Add TOML support

Addresses vert-x3#49

Using toml4j adds TOML support.

Note: I have used Jetbrains annotations in this commit, if that is not
desired I can remove them and stick with standard Java 8 methods of
ensuring method contracts when it comes to null values.

pom.xml

@@ -44,6 +44,7 @@
     <module>vertx-config-zookeeper</module>
     <module>vertx-config-consul</module>
     <module>vertx-config-vault</module>
+    <module>vertx-config-toml</module>
   </modules>
 
   <scm>

vertx-config-toml/pom.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.vertx</groupId>
+        <artifactId>vertx-config-parent</artifactId>
+        <version>3.6.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>vertx-config-toml</artifactId>
+
+    <properties>
+        <doc.skip>false</doc.skip>
+        <toml4j.version>0.7.2</toml4j.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.vertx</groupId>
+            <artifactId>vertx-config</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.moandjiezana.toml</groupId>
+            <artifactId>toml4j</artifactId>
+            <version>${toml4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains</groupId>
+            <artifactId>annotations</artifactId>
+            <version>16.0.1</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+
+
+</project>

vertx-config-toml/src/main/asciidoc/toml-format.adoc

@@ -0,0 +1,45 @@
+=== TOML Configuration Format
+
+The TOML Configuration Format extends the Vert.x Configuration Retriever and
+provides the support for the TOML Configuration Format.
+
+==== Using the TOML Configuration Format
+
+To use the TOML Configuration Format, add the following dependency to the
+_dependencies_ section of your build descriptor:
+
+* Maven (in your `pom.xml`):
+
+[source,xml,subs="+attributes"]
+----
+<dependency>
+  <groupId>io.vertx.config.toml</groupId>
+  <artifactId>vertx-config-toml</artifactId>
+  <version>${maven.version}</version>
+</dependency>
+<dependency>
+  <groupId>io.vertx</groupId>
+  <artifactId>vertx-config</artifactId>
+  <version>${maven.version}</version>
+</dependency>
+----
+
+* Gradle (in your `build.gradle` file):
+
+[source,groovy,subs="+attributes"]
+----
+compile 'io.vertx:vertx-config:${maven.version}'
+compile 'io.vertx.config.toml:vertx-config-toml:${maven.version}'
+----
+
+==== Configuring the store to use TOML
+
+Once added to your classpath or dependencies, you need to configure the
+{@link io.vertx.config.ConfigRetriever} to use this format:
+
+[source, $lang]
+----
+{@link examples.ConfigTomlExamples#example1(io.vertx.core.Vertx)}
+----
+
+You just need to set `format` to `toml`.

vertx-config-toml/src/main/java/examples/ConfigTomlExamples.java

@@ -0,0 +1,29 @@
+package examples;
+
+import io.vertx.config.ConfigRetriever;
+import io.vertx.config.ConfigRetrieverOptions;
+import io.vertx.config.ConfigStoreOptions;
+import io.vertx.core.Vertx;
+import io.vertx.core.json.JsonObject;
+
+/**
+ * @author <a href='lyndon.codes'>Lyndon Armitage</a>
+ */
+public final class ConfigTomlExamples {
+
+
+  public void example1(Vertx vertx) {
+    JsonObject storeConfig = new JsonObject().put("path", "my-config.toml");
+    ConfigStoreOptions storeOptions = new ConfigStoreOptions()
+      .setType("file")
+      .setFormat("toml")
+      .setConfig(storeConfig);
+
+    ConfigRetriever retriever = ConfigRetriever.create(
+      vertx,
+      new ConfigRetrieverOptions().addStore(storeOptions)
+    );
+
+  }
+
+}

vertx-config-toml/src/main/java/examples/package-info.java

@@ -0,0 +1,5 @@
+
+@Source
+package examples;
+
+import io.vertx.docgen.Source;

vertx-config-toml/src/main/java/io/vertx/config/toml/TomlProcessor.java

@@ -0,0 +1,84 @@
+package io.vertx.config.toml;
+
+import com.moandjiezana.toml.Toml;
+import io.vertx.config.spi.ConfigProcessor;
+import io.vertx.core.AsyncResult;
+import io.vertx.core.Future;
+import io.vertx.core.Handler;
+import io.vertx.core.Vertx;
+import io.vertx.core.buffer.Buffer;
+import io.vertx.core.json.JsonObject;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.ByteArrayInputStream;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * <p>
+ * A processor for the <a href='https://github.com/toml-lang/toml'>TOML</a>
+ * format.
+ * </p>
+ * <p>
+ * Currently using the
+ * <a href='https://github.com/mwanji/toml4j'>toml4j library</a>. If a newer
+ * version of this library becomes available, you can override the dependency
+ * (assuming the API does not change).
+ * </p>
+ *
+ * @author <a href='lyndon.codes'>Lyndon Armitage</a>
+ */
+public final class TomlProcessor implements ConfigProcessor {
+
+  public TomlProcessor() {
+  }
+
+  @NotNull
+  @Contract(pure = true)
+  @Override
+  public final String name() {
+    return "toml";
+  }
+
+  @Override
+  public final void process(
+    @NotNull Vertx vertx,
+    @Nullable JsonObject configuration,
+    @NotNull Buffer input,
+    @NotNull Handler<AsyncResult<JsonObject>> handler
+  ) {
+    Objects.requireNonNull(vertx, "vertx cannot be null");
+    Objects.requireNonNull(input, "input cannot be null");
+    Objects.requireNonNull(handler, "handler cannot be null");
+
+    if (input.length() == 0) {
+      handler.handle(Future.succeededFuture(new JsonObject()));
+      return;
+    }
+
+    vertx.executeBlocking(
+      future -> {
+        // Currently loads the whole config file into memory
+        try (
+          ByteArrayInputStream inputStream = new ByteArrayInputStream(
+            input.getBytes()
+          )
+        ) {
+
+          Toml toml = new Toml().read(inputStream);
+          Map<String, Object> asMap = Objects.requireNonNull(
+            toml.toMap(),
+            "toml library returned a null map"
+          );
+          JsonObject asJson = new JsonObject(asMap);
+          future.complete(asJson);
+        } catch (Exception e) {
+          future.fail(e);
+        }
+      },
+      handler
+    );
+  }
+}

vertx-config-toml/src/main/java/io/vertx/config/toml/package-info.java

@@ -0,0 +1,4 @@
+@ModuleGen(name = "vertx-config", groupPackage = "io.vertx")
+package io.vertx.config.toml;
+
+import io.vertx.codegen.annotations.ModuleGen;

vertx-config-toml/src/main/resources/META-INF/services/io.vertx.config.spi.ConfigProcessor

@@ -0,0 +1 @@
+io.vertx.config.toml.TomlProcessor

vertx-config-toml/src/test/java/examples/ConfigTomlExamplesTest.java

@@ -0,0 +1,32 @@
+package examples;
+
+import io.vertx.core.Vertx;
+import io.vertx.ext.unit.TestContext;
+import io.vertx.ext.unit.junit.RunTestOnContext;
+import io.vertx.ext.unit.junit.VertxUnitRunner;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+@RunWith(VertxUnitRunner.class)
+public class ConfigTomlExamplesTest {
+
+  @Rule
+  public RunTestOnContext contextRule = new RunTestOnContext();
+
+  private Vertx vertx;
+
+  @Before
+  public void setUp(TestContext context) throws Exception {
+    vertx = contextRule.vertx();
+  }
+
+  @Test
+  public void example1_doesnt_throw(TestContext context) {
+    ConfigTomlExamples examples = new ConfigTomlExamples();
+    examples.example1(vertx);
+  }
+}