| /** |
| * 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.ratis.examples.arithmetic.expression; |
| |
| import java.util.Map; |
| import java.util.regex.Pattern; |
| |
| import org.apache.ratis.examples.arithmetic.AssignmentMessage; |
| import org.apache.ratis.util.Preconditions; |
| |
| public class Variable implements Expression { |
| static final int LENGTH_LIMIT = 32; |
| public static final Pattern PATTERN = Pattern.compile("[a-zA-Z]\\w*"); |
| |
| static byte[] string2bytes(String s) { |
| final byte[] stringBytes = s.getBytes(AssignmentMessage.UTF8); |
| final byte[] bytes = new byte[stringBytes.length + 2]; |
| bytes[0] = Type.VARIABLE.byteValue(); |
| bytes[1] = (byte)stringBytes.length; |
| System.arraycopy(stringBytes, 0, bytes, 2, stringBytes.length); |
| return bytes; |
| } |
| |
| static String extractString(byte[] buf, int offset) { |
| Preconditions.assertTrue(buf[offset] == Type.VARIABLE.byteValue()); |
| final int length = buf[offset + 1]; |
| final byte[] stringBytes = new byte[length]; |
| System.arraycopy(buf, offset + 2, stringBytes, 0, length); |
| return new String(stringBytes, AssignmentMessage.UTF8); |
| } |
| |
| static byte[] copyBytes(byte[] buf, int offset) { |
| Preconditions.assertTrue(buf[offset] == Type.VARIABLE.byteValue()); |
| final int length = buf[offset + 1]; |
| final byte[] copy = new byte[length + 2]; |
| System.arraycopy(buf, offset, copy, 0, copy.length); |
| return copy; |
| } |
| |
| private final String name; |
| private final byte[] encoded; |
| |
| private Variable(String name, byte[] encoded) { |
| this.name = name; |
| this.encoded = encoded; |
| |
| if (!PATTERN.matcher(name).matches()) { |
| throw new IllegalArgumentException("The variable name \"" + name |
| + "\" does not match the pattern \"" + PATTERN + "\""); |
| } |
| if (encoded.length - 2 > LENGTH_LIMIT) { |
| throw new IllegalArgumentException("The variable name \"" + name |
| + "\" is longer than the limit = " + LENGTH_LIMIT); |
| } |
| } |
| |
| public Variable(byte[] buf, int offset) { |
| this(extractString(buf, offset), copyBytes(buf, offset)); |
| } |
| |
| public Variable(String name) { |
| this(name, string2bytes(name)); |
| } |
| |
| public String getName() { |
| return name; |
| } |
| |
| public AssignmentMessage assign(double value) { |
| return assign(new DoubleValue(value)); |
| } |
| |
| public AssignmentMessage assign(Expression e) { |
| return new AssignmentMessage(this, e); |
| } |
| |
| @Override |
| public int toBytes(byte[] buf, int offset) { |
| System.arraycopy(encoded, 0, buf, offset, encoded.length); |
| return encoded.length; |
| } |
| |
| @Override |
| public int length() { |
| return encoded.length; |
| } |
| |
| @Override |
| public Double evaluate(Map<String, Double> variableMap) { |
| final Double value = variableMap.get(name); |
| if (value == null) { |
| throw new IllegalStateException("Undefined variable \"" + name + "\""); |
| } |
| return value; |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } else if (obj == null || !(obj instanceof Variable)) { |
| return false; |
| } |
| final Variable that = (Variable)obj; |
| return this.getName().equals(that.getName()); |
| } |
| |
| @Override |
| public int hashCode() { |
| return name.hashCode(); |
| } |
| |
| @Override |
| public String toString() { |
| return name; |
| } |
| } |