[Kotlin] Refactoring for clarity

Author: jeffgbutler

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

@@ -25,7 +25,7 @@ import org.mybatis.dynamic.sql.util.Buildable
 import org.mybatis.dynamic.sql.util.Messages
 
 @MyBatisDslMarker
-sealed class KotlinBaseSubQueryBuilder : Buildable<SelectModel> {
+sealed class KotlinBaseSubQueryBuilder {
     private var selectBuilder: KotlinSelectBuilder? = null
 
     fun select(vararg selectList: BasicColumn, completer: SelectCompleter): Unit =
@@ -42,23 +42,27 @@ sealed class KotlinBaseSubQueryBuilder : Buildable<SelectModel> {
         selectBuilder = KotlinSelectBuilder(SqlBuilder.selectDistinct(selectList)).apply(completer)
     }
 
-    override fun build(): SelectModel =
+    internal fun buildSelectModel(): SelectModel =
         selectBuilder?.build()?: throw KInvalidSQLException(Messages.getString("ERROR.28")) //$NON-NLS-1$
 }
 
-class KotlinSubQueryBuilder : KotlinBaseSubQueryBuilder()
+class KotlinSubQueryBuilder : KotlinBaseSubQueryBuilder(), Buildable<SelectModel> {
+    override fun build(): SelectModel = buildSelectModel()
+}
 
-class KotlinQualifiedSubQueryBuilder : KotlinBaseSubQueryBuilder() {
+class KotlinQualifiedSubQueryBuilder : KotlinBaseSubQueryBuilder(), Buildable<SelectModel> {
     var correlationName: String? = null
 
     operator fun String.unaryPlus() {
         correlationName = this
     }
+
+    override fun build(): SelectModel = buildSelectModel()
 }
 
 typealias InsertSelectCompleter = KotlinInsertSelectSubQueryBuilder.() -> Unit
 
-class KotlinInsertSelectSubQueryBuilder : KotlinBaseSubQueryBuilder() {
+class KotlinInsertSelectSubQueryBuilder : KotlinBaseSubQueryBuilder(), Buildable<InsertSelectModel> {
     private var columnList: List<SqlColumn<*>>? = null
     private var table: SqlTable? = null
 
@@ -72,20 +76,19 @@ class KotlinInsertSelectSubQueryBuilder : KotlinBaseSubQueryBuilder() {
         this.columnList = columnList
     }
 
-    // TODO - should just be build()
-    fun buildInsertSelectModel(): InsertSelectModel {
+    override fun build(): InsertSelectModel {
         if (table == null) {
             throw KInvalidSQLException(Messages.getString("ERROR.29")) //$NON-NLS-1$
         }
 
         return if (columnList == null) {
             SqlBuilder.insertInto(table)
-                .withSelectStatement(this)
+                .withSelectStatement { buildSelectModel() }
                 .build()
         } else {
             SqlBuilder.insertInto(table)
                 .withColumnList(columnList)
-                .withSelectStatement(this)
+                .withSelectStatement { buildSelectModel() }
                 .build()
         }
     }

src/main/kotlin/org/mybatis/dynamic/sql/util/kotlin/model/ModelBuilderFunctions.kt

@@ -82,11 +82,11 @@ fun insertSelect(table: SqlTable, completer: InsertSelectCompleter): InsertSelec
     with(KotlinInsertSelectSubQueryBuilder()) {
         into(table)
         apply(completer)
-        buildInsertSelectModel()
+        build()
     }
 
 fun insertSelect(completer: InsertSelectCompleter): InsertSelectModel =
-    KotlinInsertSelectSubQueryBuilder().apply(completer).buildInsertSelectModel()
+    KotlinInsertSelectSubQueryBuilder().apply(completer).build()
 
 @Deprecated("Please switch to the insertBatch statement in the model package")
 fun <T> BatchInsertDSL.IntoGatherer<T>.into(