parser partial refactor

src/main/java/com/github/dtschust/zork/Zork.java

@@ -142,7 +142,7 @@ public class Zork {
                 for (String action : tempTrigger.action) {
                     d.dispatch(action);
                 }
-                skip = skip || tempTrigger.hasCommand;
+                skip = skip || tempTrigger.hasCommand();
                 if (tempTrigger.type.equals("single")) {
                     zorkObject.trigger.remove(x);
                 }

src/main/java/com/github/dtschust/zork/ZorkCommand.java

@@ -1,15 +1,14 @@
 package com.github.dtschust.zork;
 
 /* Special Command condition */
-public class ZorkCommand implements ZorkEvaluatable {
+public class ZorkCommand {
-    public final String command;
+    public final String commandName;
 
     public ZorkCommand(String command) {
-        this.command = command;
+        this.commandName = command;
     }
 
-    @Override
+    public boolean matchesInput(String userInput) {
-    public boolean evaluate(Zork zork) {
+        return commandName.equals(userInput);
-        return command.equals(zork.userInput);
     }
 }

src/main/java/com/github/dtschust/zork/ZorkCondition.java

@@ -3,7 +3,7 @@ package com.github.dtschust.zork;
 import com.github.dtschust.zork.parser.ZorkGame;
 
 /* Generic condition*/
-public abstract class ZorkCondition implements ZorkEvaluatable {
+public abstract class ZorkCondition {
     public final String object;
 
     protected ZorkCondition(String object) {
@@ -11,9 +11,4 @@ public abstract class ZorkCondition implements ZorkEvaluatable {
     }
 
     public abstract boolean evaluate(ZorkGame game);
-
-    @Override
-    public boolean evaluate(Zork zork) {
-        return this.evaluate(zork.game);
-    }
 }

src/main/java/com/github/dtschust/zork/ZorkConditionHas.java

@@ -31,7 +31,7 @@ public class ZorkConditionHas extends ZorkCondition {
             else {
                 ZorkContainer containerObject = (ZorkContainer) game.get("container", owner);
                 if (containerObject != null) {
-                    return evaluateCondition(containerObject.item.contains(object));
+                    return evaluateCondition(containerObject.containsItem(object));
                 }
             }
         }

src/main/java/com/github/dtschust/zork/ZorkEvaluatable.java

@@ -1,5 +0,0 @@
-package com.github.dtschust.zork;
-
-public interface ZorkEvaluatable {
-    boolean evaluate(Zork zork);
-}

src/main/java/com/github/dtschust/zork/ZorkTrigger.java

@@ -1,26 +1,36 @@
 package com.github.dtschust.zork;
 
-import java.util.ArrayList;
 import java.util.List;
 
 /*Trigger*/
 public class ZorkTrigger {
-    public final List<ZorkEvaluatable> conditions = new ArrayList<>();
+    private final List<ZorkCondition> conditions;
-    public final List<String> print = new ArrayList<>();
+    private final List<ZorkCommand> commands;
-    public final List<String> action = new ArrayList<>();
+    public final List<String> print;
-    public final String type; /*By default, single*/
+    public final List<String> action;
-    public boolean hasCommand = false;
+    /* By default, "single" */
+    public final String type;
 
-    public ZorkTrigger(String type) {
+    public boolean hasCommand() {
+        return !this.commands.isEmpty();
+    }
+
+    public ZorkTrigger(final String type,
+                       final List<ZorkCondition> conditions,
+                       final List<ZorkCommand> commands,
+                       final List<String> print,
+                       final List<String> action) {
+        this.conditions = conditions;
+        this.commands = commands;
+        this.print = print;
+        this.action = action;
         this.type = type;
     }
 
     public boolean evaluate(Zork zork) {
-        for (ZorkEvaluatable condition : conditions) {
+        if (!commands.stream().allMatch(c -> c.matchesInput(zork.userInput))) {
-            if (!condition.evaluate(zork)) {
+            return false;
-                return false;
-            }
         }
-        return true;
+        return conditions.stream().allMatch(c -> c.evaluate(zork.game));
     }
 }

