Add MatchRegistry for custom match implementations. (#390)

* Replace MatchType in favor of MatchRegistry
* Add conditionValue to Match#match interface.
* Remove the abstract AttributeMatch class.
* Remove ExactNumberMatch class.
* Add NumberComparator for standardizing Number comparisons
* Refactor Semantic Versioning to use static convenience method

Incorporating a public MatchRegistry will allow consumers to provide their own implementations of the Match interface.

Author: Mike Davis

core-api/src/main/java/com/optimizely/ab/config/audience/UserAttribute.java

@@ -20,10 +20,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.optimizely.ab.config.ProjectConfig;
-import com.optimizely.ab.config.audience.match.Match;
-import com.optimizely.ab.config.audience.match.MatchType;
-import com.optimizely.ab.config.audience.match.UnexpectedValueTypeException;
-import com.optimizely.ab.config.audience.match.UnknownMatchTypeException;
+import com.optimizely.ab.config.audience.match.*;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -87,35 +84,36 @@ public Boolean evaluate(ProjectConfig config, Map<String, ?> attributes) {
         }
         // check user attribute value is equal
         try {
-            Match matchType = MatchType.getMatchType(match, value).getMatcher();
-            Boolean result = matchType.eval(userAttributeValue);
-
+            Match matcher = MatchRegistry.getMatch(match);
+            Boolean result = matcher.eval(value, userAttributeValue);
             if (result == null) {
-                if (!attributes.containsKey(name)) {
-                    //Missing attribute value
-                    logger.debug("Audience condition \"{}\" evaluated to UNKNOWN because no value was passed for user attribute \"{}\"", this, name);
+                throw new UnknownValueTypeException();
+            }
+
+            return result;
+        } catch(UnknownValueTypeException e) {
+            if (!attributes.containsKey(name)) {
+                //Missing attribute value
+                logger.debug("Audience condition \"{}\" evaluated to UNKNOWN because no value was passed for user attribute \"{}\"", this, name);
+            } else {
+                //if attribute value is not valid
+                if (userAttributeValue != null) {
+                    logger.warn(
+                        "Audience condition \"{}\" evaluated to UNKNOWN because a value of type \"{}\" was passed for user attribute \"{}\"",
+                        this,
+                        userAttributeValue.getClass().getCanonicalName(),
+                        name);
                 } else {
-                    //if attribute value is not valid
-                    if (userAttributeValue != null) {
-                        logger.warn(
-                            "Audience condition \"{}\" evaluated to UNKNOWN because a value of type \"{}\" was passed for user attribute \"{}\"",
-                            this,
-                            userAttributeValue.getClass().getCanonicalName(),
-                            name);
-                    } else {
-                        logger.debug(
-                            "Audience condition \"{}\" evaluated to UNKNOWN because a null value was passed for user attribute \"{}\"",
-                            this,
-                            name);
-                    }
+                    logger.debug(
+                        "Audience condition \"{}\" evaluated to UNKNOWN because a null value was passed for user attribute \"{}\"",
+                        this,
+                        name);
                 }
             }
-            return result;
-        } catch (UnknownMatchTypeException | UnexpectedValueTypeException ex) {
-            logger.warn("Audience condition \"{}\" " + ex.getMessage(),
-                this);
-        } catch (NullPointerException np) {
-            logger.error("attribute or value null for match {}", match != null ? match : "legacy condition", np);
+        } catch (UnknownMatchTypeException | UnexpectedValueTypeException e) {
+            logger.warn("Audience condition \"{}\" " + e.getMessage(), this);
+        } catch (NullPointerException e) {
+            logger.error("attribute or value null for match {}", match != null ? match : "legacy condition", e);
         }
         return null;
     }

core-api/src/main/java/com/optimizely/ab/config/audience/match/DefaultMatchForLegacyAttributes.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -21,17 +21,16 @@
 /**
  * This is a temporary class.  It mimics the current behaviour for
  * legacy custom attributes.  This will be dropped for ExactMatch and the unit tests need to be fixed.
- * @param <T>
  */
-class DefaultMatchForLegacyAttributes<T> extends AttributeMatch<T> {
-    T value;
-
-    protected DefaultMatchForLegacyAttributes(T value) {
-        this.value = value;
-    }
-
+class DefaultMatchForLegacyAttributes implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        return value.equals(castToValueType(attributeValue, value));
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnexpectedValueTypeException {
+        if (!(conditionValue instanceof String)) {
+            throw new UnexpectedValueTypeException();
+        }
+        if (attributeValue == null) {
+            return false;
+        }
+        return conditionValue.toString().equals(attributeValue.toString());
     }
 }

core-api/src/main/java/com/optimizely/ab/config/audience/match/ExactMatch.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -18,18 +18,31 @@
 
 import javax.annotation.Nullable;
 
-class ExactMatch<T> extends AttributeMatch<T> {
-    T value;
-
-    protected ExactMatch(T value) {
-        this.value = value;
-    }
+import static com.optimizely.ab.internal.AttributesUtil.isValidNumber;
 
