RxCallableQueryResultBinder.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.CodeLanguage
import androidx.room.compiler.codegen.VisibilityModifier
import androidx.room.compiler.codegen.XCodeBlock
import androidx.room.compiler.codegen.XFunSpec
import androidx.room.compiler.codegen.XFunSpec.Builder.Companion.addStatement
import androidx.room.compiler.codegen.XMemberName.Companion.packageMember
import androidx.room.compiler.codegen.XPropertySpec
import androidx.room.compiler.codegen.XTypeSpec
import androidx.room.compiler.processing.XNullability
import androidx.room.compiler.processing.XType
import androidx.room.ext.AndroidTypeNames.CURSOR
import androidx.room.ext.CallableTypeSpecBuilder
import androidx.room.ext.RoomTypeNames
import androidx.room.solver.CodeGenScope
import androidx.room.solver.RxType

/**
 * Generic Result binder for Rx classes that accept a callable.
 */
internal class RxCallableQueryResultBinder(
    private val rxType: RxType,
    val typeArg: XType,
    adapter: QueryResultAdapter?
) : QueryResultBinder(adapter) {
    override fun convertAndReturn(
        roomSQLiteQueryVar: String,
        canReleaseQuery: Boolean,
        dbProperty: XPropertySpec,
        inTransaction: Boolean,
        scope: CodeGenScope
    ) {
        val callable = CallableTypeSpecBuilder(scope.language, typeArg.asTypeName()) {
            addCode(
                XCodeBlock.builder(language).apply {
                    fillInCallMethod(
                        roomSQLiteQueryVar = roomSQLiteQueryVar,
                        dbProperty = dbProperty,
                        inTransaction = inTransaction,
                        scope = scope,
                        returnType = typeArg
                    )
                }.build()
            )
        }.apply {
            if (canReleaseQuery) {
                createFinalizeMethod(roomSQLiteQueryVar)
            }
        }.build()
        scope.builder.apply {
            if (rxType.isSingle()) {
                addStatement("return %T.createSingle(%L)", rxType.version.rxRoomClassName, callable)
            } else {
                addStatement("return %T.fromCallable(%L)", rxType.className, callable)
            }
        }
    }

    private fun XCodeBlock.Builder.fillInCallMethod(
        roomSQLiteQueryVar: String,
        dbProperty: XPropertySpec,
        inTransaction: Boolean,
        returnType: XType,
        scope: CodeGenScope
    ) {
        val adapterScope = scope.fork()
        val transactionWrapper = if (inTransaction) {
            transactionWrapper(dbProperty.name)
        } else {
            null
        }
        transactionWrapper?.beginTransactionWithControlFlow()
        val shouldCopyCursor = adapter?.shouldCopyCursor() == true
        val outVar = scope.getTmpVar("_result")
        val cursorVar = scope.getTmpVar("_cursor")
        addLocalVariable(
            name = cursorVar,
            typeName = CURSOR,
            assignExpr = XCodeBlock.of(
                language = language,
                format = "%M(%N, %L, %L, %L)",
                RoomTypeNames.DB_UTIL.packageMember("query"),
                dbProperty,
                roomSQLiteQueryVar,
                if (shouldCopyCursor) "true" else "false",
                "null"
            )
        )
        beginControlFlow("try").apply {
            adapter?.convert(outVar, cursorVar, adapterScope)
            add(adapterScope.generate())
            if (
                !rxType.canBeNull &&
                (language == CodeLanguage.JAVA ||
                    (language == CodeLanguage.KOTLIN &&
                        returnType.nullability == XNullability.NULLABLE))
            ) {
                beginControlFlow("if (%L == null)", outVar).apply {
                    addStatement(
                        "throw %L",
                        XCodeBlock.ofNewInstance(
                            language,
                            rxType.version.emptyResultExceptionClassName,
                            "%L",
                            XCodeBlock.of(
                                language,
                                when (language) {
                                    CodeLanguage.KOTLIN -> "%S + %L.sql"
                                    CodeLanguage.JAVA -> "%S + %L.getSql()"
                                },
                                "Query returned empty result set: ",
                                roomSQLiteQueryVar
                            )
                        )
                    )
                }
                endControlFlow()
            }
            transactionWrapper?.commitTransaction()
            addStatement("return %L", outVar)
        }
        nextControlFlow("finally").apply {
            addStatement("%L.close()", cursorVar)
        }
        endControlFlow()
        transactionWrapper?.endTransactionWithControlFlow()
    }

    private fun XTypeSpec.Builder.createFinalizeMethod(roomSQLiteQueryVar: String) {
        addFunction(
            XFunSpec.builder(
                language = language,
                name = "finalize",
                visibility = VisibilityModifier.PROTECTED,
                // To 'override' finalize in Kotlin one does not use the 'override' keyword, but in
                // Java the @Override is needed
                isOverride = language == CodeLanguage.JAVA
            ).apply {
                addStatement("%L.release()", roomSQLiteQueryVar)
            }.build()
        )
    }
}