src/main/java/com/github/dtschust/zork/parser/DOMUtils.java

@@ -0,0 +1,88 @@
+package com.github.dtschust.zork.parser;
+
+import org.w3c.dom.CharacterData;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import java.util.*;
+
+public final class DOMUtils {
+    private DOMUtils() {
+    }
+
+
+    /**
+     * Given a DOM element with one and only one child of text node type, returns the text as a string. If there is no
+     * such node, '?' is returned
+     * Get a string from an element (XML parsing stuff)
+     *
+     * @param e the element
+     * @return the text as string, or '?'
+     */
+    public static String getInnerText(final Element e) {
+        final Node child = e.getFirstChild();
+        return child instanceof CharacterData ? ((CharacterData) child).getData() : "?";
+    }
+
+    public static String getInnerTextByTagName(final Element element, final String elementName) {
+        return getInnerTextByTagName(element, elementName, Optional.empty());
+    }
+
+    public static String getInnerTextByTagName(final Element element,
+                                               final String name,
+                                               final String defaultValue) {
+        return getInnerTextByTagName(element, name, Optional.of(defaultValue));
+    }
+
+    public static String getInnerTextByTagName(final Element element,
+                                               final String elementName,
+                                               final Optional<String> defaultValue) {
+        final NodeList field = element.getElementsByTagName(elementName);
+
+        if (field.getLength() == 0) {
+            return defaultValue.orElseThrow(() ->
+                    new IllegalArgumentException(elementName + " element count in container is not 1"));
+        }
+
+        final Node first = field.item(0);
+        if (!(first instanceof Element)) {
+            // the contract of getElementsByTagName states that it returns a list of Element objects
+            throw new IllegalStateException("unreachable");
+        }
+
+        return getInnerText((Element) first);
+    }
+
+    // the isInstance check assures the cast to T is safe, otherwise IllegalStateException is thrown
+    @SuppressWarnings("unchecked")
+    private static <T> Iterable<T> iterable(final NodeList nodeList, Class<T> type) {
+        return () -> new Iterator<>() {
+            private int index = 0;
+
+            @Override
+            public boolean hasNext() {
+                return index < nodeList.getLength();
+            }
+
+            @Override
+            public T next() {
+                if (!hasNext())
+                    throw new NoSuchElementException();
+                final Node next = nodeList.item(index++);
+                if (next == null || !type.isAssignableFrom(next.getClass())) {
+                    throw new IllegalStateException("Element in list is not of type " + type.getCanonicalName());
+                }
+                return (T) next;
+            }
+        };
+    }
+
+    static Iterable<Node> iterNodes(final NodeList nodeList) {
+        return iterable(nodeList, Node.class);
+    }
+
+    static Iterable<Element> iterator(final NodeList nodeList) {
+        return iterable(nodeList, Element.class);
+    }
+}

src/main/java/com/github/dtschust/zork/parser/ZorkReader.java

@@ -1,15 +1,24 @@
 package com.github.dtschust.zork.parser;
 
-import com.github.dtschust.zork.*;
+import com.github.dtschust.zork.ZorkCondition;
-import com.github.dtschust.zork.types.*;
+import com.github.dtschust.zork.ZorkTrigger;
-import org.w3c.dom.CharacterData;
+import com.github.dtschust.zork.parser.builders.Parsers;
+import com.github.dtschust.zork.parser.dom.Elements;
+import com.github.dtschust.zork.types.ZorkContainer;
+import com.github.dtschust.zork.types.ZorkCreature;
+import com.github.dtschust.zork.types.ZorkItem;
+import com.github.dtschust.zork.types.ZorkRoom;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
 import javax.xml.parsers.DocumentBuilderFactory;
 import java.io.File;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 public class ZorkReader {
 
@@ -19,21 +28,6 @@ public class ZorkReader {
         this.filename = filename;
     }
 
-    /* Get a string from an element (XML parsing stuff)*/
-    public static String getString(Element e) {
-        Node child = e.getFirstChild();
-        if (child instanceof CharacterData) {
-            CharacterData cd = (CharacterData) child;
-            return cd.getData();
-        }
-        return "?";
-    }
-
-    private static String getItemOrDefault(Element element, String name, String base) {
-        NodeList field = element.getElementsByTagName(name);
-        return (field.getLength() > 0) ? getString((Element) field.item(0)) : base;
-    }
-
     private static void addCreature(ZorkGame data, Element element) {
         final Set<String> vulnerabilities = new HashSet<>();
         final List<ZorkCondition> conditions = new ArrayList<>();
@@ -42,60 +36,47 @@ public class ZorkReader {
 
