1 /*
2  * Copyright 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package androidx.room.solver.query.result
18 
19 import androidx.room.ext.CommonTypeNames
20 import androidx.room.ext.L
21 import androidx.room.ext.T
22 import androidx.room.ext.typeName
23 import androidx.room.solver.CodeGenScope
24 import com.squareup.javapoet.ParameterizedTypeName
25 
26 /**
27  * Wraps a row adapter when there is only 1 item in the result, and the result's outer type is
28  * {@link java.util.Optional}.
29  *
30  * <p>n.b. this will only be useful if the project uses Java 8.
31  */
32 class OptionalQueryResultAdapter(private val resultAdapter: SingleEntityQueryResultAdapter)
33     : QueryResultAdapter(resultAdapter.rowAdapter) {
34     val type = resultAdapter.rowAdapter?.out
convertnull35     override fun convert(
36             outVarName: String, cursorVarName: String, scope: CodeGenScope) {
37         scope.builder().apply {
38             val valueVarName = scope.getTmpVar("_value")
39             resultAdapter.convert(valueVarName, cursorVarName, scope)
40             addStatement(
41                     "final $T $L = $T.ofNullable($L)",
42                     ParameterizedTypeName.get(CommonTypeNames.OPTIONAL, type?.typeName()),
43                     outVarName,
44                     CommonTypeNames.OPTIONAL,
45                     valueVarName)
46         }
47     }
48 }
49