WIP: snippet generator interface

This adds and makes use of a snippet generator interface that lets
other generators provide examples to be included in the docs.

It's unfortunately more ugly than I'd like, notbably with config.
Generators will essentially have to run much of their generator to
be able to provide an accurate example, so we have to give a fake
plugin context that they can use.

The codegen director will need to be updated to make this more
workable.

This is just a proof of concept meant to show how it might work from
the doc generator side.

Author: JordonPhillips

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/DirectedDocGen.java

@@ -5,6 +5,10 @@
 
 package software.amazon.smithy.docgen.core;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.ServiceLoader;
+import software.amazon.smithy.build.PluginContext;
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.codegen.core.directed.CreateContextDirective;
 import software.amazon.smithy.codegen.core.directed.CreateSymbolProviderDirective;
@@ -19,6 +23,8 @@
 import software.amazon.smithy.codegen.core.directed.GenerateUnionDirective;
 import software.amazon.smithy.docgen.core.generators.OperationGenerator;
 import software.amazon.smithy.docgen.core.generators.ServiceGenerator;
+import software.amazon.smithy.docgen.core.generators.SnippetGenerator;
+import software.amazon.smithy.docgen.core.generators.SnippetGenerator.SnippetComparator;
 import software.amazon.smithy.docgen.core.generators.StructureGenerator;
 import software.amazon.smithy.utils.SmithyUnstableApi;
 
@@ -28,19 +34,39 @@
 @SmithyUnstableApi
 final class DirectedDocGen implements DirectedCodegen<DocGenerationContext, DocSettings, DocIntegration> {
 
+    private final PluginContext pluginContext;
+
+    DirectedDocGen(PluginContext pluginContext) {
+        this.pluginContext = pluginContext;
+    }
+
     @Override
     public SymbolProvider createSymbolProvider(CreateSymbolProviderDirective<DocSettings> directive) {
         return new DocSymbolProvider(directive.model(), directive.settings());
     }
 
     @Override
     public DocGenerationContext createContext(CreateContextDirective<DocSettings, DocIntegration> directive) {
+        var contextGenerator = new MockPluginContextGenerator(
+                pluginContext, directive.settings().snippetGeneratorSettings());
+        var classLoader = pluginContext.getPluginClassLoader().orElse(getClass().getClassLoader());
+
+        List<SnippetGenerator> snippetGenerators = new ArrayList<>();
+        for (SnippetGenerator generator : ServiceLoader.load(SnippetGenerator.class, classLoader)) {
+            var pluginContext = contextGenerator.getStubbedContext(directive.model(), generator.name());
+            if (generator.configure(pluginContext, directive.service())) {
+                snippetGenerators.add(generator);
+            }
+        }
+        snippetGenerators = snippetGenerators.stream().sorted(new SnippetComparator()).toList();
+
         return new DocGenerationContext(
-            directive.model(),
-            directive.settings(),
-            directive.symbolProvider(),
-            directive.fileManifest(),
-            directive.integrations()
+                directive.model(),
+                directive.settings(),
+                directive.symbolProvider(),
+                directive.fileManifest(),
+                directive.integrations(),
+                snippetGenerators
         );
     }
 

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/DocGenerationContext.java

@@ -13,6 +13,7 @@
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.codegen.core.WriterDelegator;
 import software.amazon.smithy.docgen.core.DocSymbolProvider.FileExtensionDecorator;
+import software.amazon.smithy.docgen.core.generators.SnippetGenerator;
 import software.amazon.smithy.docgen.core.writers.DocWriter;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.utils.SmithyUnstableApi;
@@ -30,6 +31,7 @@ public final class DocGenerationContext implements CodegenContext<DocSettings, D
     private final WriterDelegator<DocWriter> writerDelegator;
     private final List<DocIntegration> docIntegrations;
     private final DocFormat docFormat;
+    private final List<SnippetGenerator> snippetGenerators;
 
     /**
      * Constructor.
@@ -39,13 +41,15 @@ public final class DocGenerationContext implements CodegenContext<DocSettings, D
      * @param symbolProvider The symbol provider to use to turn shapes into symbols.
      * @param fileManifest The file manifest to write to.
      * @param docIntegrations A list of integrations to apply during generation.
+     * @param snippetGenerators A list of snippet generators to add snippets to docs.
      */
     public DocGenerationContext(
             Model model,
             DocSettings docSettings,
             SymbolProvider symbolProvider,
             FileManifest fileManifest,
-            List<DocIntegration> docIntegrations
+            List<DocIntegration> docIntegrations,
+            List<SnippetGenerator> snippetGenerators
     ) {
         this.model = model;
         this.docSettings = docSettings;
@@ -74,6 +78,7 @@ public DocGenerationContext(
         this.docFormat = resolvedFormat;
         this.symbolProvider = symbolProvider;
         this.writerDelegator = new WriterDelegator<>(fileManifest, symbolProvider, resolvedFormat.writerFactory());
+        this.snippetGenerators = snippetGenerators;
     }
 
