Added support for mapping cursors

Calling "requery" on a cursor may cause the driver to re-use queries, which is unwanted behavior.

*This commit is related to issue #529 [1]*

[1] #529

Author: JaniruTEC

data/src/main/java/org/cryptomator/data/db/SQLiteCacheControl.kt

@@ -1,5 +1,6 @@
 package org.cryptomator.data.db
 
+import android.database.Cursor
 import androidx.sqlite.db.SupportSQLiteOpenHelper
 import org.cryptomator.data.db.sqlmapping.SQLMappingFunction
 import org.cryptomator.data.db.sqlmapping.asMapped
@@ -19,7 +20,21 @@ object SQLiteCacheControl {
 		override fun mapWhereClause(whereClause: String?): String {
 			return map(whereClause ?: "1 = 1")
 		}
+
+		override fun mapCursor(cursor: Cursor): Cursor {
+			return NoRequeryCursor(cursor)
+		}
 	}
 
 	fun SupportSQLiteOpenHelper.Factory.asCacheControlled(): SupportSQLiteOpenHelper.Factory = asMapped(RandomUUIDMapping)
+}
+
+private class NoRequeryCursor(
+	private val delegateCursor: Cursor
+) : Cursor by delegateCursor {
+
+	@Deprecated("Deprecated in Java")
+	override fun requery(): Boolean {
+		throw UnsupportedOperationException()
+	}
 }

data/src/main/java/org/cryptomator/data/db/sqlmapping/MappingSupportSQLiteDatabase.kt

@@ -24,19 +24,19 @@ internal class MappingSupportSQLiteDatabase(
 	}
 
 	override fun query(query: SupportSQLiteQuery): Cursor {
-		return delegate.query(map(query))
+		return mapCursor(delegate.query(map(query)))
 	}
 
 	override fun query(query: SupportSQLiteQuery, cancellationSignal: CancellationSignal?): Cursor {
-		return delegate.query(map(query), cancellationSignal)
+		return mapCursor(delegate.query(map(query), cancellationSignal))
 	}
 
 	override fun query(query: String): Cursor {
-		return delegate.query(map(query))
+		return mapCursor(delegate.query(map(query)))
 	}
 
 	override fun query(query: String, bindArgs: Array<out Any?>): Cursor {
-		return delegate.query(map(query), bindArgs)
+		return mapCursor(delegate.query(map(query), bindArgs))
 	}
 
 	override fun insert(table: String, conflictAlgorithm: Int, values: ContentValues): Long {
@@ -79,6 +79,10 @@ internal class MappingSupportSQLiteDatabase(
 		return MappingSupportSQLiteQuery(query)
 	}
 
+	private fun mapCursor(cursor: Cursor): Cursor {
+		return mappingFunction.mapCursor(cursor)
+	}
+
 	private fun mapWhereClause(whereClause: String?): String? {
 		if (whereClause != null && whereClause.isBlank()) {
 			throw IllegalArgumentException()
@@ -202,4 +206,6 @@ interface SQLMappingFunction {
 
 	fun mapWhereClause(whereClause: String?): String?
 
+	fun mapCursor(cursor: Cursor): Cursor
+
 }

data/src/test/java/org/cryptomator/data/db/sqlmapping/MappingSupportSQLiteDatabaseTest.kt

@@ -42,10 +42,12 @@ class MappingSupportSQLiteDatabaseTest {
 		identityMapping = MappingSupportSQLiteDatabase(delegateMock, object : SQLMappingFunction {
 			override fun map(sql: String): String = sql
 			override fun mapWhereClause(whereClause: String?): String? = whereClause
+			override fun mapCursor(cursor: Cursor): Cursor = cursor
 		})
 		commentMapping = MappingSupportSQLiteDatabase(delegateMock, object : SQLMappingFunction {
 			override fun map(sql: String): String = "$sql -- Comment!"
 			override fun mapWhereClause(whereClause: String?): String = map(whereClause ?: "1 = 1")
+			override fun mapCursor(cursor: Cursor): Cursor = cursor //TODO
 		})
 	}