Refactor filter/map algorithm into base class for single value Conditions

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/AbstractSingleValueCondition.java

@@ -15,7 +15,13 @@
  */
 package org.mybatis.dynamic.sql;
 
-public abstract class AbstractSingleValueCondition<T> implements VisitableCondition<T> {
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+import java.util.function.UnaryOperator;
+
+public abstract class AbstractSingleValueCondition<T, S extends AbstractSingleValueCondition<T, S>>
+        implements VisitableCondition<T> {
     protected final T value;
 
     protected AbstractSingleValueCondition(T value) {
@@ -31,5 +37,41 @@ public <R> R accept(ConditionVisitor<T, R> visitor) {
         return visitor.visit(this);
     }
 
+    protected S filter(Predicate<T> predicate, Supplier<S> empty, S self) {
+        if (shouldRender()) {
+            return predicate.test(value) ? self : empty.get();
+        } else {
+            return self;
+        }
+    }
+
+    protected S map(UnaryOperator<T> mapper, Function<T, S> constructor, S self) {
+        if (shouldRender()) {
+           return constructor.apply(mapper.apply(value));
+        }else {
+            return self;
+        }
+    }
+
+    /**
+     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
+     *     that will not render.
+     *
+     * @param predicate predicate applied to the value, if renderable
+     * @return this condition if renderable and the value matches the predicate, otherwise a condition
+     *     that will not render.
+     */
+    public abstract S filter(Predicate<T> predicate);
+
+    /**
+     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
+     *     condition that will not render (this).
+     *
+     * @param mapper a mapping function to apply to the value, if renderable
+     * @return a new condition with the result of applying the mapper to the value of this condition,
+     *     if renderable, otherwise a condition that will not render.
+     */
+    public abstract S map(UnaryOperator<T> mapper);
+
     public abstract String renderCondition(String columnName, String placeholder);
 }

src/main/java/org/mybatis/dynamic/sql/ConditionVisitor.java

@@ -20,7 +20,7 @@ public interface ConditionVisitor<T, R> {
 
     R visit(AbstractNoValueCondition<T> condition);
 
-    R visit(AbstractSingleValueCondition<T> condition);
+    R visit(AbstractSingleValueCondition<T, ?> condition);
 
     R visit(AbstractTwoValueCondition<T, ?> condition);
 

src/main/java/org/mybatis/dynamic/sql/where/condition/IsEqualTo.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsEqualTo<T> extends AbstractSingleValueCondition<T> {
+public class IsEqualTo<T> extends AbstractSingleValueCondition<T, IsEqualTo<T>> {
 
     protected IsEqualTo(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsEqualTo<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsEqualTo<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsEqualTo.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsEqualTo::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsEqualTo<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsEqualTo<>(mapper.apply(value)) : this;
+        return map(mapper, IsEqualTo::new, this);
     }
 
     public static class EmptyIsEqualTo<T> extends IsEqualTo<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsGreaterThan.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsGreaterThan<T> extends AbstractSingleValueCondition<T> {
+public class IsGreaterThan<T> extends AbstractSingleValueCondition<T, IsGreaterThan<T>> {
 
     protected IsGreaterThan(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsGreaterThan<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsGreaterThan<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsGreaterThan.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsGreaterThan::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsGreaterThan<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsGreaterThan<>(mapper.apply(value)) : this;
+        return map(mapper, IsGreaterThan::new, this);
     }
 
     public static class EmptyIsGreaterThan<T> extends IsGreaterThan<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsGreaterThanOrEqualTo.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsGreaterThanOrEqualTo<T> extends AbstractSingleValueCondition<T> {
+public class IsGreaterThanOrEqualTo<T> extends AbstractSingleValueCondition<T, IsGreaterThanOrEqualTo<T>> {
 
     protected IsGreaterThanOrEqualTo(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsGreaterThanOrEqualTo<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsGreaterThanOrEqualTo<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsGreaterThanOrEqualTo.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsGreaterThanOrEqualTo::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsGreaterThanOrEqualTo<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsGreaterThanOrEqualTo<>(mapper.apply(value)) : this;
+        return map(mapper, IsGreaterThanOrEqualTo::new, this);
     }
 
