docs: public final void castExpression() throws RecognitionException {
  		BaseDescr expr =null;
  
  		try {
  			// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:521:5: ( ( LEFT_PAREN primitiveType )=> LEFT_PAREN primitiveType RIGHT_PAREN expr= unaryExpression | ( LEFT_PAREN type )=> LEFT_PAREN type RIGHT_PAREN unaryExpressionNotPlusMinus )
  			int alt54=2;
  			int LA54_0 = input.LA(1);
  			if ( (LA54_0==LEFT_PAREN) ) {
  				int LA54_1 = input.LA(2);
  				if ( (synpred17_DRL5Expressions()) ) {
  					alt54=1;
  				}
  				else if ( (synpred18_DRL5Expressions()) ) {
  					alt54=2;
  				}
  
  				else {
  					if (state.backtracking>0) {state.failed=true; return;}
  					int nvaeMark = input.mark();
  					try {
  						input.consume();
  						NoViableAltException nvae =
  							new NoViableAltException("", 54, 1, input);
  						throw nvae;
  					} finally {
  						input.rewind(nvaeMark);
  					}
  				}
  
  			}
  
  			else {
  				if (state.backtracking>0) {state.failed=true; return;}
  				NoViableAltException nvae =
  					new NoViableAltException("", 54, 0, input);
  				throw nvae;
  			}
  
  			switch (alt54) {
  				case 1 :
  					// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:521:8: ( LEFT_PAREN primitiveType )=> LEFT_PAREN primitiveType RIGHT_PAREN expr= unaryExpression
  					{
  					match(input,LEFT_PAREN,FOLLOW_LEFT_PAREN_in_castExpression2593); if (state.failed) return;
  					pushFollow(FOLLOW_primitiveType_in_castExpression2595);
  					primitiveType();
  					state._fsp--;
  					if (state.failed) return;
  					match(input,RIGHT_PAREN,FOLLOW_RIGHT_PAREN_in_castExpression2597); if (state.failed) return;
  					pushFollow(FOLLOW_unaryExpression_in_castExpression2601);
  					expr=unaryExpression();
  					state._fsp--;
  					if (state.failed) return;
  					}
  					break;
  				case 2 :
  					// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:522:8: ( LEFT_PAREN type )=> LEFT_PAREN type RIGHT_PAREN unaryExpressionNotPlusMinus
  					{
  					match(input,LEFT_PAREN,FOLLOW_LEFT_PAREN_in_castExpression2618); if (state.failed) return;
  					pushFollow(FOLLOW_type_in_castExpression2620);
  					type();
  					state._fsp--;
  					if (state.failed) return;
  					match(input,RIGHT_PAREN,FOLLOW_RIGHT_PAREN_in_castExpression2622); if (state.failed) return;
  					pushFollow(FOLLOW_unaryExpressionNotPlusMinus_in_castExpression2624);
  					unaryExpressionNotPlusMinus();
  					state._fsp--;
  					if (state.failed) return;
  					}
  					break;
  
  			}
  		}
  
  		catch (RecognitionException re) {
  		    throw re;
  		}
  
  		finally {
  			// do for sure before leaving
  		}
  	}