org.jetbrains.kotlin.idea.MainFunctionDetector.kt Maven / Gradle / Ivy

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/*
 * Copyright 2010-2015 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.idea

import org.jetbrains.kotlin.builtins.KotlinBuiltIns
import org.jetbrains.kotlin.descriptors.*
import org.jetbrains.kotlin.name.FqName
import org.jetbrains.kotlin.psi.KtDeclaration
import org.jetbrains.kotlin.psi.KtNamedFunction
import org.jetbrains.kotlin.resolve.BindingContext
import org.jetbrains.kotlin.resolve.DescriptorUtils
import org.jetbrains.kotlin.resolve.annotations.hasJvmStaticAnnotation
import org.jetbrains.kotlin.resolve.descriptorUtil.module
import org.jetbrains.kotlin.resolve.scopes.MemberScope
import org.jetbrains.kotlin.types.Variance

class MainFunctionDetector {
    private val getFunctionDescriptor: (KtNamedFunction) -> FunctionDescriptor

    /** Assumes that the function declaration is already resolved and the descriptor can be found in the `bindingContext`.  */
    constructor(bindingContext: BindingContext) {
        this.getFunctionDescriptor = { function ->
            bindingContext.get(BindingContext.FUNCTION, function) ?: throw IllegalStateException("No descriptor resolved for " + function + " " + function.text)
        }
    }

    constructor(functionResolver: (KtNamedFunction) -> FunctionDescriptor) {
        this.getFunctionDescriptor = functionResolver
    }

    fun hasMain(declarations: List): Boolean {
        return findMainFunction(declarations) != null
    }

    fun isMain(function: KtNamedFunction): Boolean {
        if (function.isLocal) {
            return false
        }

        if (function.valueParameters.size != 1 || !function.typeParameters.isEmpty()) {
            return false
        }

        /* Psi only check for kotlin.jvm.jvmName annotation */
        if ("main" != function.name && !hasAnnotationWithExactNumberOfArguments(function, 1)) {
            return false
        }

        /* Psi only check for kotlin.jvm.jvmStatic annotation */
        if (!function.isTopLevel && !hasAnnotationWithExactNumberOfArguments(function, 0)) {
            return false
        }

        return isMain(getFunctionDescriptor(function))
    }

    fun getMainFunction(module: ModuleDescriptor): FunctionDescriptor? = getMainFunction(module, module.getPackage(FqName.ROOT))

    private fun getMainFunction(module: ModuleDescriptor, packageView: PackageViewDescriptor): FunctionDescriptor? {
        for (packageFragment in packageView.fragments.filter { it.module == module }) {
            DescriptorUtils.getAllDescriptors(packageFragment.getMemberScope())
                    .filterIsInstance()
                    .firstOrNull { isMain(it) }
                    ?.let { return it }
        }

        for (subpackageName in module.getSubPackagesOf(packageView.fqName, MemberScope.ALL_NAME_FILTER)) {
            getMainFunction(module, module.getPackage(subpackageName))?.let { return it }
        }

        return null
    }

    private fun findMainFunction(declarations: List) =
        declarations.filterIsInstance().find { isMain(it) }

    companion object {

        fun isMain(descriptor: DeclarationDescriptor): Boolean {
            if (descriptor !is FunctionDescriptor) return false

            if (getJVMFunctionName(descriptor) != "main") {
                return false
            }

            val parameters = descriptor.valueParameters
            if (parameters.size != 1 || !descriptor.typeParameters.isEmpty()) return false

            val parameter = parameters[0]
            val parameterType = parameter.type
            if (!KotlinBuiltIns.isArray(parameterType)) return false

            val typeArguments = parameterType.arguments
            if (typeArguments.size != 1) return false

            val typeArgument = typeArguments[0].type
            if (!KotlinBuiltIns.isString(typeArgument)) {
                return false
            }
            if (typeArguments[0].projectionKind === Variance.IN_VARIANCE) {
                return false
            }

            val returnType = descriptor.returnType
            if (returnType == null ||  !KotlinBuiltIns.isUnit(returnType)) return false

            if (DescriptorUtils.isTopLevelDeclaration(descriptor)) return true

            val containingDeclaration = descriptor.containingDeclaration
            return containingDeclaration is ClassDescriptor
                   && containingDeclaration.kind.isSingleton
                   && descriptor.hasJvmStaticAnnotation()
        }

        private fun getJVMFunctionName(functionDescriptor: FunctionDescriptor): String {
            return DescriptorUtils.getJvmName(functionDescriptor) ?: functionDescriptor.name.asString()
        }

        private fun hasAnnotationWithExactNumberOfArguments(function: KtNamedFunction, number: Int) =
            function.annotationEntries.any { it.valueArguments.size == number }
    }
}