SingleItemQueryResultAdapter.kt
/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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 androidx.room.solver.query.result
import androidx.room.compiler.codegen.CodeLanguage
import androidx.room.compiler.processing.XNullability
import androidx.room.solver.CodeGenScope
/**
* Wraps a row adapter when there is only 1 item in the result
*/
class SingleItemQueryResultAdapter(
private val rowAdapter: RowAdapter
) : QueryResultAdapter(listOf(rowAdapter)) {
val type = rowAdapter.out
override fun convert(outVarName: String, cursorVarName: String, scope: CodeGenScope) {
scope.builder.apply {
rowAdapter.onCursorReady(cursorVarName = cursorVarName, scope = scope)
addLocalVariable(outVarName, type.asTypeName())
beginControlFlow("if (%L.moveToFirst())", cursorVarName).apply {
rowAdapter.convert(outVarName, cursorVarName, scope)
}
nextControlFlow("else").apply {
val defaultValue = rowAdapter.out.defaultValue()
if (
language == CodeLanguage.KOTLIN &&
type.nullability == XNullability.NONNULL &&
defaultValue == "null"
) {
// TODO(b/249984504): Generate / output a better message.
addStatement("error(%S)", "Cursor was empty, but expected a single item.")
} else {
addStatement("%L = %L", outVarName, rowAdapter.out.defaultValue())
}
}
endControlFlow()
}
}
}