tagan.codegen-impl.1.4.1.source-code.ScopedProviderGenerator.kt Maven / Gradle / Ivy

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Yatagan is a Dependency Injection framework, specializing on runtime performance and build speed. Supports code generation (apt/kapt/ksp) or reflection.

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/*
 * Copyright 2022 Yandex LLC
 *
 * 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 com.yandex.yatagan.codegen.impl

import com.squareup.javapoet.ClassName
import com.yandex.yatagan.codegen.poetry.TypeSpecBuilder
import com.yandex.yatagan.codegen.poetry.buildClass
import com.yandex.yatagan.core.graph.BindingGraph
import javax.inject.Inject
import javax.inject.Singleton
import javax.lang.model.element.Modifier.FINAL
import javax.lang.model.element.Modifier.PRIVATE
import javax.lang.model.element.Modifier.PUBLIC
import javax.lang.model.element.Modifier.STATIC
import javax.lang.model.element.Modifier.VOLATILE

@Singleton
internal class ScopedProviderGenerator @Inject constructor(
    private val componentImplName: ClassName,
    private val options: ComponentGenerator.Options,
    graph: BindingGraph,
) : ComponentGenerator.Contributor {
    private var isUsed = false
    private val useDoubleChecking = graph.requiresSynchronizedAccess
    val name: ClassName = componentImplName.nestedClass(if (useDoubleChecking) "DoubleCheck" else "CachingProviderImpl")
        get() = field.also { isUsed = true }

    override fun generate(builder: TypeSpecBuilder) {
        if (!isUsed) return
        builder.nestedType {
            buildClass(name) {
                implements(Names.Lazy)
                modifiers(PRIVATE, STATIC, FINAL)
                field(componentImplName, "mDelegate") { modifiers(PRIVATE, FINAL) }
                field(ClassName.INT, "mIndex") { modifiers(PRIVATE, FINAL) }
                field(ClassName.OBJECT, "mValue") {
                    modifiers(PRIVATE)
                    if (useDoubleChecking) {
                        modifiers(VOLATILE)
                    }
                }
                constructor {
                    parameter(componentImplName, "factory")
                    parameter(ClassName.INT, "index")
                    +"mDelegate = factory"
                    +"mIndex = index"
                }

                method("get") {
                    modifiers(PUBLIC)
                    annotation()
                    returnType(ClassName.OBJECT)
                    +"%T local = mValue".formatCode(ClassName.OBJECT)
                    controlFlow("if (local == null)") {
                        if (useDoubleChecking) {
                            controlFlow("synchronized (this)") {
                                +"local = mValue"
                                controlFlow("if (local == null)") {
                                    +"local = mDelegate.%N(mIndex)".formatCode(SlotSwitchingGenerator.FactoryMethodName)
                                    +"mValue = local"
                                }
                            }
                        } else {
                            if (options.enableThreadChecks) {
                                +"%T.assertThreadAccess()".formatCode(Names.ThreadAssertions)
                            }
                            +"local = mDelegate.%N(mIndex)".formatCode(SlotSwitchingGenerator.FactoryMethodName)
                            +"mValue = local"
                        }
                    }
                    +"return local"
                }
            }
        }
    }
}