Enhance build scripts to check for up-to-date artifacts before creation

Don't rebuild jars if nothing changed!

See eclipse-pde/eclipse.pde#2233

Author: iloveeclipse

org.eclipse.jdt.debug.ui/scripts/buildExtraJAR.xml

@@ -15,7 +15,7 @@
 
 <project name="Build Snippet support JAR" default="build" basedir="..">
 
-	<target name="build" description="Cleans, builds and refreshes the impacted resources" depends="clean, snippetsupport.jar"/>
+	<target name="build" description="Builds and refreshes the impacted resources" depends="snippetsupport.jar"/>
 
 	<!-- Empty target for "After a Clean" task (we don't want to rebuild the Jar here, e.g. on checkout). -->
 	<target name="dummy_clean"/>
@@ -29,14 +29,21 @@
 		<property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>
 	</target>
 
-	<target name="snippetsupport.jar" depends="init" description="Creates the snippetsupport.jar">
+	<target name="checkSourceUpToDate" depends="init" description="Checks if the JAR is up to date with the source">
+		<uptodate property="jarUpToDate" targetfile="${build.result.folder}/snippetsupport.jar">
+			<srcfiles dir="Snippet Support/" includes="**/*"/>
+		</uptodate>
+	</target>
+
+	<target name="snippetsupport.jar" depends="init, checkSourceUpToDate" unless="jarUpToDate" description="Creates the snippetsupport.jar">
 		<property name="destdir" value="${temp.folder}/snippetsupport.jar.bin"/>
+		<delete dir="${temp.folder}"/>
 		<delete dir="${destdir}"/>
 		<mkdir dir="${destdir}"/>
 		<!-- Keep target level as low as possible!
 			snippetsupport.jar is used on the classpath of a separate VM that
 			uses the JRE that's on the build path of the scrapbook file's project. -->
-		<javac target="1.7" source="1.7" destdir="${destdir}"
+		<javac target="1.8" source="1.8" destdir="${destdir}"
 			failonerror="true"
 			verbose="false"
 			debug="on"
@@ -53,4 +60,4 @@
 		<delete file="${build.result.folder}/snippetsupport.jar"/>
 		<delete dir="${temp.folder}"/>
 	</target>
-</project>
+</project>

org.eclipse.jdt.launching/scripts/buildLaunchingSupportJAR.xml

@@ -15,7 +15,7 @@
 
 <project name="Build Launching Support JAR" default="build" basedir="..">
 
-	<target name="build" description="Cleans, builds and refreshes" depends="clean, lib/launchingsupport.jar"/>
+	<target name="build" description="Builds and refreshes" depends="lib/launchingsupport.jar"/>
 
 	<target name="init" depends="properties">
 		<property name="temp.folder" value="${basedir}/temp.folder"/>
@@ -26,12 +26,13 @@
 		<property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>
 	</target>
 
-	<target name="lib/launchingsupport.jar" description= "Creates the launchingsupport.jar" depends="init">
+	<target name="lib/launchingsupport.jar" description= "Creates the launchingsupport.jar" depends="init,checkSourceUpToDate" unless="jarUpToDate">
 		<property name="destdir" value="${temp.folder}/lib/launchingsupport.jar.bin"/>
+		<delete dir="${temp.folder}"/>
 		<delete dir="${destdir}"/>
 		<mkdir dir="${destdir}"/>
 		<!-- compile the source code -->
-		<javac target="1.1" source="1.3" destdir="${destdir}" failonerror="false" verbose="false" debug="on" includeJavaRuntime= "yes" includeAntRuntime="no"
+		<javac target="1.8" source="1.8" destdir="${destdir}" failonerror="false" verbose="false" debug="on" includeJavaRuntime= "yes" includeAntRuntime="no"
 			 classpath="">
 			<src path="support/"/>
 		</javac>
@@ -47,4 +48,10 @@
 		<delete file="${build.result.folder}/lib/launchingsupport.jar"/>
 		<delete dir="${temp.folder}"/>
 	</target>
-</project>
+
+	<target name="checkSourceUpToDate">
+		<uptodate property="jarUpToDate" targetfile="${build.result.folder}/lib/launchingsupport.jar">
+			<srcfiles dir="support" includes="**/*"/>
+		</uptodate>
+	</target>
+</project>