Need help on Hive.g and parser!

[Shyam Sarkar]

Hello,

Someone please explain the following build.xml spec for grammar build
(required and not required) ::

===================================================================

<uptodate property="grammarBuild.notRequired">
    <srcfiles dir= "${src.dir}/org/apache/hadoop/hive/ql/parse" 
includes="**/*.g"/>
    <mapper type="merge" 
to="${build.dir.hive}/ql/gen-java/org/apache/hadoop/hive/ql/parse/HiveParser.java"/>
  </uptodate>

  <target name="build-grammar" unless="grammarBuild.notRequired">
    <echo>Building Grammar ${src.dir}/org/apache/hadoop/hive/ql/parse/Hive.g  
....</echo>
    <java classname="org.antlr.Tool" classpathref="classpath" fork="true">
       <arg value="-fo" />
       <arg 
value="${build.dir.hive}/ql/gen-java/org/apache/hadoop/hive/ql/parse" />
       <arg value="${src.dir}/org/apache/hadoop/hive/ql/parse/Hive.g" />
    </java>
  </target>
=============================================================

Also can someone tell me which parser generator is used? I used JavaCC
in the past.

Thanks,
shyam_sar...@yahoo.com