Add support for union queries in Kotlin

CHANGELOG.md

@@ -19,6 +19,7 @@ If you have written your own set of functions to extend the library, you will no
 - Added the ability to write a function that will change the column data type ([#197](https://github.com/mybatis/mybatis-dynamic-sql/issues/197))
 - Added the `applyOperator` function to make it easy to use non-standard database operators in expressions ([#220](https://github.com/mybatis/mybatis-dynamic-sql/issues/220))
 - Added convenience methods for count(column) and count(distinct column)([#221](https://github.com/mybatis/mybatis-dynamic-sql/issues/221))
+- Added support for union queries in Kotlin([#187](https://github.com/mybatis/mybatis-dynamic-sql/issues/187))
 
 ## Release 1.1.4 - November 23, 2019
 

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/CriteriaCollector.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import org.mybatis.dynamic.sql.VisitableCondition
 
 typealias CriteriaReceiver = CriteriaCollector.() -> CriteriaCollector
 
+@MyBatisDslMarker
 class CriteriaCollector {
     val criteria = mutableListOf<SqlCriterion<*>>()
 

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/JoinCollector.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import org.mybatis.dynamic.sql.select.join.JoinCriterion
 
 typealias JoinReceiver = JoinCollector.() -> JoinCollector
 
+@MyBatisDslMarker
 class JoinCollector {
     val onJoinCriterion: JoinCriterion by lazy { internalOnCriterion }
     val andJoinCriteria = mutableListOf<JoinCriterion>()

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinBaseBuilders.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -20,10 +20,12 @@ import org.mybatis.dynamic.sql.SqlTable
 import org.mybatis.dynamic.sql.VisitableCondition
 import org.mybatis.dynamic.sql.select.AbstractQueryExpressionDSL
 import org.mybatis.dynamic.sql.select.SelectModel
-import org.mybatis.dynamic.sql.util.Buildable
 import org.mybatis.dynamic.sql.where.AbstractWhereDSL
 
-abstract class KotlinBaseBuilder<M, W : AbstractWhereDSL<W>, B : KotlinBaseBuilder<M, W, B>> : Buildable<M> {
+@DslMarker annotation class MyBatisDslMarker
+
+@MyBatisDslMarker
+abstract class KotlinBaseBuilder<W : AbstractWhereDSL<W>, B : KotlinBaseBuilder<W, B>> {
     fun <T> where(column: BindableColumn<T>, condition: VisitableCondition<T>): B =
         applySelf {
             getWhere().where(column, condition)
@@ -69,7 +71,7 @@ abstract class KotlinBaseBuilder<M, W : AbstractWhereDSL<W>, B : KotlinBaseBuild
 
 abstract class KotlinBaseJoiningBuilder<T : AbstractQueryExpressionDSL<T, SelectModel>, W : AbstractWhereDSL<W>, B : KotlinBaseJoiningBuilder<T, W, B>>(
     private val dsl: AbstractQueryExpressionDSL<T, SelectModel>
-) : KotlinBaseBuilder<SelectModel, W, B>() {
+) : KotlinBaseBuilder<W, B>() {
 
     fun join(table: SqlTable, receiver: JoinReceiver): B =
         applySelf {

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinCountBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -22,7 +22,7 @@ import org.mybatis.dynamic.sql.util.Buildable
 typealias CountCompleter = KotlinCountBuilder.() -> Buildable<SelectModel>
 
 class KotlinCountBuilder(private val dsl: CountDSL<SelectModel>) :
-    KotlinBaseJoiningBuilder<CountDSL<SelectModel>, CountDSL<SelectModel>.CountWhereBuilder, KotlinCountBuilder>(dsl) {
+    KotlinBaseJoiningBuilder<CountDSL<SelectModel>, CountDSL<SelectModel>.CountWhereBuilder, KotlinCountBuilder>(dsl), Buildable<SelectModel> {
 
     fun allRows() = this
 

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinDeleteBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -22,7 +22,7 @@ import org.mybatis.dynamic.sql.util.Buildable
 typealias DeleteCompleter = KotlinDeleteBuilder.() -> Buildable<DeleteModel>
 
 class KotlinDeleteBuilder(private val dsl: DeleteDSL<DeleteModel>) :
-        KotlinBaseBuilder<DeleteModel, DeleteDSL<DeleteModel>.DeleteWhereBuilder, KotlinDeleteBuilder>() {
+        KotlinBaseBuilder<DeleteDSL<DeleteModel>.DeleteWhereBuilder, KotlinDeleteBuilder>(), Buildable<DeleteModel> {
 
