PositionalDataSourceQueryResultBinder.kt

/*
 * Copyright (C) 2017 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.VisibilityModifier
import androidx.room.compiler.codegen.XFunSpec
import androidx.room.compiler.codegen.XFunSpec.Builder.Companion.addStatement
import androidx.room.compiler.codegen.XPropertySpec
import androidx.room.compiler.codegen.XTypeName
import androidx.room.compiler.codegen.XTypeSpec
import androidx.room.ext.AndroidTypeNames.CURSOR
import androidx.room.ext.CommonTypeNames.LIST
import androidx.room.ext.RoomTypeNames
import androidx.room.solver.CodeGenScope

/**
 * Used by Paging2 pipeline
 */
class PositionalDataSourceQueryResultBinder(
    val listAdapter: ListQueryResultAdapter?,
    val tableNames: Set<String>,
) : QueryResultBinder(listAdapter) {
    val itemTypeName: XTypeName =
        listAdapter?.rowAdapters?.firstOrNull()?.out?.asTypeName() ?: XTypeName.ANY_OBJECT
    val typeName: XTypeName = RoomTypeNames.LIMIT_OFFSET_DATA_SOURCE.parametrizedBy(itemTypeName)

    override fun convertAndReturn(
        roomSQLiteQueryVar: String,
        canReleaseQuery: Boolean,
        dbProperty: XPropertySpec,
        inTransaction: Boolean,
        scope: CodeGenScope
    ) {
        // first comma for table names comes from the string since it might be empty in which case
        // we don't need a comma. If list is empty, this prevents generating bad code (it is still
        // an error to have empty list but that is already reported while item is processed)
        val tableNamesList = tableNames.joinToString("") { ", \"$it\"" }
        val spec = XTypeSpec.anonymousClassBuilder(
            language = scope.language,
            "%N, %L, %L, %L%L",
            dbProperty,
            roomSQLiteQueryVar,
            inTransaction,
            true,
            tableNamesList
        ).apply {
            superclass(typeName)
            addConvertRowsMethod(scope)
        }.build()
        scope.builder.addStatement("return %L", spec)
    }

    private fun XTypeSpec.Builder.addConvertRowsMethod(scope: CodeGenScope) {
        addFunction(
            XFunSpec.builder(
                language = language,
                name = "convertRows",
                visibility = VisibilityModifier.PROTECTED,
                isOverride = true
            ).apply {
                returns(LIST.parametrizedBy(itemTypeName))
                val cursorParamName = "cursor"
                addParameter(
                    CURSOR,
                    cursorParamName
                )
                val resultVar = scope.getTmpVar("_res")
                val rowsScope = scope.fork()
                listAdapter?.convert(resultVar, cursorParamName, rowsScope)
                addCode(rowsScope.generate())
                addStatement("return %L", resultVar)
            }.build()
        )
    }
}