| /* |
| * 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.asterix.external.classad; |
| |
| import java.io.BufferedReader; |
| import java.io.File; |
| import java.io.IOException; |
| import java.nio.charset.StandardCharsets; |
| import java.nio.file.Files; |
| |
| public class FileLexerSource extends LexerSource { |
| // This source allows input from a file |
| private BufferedReader reader; |
| private boolean unread; |
| private boolean finished; |
| private boolean nextRead; |
| private char nextChar; |
| |
| public FileLexerSource(File file) throws IOException { |
| this.reader = Files.newBufferedReader(file.toPath(), StandardCharsets.UTF_8); |
| } |
| |
| public void setNewSource(File file) throws IOException { |
| if (this.reader != null) { |
| reader.close(); |
| } |
| this.reader = Files.newBufferedReader(file.toPath(), StandardCharsets.UTF_8); |
| } |
| |
| @Override |
| public char readCharacter() throws IOException { |
| if (unread) { |
| unread = false; |
| return previousCharacter; |
| } else if (nextRead) { |
| nextRead = false; |
| return nextChar; |
| } |
| previousCharacter = (char) reader.read(); |
| return previousCharacter; |
| } |
| |
| @Override |
| public void unreadCharacter() throws IOException { |
| if (nextRead) { |
| throw new IOException("Unexpected Situation"); |
| } else if (unread) { |
| throw new IOException("This lexer source supports only one step back"); |
| } |
| unread = true; |
| } |
| |
| @Override |
| public boolean atEnd() throws IOException { |
| if (finished) { |
| return true; |
| } else if (nextRead) { |
| return false; |
| } |
| nextChar = (char) reader.read(); |
| if (nextChar < 0) { |
| finished = true; |
| } else { |
| nextRead = true; |
| } |
| return finished; |
| } |
| |
| @Override |
| public char[] getBuffer() { |
| return null; |
| } |
| } |