 
         NodeList attacks = element.getElementsByTagName("attack");
-        for (Element attack : iterElements(attacks)) {
+        for (Element attack : DOMUtils.iterator(attacks)) {
+            final List<ZorkCondition> conditionsList = Elements.byTagName(attack, "condition").stream()
+                    .map(Parsers.condition::parse)
+                    .collect(Collectors.toList());
+            conditions.addAll(conditionsList);
 
-            readConditionsInTrigger(attack, conditions);
+            for (Element print : DOMUtils.iterator(attack.getElementsByTagName("print"))) {
-
+                prints.add(DOMUtils.getInnerText(print));
-            for (Element print : iterElements(attack.getElementsByTagName("print"))) {
-                prints.add(getString(print));
             }
-            for (Element action : iterElements(attack.getElementsByTagName("action"))) {
+            for (Element action : DOMUtils.iterator(attack.getElementsByTagName("action"))) {
-                actions.add(getString(action));
+                actions.add(DOMUtils.getInnerText(action));
             }
         }
 
-        for (Element vuln : iterElements(element.getElementsByTagName("vulnerability"))) {
+        for (Element vuln : DOMUtils.iterator(element.getElementsByTagName("vulnerability"))) {
-            vulnerabilities.add(getString(vuln));
+            vulnerabilities.add(DOMUtils.getInnerText(vuln));
         }
 
         /* Get all possible creature attributes */
         ZorkCreature tempCreature = new ZorkCreature(
-                getItemOrDefault(element, "name", ""),
+                DOMUtils.getInnerTextByTagName(element, "name", ""),
-                getItemOrDefault(element, "description", ""),
+                DOMUtils.getInnerTextByTagName(element, "description", ""),
                 vulnerabilities,
                 conditions,
                 prints,
                 actions
         );
 
-        readTriggersInObject(element, tempCreature);
+        final List<ZorkTrigger> triggers = Elements.byTagName(element, "trigger").stream()
-        tempCreature.updateStatus(getItemOrDefault(element, "status", ""));
+                .map(Parsers.trigger::parse)
+                .collect(Collectors.toList());
+        tempCreature.trigger.addAll(triggers);
+
+        tempCreature.updateStatus(DOMUtils.getInnerTextByTagName(element, "status", ""));
 
         /* Put each creature in the creatures hashmap, the generic object hashmap, and the objectlookup hashmap*/
         data.addObjectThroughLookup("creature", tempCreature);
     }
 
     private static void addContainer(ZorkGame data, Element element) {
-        /*Get all possible container attributes*/
+        final ZorkContainer tempCont = Parsers.container.parse(element);
-        ZorkContainer tempCont = new ZorkContainer(
-                getItemOrDefault(element, "name", ""),
-                getItemOrDefault(element, "description", "")
-        );
-
-        readTriggersInObject(element, tempCont);
-        tempCont.updateStatus(getItemOrDefault(element, "status", ""));
-
-        /*Initially assume a closed container*/
-        for (Element accept : iterElements(element.getElementsByTagName("accept"))) {
-            /* If container has an accepts attribute, then it is always open*/
-            tempCont.open();
-            tempCont.accept.add(getString(accept));
-        }
-
-        for (Element item : iterElements(element.getElementsByTagName("item"))) {
-            String itemName = getString(item);
-            tempCont.item.add(itemName);
-        }
 
         /* Put each container in the containers hashmap, the generic object hashmap, and the objectlookup hashmap*/
         data.addObjectThroughLookup("container", tempCont);
@@ -107,139 +88,74 @@ public class ZorkReader {
 
         NodeList turnOn = element.getElementsByTagName("turnon");
         if (turnOn.getLength() > 0) {
-            for (Element print : iterElements(element.getElementsByTagName("print"))) {
+            for (Element print : DOMUtils.iterator(element.getElementsByTagName("print"))) {
-                prints.add(getString(print));
+                prints.add(DOMUtils.getInnerText(print));
             }
-            for (Element action : iterElements(element.getElementsByTagName("action"))) {
+            for (Element action : DOMUtils.iterator(element.getElementsByTagName("action"))) {
-                actions.add(getString(action));
+                actions.add(DOMUtils.getInnerText(action));
             }
         }
 
