ -151,7 +151,7 @@ private void generateAddOperationMiddleware() {
         Symbol stackSymbol = SymbolUtils.createPointableSymbolBuilder("Stack", SmithyGoDependency.SMITHY_MIDDLEWARE)
                 .build();
 
-        writer.openBlock("func $L(stack $P, options Options) (err error) {", "}",
+        writer.openBlock("func (c *Client) $L(stack $P, options Options) (err error) {", "}",
                 getAddOperationMiddlewareFuncName(operationSymbol), stackSymbol,
                 () -> {
                     generateOperationProtocolMiddlewareAdders();

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/ServiceGenerator.java

@@ -22,6 +22,8 @@
 import java.util.stream.Collectors;
 import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.codegen.core.SymbolProvider;
+import software.amazon.smithy.go.codegen.integration.ClientMember;
+import software.amazon.smithy.go.codegen.integration.ClientMemberResolver;
 import software.amazon.smithy.go.codegen.integration.ConfigField;
 import software.amazon.smithy.go.codegen.integration.ConfigFieldResolver;
 import software.amazon.smithy.go.codegen.integration.GoIntegration;
@@ -82,13 +84,32 @@ public void run() {
                 CodegenUtils.getServiceTitle(service, "the API")));
         writer.openBlock("type $T struct {", "}", serviceSymbol, () -> {
             writer.write("options $L", CONFIG_NAME);
+
+            // Add client members resolved from runtime plugins to the client struct.
+            for (ClientMember clientMember : getAllClientMembers()) {
+                writer.write("");
+                clientMember.getDocumentation().ifPresent(writer::writeDocs);
+                writer.write("$L $P", clientMember.getName(), clientMember.getType());
+            }
         });
 
         generateConstructor(serviceSymbol);
         generateConfig();
         generateClientInvokeOperation();
     }
 
+    private void writeClientMemberResolvers(
+            GoWriter writer,
+            RuntimeClientPlugin plugin,
+            Predicate<ClientMemberResolver> predicate
+    ) {
+        plugin.getClientMemberResolvers().stream().filter(predicate)
+                .forEach(resolver -> {
+                   writer.write("$T(client)", resolver.getResolver());
+                   writer.write("");
+                });
+    }
+
     private void writeConfigFieldResolvers(
             GoWriter writer,
             RuntimeClientPlugin plugin,
@@ -136,6 +157,11 @@ private void generateConstructor(Symbol serviceSymbol) {
                         writer.write("options: options,");
                     }).write("");
 
+                    // Run any client member resolver functions registered by runtime plugins.
+                    for (RuntimeClientPlugin plugin : plugins) {
+                        writeClientMemberResolvers(writer, plugin, resolver -> true);
+                    }
+
                     writer.write("return client");
                 });
     }
@@ -179,7 +205,6 @@ private void generateConfig() {
                                     writer.write("o.$L = v", configField.getName());
                                 });
                             }).write("");
-
                 });
 
         generateApplicationProtocolTypes();
@@ -209,6 +234,21 @@ private List<ConfigField> getAllConfigFields() {
                 .collect(Collectors.toList());
     }
 
+    private List<ClientMember> getAllClientMembers() {
+        List<ClientMember> clientMembers = new ArrayList<>();
+        for (RuntimeClientPlugin runtimeClientPlugin : runtimePlugins) {
+            if (!runtimeClientPlugin.matchesService(model, service)) {
+                continue;
+            }
+
+            clientMembers.addAll(runtimeClientPlugin.getClientMembers());
+        }
+        return clientMembers.stream()
+                .distinct()
+                .sorted(Comparator.comparing(ClientMember::getName))
+                .collect(Collectors.toList());
+    }
+
     private void generateApplicationProtocolConfig() {
         ensureSupportedProtocol();
         writer.writeDocs(

