Rework Java template generation for Maven build

This uses the JRuby rake-maven-plugin to generate the templates
as part of the Maven build. The generated output for the Java
templates will be under java/api/target/generated-sources/java.

Author: headius

java/api/pom.xml

@@ -9,21 +9,84 @@
   </parent>
 
   <artifactId>prism-parser-api</artifactId>
-  <name>Java Prism</name>
+  <name>Java Prism API</name>
   <description>Java API for the Prism Ruby language parser</description>
   <url>https://github.com/ruby/prism</url>
 
+  <repositories>
+    <repository>
+      <id>mavengems</id>
+      <url>mavengem:https://rubygems.org</url>
+    </repository>
+  </repositories>
+
   <dependencies>
     <dependency>
       <groupId>org.ruby-lang</groupId>
       <artifactId>prism-parser-native</artifactId>
       <version>0.0.2-SNAPSHOT</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>rubygems</groupId>
+      <artifactId>rake</artifactId>
+      <version>13.0.3</version>
+      <type>gem</type>
+    </dependency>
+    <dependency>
+      <groupId>rubygems</groupId>
+      <artifactId>rake-compiler</artifactId>
+      <version>1.3.1</version>
+      <type>gem</type>
+    </dependency>
   </dependencies>
 
   <build>
+    <extensions>
+      <extension>
+        <groupId>org.jruby.maven</groupId>
+        <artifactId>mavengem-wagon</artifactId>
+        <version>2.0.2</version>
+      </extension>
+    </extensions>
     <plugins>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+        <version>3.6.1</version>
+        <executions>
+          <execution>
+            <id>add-source</id>
+            <phase>generate-sources</phase>
+            <goals>
+              <goal>add-source</goal>
+            </goals>
+            <configuration>
+              <sources>
+                <source>target/generated-sources/java</source>
+              </sources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.jruby.maven</groupId>
+        <artifactId>rake-maven-plugin</artifactId>
+        <version>3.0.6</version>
+        <executions>
+          <execution>
+            <id>generate templated Java sources</id>
+            <phase>generate-sources</phase>
+            <goals>
+              <goal>rake</goal>
+            </goals>
+            <configuration>
+              <launchDirectory>${project.basedir}/../..</launchDirectory>
+              <rakeArgs>PRISM_EXCLUDE_PRETTYPRINT=1 PRISM_SERIALIZE_ONLY_SEMANTICS_FIELDS=1 templates</rakeArgs>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>templating-maven-plugin</artifactId>