Improvements to the Paging Implementation

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/select/MultiSelectDSL.java

@@ -65,19 +65,19 @@ public MultiSelectDSL orderBy(Collection<? extends SortSpecification> columns) {
     @Override
     public LimitFinisher<MultiSelectModel> limitWhenPresent(Long limit) {
         this.limit = limit;
-        return new LF();
+        return new LocalLimitFinisher();
     }
 
     @Override
     public OffsetFirstFinisher<MultiSelectModel> offsetWhenPresent(Long offset) {
         this.offset = offset;
-        return new OFF();
+        return new LocalOffsetFirstFinisher();
     }
 
     @Override
     public FetchFirstFinisher<MultiSelectModel> fetchFirstWhenPresent(Long fetchFirstRows) {
         this.fetchFirstRows = fetchFirstRows;
-        return new FFF();
+        return () -> MultiSelectDSL.this;
     }
 
     @NotNull
@@ -106,38 +106,27 @@ public MultiSelectDSL configureStatement(Consumer<StatementConfiguration> consum
         return this;
     }
 
-    class FFF implements FetchFirstFinisher<MultiSelectModel> {
-        @Override
-        public Buildable<MultiSelectModel> rowsOnly() {
-            return MultiSelectDSL.this;
-        }
-    }
-
-    class LF implements LimitFinisher<MultiSelectModel> {
-        @Override
-        public Buildable<MultiSelectModel> offsetWhenPresent(Long offset) {
-            MultiSelectDSL.this.offset = offset;
-            return MultiSelectDSL.this;
-        }
-
+    abstract class BaseBuildable implements Buildable<MultiSelectModel> {
         @NotNull
         @Override
         public MultiSelectModel build() {
             return MultiSelectDSL.this.build();
         }
     }
 
-    class OFF implements OffsetFirstFinisher<MultiSelectModel> {
+    class LocalOffsetFirstFinisher extends BaseBuildable implements OffsetFirstFinisher<MultiSelectModel> {
         @Override
         public FetchFirstFinisher<MultiSelectModel> fetchFirstWhenPresent(Long fetchFirstRows) {
             MultiSelectDSL.this.fetchFirstRows = fetchFirstRows;
-            return new FFF();
+            return () -> MultiSelectDSL.this;
         }
+    }
 
-        @NotNull
+    class LocalLimitFinisher extends BaseBuildable implements LimitFinisher<MultiSelectModel> {
         @Override
-        public MultiSelectModel build() {
-            return MultiSelectDSL.this.build();
+        public Buildable<MultiSelectModel> offsetWhenPresent(Long offset) {
+            MultiSelectDSL.this.offset = offset;
+            return MultiSelectDSL.this;
         }
     }
 }

src/main/java/org/mybatis/dynamic/sql/select/PagingDSL.java

@@ -52,6 +52,7 @@ default FetchFirstFinisher<T> fetchFirst(long fetchFirstRows) {
         FetchFirstFinisher<T> fetchFirstWhenPresent(Long fetchFirstRows);
     }
 
+    @FunctionalInterface
     interface FetchFirstFinisher<T> {
         Buildable<T> rowsOnly();
     }

src/main/java/org/mybatis/dynamic/sql/select/SelectDSL.java

@@ -109,17 +109,17 @@ void orderBy(Collection<? extends SortSpecification> columns) {
 
     public LimitFinisher<R> limitWhenPresent(Long limit) {
         this.limit = limit;
-        return new LF();
+        return new LocalLimitFinisher();
     }
 
     public OffsetFirstFinisher<R> offsetWhenPresent(Long offset) {
         this.offset = offset;
-        return new OFF();
+        return new LocalOffsetFirstFinisher();
     }
 
     public FetchFirstFinisher<R> fetchFirstWhenPresent(Long fetchFirstRows) {
         this.fetchFirstRows = fetchFirstRows;
-        return new FFF();
+        return () -> SelectDSL.this;
     }
 
     @Override
@@ -153,38 +153,27 @@ private Optional<PagingModel> buildPagingModel() {
                 .build();
     }
 
-    class FFF implements FetchFirstFinisher<R> {
-        @Override
-        public Buildable<R> rowsOnly() {
-            return SelectDSL.this;
-        }
-    }
-
-    class LF implements LimitFinisher<R> {
-        @Override
-        public Buildable<R> offsetWhenPresent(Long offset) {
-            SelectDSL.this.offset = offset;
-            return SelectDSL.this;
-        }
-
+    abstract class BaseBuildable implements Buildable<R> {
         @NotNull
         @Override
         public R build() {
             return SelectDSL.this.build();
         }
     }
 
-    class OFF implements OffsetFirstFinisher<R> {
+    class LocalOffsetFirstFinisher extends BaseBuildable implements OffsetFirstFinisher<R> {
         @Override
         public FetchFirstFinisher<R> fetchFirstWhenPresent(Long fetchFirstRows) {
             SelectDSL.this.fetchFirstRows = fetchFirstRows;
-            return new FFF();
+            return () -> SelectDSL.this;
         }
+    }
 
-        @NotNull
+    class LocalLimitFinisher extends BaseBuildable implements LimitFinisher<R> {
         @Override
-        public R build() {
-            return SelectDSL.this.build();
+        public Buildable<R> offsetWhenPresent(Long offset) {
+            SelectDSL.this.offset = offset;
+            return SelectDSL.this;
         }
     }
 }