[GitHub] [iotdb] MarcosZyk commented on a diff in pull request #8400: [IOTDB-5168] Refactor traverse of AbstractTreeVisitor to FA-based traverse

[GitBox <gi...@apache.org>]

MarcosZyk commented on code in PR #8400:
URL: https://github.com/apache/iotdb/pull/8400#discussion_r1045711530


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node-commons/src/main/java/org/apache/iotdb/commons/path/fa/SimpleNFA.java:
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@@ -0,0 +1,332 @@
+/*
+ * 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.iotdb.commons.path.fa;
+
+import org.apache.iotdb.commons.path.PartialPath;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import static org.apache.iotdb.commons.conf.IoTDBConstant.MULTI_LEVEL_PATH_WILDCARD;
+import static org.apache.iotdb.commons.conf.IoTDBConstant.ONE_LEVEL_PATH_WILDCARD;
+
+/**
+ * Given path pattern root.sg.*.s, the SimpleNFA is:
+ *
+ * <p>initial -(root)-> state[0] -(sg)-> state[1] -(*)-> state[2] -(s)-> state[3] <br>
+ * state[3] is final state
+ *
+ * <p>Given path pattern root.**.d.s, the SimpleNFA is:
+ *
+ * <p>initial -(root)-> state[0] -(*)-> state[1] -(d)-> state[2] -(s)-> state[3] <br>
+ * with extra: state[2] -(*)-> state[1] <br>
+ * state[3] is final state
+ *
+ * <p>Given path pattern root.sg.d with prefix match, the SimpleNFA is:
+ *
+ * <p>initial -(root)-> state[0] -(sg)-> state[1] -(d)-> state[2] -(*)-> state[3] <br>
+ * both state[2] and state[3] are final states
+ */
+public class SimpleNFA implements IPatternFA {
+
+  // raw nodes of pathPattern
+  private final String[] nodes;
+
+  // used for pattern node like d*
+  private final Map<Integer, Pattern> regexPatternMap = new HashMap<>();
+
+  // initial state of this NFA and the only transition from this state is "root"
+  private final SimpleNFAState initialState = new SimpleNFAState(-1);
+  // all states corresponding to raw pattern nodes, with an extra prefixMatch state
+  private final SimpleNFAState[] states;
+
+  // singletonMap, "root"
+  private final Map<String, IFATransition> initialTransition;
+  // the transition matches only specific value
+  private final Map<String, IFATransition>[] preciseMatchTransitionTable;

Review Comment:
   Description added.



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