         /* Get all possible item attributes*/
         ZorkItem tempItem = new ZorkItem(
-                getItemOrDefault(element, "name", ""),
+                DOMUtils.getInnerTextByTagName(element, "name", ""),
-                getItemOrDefault(element, "description", ""),
+                DOMUtils.getInnerTextByTagName(element, "description", ""),
-                getItemOrDefault(element, "writing", ""),
+                DOMUtils.getInnerTextByTagName(element, "writing", ""),
                 prints,
                 actions
         );
 
-        readTriggersInObject(element, tempItem);
+        final List<ZorkTrigger> triggers = Elements.byTagName(element, "trigger").stream()
+                .map(Parsers.trigger::parse)
+                .collect(Collectors.toList());
+        tempItem.trigger.addAll(triggers);
 
         /* Put each item in the items hashmap, the generic objects hashmap, and store its type in object lookup */
         data.addObjectThroughLookup("item", tempItem);
-        tempItem.updateStatus(getItemOrDefault(element, "status", ""));
+        tempItem.updateStatus(DOMUtils.getInnerTextByTagName(element, "status", ""));
     }
 
     private static void addRoom(ZorkGame data, Element element) {
 
         /*Get all possible Room attributes*/
         ZorkRoom tempRoom = new ZorkRoom(
-                getItemOrDefault(element, "name", ""),
+                DOMUtils.getInnerTextByTagName(element, "name", ""),
-                getItemOrDefault(element, "description", ""),
+                DOMUtils.getInnerTextByTagName(element, "description", ""),
-                getItemOrDefault(element, "type", "regular")
+                DOMUtils.getInnerTextByTagName(element, "type", "regular")
         );
 
-        readTriggersInObject(element, tempRoom);
+        final List<ZorkTrigger> triggers = Elements.byTagName(element, "trigger").stream()
-        tempRoom.updateStatus(getItemOrDefault(element, "status", ""));
+                .map(Parsers.trigger::parse)
+                .collect(Collectors.toList());
+        tempRoom.trigger.addAll(triggers);
 
-        for (Element item : iterElements(element.getElementsByTagName("item"))) {
+        tempRoom.updateStatus(DOMUtils.getInnerTextByTagName(element, "status", ""));
-            String itemName = getString(item);
+
+        for (Element item : DOMUtils.iterator(element.getElementsByTagName("item"))) {
+            String itemName = DOMUtils.getInnerText(item);
             tempRoom.item.add(itemName);
         }
 
-        for (Element creature : iterElements(element.getElementsByTagName("creature"))) {
+        for (Element creature : DOMUtils.iterator(element.getElementsByTagName("creature"))) {
-            String creatureName = getString(creature);
+            String creatureName = DOMUtils.getInnerText(creature);
             tempRoom.creature.add(creatureName);
         }
 
-        for (Element container : iterElements(element.getElementsByTagName("container"))) {
+        for (Element container : DOMUtils.iterator(element.getElementsByTagName("container"))) {
-            String containerName = getString(container);
+            String containerName = DOMUtils.getInnerText(container);
             tempRoom.container.add(containerName);
         }
 
-        for (Element border : iterElements(element.getElementsByTagName("border"))) {
+        for (Element border : DOMUtils.iterator(element.getElementsByTagName("border"))) {
-            String borderDirection = getString((Element) border.getElementsByTagName("direction").item(0));
+            String borderDirection = DOMUtils.getInnerText((Element) border.getElementsByTagName("direction").item(0));
-            String borderName = getString((Element) border.getElementsByTagName("name").item(0));
+            String borderName = DOMUtils.getInnerText((Element) border.getElementsByTagName("name").item(0));
             tempRoom.border.put(borderDirection, borderName);
         }
         /*Add this room to the rooms hashmap, put it in the generic objects hashmap, and store it's type in the objectlookup hashmap*/
         data.addObjectThroughLookup("room", tempRoom);
     }
 
