kotlin-fork/plugins/noarg/noarg-cli/src/NoArgExpressionCodegenExtension.kt

/*
 * Copyright 2010-2017 JetBrains s.r.o.
 *
 * 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 org.jetbrains.kotlin.noarg

import org.jetbrains.kotlin.codegen.*
import org.jetbrains.kotlin.codegen.extensions.ExpressionCodegenExtension
import org.jetbrains.kotlin.descriptors.*
import org.jetbrains.kotlin.descriptors.annotations.Annotations
import org.jetbrains.kotlin.descriptors.impl.ClassConstructorDescriptorImpl
import org.jetbrains.kotlin.psi.KtClass
import org.jetbrains.kotlin.resolve.descriptorUtil.getSuperClassOrAny
import org.jetbrains.kotlin.resolve.descriptorUtil.hasDefaultValue
import org.jetbrains.kotlin.resolve.jvm.AsmTypes
import org.jetbrains.kotlin.resolve.jvm.annotations.findJvmOverloadsAnnotation
import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodSignature
import org.jetbrains.kotlin.codegen.FunctionGenerationStrategy.CodegenBased
import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
import org.jetbrains.org.objectweb.asm.Opcodes

class NoArgExpressionCodegenExtension(val invokeInitializers: Boolean = false) : ExpressionCodegenExtension {
    override fun generateClassSyntheticParts(codegen: ImplementationBodyCodegen) = with(codegen) {
        if (shouldGenerateNoArgConstructor()) {
            generateNoArgConstructor()
        }
    }

    private fun ImplementationBodyCodegen.generateNoArgConstructor() {
        val superClassInternalName = typeMapper.mapClass(descriptor.getSuperClassOrAny()).internalName

        val constructorDescriptor = createNoArgConstructorDescriptor(descriptor)

        val superClass = descriptor.getSuperClassOrAny()

        // If a parent sealed class has not a zero-parameter constructor, user must write @NoArg annotation for the parent class as well,
        // and then we generate <init>()V
        val isParentASealedClassWithDefaultConstructor =
                superClass.modality == Modality.SEALED && superClass.constructors.any { it.isZeroParameterConstructor() }

        functionCodegen.generateMethod(JvmDeclarationOrigin.NO_ORIGIN, constructorDescriptor, object: CodegenBased(state) {
            override fun doGenerateBody(codegen: ExpressionCodegen, signature: JvmMethodSignature) {
                codegen.v.load(0, AsmTypes.OBJECT_TYPE)

                if (isParentASealedClassWithDefaultConstructor) {
                    codegen.v.aconst(null)
                    codegen.v.visitMethodInsn(Opcodes.INVOKESPECIAL, superClassInternalName, "<init>",
                                              "(Lkotlin/jvm/internal/DefaultConstructorMarker;)V", false)
                }
                else {
                    codegen.v.visitMethodInsn(Opcodes.INVOKESPECIAL, superClassInternalName, "<init>", "()V", false)
                }

                if (invokeInitializers) {
                    generateInitializers(codegen)
                }
                codegen.v.visitInsn(Opcodes.RETURN)
            }
        })
    }

    private fun createNoArgConstructorDescriptor(containingClass: ClassDescriptor): ConstructorDescriptor {
        return ClassConstructorDescriptorImpl.createSynthesized(containingClass, Annotations.EMPTY, false, SourceElement.NO_SOURCE).apply {
            initialize(null, calculateDispatchReceiverParameter(), emptyList(), emptyList(),
                       containingClass.builtIns.unitType, Modality.OPEN, Visibilities.PUBLIC)
        }
    }

    private fun KtClass.isNoArgClass() = this.getUserData(NO_ARG_CLASS_KEY) ?: false

    private fun ImplementationBodyCodegen.shouldGenerateNoArgConstructor(): Boolean {
        val origin = myClass as? KtClass ?: return false

        if (descriptor.kind != ClassKind.CLASS || !origin.isNoArgClass()) {
            return false
        }

        return descriptor.constructors.none { it.isZeroParameterConstructor() }
    }

    private fun ClassConstructorDescriptor.isZeroParameterConstructor(): Boolean {
        val parameters = this.valueParameters
        return parameters.isEmpty()
               || (parameters.all { it.hasDefaultValue() } && (isPrimary || findJvmOverloadsAnnotation() != null))
    }
}