Merge branch 'inference-rules-engine'

easy-rules-core/src/main/java/org/jeasy/rules/core/DefaultRulesEngine.java

@@ -121,7 +121,7 @@ public Map<Rule, Boolean> check(Rules rules, Facts facts) {
         return result;
     }
 
-    private void apply(Rules rules, Facts facts) {
+    void apply(Rules rules, Facts facts) {
         LOGGER.info("Rules evaluation started");
         for (Rule rule : rules) {
             final String name = rule.getName();

easy-rules-core/src/main/java/org/jeasy/rules/core/InferenceRulesEngine.java

@@ -0,0 +1,113 @@
+/**
+ * The MIT License
+ *
+ *  Copyright (c) 2017, Mahmoud Ben Hassine ([email protected])
+ *
+ *  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 org.jeasy.rules.core;
+
+import org.jeasy.rules.api.*;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.*;
+
+/**
+ * Inference {@link RulesEngine} implementation.
+ *
+ * Rules are selected based on given facts and fired according to their natural order which is priority by default.
+ *
+ * The engine continuously select and fire rules until no more rules are applicable.
+ *
+ * @author Mahmoud Ben Hassine ([email protected])
+ */
+public final class InferenceRulesEngine implements RulesEngine {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(InferenceRulesEngine.class);
+
+    private RulesEngineParameters parameters;
+    private List<RuleListener> ruleListeners;
+    private DefaultRulesEngine delegate;
+
+    /**
+     * Create a new inference rules engine with default parameters.
+     */
+    public InferenceRulesEngine() {
+        this(new RulesEngineParameters());
+    }
+
+    /**
+     * Create a new inference rules engine.
+     * @param parameters of the engine
+     */
+    public InferenceRulesEngine(RulesEngineParameters parameters) {
+        this(parameters, new ArrayList<RuleListener>());
+    }
+
+    /**
+     * Create a new inference rules engine.
+     * @param parameters of the engine
+     * @param ruleListeners to apply for each rule
+     */
+    public InferenceRulesEngine(RulesEngineParameters parameters, List<RuleListener> ruleListeners) {
+        this.parameters = parameters;
+        this.ruleListeners = ruleListeners;
+        delegate = new DefaultRulesEngine(parameters, ruleListeners);
+    }
+
+    @Override
+    public RulesEngineParameters getParameters() {
+        return parameters;
+    }
+
+    @Override
+    public List<RuleListener> getRuleListeners() {
+        return ruleListeners;
+    }
+
+    @Override
+    public void fire(Rules rules, Facts facts) {
+        Set<Rule> selectedRules;
+        do {
+            LOGGER.info("Selecting candidate rules based on the following {}", facts);
+            selectedRules = selectCandidates(rules, facts);
+            if(!selectedRules.isEmpty()) {
+                delegate.apply(new Rules(selectedRules), facts);
+            } else {
+                LOGGER.info("No candidate rules found for {}", facts);
+            }
+        } while (!selectedRules.isEmpty());
+    }
+
+    private Set<Rule> selectCandidates(Rules rules, Facts facts) {
+        Set<Rule> candidates = new TreeSet<>();
+        for (Rule rule : rules) {
+            if (rule.evaluate(facts)) {
+                candidates.add(rule);
+            }
+        }
+        return candidates;
+    }
+
+    @Override
+    public Map<Rule, Boolean> check(Rules rules, Facts facts) {
+        return delegate.check(rules, facts);
+    }
+}

easy-rules-core/src/main/java/org/jeasy/rules/core/RulesEngineParameters.java

@@ -24,8 +24,13 @@
 package org.jeasy.rules.core;
 
 /**
- * Parameters of the rules engine.
- * 
+ * Parameters of a rules engine.
+ *
+ * <ul>
+ *     <li>When parameters are used with a {@link DefaultRulesEngine}, they are applied on all registered rules.</li>
+ *     <li>When parameters are used with a {@link InferenceRulesEngine}, they are applied on candidate rules in each iteration.</li>
+ * </ul>
+ *
  * @author Mahmoud Ben Hassine ([email protected])
  */
 public class RulesEngineParameters {

