Convert Gson integration to compile-only source set (#1510)

Author: nedtwigg

CHANGES.md

@@ -19,6 +19,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * The default list of type annotations used by `formatAnnotations` has had 8 more annotations from the Checker Framework added [#1494](https://github.com/diffplug/spotless/pull/1494)
 ### Changes
 * Rename `YamlJacksonStep` into `JacksonYamlStep` while normalizing Jackson usage ([#1492](https://github.com/diffplug/spotless/pull/1492))
+* Convert `gson` integration to use a compile-only source set ([#1510](https://github.com/diffplug/spotless/pull/1510)).
 
 ## [2.32.0] - 2023-01-13
 ### Added

lib/build.gradle

@@ -15,7 +15,8 @@ def NEEDS_GLUE = [
 	'flexmark',
 	'diktat',
 	'scalafmt',
-	'jackson'
+	'jackson',
+	'gson'
 ]
 for (glue in NEEDS_GLUE) {
 	sourceSets.register(glue) {
@@ -108,6 +109,8 @@ dependencies {
 
 	// used for markdown formatting
 	flexmarkCompileOnly 'com.vladsch.flexmark:flexmark-all:0.62.2'
+
+	gsonCompileOnly 'com.google.code.gson:gson:2.10.1'
 }
 
 // we'll hold the core lib to a high standard

lib/src/gson/java/com/diffplug/spotless/glue/gson/GsonFormatterFunc.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2023 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 com.diffplug.spotless.glue.gson;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Collections;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.stream.JsonWriter;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.ThrowingEx;
+import com.diffplug.spotless.json.gson.GsonConfig;
+
+public class GsonFormatterFunc implements FormatterFunc {
+
+	private static final String FAILED_TO_PARSE_ERROR_MESSAGE = "Unable to format JSON";
+
+	private final Gson gson;
+	private final GsonConfig gsonConfig;
+	private final String generatedIndent;
+
+	public GsonFormatterFunc(GsonConfig gsonConfig) {
+		GsonBuilder gsonBuilder = new GsonBuilder().serializeNulls();
+		if (!gsonConfig.isEscapeHtml()) {
+			gsonBuilder = gsonBuilder.disableHtmlEscaping();
+		}
+		this.gson = gsonBuilder.create();
+		this.gsonConfig = gsonConfig;
+		this.generatedIndent = generateIndent(gsonConfig.getIndentSpaces());
+	}
+
+	@Override
+	public String apply(String inputString) {
+		String result;
+		if (inputString.isEmpty()) {
+			result = "";
+		} else {
+			JsonElement jsonElement = gson.fromJson(inputString, JsonElement.class);
+			if (jsonElement == null) {
+				throw new AssertionError(FAILED_TO_PARSE_ERROR_MESSAGE);
+			}
+			if (gsonConfig.isSortByKeys() && jsonElement.isJsonObject()) {
+				jsonElement = sortByKeys(jsonElement.getAsJsonObject());
+			}
+			try (StringWriter stringWriter = new StringWriter()) {
+				JsonWriter jsonWriter = new JsonWriter(stringWriter);
+				jsonWriter.setIndent(this.generatedIndent);
+				gson.toJson(jsonElement, jsonWriter);
+				result = stringWriter + "\n";
+			} catch (IOException ioException) {
+				throw ThrowingEx.asRuntime(ioException);
+			}
+		}
+		return result;
+	}
+
+	private JsonElement sortByKeys(JsonObject jsonObject) {
+		JsonObject result = new JsonObject();
+		jsonObject.keySet().stream().sorted()
+				.forEach(key -> {
+					JsonElement element = jsonObject.get(key);
+					if (element.isJsonObject()) {
+						element = sortByKeys(element.getAsJsonObject());
+					}
+					result.add(key, element);
+				});
+		return result;
+	}
+
+	private String generateIndent(int indentSpaces) {
+		return String.join("", Collections.nCopies(indentSpaces, " "));
+	}
+
+}

lib/src/main/java/com/diffplug/spotless/json/gson/GsonBuilderWrapper.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2023 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 com.diffplug.spotless.json.gson;
+
+import java.io.Serializable;
+
+public class GsonConfig implements Serializable {
+	private static final long serialVersionUID = 6039715618937332633L;
+
+	private boolean sortByKeys;
+	private boolean escapeHtml;
+	private int indentSpaces;
+	private String version;
+
+	public GsonConfig(boolean sortByKeys, boolean escapeHtml, int indentSpaces, String version) {
+		this.sortByKeys = sortByKeys;
+		this.escapeHtml = escapeHtml;
+		this.indentSpaces = indentSpaces;
+		this.version = version;
+	}
+
+	public boolean isSortByKeys() {
+		return sortByKeys;
+	}
+
+	public void setSortByKeys(boolean sortByKeys) {
+		this.sortByKeys = sortByKeys;
+	}
+
+	public boolean isEscapeHtml() {
+		return escapeHtml;
+	}
+
+	public void setEscapeHtml(boolean escapeHtml) {
+		this.escapeHtml = escapeHtml;
+	}
+
+	public int getIndentSpaces() {
+		return indentSpaces;
+	}
+
+	public void setIndentSpaces(int indentSpaces) {
+		this.indentSpaces = indentSpaces;
+	}
+
+	public String getVersion() {
+		return version;
+	}
+
+	public void setVersion(String version) {
+		this.version = version;
+	}
+}

lib/src/main/java/com/diffplug/spotless/json/gson/GsonConfig.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 DiffPlug
+ * Copyright 2022-2023 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,8 +17,8 @@
 
 import java.io.IOException;
 import java.io.Serializable;
-import java.io.StringWriter;
-import java.util.Collections;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
 import java.util.Objects;
 
 import com.diffplug.spotless.FormatterFunc;
@@ -28,78 +28,38 @@
 
 public class GsonStep {
 	private static final String MAVEN_COORDINATES = "com.google.code.gson:gson";
+	private static final String INCOMPATIBLE_ERROR_MESSAGE = "There was a problem interacting with Gson; maybe you set an incompatible version?";
 
