Add JVM-based JSON formatter

CHANGES.md

@@ -11,6 +11,10 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 
 ## [Unreleased]
 
+### Added
+* Added formatter for [JVM-based JSON formatting](https://github.com/diffplug/spotless/issues/850)
+* Added Gradle configuration JVM-based JSON formatting
+
 ## [2.14.0] - 2021-06-10
 ### Added
 * Added support for `eclipse-cdt` at `4.19.0`. Note that version requires Java 11 or higher.

lib/src/main/java/com/diffplug/spotless/json/JsonSimpleStep.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2021 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;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Objects;
+
+import com.diffplug.spotless.FormatterFunc;
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.JarState;
+import com.diffplug.spotless.Provisioner;
+
+/**
+ * Simple JSON formatter which reformats the file according to the org.json library's default pretty-printing, but has no ability to customise more than the indentation size.
+ */
+public final class JsonSimpleStep {
+	private static final String MAVEN_COORDINATE = "org.json:json:";
+	private static final String DEFAULT_VERSION = "20210307";
+
+	public static FormatterStep create(int indent, Provisioner provisioner) {
+		Objects.requireNonNull(provisioner, "provisioner cannot be null");
+		return FormatterStep.createLazy("json", () -> new State(indent, provisioner), State::toFormatter);
+	}
+
+	private static final class State implements Serializable {
+		private static final long serialVersionUID = 1L;
+
+		private final int indentSpaces;
+		private final JarState jarState;
+
+		private State(int indent, Provisioner provisioner) throws IOException {
+			this.indentSpaces = indent;
+			this.jarState = JarState.from(MAVEN_COORDINATE + DEFAULT_VERSION, provisioner);
+		}
+
+		FormatterFunc toFormatter() {
+			Method objectToString;
+			Method arrayToString;
+			Constructor<?> objectConstructor;
+			Constructor<?> arrayConstructor;
+			try {
+				ClassLoader classLoader = jarState.getClassLoader();
+				Class<?> jsonObject = classLoader.loadClass("org.json.JSONObject");
+				Class<?>[] constructorArguments = new Class[]{String.class};
+				objectConstructor = jsonObject.getConstructor(constructorArguments);
+				objectToString = jsonObject.getMethod("toString", int.class);
+
+				Class<?> jsonArray = classLoader.loadClass("org.json.JSONArray");
+				arrayConstructor = jsonArray.getConstructor(constructorArguments);
+				arrayToString = jsonArray.getMethod("toString", int.class);
+			} catch (ClassNotFoundException | NoSuchMethodException e) {
+				throw new IllegalStateException("There was a problem preparing org.json dependencies", e);
+			}
+
+			return s -> {
+				String prettyPrinted = null;
+				if (s.isEmpty()) {
+					prettyPrinted = s;
+				}
+				if (s.startsWith("{")) {
+					try {
+						Object parsed = objectConstructor.newInstance(s);
+						prettyPrinted = objectToString.invoke(parsed, indentSpaces) + "\n";
+					} catch (InvocationTargetException ignored) {
+						// ignore if we cannot convert to JSON string
+					}
+				}
+				if (s.startsWith("[")) {
+					try {
+						Object parsed = arrayConstructor.newInstance(s);
+						prettyPrinted = arrayToString.invoke(parsed, indentSpaces) + "\n";
+					} catch (InvocationTargetException ignored) {
+						// ignore if we cannot convert to JSON string
+					}
+				}
+
+				if (prettyPrinted == null) {
+					throw new AssertionError("Invalid JSON file provided");
+				}
+
+				return prettyPrinted;
+			};
+		}
+	}
+
+	private JsonSimpleStep() {
+		// cannot be directly instantiated
+	}
+}

lib/src/main/java/com/diffplug/spotless/json/package-info.java

@@ -0,0 +1,7 @@
+@ParametersAreNonnullByDefault
+@ReturnValuesAreNonnullByDefault
+package com.diffplug.spotless.extra.json.java;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
+import com.diffplug.spotless.annotations.ReturnValuesAreNonnullByDefault;

plugin-gradle/CHANGES.md

@@ -4,6 +4,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 
 ## [Unreleased]
 
+### Added
+* Added Gradle configuration [JVM-based JSON formatting](https://github.com/diffplug/spotless/issues/850)
 ### Fixed
 * Fixed IndexOutOfBoundsException in parallel execution of `eclipse-groovy` formatter ([#877](https://github.com/diffplug/spotless/issues/877))
 

plugin-gradle/README.md

@@ -68,6 +68,7 @@ Spotless supports all of Gradle's built-in performance features (incremental bui
   - [Antlr4](#antlr4) ([antlr4formatter](#antlr4formatter))
   - [SQL](#sql) ([dbeaver](#dbeaver), [prettier](#prettier))
   - [Typescript](#typescript) ([tsfmt](#tsfmt), [prettier](#prettier))
+  - [JSON](#json)
   - Multiple languages
     - [Prettier](#prettier) ([plugins](#prettier-plugins), [npm detection](#npm-detection), [`.npmrc` detection](#npmrc-detection))
       - javascript, jsx, angular, vue, flow, typescript, css, less, scss, html, json, graphql, markdown, ymaml
@@ -527,6 +528,36 @@ spotless {
 
 For details, see the [npm detection](#npm-detection) and [`.npmrc` detection](#npmrc-detection) sections of prettier, which apply also to tsfmt.
 