     public static class EmptyIsGreaterThanOrEqualTo<T> extends IsGreaterThanOrEqualTo<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsLessThan.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsLessThan<T> extends AbstractSingleValueCondition<T> {
+public class IsLessThan<T> extends AbstractSingleValueCondition<T, IsLessThan<T>> {
 
     protected IsLessThan(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsLessThan<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsLessThan<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsLessThan.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsLessThan::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsLessThan<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsLessThan<>(mapper.apply(value)) : this;
+        return map(mapper, IsLessThan::new, this);
     }
 
     public static class EmptyIsLessThan<T> extends IsLessThan<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsLessThanOrEqualTo.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsLessThanOrEqualTo<T> extends AbstractSingleValueCondition<T> {
+public class IsLessThanOrEqualTo<T> extends AbstractSingleValueCondition<T, IsLessThanOrEqualTo<T>> {
 
     protected IsLessThanOrEqualTo(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsLessThanOrEqualTo<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsLessThanOrEqualTo<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsLessThanOrEqualTo.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsLessThanOrEqualTo::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsLessThanOrEqualTo<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsLessThanOrEqualTo<>(mapper.apply(value)) : this;
+        return map(mapper, IsLessThanOrEqualTo::new, this);
     }
 
     public static class EmptyIsLessThanOrEqualTo<T> extends IsLessThanOrEqualTo<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsLike.java

@@ -20,7 +20,7 @@
 
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 
-public class IsLike<T> extends AbstractSingleValueCondition<T> {
+public class IsLike<T> extends AbstractSingleValueCondition<T, IsLike<T>> {
 
     protected IsLike(T value) {
         super(value);
@@ -63,32 +63,14 @@ public IsLike<T> then(UnaryOperator<T> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsLike<T> filter(Predicate<T> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsLike.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsLike::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsLike<T> map(UnaryOperator<T> mapper) {
-        return shouldRender() ? new IsLike<>(mapper.apply(value)) : this;
+        return map(mapper, IsLike::new, this);
     }
 
     public static class EmptyIsLike<T> extends IsLike<T> {

src/main/java/org/mybatis/dynamic/sql/where/condition/IsLikeCaseInsensitive.java

@@ -21,7 +21,7 @@
 import org.mybatis.dynamic.sql.AbstractSingleValueCondition;
 import org.mybatis.dynamic.sql.util.StringUtilities;
 
-public class IsLikeCaseInsensitive extends AbstractSingleValueCondition<String> {
+public class IsLikeCaseInsensitive extends AbstractSingleValueCondition<String, IsLikeCaseInsensitive> {
     protected IsLikeCaseInsensitive(String value) {
         super(value);
     }
@@ -68,32 +68,14 @@ public IsLikeCaseInsensitive then(UnaryOperator<String> mapper) {
         return map(mapper);
     }
 
-    /**
-     * If renderable and the value matches the predicate, returns this condition. Else returns a condition
-     *     that will not render.
-     *
-     * @param predicate predicate applied to the value, if renderable
-     * @return this condition if renderable and the value matches the predicate, otherwise a condition
-     *     that will not render.
-     */
+    @Override
     public IsLikeCaseInsensitive filter(Predicate<String> predicate) {
-        if (shouldRender()) {
-            return predicate.test(value) ? this : EmptyIsLikeCaseInsensitive.empty();
-        } else {
-            return this;
-        }
+        return filter(predicate, EmptyIsLikeCaseInsensitive::empty, this);
     }
 
-    /**
-     * If renderable, apply the mapping to the value and return a new condition with the new value. Else return a
-     *     condition that will not render (this).
-     *
-     * @param mapper a mapping function to apply to the value, if renderable
-     * @return a new condition with the result of applying the mapper to the value of this condition,
-     *     if renderable, otherwise a condition that will not render.
-     */
+    @Override
     public IsLikeCaseInsensitive map(UnaryOperator<String> mapper) {
-        return shouldRender() ? new IsLikeCaseInsensitive(mapper.apply(value)) : this;
+        return map(mapper, IsLikeCaseInsensitive::new, this);
     }
 
     public static class EmptyIsLikeCaseInsensitive extends IsLikeCaseInsensitive {