| /* |
| * 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.reasoner.rulesys.impl; |
| |
| import org.apache.jena.graph.* ; |
| import org.apache.jena.reasoner.rulesys.Rule ; |
| |
| /** |
| * Represents a single frame in the LP interpreter's environment stack. The |
| * environment stack represents the AND part of the search tree - it is a sequence |
| * of nested predicate calls. |
| * <p> |
| * This is used in the inner loop of the interpreter and so is a pure data structure |
| * not an abstract data type and assumes privileged access to the interpreter state. |
| * </p> |
| */ |
| public class EnvironmentFrame extends FrameObject { |
| |
| /** The set of permanent variables Y(i) in use by this frame. */ |
| Node[] pVars; |
| |
| /** The code the the clause currently being processed */ |
| RuleClauseCode clause; |
| |
| /** The continuation program counter offet in the parent clause's byte code */ |
| int cpc; |
| |
| /** The continuation argument counter offset in the parent clause's arg stream */ |
| int cac; |
| |
| /** |
| * Constructor |
| * @param clause the compiled code being interpreted by this env frame |
| */ |
| public EnvironmentFrame(RuleClauseCode clause) { |
| this.clause = clause; |
| } |
| |
| /** |
| * Allocate a vector of permanent variables for use in the rule execution. |
| */ |
| public void allocate(int n) { |
| pVars = new Node[n]; |
| } |
| |
| /** |
| * Return the rule associated with this environment, null if no such rule. |
| */ |
| public Rule getRule() { |
| if (clause != null) { |
| return clause.rule; |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * Printable string for debugging. |
| */ |
| @Override |
| public String toString() { |
| if (clause == null || clause.rule == null) { |
| return "[anon]"; |
| } else { |
| return "[" + clause.rule.toShortString() + "]"; |
| } |
| } |
| } |