Bytecode pattern #553 (#896)

* Added bytecode pattern

* Diagram changed and added licence information

* Added bytecode module to main pom.

* Fixed missing dependency error

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

@@ -0,0 +1,79 @@
+/**
+ * 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

@@ -0,0 +1,65 @@
+/**
+ * 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");
+  }
+}

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

@@ -0,0 +1,142 @@
+/**
+ * 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 java.util.Stack;
+
+/**
+ * Implementation of virtual machine
+ */
+public class VirtualMachine {
+
+  private Stack<Integer> stack = new Stack();
+
+  private Wizard[] wizards = new Wizard[2];
+
+  /**
+   * Constructor
+   */
+  public VirtualMachine() {
+    for (int i = 0; i < wizards.length; i++) {
+      wizards[i] = new Wizard();
+    }
+  }
+
+  /**
+   * Executes provided bytecode
+   * @param bytecode to execute
+   */
+  public void execute(int[] bytecode) {
+    for (int i = 0; i < bytecode.length; i++) {
+      Instruction instruction = Instruction.getInstruction(bytecode[i]);
+      int wizard;
+      int amount;
+      switch (instruction) {
+        case LITERAL:
+          // Read the next byte from the bytecode.
+          int value = bytecode[++i];
+          stack.push(value);
+          break;
+        case SET_AGILITY:
+          amount = stack.pop();
+          wizard = stack.pop();
+          setAgility(wizard, amount);
+          break;
+        case SET_WISDOM:
+          amount = stack.pop();
+          wizard = stack.pop();
+          setWisdom(wizard, amount);
+          break;
+        case SET_HEALTH:
+          amount = stack.pop();
+          wizard = stack.pop();
+          setHealth(wizard, amount);
+          break;
+        case GET_HEALTH:
+          wizard = stack.pop();
+          stack.push(getHealth(wizard));
+          break;
+        case GET_AGILITY:
+          wizard = stack.pop();
+          stack.push(getAgility(wizard));
+          break;
+        case GET_WISDOM:
+          wizard = stack.pop();
+          stack.push(getWisdom(wizard));
+          break;
+        case ADD:
+          int a = stack.pop();
+          int b = stack.pop();
+          stack.push(a + b);
+          break;
+        case DIVIDE:
+          a = stack.pop();
+          b = stack.pop();
+          stack.push(b / a);
+          break;
+        case PLAY_SOUND:
+          wizard = stack.pop();
+          getWizards()[wizard].playSound();
+          break;
+        case SPAWN_PARTICLES:
+          wizard = stack.pop();
+          getWizards()[wizard].spawnParticles();
+          break;
+        default:
+          throw new IllegalArgumentException("Invalid instruction value");
+      }
+    }
+  }
+
+  public Stack<Integer> getStack() {
+    return stack;
+  }
+
+  public void setHealth(int wizard, int amount) {
+    wizards[wizard].setHealth(amount);
+  }
+
+  public void setWisdom(int wizard, int amount) {
+    wizards[wizard].setWisdom(amount);
+  }
+
+  public void setAgility(int wizard, int amount) {
+    wizards[wizard].setAgility(amount);
+  }
+
+  public int getHealth(int wizard) {
+    return wizards[wizard].getHealth();
+  }
+
+  public int getWisdom(int wizard) {
+    return wizards[wizard].getWisdom();
+  }
+
+  public int getAgility(int wizard) {
+    return wizards[wizard].getAgility();
+  }
+
+  public Wizard[] getWizards() {
+    return wizards;
+  }
+}

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

@@ -0,0 +1,83 @@
+/**
+ * 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 org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This class represent game objects which properties can be changed by instructions interpreted by virtual machine
+ */
+public class Wizard {
+  private static final Logger LOGGER = LoggerFactory.getLogger(Wizard.class);
+
+  private int health;
+
+  private int agility;
+  private int wisdom;
+
+  private int numberOfPlayedSounds;
+  private int numberOfSpawnedParticles;
+
+  public int getHealth() {
+    return health;
+  }
+
+  public void setHealth(int health) {
+    this.health = health;
+  }
+
+  public int getAgility() {
+    return agility;
+  }
+
+  public void setAgility(int agility) {
+    this.agility = agility;
+  }
+
+  public int getWisdom() {
+    return wisdom;
+  }
+
+  public void setWisdom(int wisdom) {
+    this.wisdom = wisdom;
+  }
+
+  public void playSound() {
+    LOGGER.info("Playing sound");
+    numberOfPlayedSounds++;
+  }
+
+  public void spawnParticles() {
+    LOGGER.info("Spawning particles");
+    numberOfSpawnedParticles++;
+  }
+
+  public int getNumberOfPlayedSounds() {
+    return numberOfPlayedSounds;
+  }
+
+  public int getNumberOfSpawnedParticles() {
+    return numberOfSpawnedParticles;
+  }
+}

bytecode/src/main/java/com/iluwatar/bytecode/util/InstructionConverterUtil.java

@@ -0,0 +1,76 @@
+/**
+ * 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.util;
+
+import com.iluwatar.bytecode.Instruction;
+
+/**
+ * Utility class used for instruction validation and conversion
+ */
+public class InstructionConverterUtil {
+  /**
+   * Converts instructions represented as String
+   *
+   * @param instructions to convert
+   * @return array of int representing bytecode
+   */
+  public static int[] convertToByteCode(String instructions) {
+    if (instructions == null || instructions.trim().length() == 0) {
+      return new int[0];
+    }
+
+    String[] splitedInstructions = instructions.trim().split(" ");
+    int[] bytecode = new int[splitedInstructions.length];
+    for (int i = 0; i < splitedInstructions.length; i++) {
+      if (isValidInstruction(splitedInstructions[i])) {
+        bytecode[i] = Instruction.valueOf(splitedInstructions[i]).getIntValue();
+      } else if (isValidInt(splitedInstructions[i])) {
+        bytecode[i] = Integer.valueOf(splitedInstructions[i]);
+      } else {
+        throw new IllegalArgumentException("Invalid instruction or number: " + splitedInstructions[i]);
+      }
+    }
+
+    return bytecode;
+  }
+
+  private static boolean isValidInstruction(String instruction) {
+    try {
+      Instruction.valueOf(instruction);
+      return true;
+    } catch (IllegalArgumentException e) {
+      return false;
+    }
+  }
+
+  private static boolean isValidInt(String value) {
+    try {
+      Integer.parseInt(value);
+      return true;
+    } catch (NumberFormatException e) {
+      return false;
+    }
+  }
+
+
+}