docs: public final void castExpression() throws RecognitionException {
  		BaseDescr expr =null;
  
  		try {
  			// src/main/resources/org/drools/compiler/lang/DRL6Expressions.g:540:5: ( ( LEFT_PAREN primitiveType )=> LEFT_PAREN primitiveType RIGHT_PAREN expr= unaryExpression | ( LEFT_PAREN type )=> LEFT_PAREN type RIGHT_PAREN unaryExpressionNotPlusMinus )
  			int alt55=2;
  			int LA55_0 = input.LA(1);
  			if ( (LA55_0==LEFT_PAREN) ) {
  				int LA55_1 = input.LA(2);
  				if ( (synpred20_DRL6Expressions()) ) {
  					alt55=1;
  				}
  				else if ( (synpred21_DRL6Expressions()) ) {
  					alt55=2;
  				}
  
  				else {
  					if (state.backtracking>0) {state.failed=true; return;}
  					int nvaeMark = input.mark();
  					try {
  						input.consume();
  						NoViableAltException nvae =
  							new NoViableAltException("", 55, 1, input);
  						throw nvae;
  					} finally {
  						input.rewind(nvaeMark);
  					}
  				}
  
  			}
  
  			else {
  				if (state.backtracking>0) {state.failed=true; return;}
  				NoViableAltException nvae =
  					new NoViableAltException("", 55, 0, input);
  				throw nvae;
  			}
  
  			switch (alt55) {
  				case 1 :
  					// src/main/resources/org/drools/compiler/lang/DRL6Expressions.g:540:8: ( LEFT_PAREN primitiveType )=> LEFT_PAREN primitiveType RIGHT_PAREN expr= unaryExpression
  					{
  					match(input,LEFT_PAREN,FOLLOW_LEFT_PAREN_in_castExpression2727); if (state.failed) return;
  					pushFollow(FOLLOW_primitiveType_in_castExpression2729);
  					primitiveType();
  					state._fsp--;
  					if (state.failed) return;
  					match(input,RIGHT_PAREN,FOLLOW_RIGHT_PAREN_in_castExpression2731); if (state.failed) return;
  					pushFollow(FOLLOW_unaryExpression_in_castExpression2735);
  					expr=unaryExpression();
  					state._fsp--;
  					if (state.failed) return;
  					}
  					break;
  				case 2 :
  					// src/main/resources/org/drools/compiler/lang/DRL6Expressions.g:541:8: ( LEFT_PAREN type )=> LEFT_PAREN type RIGHT_PAREN unaryExpressionNotPlusMinus
  					{
  					match(input,LEFT_PAREN,FOLLOW_LEFT_PAREN_in_castExpression2752); if (state.failed) return;
  					pushFollow(FOLLOW_type_in_castExpression2754);
  					type();
  					state._fsp--;
  					if (state.failed) return;
  					match(input,RIGHT_PAREN,FOLLOW_RIGHT_PAREN_in_castExpression2756); if (state.failed) return;
  					pushFollow(FOLLOW_unaryExpressionNotPlusMinus_in_castExpression2758);
  					unaryExpressionNotPlusMinus();
  					state._fsp--;
  					if (state.failed) return;
  					}
  					break;
  
  			}
  		}
  
  		catch (RecognitionException re) {
  		    throw re;
  		}
  
  		finally {
  			// do for sure before leaving
  		}
  	}