-    private static void readTriggersInObject(Element element, ZorkObject tempRoom) {
-        for (Element trigger : iterElements(element.getElementsByTagName("trigger"))) {
-            ZorkTrigger tempTrigger = new ZorkTrigger(getItemOrDefault(element, "type", "single"));
-            for (Element command : iterElements(trigger.getElementsByTagName("command"))) {
-                ZorkCommand tempCommand = new ZorkCommand(getString(command));
-                tempTrigger.conditions.add(tempCommand);
-                tempTrigger.hasCommand = true;
-            }
-
-            readConditionsInTrigger(trigger, tempTrigger.conditions);
-
-            for (Element print : iterElements(trigger.getElementsByTagName("print"))) {
-                tempTrigger.print.add(getString(print));
-            }
-            for (Element action : iterElements(trigger.getElementsByTagName("action"))) {
-                tempTrigger.action.add(getString(action));
-            }
-
-            tempRoom.trigger.add(tempTrigger);
-        }
-    }
-
-    private static void readConditionsInTrigger(Element trigger, List<? super ZorkCondition> conditionsList) {
-        for (Element condition : iterElements(trigger.getElementsByTagName("condition"))) {
-            NodeList object = condition.getElementsByTagName("object");
-            NodeList has = condition.getElementsByTagName("has");
-            if (has.getLength() > 0) {
-                NodeList owner = condition.getElementsByTagName("owner");
-                ZorkConditionHas tempConditionHas = new ZorkConditionHas(
-                        getString((Element) has.item(0)),
-                        getString((Element) object.item(0)),
-                        getString((Element) owner.item(0))
-                );
-                conditionsList.add(tempConditionHas);
-            } else {
-                NodeList sstatus = condition.getElementsByTagName("status");
-                ZorkConditionStatus tempConditionStatus = new ZorkConditionStatus(
-                        getString((Element) sstatus.item(0)),
-                        getString((Element) object.item(0))
-                );
-                conditionsList.add(tempConditionStatus);
-            }
-        }
-    }
-
-    private static <T> Iterable<T> iterable(final NodeList nodeList) {
-        return () -> new Iterator<>() {
-            private int index = 0;
-
-            @Override
-            public boolean hasNext() {
-                return index < nodeList.getLength();
-            }
-
-            @Override
-            public T next() {
-                if (!hasNext())
-                    throw new NoSuchElementException();
-                return (T) nodeList.item(index++);
-            }
-        };
-    }
-
-    private static Iterable<Node> iterNodes(final NodeList nodeList) {
-        return iterable(nodeList);
-    }
-
-    private static Iterable<Element> iterElements(final NodeList nodeList) {
-        return iterable(nodeList);
-    }
-
     public ZorkGame build() {
-
         ZorkGame data = new ZorkGame();
 
         File file = new File(filename);
@@ -259,7 +175,7 @@ public class ZorkReader {
             Element rootElement = builder.newDocumentBuilder().parse(file).getDocumentElement();
 
             /* Every single first generation child is a room, container, creature, or item.  So load them in*/
-            for (Node node : iterNodes(rootElement.getChildNodes())) {
+            for (Node node : DOMUtils.iterNodes(rootElement.getChildNodes())) {
                 Element element;
                 if (node instanceof Element) {
                     element = (Element) node;
@@ -287,6 +203,7 @@ public class ZorkReader {
                 }
             }
         } catch (Exception e) {
+            e.printStackTrace();
             System.out.println("Invalid XML file, exiting");
             System.exit(-1);
             //e.printStackTrace();

src/main/java/com/github/dtschust/zork/parser/builders/Parsers.java

@@ -0,0 +1,18 @@
+package com.github.dtschust.zork.parser.builders;
+
+import com.github.dtschust.zork.ZorkCondition;
+import com.github.dtschust.zork.ZorkTrigger;
+import com.github.dtschust.zork.types.ZorkContainer;
+
+/**
+ * Inversion of control for Zork parse strategies
+ */
+public final class Parsers {
+    public static final ZorkParseStrategy<ZorkCondition> condition = new ZorkConditionParseStrategy();
+    public static final ZorkParseStrategy<ZorkTrigger> trigger = new ZorkTriggerListParseStrategy(condition);
+    public static final ZorkParseStrategy<ZorkContainer> container = new ZorkContainerParseStrategy(trigger);
+
+    private Parsers() {
+
+    }
+}

src/main/java/com/github/dtschust/zork/parser/builders/ZorkConditionParseStrategy.java

