| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.jena.sparql.algebra.optimize; |
| |
| import java.util.ArrayList ; |
| import java.util.List ; |
| |
| import org.apache.jena.sparql.algebra.Op ; |
| import org.apache.jena.sparql.algebra.TransformCopy ; |
| import org.apache.jena.sparql.algebra.Transformer ; |
| import org.apache.jena.sparql.expr.* ; |
| |
| /** |
| * An expression transform that simplifies expressions by constant folding |
| * wherever possible |
| */ |
| public class ExprTransformConstantFold extends ExprTransformCopy { |
| |
| public ExprTransformConstantFold() {} |
| |
| @Override |
| public Expr transform(ExprFunction1 func, Expr expr1) { |
| if (isFoldable(expr1)) { |
| try { |
| return func.eval(expr1.getConstant()) ; |
| } catch (Exception ex) { /* Drop through */ } |
| } |
| return super.transform(func, expr1); |
| } |
| |
| @Override |
| public Expr transform(ExprFunction2 func, Expr expr1, Expr expr2) { |
| if (isFoldable(expr1, expr2)) { |
| try { |
| return func.eval(expr1.getConstant(), expr2.getConstant()) ; |
| } catch (Exception ex) { /* Drop through */ } |
| } |
| return super.transform(func, expr1, expr2); |
| } |
| |
| @Override |
| public Expr transform(ExprFunction3 func, Expr expr1, Expr expr2, Expr expr3) { |
| if (isFoldable(expr1, expr2, expr3)) { |
| try { |
| return func.eval(expr1.getConstant(), expr2.getConstant(), expr3.getConstant()) ; |
| } catch (Exception ex) { /* Drop through */ } |
| } |
| return super.transform(func, expr1, expr2, expr3); |
| } |
| |
| @Override |
| public Expr transform(ExprFunctionN func, ExprList args) { |
| if (isFoldable(args)) { |
| List<NodeValue> args2 = new ArrayList<>() ; |
| // Need to "cast" to constants |
| for ( Expr e : args ) |
| args2.add(e.getConstant()) ; |
| try { |
| return func.eval(args2) ; |
| } catch (Exception ex) { /* Drop through */ } |
| } |
| return super.transform(func, args); |
| } |
| |
| @Override |
| public Expr transform(ExprFunctionOp funcOp, ExprList args, Op opArg) { |
| // Manually transform each argument |
| Op op = Transformer.transform(new TransformCopy(), this, funcOp.getGraphPattern()); |
| ExprList newArgs = new ExprList(); |
| for (int i = 0; i < args.size(); i++) { |
| Expr curr = args.get(i); |
| Expr newArg = ExprTransformer.transform(this, curr) ; |
| newArgs.add(newArg); |
| } |
| return funcOp.copy(newArgs, op); |
| } |
| |
| private boolean isFoldable(ExprList exprs) { |
| for (Expr e : exprs) { |
| if (e == null || !e.isConstant()) |
| return false; |
| } |
| return true; |
| } |
| |
| private boolean isFoldable(Expr... exprs) { |
| for (Expr e : exprs) { |
| if (e == null || !e.isConstant()) |
| return false; |
| } |
| return true; |
| } |
| } |