+## JSON
+
+- `com.diffplug.gradle.spotless.JsonExtension` [javadoc](https://javadoc.io/static/com.diffplug.spotless/spotless-plugin-gradle/5.13.0/com/diffplug/gradle/spotless/JsonExtension.html), [code](https://github.com/diffplug/spotless/blob/main/plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JsonExtension.java)
+
+```gradle
+spotless {
+  json {
+    target 'src/**/*.json' // you have to set the target manually
+    simple() // has its own section below
+    prettier().config(['parser': 'json']) // see Prettier section below
+    eclipseWtp('json') // see Eclipse web tools platform section
+  }
+}
+```
+
+### simple
+
+Uses a JSON pretty-printer that optionally allows configuring the number of spaces that are used to pretty print objects:
+
+```gradle
+spotless {
+  json {
+    target 'src/**/*.json'
+    simple()
+    // optional: specify the number of spaces to use
+    simple().indentWithSpaces(6)
+  }
+}
+```
+
 <a name="applying-prettier-to-javascript--flow--typescript--css--scss--less--jsx--graphql--yaml--etc"></a>
 
 ## Prettier

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JsonExtension.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2016-2021 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.gradle.spotless;
+
+import javax.inject.Inject;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.json.JsonSimpleStep;
+
+public class JsonExtension extends FormatExtension {
+	private static final int DEFAULT_INDENTATION = 4;
+	static final String NAME = "json";
+
+	@Inject
+	public JsonExtension(SpotlessExtension spotless) {
+		super(spotless);
+	}
+
+	@Override
+	protected void setupTask(SpotlessTask task) {
+		if (target == null) {
+			throw noDefaultTargetException();
+		}
+		super.setupTask(task);
+	}
+
+	public SimpleConfig simple() {
+		return new SimpleConfig(DEFAULT_INDENTATION);
+	}
+
+	public class SimpleConfig {
+		private int indent;
+
+		public SimpleConfig(int indent) {
+			this.indent = indent;
+			addStep(createStep());
+		}
+
+		public void indentWithSpaces(int indent) {
+			this.indent = indent;
+			replaceStep(createStep());
+		}
+
+		private FormatterStep createStep() {
+			return JsonSimpleStep.create(indent, provisioner());
+		}
+	}
+
+}

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessExtension.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 DiffPlug
+ * Copyright 2016-2021 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -169,6 +169,12 @@ public void python(Action<PythonExtension> closure) {
 		format(PythonExtension.NAME, PythonExtension.class, closure);
 	}
 
+	/** Configures the special JSON-specific extension. */
+	public void json(Action<JsonExtension> closure) {
+		requireNonNull(closure);
+		format(JsonExtension.NAME, JsonExtension.class, closure);
+	}
+
 	/** Configures a custom extension. */
 	public void format(String name, Action<FormatExtension> closure) {
 		requireNonNull(name, "name");

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/JsonExtensionTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2021 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.gradle.spotless;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+public class JsonExtensionTest extends GradleIntegrationHarness {
+	@Test
+	public void defaultFormatting() throws IOException {
+		setFile("build.gradle").toLines(
+				"buildscript { repositories { mavenCentral() } }",
+				"plugins {",
+				"    id 'java'",
+				"    id 'com.diffplug.spotless'",
+				"}",
+				"spotless {",
+				"    json {",
+				"    target 'examples/**/*.json'",
+				"    simple()",
+				"}",
+				"}");
+		setFile("src/main/resources/example.json").toResource("json/nestedObjectBefore.json");
+		setFile("examples/main/resources/example.json").toResource("json/nestedObjectBefore.json");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/resources/example.json").sameAsResource("json/nestedObjectBefore.json");
+		assertFile("examples/main/resources/example.json").sameAsResource("json/nestedObjectAfter.json");
+	}
+
+	@Test
+	public void formattingWithCustomNumberOfSpaces() throws IOException {
+		setFile("build.gradle").toLines(
+				"buildscript { repositories { mavenCentral() } }",
+				"plugins {",
+				"    id 'java'",
+				"    id 'com.diffplug.spotless'",
+				"}",
+				"spotless {",
+				"    json {",
+				"    target 'src/**/*.json'",
+				"    simple().indentWithSpaces(6)",
+				"}",
+				"}");
+		setFile("src/main/resources/example.json").toResource("json/singletonArrayBefore.json");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("src/main/resources/example.json").sameAsResource("json/singletonArrayAfter6Spaces.json");
+	}
+}