     @Override
@@ -112,4 +117,11 @@ public List<DocIntegration> integrations() {
     public DocFormat docFormat() {
         return this.docFormat;
     }
+
+    /**
+     * @return returns the generators used to add snippets to docs.
+     */
+    public List<SnippetGenerator> snippetGenerators() {
+        return snippetGenerators;
+    }
 }

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/DocSettings.java

@@ -6,6 +6,7 @@
 package software.amazon.smithy.docgen.core;
 
 import java.util.Objects;
+import software.amazon.smithy.model.node.Node;
 import software.amazon.smithy.model.node.ObjectNode;
 import software.amazon.smithy.model.shapes.ShapeId;
 import software.amazon.smithy.utils.SmithyUnstableApi;
@@ -16,9 +17,12 @@
  *
  * @param service The shape id of the service to generate documentation for.
  * @param format The format to generate documentation in. The default is markdown.
+ * @param snippetGeneratorSettings Settings to pass along to snippet generators. By
+ *        default, the settings for the plugin in the current projection will be used,
+ *        if available.
  */
 @SmithyUnstableApi
-public record DocSettings(ShapeId service, String format) {
+public record DocSettings(ShapeId service, String format, ObjectNode snippetGeneratorSettings) {
 
     /**
      * Settings for documentation generation. These can be set in the
@@ -30,6 +34,7 @@ public record DocSettings(ShapeId service, String format) {
     public DocSettings {
         Objects.requireNonNull(service);
         Objects.requireNonNull(format);
+        Objects.requireNonNull(snippetGeneratorSettings);
     }
 
     /**
@@ -41,7 +46,8 @@ public record DocSettings(ShapeId service, String format) {
     public static DocSettings fromNode(ObjectNode pluginSettings) {
         return new DocSettings(
             pluginSettings.expectStringMember("service").expectShapeId(),
-            pluginSettings.getStringMemberOrDefault("format", "sphinx-markdown")
+            pluginSettings.getStringMemberOrDefault("format", "sphinx-markdown"),
+            pluginSettings.getObjectMember("snippetGeneratorSettings").orElse(Node.objectNode())
         );
     }
 }

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/MockPluginContextGenerator.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.docgen.core;
+
+import java.util.Optional;
+import software.amazon.smithy.build.MockManifest;
+import software.amazon.smithy.build.PluginContext;
+import software.amazon.smithy.build.model.ProjectionConfig;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.node.ObjectNode;
+import software.amazon.smithy.utils.SmithyUnstableApi;
+
+/**
+ * Generates mock plugin contexts to pass along to snippet generators.
+ */
+@SmithyUnstableApi
+class MockPluginContextGenerator {
+    private final PluginContext baseContext;
+    private final ObjectNode pluginSettings;
+
+    /**
+     * Constructs a MockPluginContextGenerator.
+     *
+     * @param baseContext The context to base plugin context generation on.
+     * @param pluginSettings Settings specifically given to pass to plugins via the doc generator.
+     */
+    MockPluginContextGenerator(PluginContext baseContext, ObjectNode pluginSettings) {
+        if (baseContext.getProjection().isEmpty()) {
+            // PluginContext will NPE if there's no projection config so you have to do it manually
+            // until that gets fixed.
+            var builder = PluginContext.builder()
+                    .projection(baseContext.getProjectionName(), ProjectionConfig.builder().build())
+                    .model(baseContext.getModel())
+                    .originalModel(baseContext.getOriginalModel().orElse(baseContext.getModel()))
+                    .events(baseContext.getEvents())
+                    .settings(baseContext.getSettings())
+                    .fileManifest(baseContext.getFileManifest())
+                    .sources(baseContext.getSources());
+            baseContext.getPluginClassLoader().ifPresent(builder::pluginClassLoader);
+            baseContext.getOriginalModel().ifPresent(builder::originalModel);
+            baseContext.getArtifactName().ifPresent(builder::artifactName);
+            baseContext = builder.build();
+        }
+        this.baseContext = baseContext;
+        this.pluginSettings = pluginSettings;
+    }
+
+    /**
+     * Create a new plugin context with the given model and plugin name.
+     *
+     * @param model The version of the model to hand to the plugin.
+     * @param pluginName The name of the plugin. This is used to search for existing config.
+     * @return Returns a plugin context with the given model and config for the named plugin.
+     */
+    PluginContext getStubbedContext(Model model, String pluginName) {
+        ObjectNode settings = pluginSettings.getObjectMember(pluginName)
+                .or(() -> baseContext.getProjection()
+                        .map(ProjectionConfig::getPlugins)
+                        .flatMap(plugins -> Optional.ofNullable(plugins.get(pluginName))))
+                .orElse(Node.objectNode());
+
+        return baseContext.toBuilder()
+                .fileManifest(new MockManifest())
+                .artifactName(pluginName)
+                .model(model)
+                .settings(settings)
+                .build();
+    }
+}