easy-rules-core/src/test/java/org/jeasy/rules/core/InferenceRulesEngineTest.java

@@ -0,0 +1,138 @@
+/**
+ * The MIT License
+ *
+ *  Copyright (c) 2017, Mahmoud Ben Hassine ([email protected])
+ *
+ *  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 org.jeasy.rules.core;
+
+import org.jeasy.rules.annotation.*;
+import org.jeasy.rules.api.Facts;
+import org.jeasy.rules.api.Rules;
+import org.jeasy.rules.api.RulesEngine;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class InferenceRulesEngineTest {
+
+    @Test
+    public void testCandidateSelection() throws Exception {
+        // Given
+        Facts facts = new Facts();
+        facts.put("foo", true);
+        DummyRule dummyRule = new DummyRule();
+        AnotherDummyRule anotherDummyRule = new AnotherDummyRule();
+        Rules rules = new Rules(dummyRule, anotherDummyRule);
+        RulesEngine rulesEngine = new InferenceRulesEngine();
+
+        // When
+        rulesEngine.fire(rules, facts);
+
+        // Then
+        assertThat(dummyRule.isExecuted()).isTrue();
+        assertThat(anotherDummyRule.isExecuted()).isFalse();
+    }
+
+    @Test
+    public void testCandidateOrdering() throws Exception {
+        // Given
+        Facts facts = new Facts();
+        facts.put("foo", true);
+        facts.put("bar", true);
+        DummyRule dummyRule = new DummyRule();
+        AnotherDummyRule anotherDummyRule = new AnotherDummyRule();
+        Rules rules = new Rules(dummyRule, anotherDummyRule);
+        RulesEngine rulesEngine = new InferenceRulesEngine();
+
+        // When
+        rulesEngine.fire(rules, facts);
+
+        // Then
+        assertThat(dummyRule.isExecuted()).isTrue();
+        assertThat(anotherDummyRule.isExecuted()).isTrue();
+        assertThat(dummyRule.getTimestamp()).isLessThanOrEqualTo(anotherDummyRule.getTimestamp());
+    }
+
+    @Rule
+    class DummyRule {
+
+        private boolean isExecuted;
+        private long timestamp;
+
+        @Condition
+        public boolean when(@Fact("foo") boolean foo) {
+            return foo;
+        }
+
+        @Action
+        public void then(Facts facts) {
+            isExecuted = true;
+            timestamp = System.currentTimeMillis();
+            facts.remove("foo");
+        }
+
+        @Priority
+        public int priority() {
+            return 1;
+        }
+
+        public boolean isExecuted() {
+            return isExecuted;
+        }
+
+        public long getTimestamp() {
+            return timestamp;
+        }
+    }
+
+    @Rule
+    class AnotherDummyRule {
+
+        private boolean isExecuted;
+        private long timestamp;
+
+        @Condition
+        public boolean when(@Fact("bar") boolean bar) {
+            return bar;
+        }
+
+        @Action
+        public void then(Facts facts) {
+            isExecuted = true;
+            timestamp = System.currentTimeMillis();
+            facts.remove("bar");
+        }
+
+        @Priority
+        public int priority() {
+            return 2;
+        }
+
+        public boolean isExecuted() {
+            return isExecuted;
+        }
+
+        public long getTimestamp() {
+            return timestamp;
+        }
+    }
+
+}

easy-rules-tutorials/pom.xml

@@ -18,6 +18,7 @@
         <maven-war-plugin.version>2.6</maven-war-plugin.version>
         <tomcat7-maven-plugin.version>2.2</tomcat7-maven-plugin.version>
         <maven-dependency-plugin.version>2.10</maven-dependency-plugin.version>
+        <slf4j.version>1.7.25</slf4j.version>
     </properties>
 
     <scm>
@@ -63,6 +64,13 @@
             <version>${project.version}</version>
         </dependency>
 
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j.version}</version>
+        </dependency>
+
+
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>
@@ -141,6 +149,50 @@
                 </plugins>
             </build>
         </profile>
+        <profile>
+            <id>runWeatherTutorial</id>
+            <build>
+                <defaultGoal>exec:java</defaultGoal>
+                <plugins>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>exec-maven-plugin</artifactId>
+                        <version>${maven-exec-plugin.version}</version>
+                        <configuration>
+                            <mainClass>org.jeasy.rules.tutorials.weather.Launcher</mainClass>
+                            <systemProperties>
+                                <systemProperty>
+                                    <key>java.util.logging.SimpleFormatter.format</key>
+                                    <value>[%1$tc] %4$s: %5$s%n</value>
+                                </systemProperty>
+                            </systemProperties>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+        <profile>
+            <id>runAircoTutorial</id>
+            <build>
+                <defaultGoal>exec:java</defaultGoal>
+                <plugins>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>exec-maven-plugin</artifactId>
+                        <version>${maven-exec-plugin.version}</version>
+                        <configuration>
+                            <mainClass>org.jeasy.rules.tutorials.airco.Launcher</mainClass>
+                            <systemProperties>
+                                <systemProperty>
+                                    <key>java.util.logging.SimpleFormatter.format</key>
+                                    <value>[%1$tc] %4$s: %5$s%n</value>
+                                </systemProperty>
+                            </systemProperties>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
         <profile>
             <id>runShopTutorial</id>
             <build>

easy-rules-tutorials/src/main/java/org/jeasy/rules/tutorials/airco/AirConditioningRule.java

@@ -0,0 +1,24 @@
+package org.jeasy.rules.tutorials.airco;
+
+import org.jeasy.rules.annotation.Action;
+import org.jeasy.rules.annotation.Condition;
+import org.jeasy.rules.annotation.Fact;
+import org.jeasy.rules.annotation.Rule;
+import org.jeasy.rules.api.Facts;
+
+@Rule(name = "air conditioning rule", description = "if it is hot, decrease temperature" )
+public class AirConditioningRule {
+
+    @Condition
+    public boolean isItHot(@Fact("temperature") int temperature) {
+        return temperature > 25;
+    }
+
+    @Action
+    public void coolAir(Facts facts) {
+        System.out.println("It is hot! cooling air..");
+        Integer temperature = (Integer) facts.get("temperature");
+        facts.put("temperature", temperature - 1);
+    }
+
+}