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/ClientMember.java

@@ -0,0 +1,133 @@
+/*
+ * Copyright 2021 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.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.go.codegen.integration;
+
+import java.util.Objects;
+import java.util.Optional;
+import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.utils.SmithyBuilder;
+import software.amazon.smithy.utils.ToSmithyBuilder;
+
+/**
+ * Represents a member field on a client struct.
+ */
+public class ClientMember implements ToSmithyBuilder<ClientMember> {
+    private final String name;
+    private final Symbol type;
+    private final String documentation;
+
+    public ClientMember(Builder builder) {
+        this.name = Objects.requireNonNull(builder.name);
+        this.type = Objects.requireNonNull(builder.type);
+        this.documentation = builder.documentation;
+    }
+
+    /**
+     * @return Returns the name of the client member field.
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * @return Returns the type Symbol for the member field.
+     */
+    public Symbol getType() {
+        return type;
+    }
+
+    /**
+     * @return Gets the optional documentation for the member field.
+     */
+    public Optional<String> getDocumentation() {
+        return Optional.ofNullable(documentation);
+    }
+
+    @Override
+    public SmithyBuilder<ClientMember> toBuilder() {
+        return builder().type(type).name(name).documentation(documentation);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        ClientMember that = (ClientMember) o;
+        return Objects.equals(getName(), that.getName())
+                && Objects.equals(getType(), that.getType())
+                && Objects.equals(getDocumentation(), that.getDocumentation());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getName(), getType(), getDocumentation());
+    }
+
+    /**
+     * Builds a ClientMember.
+     */
+    public static class Builder implements SmithyBuilder<ClientMember> {
+        private String name;
+        private Symbol type;
+        private String documentation;
+
+        @Override
+        public ClientMember build() {
+            return new ClientMember(this);
+        }
+
+        /**
+         * Set the name of the member field on client.
+         *
+         * @param name is the name of the field on the client.
+         * @return Returns the builder.
+         */
+        public Builder name(String name) {
+            this.name = name;
+            return this;
+        }
+
+        /**
+         * Sets the type of the client field.
+         *
+         * @param type A Symbol representing the type of the client field.
+         * @return Returns the builder.
+         */
+        public Builder type(Symbol type) {
+            this.type = type;
+            return this;
+        }
+
+        /**
+         * Sets the documentation for the client field.
+         *
+         * @param documentation The documentation for the client field.
+         * @return Returns the builder.
+         */
+        public Builder documentation(String documentation) {
+            this.documentation = documentation;
+            return this;
+        }
+    }
+}

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/ClientMemberResolver.java

@@ -0,0 +1,79 @@
+/*
+ * 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.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.go.codegen.integration;
+
+import java.util.Objects;
+import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.utils.SmithyBuilder;
+
+/**
+ * Represent symbol that points to a function that operates
+ * on the client member fields during client construction.
+ *
+ * Any configuration that a plugin requires in order to function should be
+ * checked in this function, either setting a default value if possible or
+ * returning an error if not.
+ */
+public final class ClientMemberResolver {
+    private final Symbol resolver;
+
+    private ClientMemberResolver(Builder builder) {
+        resolver = SmithyBuilder.requiredState("resolver", builder.resolver);
+    }
+
+    public Symbol getResolver() {
+        return resolver;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        ClientMemberResolver that = (ClientMemberResolver) o;
+        return resolver.equals(that.resolver);
+    }
+
+    /**
+     * Returns a hash code value for the object.
+     * @return the hash code.
+     */
+    @Override
+    public int hashCode() {
+        return Objects.hash(resolver);
+    }
+
+    public static class Builder implements SmithyBuilder<ClientMemberResolver> {
+        private Symbol resolver;
+
+        public Builder resolver(Symbol resolver) {
+            this.resolver = resolver;
+            return this;
+        }
+
+        @Override
+        public ClientMemberResolver build() {
+            return new ClientMemberResolver(this);
+        }
+    }
+}

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/GoIntegration.java

@@ -153,22 +153,6 @@ default List<ProtocolGenerator> getProtocolGenerators() {
         return Collections.emptyList();
     }
 
-    /**
-     * Adds additional client config interface fields.
-     *
-     * @param settings Settings used to generate.
-     * @param model Model to generate from.
-     * @param symbolProvider Symbol provider used for codegen.
-     * @param writer TypeScript writer to write to.
-     */
-    default void addConfigInterfaceFields(
-            GoSettings settings,
-            Model model,
-            SymbolProvider symbolProvider,
-            GoWriter writer
-    ) {
-        // pass
-    }
 
     /**
      * Processes the finalized model before runtime plugins are consumed and