@@ -0,0 +1,25 @@
+package com.github.dtschust.zork.parser.builders;
+
+import com.github.dtschust.zork.ZorkCondition;
+import com.github.dtschust.zork.ZorkConditionHas;
+import com.github.dtschust.zork.ZorkConditionStatus;
+import com.github.dtschust.zork.parser.DOMUtils;
+import org.w3c.dom.Element;
+
+public class ZorkConditionParseStrategy implements ZorkParseStrategy<ZorkCondition> {
+    @Override
+    public ZorkCondition parse(final Element conditionElement) {
+        if (conditionElement.getElementsByTagName("has").getLength() > 0) {
+            return new ZorkConditionHas(
+                    DOMUtils.getInnerTextByTagName(conditionElement, "has"),
+                    DOMUtils.getInnerTextByTagName(conditionElement, "object"),
+                    DOMUtils.getInnerTextByTagName(conditionElement, "owner")
+            );
+        } else {
+            return new ZorkConditionStatus(
+                    DOMUtils.getInnerTextByTagName(conditionElement, "status"),
+                    DOMUtils.getInnerTextByTagName(conditionElement, "object")
+            );
+        }
+    }
+}

src/main/java/com/github/dtschust/zork/parser/builders/ZorkContainerParseStrategy.java

@@ -0,0 +1,40 @@
+package com.github.dtschust.zork.parser.builders;
+
+import com.github.dtschust.zork.ZorkTrigger;
+import com.github.dtschust.zork.parser.DOMUtils;
+import com.github.dtschust.zork.parser.dom.Elements;
+import com.github.dtschust.zork.types.ZorkContainer;
+import org.w3c.dom.Element;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ZorkContainerParseStrategy implements ZorkParseStrategy<ZorkContainer> {
+    private final ZorkParseStrategy<ZorkTrigger> triggerStrategy;
+
+    public ZorkContainerParseStrategy(ZorkParseStrategy<ZorkTrigger> triggerStrategy) {
+        this.triggerStrategy = triggerStrategy;
+    }
+
+    @Override
+    public ZorkContainer parse(final Element element) {
+        final String name = DOMUtils.getInnerTextByTagName(element, "name", "");
+
+        final String description = DOMUtils.getInnerTextByTagName(element, "description", "");
+
+        final List<ZorkTrigger> triggers = Elements.byTagName(element, "trigger").stream()
+                .map(triggerStrategy::parse)
+                .collect(Collectors.toList());
+
+        final String status = DOMUtils.getInnerTextByTagName(element, "status", "");
+
+        final List<String> accepts = Elements.innerTextByTagName(element, "accept");
+
+        // If a container has an accepts attribute, then it is always open
+        final boolean open = !accepts.isEmpty();
+
+        final List<String> items = Elements.innerTextByTagName(element, "item");
+
+        return new ZorkContainer(name, description, open, status, items, accepts, triggers);
+    }
+}

src/main/java/com/github/dtschust/zork/parser/builders/ZorkParseStrategy.java

@@ -0,0 +1,7 @@
+package com.github.dtschust.zork.parser.builders;
+
+import org.w3c.dom.Element;
+
+public interface ZorkParseStrategy<T> {
+    T parse(Element source);
+}

src/main/java/com/github/dtschust/zork/parser/builders/ZorkTriggerListParseStrategy.java

@@ -0,0 +1,41 @@
+package com.github.dtschust.zork.parser.builders;
+
+import com.github.dtschust.zork.ZorkCommand;
+import com.github.dtschust.zork.ZorkCondition;
+import com.github.dtschust.zork.ZorkTrigger;
+import com.github.dtschust.zork.parser.DOMUtils;
+import com.github.dtschust.zork.parser.dom.Elements;
+import org.w3c.dom.Element;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class ZorkTriggerListParseStrategy implements ZorkParseStrategy<ZorkTrigger> {
+
+    private final ZorkParseStrategy<ZorkCondition> conditionStrategy;
+
+    public ZorkTriggerListParseStrategy(final ZorkParseStrategy<ZorkCondition> conditionStrategy) {
+        this.conditionStrategy = conditionStrategy;
+    }
+
+    @Override
+    public ZorkTrigger parse(final Element trigger) {
+        final String type = DOMUtils.getInnerTextByTagName((Element) trigger.getParentNode(), "type", "single");
+
+        final List<ZorkCommand> commands = Elements.byTagName(trigger, "command").stream()
+                .map(DOMUtils::getInnerText)
+                .map(ZorkCommand::new)
+                .collect(Collectors.toList());
+
+        final boolean hasCommand = !commands.isEmpty();
+
+        final List<ZorkCondition> conditions = Elements.byTagName(trigger, "condition").stream()
+                .map(conditionStrategy::parse)
+                .collect(Collectors.toList());
+
+        final List<String> prints = Elements.innerTextByTagName(trigger, "print");
+        final List<String> actions = Elements.innerTextByTagName(trigger, "action");
+
+        return new ZorkTrigger(type, conditions, commands, prints, actions);
+    }
+}

