001 package aima.basic;
002
003 import java.util.ArrayList;
004 import java.util.List;
005
006 /**
007 * Artificial Intelligence A Modern Approach (2nd Edition): page 32.
008 *
009 * Environment.
010 */
011
012 /**
013 * @author Ravi Mohan
014 *
015 */
016 public abstract class Environment {
017
018 protected ArrayList<EnvironmentObject> objects;
019
020 protected ArrayList<Agent> agents;
021
022 protected ArrayList<BasicEnvironmentView> views;
023
024 public abstract void executeAction(Agent a, String act);
025
026 public abstract Percept getPerceptSeenBy(Agent anAgent);
027
028 protected Environment() {
029 agents = new ArrayList<Agent>();
030 objects = new ArrayList<EnvironmentObject>();
031 views = new ArrayList<BasicEnvironmentView>();
032 }
033
034 public void registerView(BasicEnvironmentView bev) {
035 views.add(bev);
036 }
037
038 public void updateViews(String command) {
039
040 for (BasicEnvironmentView view : views) {
041 view.envChanged(command);
042 }
043 }
044
045 public boolean isDone() {
046
047 for (Agent agent : agents) {
048 if (agent.isAlive()) {
049 return false;
050 }
051 }
052
053 return true;
054 }
055
056 public void createExogenousChange() {
057
058 }
059
060 public void step() {
061 if (!(this.isDone())) {
062
063 for (Agent agent : agents) {
064
065 String anAction = agent.execute(this.getPerceptSeenBy(agent));
066
067 updateViews(anAction);
068 this.executeAction(agent, anAction);
069 }
070 this.createExogenousChange();
071 }
072 }
073
074 public void step(int n) {
075
076 for (int i = 0; i < n; i++) {
077
078 step();
079
080 }
081 }
082
083 public void stepUntilDone() {
084 while (!(this.isDone())) {
085 step();
086 }
087 }
088
089 public ArrayList getAgents() {
090 return agents;
091 }
092
093 public ArrayList getObjects() {
094 return objects;
095 }
096
097 public boolean alreadyContains(EnvironmentObject o) {
098
099 boolean retval = false;
100
101 for (EnvironmentObject eo : objects) {
102 if (eo.equals(o)) {
103 retval = true;
104 }
105 }
106
107 return retval;
108 }
109
110 public boolean alreadyContains(Agent anAgent) {
111 boolean retval = false;
112 for (Agent agent : agents) {
113 if (agent.equals(anAgent)) {
114 retval = true;
115 }
116 }
117 return retval;
118 }
119
120 public void addAgent(Agent a, String attributeName, Object attributeValue) {
121 if (!(alreadyContains(a))) {
122 a.setAttribute(attributeName, attributeValue);
123 agents.add(a);
124 }
125 }
126
127 public void addObject(EnvironmentObject o, String attributeName,
128 Object attributeValue) {
129 if (!(alreadyContains(o))) {
130 o.setAttribute(attributeName, attributeValue);
131 objects.add(o);
132 }
133 }
134
135 public void addObject(EnvironmentObject o) {
136 if (!(alreadyContains(o))) {
137 objects.add(o);
138 }
139 }
140
141 public void addAgent(Agent a) {
142 if (!(alreadyContains(a))) {
143 agents.add(a);
144 }
145 }
146
147 public List<ObjectWithDynamicAttributes> getAllObjects() {
148 List<ObjectWithDynamicAttributes> l = new ArrayList<ObjectWithDynamicAttributes>();
149 l.addAll(objects);
150 l.addAll(agents);
151 return l;
152 }
153
154 }