Bytecode pattern iluwatar#553 (iluwatar#896)

* Added bytecode pattern

* Diagram changed and added licence information

* Added bytecode module to main pom.

* Fixed missing dependency error

bytecode/README.md

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+---
+layout: pattern
+title: Bytecode
+folder: bytecode
+permalink: /patterns/bytecode/
+categories: Behavioral
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+Allows to encode behaviour as instructions for virtual machine.
+
+## Applicability
+Use the Bytecode pattern when you have a lot of behavior you need to define and your
+game’s implementation language isn’t a good fit because:
+
+* it’s too low-level, making it tedious or error-prone to program in.
+* iterating on it takes too long due to slow compile times or other tooling issues.
+* it has too much trust. If you want to ensure the behavior being defined can’t break the game, you need to sandbox it from the rest of the codebase.
+
+## Credits
+
+* [Game programming patterns](http://gameprogrammingpatterns.com/bytecode.html)

bytecode/etc/bytecode.ucls

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+<?xml version="1.0" encoding="UTF-8"?>
+<class-diagram version="1.2.3" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
+  associations="true" dependencies="false" nesting-relationships="true" router="FAN">  
+  <class id="1" language="java" name="com.iluwatar.bytecode.VirtualMachine" project="bytecode" 
+    file="/bytecode/src/main/java/com/iluwatar/bytecode/VirtualMachine.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="455" y="173"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="2" language="java" name="com.iluwatar.bytecode.App" project="bytecode" 
+    file="/bytecode/src/main/java/com/iluwatar/bytecode/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="148" y="110"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <class id="3" language="java" name="com.iluwatar.bytecode.Wizard" project="bytecode" 
+    file="/bytecode/src/main/java/com/iluwatar/bytecode/Wizard.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="148" y="416"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
+  </class>  
+  <association id="4">    
+    <end type="SOURCE" refId="1" navigable="false" variant="ASSOCIATION">      
+      <attribute id="5" name="wizards">        
+        <position height="18" width="48" x="296" y="291"/>      
+      </attribute>      
+      <multiplicity id="6" minimum="0" maximum="2147483647">        
+        <position height="0" width="0" x="-327" y="-27"/>      
+      </multiplicity>    
+    </end>    
+    <end type="TARGET" refId="3" navigable="true" variant="ASSOCIATION"/>    
+    <display labels="true" multiplicity="true"/>  
+  </association>  
+  <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+    sort-features="false" accessors="true" visibility="true">    
+    <attributes public="true" package="true" protected="true" private="true" static="true"/>    
+    <operations public="true" package="true" protected="true" private="true" static="true"/>  
+  </classifier-display>  
+  <association-display labels="true" multiplicity="true"/>
+</class-diagram>

bytecode/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2019 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>java-design-patterns</artifactId>
+        <groupId>com.iluwatar</groupId>
+        <version>1.21.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>bytecode</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

bytecode/src/main/java/com/iluwatar/bytecode/App.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.bytecode;
+
+import com.iluwatar.bytecode.util.InstructionConverterUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The intention of Bytecode pattern is to give behavior the flexibility of data by encoding it as instructions
+ * for a virtual machine.
+ * An instruction set defines the low-level operations that can be performed. A series of instructions is encoded as
+ * a sequence of bytes. A virtual machine executes these instructions one at a time,
+ * using a stack for intermediate values. By combining instructions, complex high-level behavior can be defined.
+ *
+ * This pattern should be used when there is a need to define high number of behaviours and implementation engine
+ * is not a good choice because
+ * It is too lowe level
+ * Iterating on it takes too long due to slow compile times or other tooling issues.
+ * It has too much trust. If you want to ensure the behavior being defined can’t break the game,
+ * you need to sandbox it from the rest of the codebase.
+ *
+ */
+public class App {
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+  /**
+   * Main app method
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    VirtualMachine vm = new VirtualMachine();
+
+    Wizard wizard = new Wizard();
+    wizard.setHealth(45);
+    wizard.setAgility(7);
+    wizard.setWisdom(11);
+    vm.getWizards()[0] = wizard;
+
+    interpretInstruction("LITERAL 0", vm);
+    interpretInstruction( "LITERAL 0", vm);
+    interpretInstruction( "GET_HEALTH", vm);
+    interpretInstruction( "LITERAL 0", vm);
+    interpretInstruction( "GET_AGILITY", vm);
+    interpretInstruction( "LITERAL 0", vm);
+    interpretInstruction( "GET_WISDOM ", vm);
+    interpretInstruction( "ADD", vm);
+    interpretInstruction( "LITERAL 2", vm);
+    interpretInstruction( "DIVIDE", vm);
+    interpretInstruction( "ADD", vm);
+    interpretInstruction( "SET_HEALTH", vm);
+  }
+
+  private static void interpretInstruction(String instruction, VirtualMachine vm) {
+    InstructionConverterUtil converter = new InstructionConverterUtil();
+    vm.execute(converter.convertToByteCode(instruction));
+    LOGGER.info(instruction + String.format("%" + (12 - instruction.length()) + "s", "" ) + vm.getStack());
+  }
+}

bytecode/src/main/java/com/iluwatar/bytecode/Instruction.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.bytecode;
+
+/**
+ * Representation of instructions understandable by virtual machine
+ */
+public enum Instruction {
+
+  LITERAL(1),
+  SET_HEALTH(2),
+  SET_WISDOM (3),
+  SET_AGILITY(4),
+  PLAY_SOUND(5),
+  SPAWN_PARTICLES(6),
+  GET_HEALTH(7),
+  GET_AGILITY(8),
+  GET_WISDOM(9),
+  ADD(10),
+  DIVIDE (11);
+
+  private int value;
+
+  Instruction(int value) {
+    this.value = value;
+  }
+
+  public int getIntValue() {
+    return value;
+  }
+
+  /**
+   * Converts integer value to Instruction
+   * @param value value of instruction
+   * @return representation of the instruction
+   */
+  public static Instruction getInstruction(int value) {
+    for (int i = 0; i < Instruction.values().length; i++) {
+      if (Instruction.values()[i].getIntValue() == value) {
+        return Instruction.values()[i];
+      }
+    }
+    throw new IllegalArgumentException("Invalid instruction value");
+  }
+}