+	@Deprecated
 	public static FormatterStep create(int indentSpaces, boolean sortByKeys, boolean escapeHtml, String version, Provisioner provisioner) {
+		return create(new GsonConfig(sortByKeys, escapeHtml, indentSpaces, version), provisioner);
+	}
+
+	public static FormatterStep create(GsonConfig gsonConfig, Provisioner provisioner) {
 		Objects.requireNonNull(provisioner, "provisioner cannot be null");
-		return FormatterStep.createLazy("gson", () -> new State(indentSpaces, sortByKeys, escapeHtml, version, provisioner), State::toFormatter);
+		return FormatterStep.createLazy("gson", () -> new State(gsonConfig, provisioner), State::toFormatter);
 	}
 
 	private static final class State implements Serializable {
-		private static final long serialVersionUID = -1493479043249379485L;
+		private static final long serialVersionUID = -3240568265160440420L;
 
-		private final int indentSpaces;
-		private final boolean sortByKeys;
-		private final boolean escapeHtml;
 		private final JarState jarState;
+		private final GsonConfig gsonConfig;
 
-		private State(int indentSpaces, boolean sortByKeys, boolean escapeHtml, String version, Provisioner provisioner) throws IOException {
-			this.indentSpaces = indentSpaces;
-			this.sortByKeys = sortByKeys;
-			this.escapeHtml = escapeHtml;
-			this.jarState = JarState.from(MAVEN_COORDINATES + ":" + version, provisioner);
+		private State(GsonConfig gsonConfig, Provisioner provisioner) throws IOException {
+			this.gsonConfig = gsonConfig;
+			this.jarState = JarState.from(MAVEN_COORDINATES + ":" + gsonConfig.getVersion(), provisioner);
 		}
 
 		FormatterFunc toFormatter() {
-			JsonWriterWrapper jsonWriterWrapper = new JsonWriterWrapper(jarState);
-			JsonElementWrapper jsonElementWrapper = new JsonElementWrapper(jarState);
-			JsonObjectWrapper jsonObjectWrapper = new JsonObjectWrapper(jarState, jsonElementWrapper);
-			GsonBuilderWrapper gsonBuilderWrapper = new GsonBuilderWrapper(jarState);
-			GsonWrapper gsonWrapper = new GsonWrapper(jarState, jsonElementWrapper, jsonWriterWrapper);
-
-			Object gsonBuilder = gsonBuilderWrapper.serializeNulls(gsonBuilderWrapper.createGsonBuilder());
-			if (!escapeHtml) {
-				gsonBuilder = gsonBuilderWrapper.disableHtmlEscaping(gsonBuilder);
+			try {
+				Class<?> formatterFunc = jarState.getClassLoader().loadClass("com.diffplug.spotless.glue.gson.GsonFormatterFunc");
+				Constructor<?> constructor = formatterFunc.getConstructor(GsonConfig.class);
+				return (FormatterFunc) constructor.newInstance(gsonConfig);
+			} catch (ClassNotFoundException | NoSuchMethodException | InvocationTargetException
+					| InstantiationException | IllegalAccessException | NoClassDefFoundError cause) {
+				throw new IllegalStateException(INCOMPATIBLE_ERROR_MESSAGE, cause);
 			}
-			Object gson = gsonBuilderWrapper.create(gsonBuilder);
-
-			return inputString -> {
-				String result;
-				if (inputString.isEmpty()) {
-					result = "";
-				} else {
-					Object jsonElement = gsonWrapper.fromJson(gson, inputString, jsonElementWrapper.getWrappedClass());
-					if (jsonElement == null) {
-						throw new AssertionError(GsonWrapperBase.FAILED_TO_PARSE_ERROR_MESSAGE);
-					}
-					if (sortByKeys && jsonElementWrapper.isJsonObject(jsonElement)) {
-						jsonElement = sortByKeys(jsonObjectWrapper, jsonElementWrapper, jsonElement);
-					}
-					try (StringWriter stringWriter = new StringWriter()) {
-						Object jsonWriter = jsonWriterWrapper.createJsonWriter(stringWriter);
-						jsonWriterWrapper.setIndent(jsonWriter, generateIndent(indentSpaces));
-						gsonWrapper.toJson(gson, jsonElement, jsonWriter);
-						result = stringWriter + "\n";
-					}
-				}
-				return result;
-			};
-		}
-
-		private Object sortByKeys(JsonObjectWrapper jsonObjectWrapper, JsonElementWrapper jsonElementWrapper, Object jsonObject) {
-			Object result = jsonObjectWrapper.createJsonObject();
-			jsonObjectWrapper.keySet(jsonObject).stream().sorted()
-					.forEach(key -> {
-						Object element = jsonObjectWrapper.get(jsonObject, key);
-						if (jsonElementWrapper.isJsonObject(element)) {
-							element = sortByKeys(jsonObjectWrapper, jsonElementWrapper, element);
-						}
-						jsonObjectWrapper.add(result, key, element);
-					});
-			return result;
-		}
-
-		private String generateIndent(int indentSpaces) {
-			return String.join("", Collections.nCopies(indentSpaces, " "));
 		}
 	}