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/SmithyDocPlugin.java

@@ -42,7 +42,7 @@ public void execute(PluginContext pluginContext) {
         CodegenDirector<DocWriter, DocIntegration, DocGenerationContext, DocSettings> runner
                 = new CodegenDirector<>();
 
-        runner.directedCodegen(new DirectedDocGen());
+        runner.directedCodegen(new DirectedDocGen(pluginContext));
         runner.integrationClass(DocIntegration.class);
         runner.fileManifest(pluginContext.getFileManifest());
         runner.model(getValidatedModel(pluginContext.getModel()).unwrap());

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/generators/ExampleInputGenerator.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.docgen.core.generators;
+
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.traits.ExamplesTrait.Example;
+
+public class ExampleInputGenerator implements SnippetGenerator {
+    @Override
+    public String name() {
+        return "input";
+    }
+
+    @Override
+    public boolean isWireProtocolGenerator() {
+        return true;
+    }
+
+    @Override
+    public String tabTitle() {
+        return "Input";
+    }
+
+    @Override
+    public String language() {
+        return "json";
+    }
+
+    @Override
+    public String generateShapeSnippet(Shape shape, Node value) {
+        return "";
+    }
+
+    @Override
+    public String generateExampleSnippet(OperationShape operation, Example example) {
+        return Node.prettyPrintJson(example.getInput());
+    }
+}

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/generators/ExampleOutputGenerator.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.docgen.core.generators;
+
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.traits.ExamplesTrait.Example;
+
+public class ExampleOutputGenerator implements SnippetGenerator {
+    @Override
+    public String name() {
+        return "output";
+    }
+
+    @Override
+    public String tabTitle() {
+        return "Output";
+    }
+
+    @Override
+    public String language() {
+        return "json";
+    }
+
+    @Override
+    public String generateShapeSnippet(Shape shape, Node value) {
+        return "";
+    }
+
+    @Override
+    public String generateExampleSnippet(OperationShape operation, Example example) {
+        return Node.prettyPrintJson(example.getOutput().orElse(Node.objectNode()));
+    }
+}

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/generators/OperationGenerator.java

@@ -20,7 +20,6 @@
 import software.amazon.smithy.docgen.core.sections.ShapeSection;
 import software.amazon.smithy.docgen.core.writers.DocWriter;
 import software.amazon.smithy.docgen.core.writers.DocWriter.ListType;
-import software.amazon.smithy.model.node.Node;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.ServiceShape;
 import software.amazon.smithy.model.traits.ExamplesTrait;
@@ -144,17 +143,11 @@ private void writeExamples(
             example.getDocumentation().ifPresent(writer::writeCommonMark);
 
             writer.openTabGroup();
-            // TODO: create example writer interface allow integrations to register them
-
-            // This is just a dummy placehodler tab here to exercise tab creation before
-            // there's an interface for it.
-            writer.openCodeTab("Input", "json");
-            writer.write(Node.prettyPrintJson(example.getInput()));
-            writer.closeCodeTab();
-            writer.openCodeTab("Output", "json");
-            writer.write(Node.prettyPrintJson(example.getOutput().orElse(Node.objectNode())));
-            writer.closeCodeTab();
-
+            for (var snippetGenerator : context.snippetGenerators()) {
+                writer.openCodeTab(snippetGenerator.tabTitle(), snippetGenerator.language());
+                writer.write(snippetGenerator.generateExampleSnippet(operation, example));
+                writer.closeCodeTab();
+            }
             writer.closeTabGroup();
 
             writer.closeHeading();