src/main/java/com/github/dtschust/zork/parser/dom/Elements.java

@@ -0,0 +1,44 @@
+package com.github.dtschust.zork.parser.dom;
+
+import com.github.dtschust.zork.parser.DOMUtils;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import java.util.AbstractList;
+import java.util.List;
+import java.util.RandomAccess;
+import java.util.stream.Collectors;
+
+public class Elements extends AbstractList<Element> implements RandomAccess {
+    private final NodeList list;
+
+    public static Elements byTagName(final Element parent, final String name) {
+        return new Elements(parent.getElementsByTagName(name));
+    }
+
+    public static List<String> innerTextByTagName(final Element parent, final String name) {
+        return Elements.byTagName(parent, name).stream()
+                .map(DOMUtils::getInnerText)
+                .collect(Collectors.toList());
+    }
+
+    private Elements(final NodeList l) {
+        list = l;
+    }
+
+    @Override
+    public Element get(int index) {
+        final Node e = list.item(index);
+        if (!(e instanceof Element)) {
+            // the contract of getElementsByTagName states that it returns a list of Element objects
+            throw new IllegalStateException("unreachable");
+        }
+        return (Element) e;
+    }
+
+    @Override
+    public int size() {
+        return list.getLength();
+    }
+}

src/main/java/com/github/dtschust/zork/types/ZorkContainer.java

@@ -1,20 +1,43 @@
 package com.github.dtschust.zork.types;
 
-import java.util.ArrayList;
+import com.github.dtschust.zork.ZorkTrigger;
-import java.util.HashSet;
+
-import java.util.List;
+import java.util.*;
-import java.util.Set;
 
 /* Container*/
 public class ZorkContainer extends ZorkObject {
-    public final Set<String> item = new HashSet<>();
+    public final Set<String> item;
-    public final List<String> accept = new ArrayList<>();
+    private final List<String> accepts;
-    protected boolean open = false;
+    private boolean open;
 
-    public ZorkContainer(String name, String description) {
+    public ZorkContainer(final String name,
-        super(name, description);
+                         final String description,
+                         final boolean open,
+                         final String status,
+                         final Collection<String> items,
+                         final Collection<String> accepts,
+                         final Collection<ZorkTrigger> triggers) {
+        super(name, description, status, triggers);
+        this.open = open;
+        this.item = new HashSet<>(items);
+        this.accepts = new ArrayList<>(accepts);
     }
 
+    public void addItem(final String item) {
+        this.item.add(item);
+    }
+
+    public void removeItem(final String item) {
+        this.item.remove(item);
+    }
+
+    public boolean containsItem(final String item) {
+        return this.item.contains(item);
+    }
+
+    public boolean isEmpty() {
+        return this.item.isEmpty();
+    }
 
     public boolean isOpen() {
         return open;
@@ -23,5 +46,4 @@ public class ZorkContainer extends ZorkObject {
     public void open() {
         open = true;
     }
-
 }

src/main/java/com/github/dtschust/zork/types/ZorkObject.java

@@ -3,20 +3,32 @@ package com.github.dtschust.zork.types;
 import com.github.dtschust.zork.ZorkTrigger;
 
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 /* Generic object, everything inherits from this*/
 public abstract class ZorkObject {
     public final String name;
     public final String description;
-    public final List<ZorkTrigger> trigger = new ArrayList<>();
+    public final List<ZorkTrigger> trigger;
     private String status;
 
     protected ZorkObject(String name, String description) {
+        this(name, description, null, Collections.emptyList());
+    }
+
+    protected ZorkObject(final String name,
+                         final String description,
+                         final String status,
+                         final Collection<ZorkTrigger> triggers) {
         this.name = name;
         this.description = description;
+        this.status = status;
+        this.trigger = new ArrayList<>(triggers);
     }
 
+
     public void updateStatus(String status) {
         this.status = status;
     }