feat(package): hemar: antlr grammar, but still does not work

package/hemar/grammar/antlr/default.nix

@@ -0,0 +1,36 @@
+{ stdenv, symlinkJoin, jre, antlr4, runtimeShell, jdk }:
+
+let
+  hemar-grammar = stdenv.mkDerivation {
+    pname = "hemar-grammar";
+    version = "0.1.0";
+
+    src = ./.; # directory with Hemar.g4
+
+    nativeBuildInputs = [
+      antlr4
+      jdk
+    ];
+
+    buildPhase = ''
+      antlr4 HemarLexer.g4 HemarParser.g4
+      javac *.java
+    '';
+
+    installPhase = ''
+      mkdir -p "$out/lib" "$out/bin"
+      cp *.class *.tokens "$out/lib"
+
+      cat > "$out/bin/hemar-grammar" <<EOF
+#!${runtimeShell}
+CLASSPATH="$out/lib:${antlr4}/share/java/*"
+exec ${jre}/bin/java -cp "\$CLASSPATH" org.antlr.v4.gui.TestRig Hemar hemar "\$@"
+EOF
+      chmod +x "$out/bin/hemar-grammar"
+    '';
+  };
+in
+symlinkJoin {
+  name = "hemar-grammar";
+  paths = [ hemar-grammar ];
+}