code: /*
   * 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.skywalking.oal.rt.parser;
  
  import java.io.IOException;
  import java.io.Reader;
  import org.antlr.v4.runtime.CharStreams;
  import org.antlr.v4.runtime.CommonTokenStream;
  import org.antlr.v4.runtime.tree.ParseTree;
  import org.antlr.v4.runtime.tree.ParseTreeWalker;
  import org.apache.skywalking.oal.rt.grammar.OALLexer;
  import org.apache.skywalking.oal.rt.grammar.OALParser;
  
  /**
   * Script reader and parser.
   */
  public class ScriptParser {
      private OALLexer lexer;
  
      private String sourcePackage;
  
      private ScriptParser() {
  
      }
  
      public static ScriptParser createFromFile(Reader scriptReader, String sourcePackage) throws IOException {
          ScriptParser parser = new ScriptParser();
          parser.lexer = new OALLexer(CharStreams.fromReader(scriptReader));
          parser.sourcePackage = sourcePackage;
          return parser;
      }
  
      public static ScriptParser createFromScriptText(String script, String sourcePackage) throws IOException {
          ScriptParser parser = new ScriptParser();
          parser.lexer = new OALLexer(CharStreams.fromString(script));
          parser.sourcePackage = sourcePackage;
          return parser;
      }
  
      public OALScripts parse() throws IOException {
          OALScripts scripts = new OALScripts();
  
          CommonTokenStream tokens = new CommonTokenStream(lexer);
  
          OALParser parser = new OALParser(tokens);
  
          ParseTree tree = parser.root();
          ParseTreeWalker walker = new ParseTreeWalker();
  
          walker.walk(new OALListener(scripts, sourcePackage), tree);
  
          return scripts;
      }
  
      public void close() {
      }
  }
  