+/**
+ * ExactMatch supports matching Numbers, Strings and Booleans. Numbers are first converted to doubles
+ * before the comparison is evaluated. See {@link NumberComparator} Strings and Booleans are evaulated
+ * via the Object equals method.
+ */
+class ExactMatch implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        T converted = castToValueType(attributeValue, value);
-        if (value != null && converted == null) return null;
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnexpectedValueTypeException {
+        if (isValidNumber(attributeValue)) {
+            if (isValidNumber(conditionValue)) {
+                return NumberComparator.compareUnsafe(attributeValue, conditionValue) == 0;
+            }
+            return null;
+        }
+
+        if (!(conditionValue instanceof String || conditionValue instanceof Boolean)) {
+            throw new UnexpectedValueTypeException();
+        }
+
+        if (attributeValue == null || attributeValue.getClass() != conditionValue.getClass()) {
+            return null;
+        }
 
-        return value == null ? attributeValue == null : value.equals(converted);
+        return conditionValue.equals(attributeValue);
     }
 }

core-api/src/main/java/com/optimizely/ab/config/audience/match/ExactNumberMatch.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -16,20 +16,14 @@
  */
 package com.optimizely.ab.config.audience.match;
 
-import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
-
 import javax.annotation.Nullable;
 
+/**
+ * ExistsMatch checks that the attribute value is NOT null.
+ */
 class ExistsMatch implements Match {
-    @SuppressFBWarnings("URF_UNREAD_FIELD")
-    Object value;
-
-    protected ExistsMatch(Object value) {
-        this.value = value;
-    }
-
     @Nullable
-    public Boolean eval(Object attributeValue) {
+    public Boolean eval(Object conditionValue, Object attributeValue) {
         return attributeValue != null;
     }
 }

core-api/src/main/java/com/optimizely/ab/config/audience/match/ExistsMatch.java

@@ -18,24 +18,12 @@
 
 import javax.annotation.Nullable;
 
-import static com.optimizely.ab.internal.AttributesUtil.isValidNumber;
-
-class GEMatch extends AttributeMatch<Number> {
-    Number value;
-
-    protected GEMatch(Number value) {
-        this.value = value;
-    }
-
+/**
+ * GEMatch performs a "greater than or equal to" number comparison via {@link NumberComparator}.
+ */
+class GEMatch implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        try {
-            if(isValidNumber(attributeValue)) {
-                return castToValueType(attributeValue, value).doubleValue() >= value.doubleValue();
-            }
-        } catch (Exception e) {
-            return null;
-        }
-        return null;
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnknownValueTypeException {
+        return NumberComparator.compare(attributeValue, conditionValue) >= 0;
     }
 }

core-api/src/main/java/com/optimizely/ab/config/audience/match/GEMatch.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -18,24 +18,12 @@
 
 import javax.annotation.Nullable;
 
-import static com.optimizely.ab.internal.AttributesUtil.isValidNumber;
-
-class GTMatch extends AttributeMatch<Number> {
-    Number value;
-
-    protected GTMatch(Number value) {
-        this.value = value;
-    }
-
+/**
+ * GTMatch performs a "greater than" number comparison via {@link NumberComparator}.
+ */
+class GTMatch implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        try {
-            if(isValidNumber(attributeValue)) {
-                return castToValueType(attributeValue, value).doubleValue() > value.doubleValue();
-            }
-        } catch (Exception e) {
-            return null;
-        }
-        return null;
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnknownValueTypeException {
+        return NumberComparator.compare(attributeValue, conditionValue) > 0;
     }
 }

core-api/src/main/java/com/optimizely/ab/config/audience/match/GTMatch.java

@@ -18,25 +18,13 @@
 
 import javax.annotation.Nullable;
 
-import static com.optimizely.ab.internal.AttributesUtil.isValidNumber;
-
-class LEMatch extends AttributeMatch<Number> {
-    Number value;
-
-    protected LEMatch(Number value) {
-        this.value = value;
-    }
-
+/**
+ * GEMatch performs a "less than or equal to" number comparison via {@link NumberComparator}.
+ */
+class LEMatch implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        try {
-            if(isValidNumber(attributeValue)) {
-                return castToValueType(attributeValue, value).doubleValue() <= value.doubleValue();
-            }
-        } catch (Exception e) {
-            return null;
-        }
-        return null;
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnknownValueTypeException {
+        return NumberComparator.compare(attributeValue, conditionValue) <= 0;
     }
 }
 

core-api/src/main/java/com/optimizely/ab/config/audience/match/LEMatch.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -18,25 +18,12 @@
 
 import javax.annotation.Nullable;
 
-import static com.optimizely.ab.internal.AttributesUtil.isValidNumber;
-
-class LTMatch extends AttributeMatch<Number> {
-    Number value;
-
-    protected LTMatch(Number value) {
-        this.value = value;
-    }
-
+/**
+ * GTMatch performs a "less than" number comparison via {@link NumberComparator}.
+ */
+class LTMatch implements Match {
     @Nullable
-    public Boolean eval(Object attributeValue) {
-        try {
-            if(isValidNumber(attributeValue)) {
-                return castToValueType(attributeValue, value).doubleValue() < value.doubleValue();
-            }
-        } catch (Exception e) {
-            return null;
-        }
-        return null;
+    public Boolean eval(Object conditionValue, Object attributeValue) throws UnknownValueTypeException {
+        return NumberComparator.compare(attributeValue, conditionValue) < 0;
     }
 }
-

core-api/src/main/java/com/optimizely/ab/config/audience/match/LTMatch.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2018-2019, Optimizely and contributors
+ *    Copyright 2018-2020, Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -20,5 +20,5 @@
 
 public interface Match {
     @Nullable
-    Boolean eval(Object attributeValue);
+    Boolean eval(Object conditionValue, Object attributeValue) throws UnexpectedValueTypeException, UnknownValueTypeException;
 }