     fun allRows() = this
 

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinQueryBuilder.kt

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2019 the original author or authors.
+ *    Copyright 2016-2020 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@ import org.mybatis.dynamic.sql.util.Buildable
 typealias SelectCompleter = KotlinQueryBuilder.() -> Buildable<SelectModel>
 
 class KotlinQueryBuilder(private val dsl: QueryExpressionDSL<SelectModel>) :
-    KotlinBaseJoiningBuilder<QueryExpressionDSL<SelectModel>, QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder, KotlinQueryBuilder>(dsl) {
+    KotlinBaseJoiningBuilder<QueryExpressionDSL<SelectModel>, QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder, KotlinQueryBuilder>(dsl), Buildable<SelectModel> {
 
     fun groupBy(vararg columns: BasicColumn) =
             apply {
@@ -50,6 +50,16 @@ class KotlinQueryBuilder(private val dsl: QueryExpressionDSL<SelectModel>) :
 
     fun allRows() = this
 
+    fun union(union: KotlinUnionBuilder.() -> Unit) =
+        apply {
+            union(KotlinUnionBuilder(dsl.union()))
+        }
+
+    fun unionAll(unionAll: KotlinUnionBuilder.() -> Unit) =
+        apply {
+            unionAll(KotlinUnionBuilder(dsl.unionAll()))
+        }
+
     override fun build(): SelectModel = dsl.build()
 
     override fun getWhere(): QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder = dsl.where()

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinUnionBuilders.kt

@@ -0,0 +1,54 @@
+/**
+ *    Copyright 2016-2020 the original author or authors.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+package org.mybatis.dynamic.sql.util.kotlin
+
+import org.mybatis.dynamic.sql.BasicColumn
+import org.mybatis.dynamic.sql.SqlTable
+import org.mybatis.dynamic.sql.select.QueryExpressionDSL
+import org.mybatis.dynamic.sql.select.SelectModel
+
+@MyBatisDslMarker
+class KotlinUnionBuilder(private val unionBuilder: QueryExpressionDSL<SelectModel>.UnionBuilder) {
+    fun select(vararg selectList: BasicColumn) =
+        select(selectList.toList())
+
+    fun select(selectList: List<BasicColumn>) =
+        KotlinUnionFromGatherer(unionBuilder.select(selectList))
+
+    fun selectDistinct(vararg selectList: BasicColumn) =
+        selectDistinct(selectList.toList())
+
+    fun selectDistinct(selectList: List<BasicColumn>) =
+        KotlinUnionFromGatherer(unionBuilder.selectDistinct(selectList))
+}
+
+class KotlinUnionFromGatherer(private val fromGatherer: QueryExpressionDSL.FromGatherer<SelectModel>) {
+    fun from(table: SqlTable, enhance: KotlinUnionQueryBuilder.() -> Unit) =
+        enhance(KotlinUnionQueryBuilder(fromGatherer.from(table)))
+
+    fun from(table: SqlTable, alias: String, enhance: KotlinUnionQueryBuilder.() -> Unit) =
+        enhance(KotlinUnionQueryBuilder(fromGatherer.from(table, alias)))
+}
+
+class KotlinUnionQueryBuilder(private val unionDsl: QueryExpressionDSL<SelectModel>) :
+    KotlinBaseJoiningBuilder<QueryExpressionDSL<SelectModel>, QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder,
+            KotlinUnionQueryBuilder>(unionDsl) {
+    fun allRows() = this
+
+    override fun self() = this
+
+    override fun getWhere(): QueryExpressionDSL<SelectModel>.QueryExpressionWhereBuilder = unionDsl.where()
+}

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/KotlinUpdateBuilder.kt

@@ -33,7 +33,7 @@ typealias MultiRowInsertCompleter<T> = MultiRowInsertDSL<T>.() -> MultiRowInsert
 typealias UpdateCompleter = KotlinUpdateBuilder.() -> Buildable<UpdateModel>
 
 class KotlinUpdateBuilder(private val dsl: UpdateDSL<UpdateModel>) :
-    KotlinBaseBuilder<UpdateModel, UpdateDSL<UpdateModel>.UpdateWhereBuilder, KotlinUpdateBuilder>() {
+    KotlinBaseBuilder<UpdateDSL<UpdateModel>.UpdateWhereBuilder, KotlinUpdateBuilder>(), Buildable<UpdateModel> {
 
     fun <T> set(column: SqlColumn<T>): UpdateDSL<UpdateModel>.SetClauseFinisher<T> = dsl.set(column)