src/java.base/share/classes/java/lang/reflect/Constructor.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
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package java.lang.reflect;

import jdk.internal.access.SharedSecrets;
import jdk.internal.misc.VM;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.ConstructorAccessor;
import jdk.internal.reflect.Reflection;
import jdk.internal.vm.annotation.ForceInline;
import jdk.internal.vm.annotation.Stable;
import sun.reflect.annotation.TypeAnnotation;
import sun.reflect.annotation.TypeAnnotationParser;
import sun.reflect.generics.repository.ConstructorRepository;
import sun.reflect.generics.repository.GenericDeclRepository;
import sun.reflect.generics.factory.CoreReflectionFactory;
import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.scope.ConstructorScope;
import java.lang.annotation.Annotation;
import java.lang.annotation.AnnotationFormatError;
import java.util.StringJoiner;

/**
 * {@code Constructor} provides information about, and access to, a single
 * constructor for a class.
 *
 * <p>{@code Constructor} permits widening conversions to occur when matching the
 * actual parameters to newInstance() with the underlying
 * constructor's formal parameters, but throws an
 * {@code IllegalArgumentException} if a narrowing conversion would occur.
 *
 * @param <T> the class in which the constructor is declared
 *
 * @see Member
 * @see java.lang.Class
 * @see java.lang.Class#getConstructors()
 * @see java.lang.Class#getConstructor(Class[])
 * @see java.lang.Class#getDeclaredConstructors()
 *
 * @author      Kenneth Russell
 * @author      Nakul Saraiya
 * @since 1.1
 */
public final class Constructor<T> extends Executable {
    private final Class<T>            clazz;
    private final int                 slot;
    private final Class<?>[]          parameterTypes;
    private final Class<?>[]          exceptionTypes;
    private final int                 modifiers;
    // Generics and annotations support
    private final transient String    signature;
    private final byte[]              annotations;
    private final byte[]              parameterAnnotations;

    // Generics infrastructure
    // Accessor for factory
    private GenericsFactory getFactory() {
        // create scope and factory
        return CoreReflectionFactory.make(this, ConstructorScope.make(this));
    }

    // Accessor for generic info repository
    @Override
    ConstructorRepository getGenericInfo() {
        var genericInfo = this.genericInfo;
        if (genericInfo == null) {
            var root = this.root;
            if (root != null) {
                genericInfo = root.getGenericInfo();
            } else {
                genericInfo = ConstructorRepository.make(getSignature(), getFactory());
            }
            this.genericInfo = genericInfo;
        }
        return genericInfo;
    }

    /**
     * Constructors are mutable due to {@link AccessibleObject#setAccessible(boolean)}.
     * Thus, we return a new copy of a root each time a constructor is returned.
     * Some lazily initialized immutable states can be stored on root and shared to the copies.
     */
    private Constructor<T> root;
    private transient volatile ConstructorRepository genericInfo;
    private @Stable ConstructorAccessor constructorAccessor;
    // End shared states

    @Override
    Constructor<T> getRoot() {
        return root;
    }

    /**
     * Package-private constructor used by ReflectAccess to enable
     * instantiation of these objects in Java code from the java.lang
     * package via jdk.internal.access.JavaLangReflectAccess.
     */
    Constructor(Class<T> declaringClass,
                Class<?>[] parameterTypes,
                Class<?>[] checkedExceptions,
                int modifiers,
                int slot,
                String signature,
                byte[] annotations,
                byte[] parameterAnnotations) {
        this.clazz = declaringClass;
        this.parameterTypes = parameterTypes;
        this.exceptionTypes = checkedExceptions;
        this.modifiers = modifiers;
        this.slot = slot;
        this.signature = signature;
        this.annotations = annotations;
        this.parameterAnnotations = parameterAnnotations;
    }

    /**
     * Package-private routine (exposed to java.lang.Class via
     * ReflectAccess) which returns a copy of this Constructor. The copy's
     * "root" field points to this Constructor.
     */
    Constructor<T> copy() {
        if (this.root != null)
            throw new IllegalArgumentException("Can not copy a non-root Constructor");

        Constructor<T> res = new Constructor<>(clazz,
                                               parameterTypes,
                                               exceptionTypes, modifiers, slot,
                                               signature,
                                               annotations,
                                               parameterAnnotations);
        res.root = this;
        // Might as well eagerly propagate this if already present
        res.constructorAccessor = constructorAccessor;
        res.genericInfo = genericInfo;
        return res;
    }

    // Creates a new root constructor with a custom accessor for serialization hooks.
    Constructor<T> newWithAccessor(ConstructorAccessor accessor) {
        var res = new Constructor<>(clazz, parameterTypes, exceptionTypes, modifiers, slot,
                signature, annotations, parameterAnnotations);
        res.constructorAccessor = accessor;
        return res;
    }

    /**
     * {@inheritDoc}
     *
     * <p> A {@code SecurityException} is thrown if this object is a
     * {@code Constructor} object for the class {@code Class} and {@code flag}
     * is true. </p>
     *
     * @param flag {@inheritDoc}
     *
     * @throws InaccessibleObjectException {@inheritDoc}
     * @throws SecurityException if this is a constructor for {@code java.lang.Class}
     */
    @Override
    @CallerSensitive
    public void setAccessible(boolean flag) {
        if (flag) {
            checkCanSetAccessible(Reflection.getCallerClass());
        }
        setAccessible0(flag);
    }

    @Override
    void checkCanSetAccessible(Class<?> caller) {
        checkCanSetAccessible(caller, clazz);
        if (clazz == Class.class) {
            // can we change this to InaccessibleObjectException?
            throw new SecurityException("Cannot make a java.lang.Class"
                                        + " constructor accessible");
        }
    }

    @Override
    boolean hasGenericInformation() {
        return (getSignature() != null);
    }

    @Override
    byte[] getAnnotationBytes() {
        return annotations;
    }

    /**
     * Returns the {@code Class} object representing the class that
     * declares the constructor represented by this object.
     */
    @Override
    public Class<T> getDeclaringClass() {
        return clazz;
    }

    /**
     * Returns the name of this constructor, as a string.  This is
     * the binary name of the constructor's declaring class.
     */
    @Override
    public String getName() {
        return getDeclaringClass().getName();
    }

    /**
     * {@inheritDoc}
     * @jls 8.8.3 Constructor Modifiers
     */
    @Override
    public int getModifiers() {
        return modifiers;
    }

    /**
     * {@inheritDoc}
     * @throws GenericSignatureFormatError {@inheritDoc}
     * @since 1.5
     */
    @Override
    @SuppressWarnings("unchecked")
    public TypeVariable<Constructor<T>>[] getTypeParameters() {
      if (getSignature() != null) {
        return (TypeVariable<Constructor<T>>[])getGenericInfo().getTypeParameters();
      } else
          return (TypeVariable<Constructor<T>>[])GenericDeclRepository.EMPTY_TYPE_VARS;
    }


    @Override
    Class<?>[] getSharedParameterTypes() {
        return parameterTypes;
    }

    @Override
    Class<?>[] getSharedExceptionTypes() {
        return exceptionTypes;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Class<?>[] getParameterTypes() {
        return parameterTypes.length == 0 ? parameterTypes : parameterTypes.clone();
    }

    /**
     * {@inheritDoc}
     * @since 1.8
     */
    public int getParameterCount() { return parameterTypes.length; }

    /**
     * {@inheritDoc}
     * @throws GenericSignatureFormatError {@inheritDoc}
     * @throws TypeNotPresentException {@inheritDoc}
     * @throws MalformedParameterizedTypeException {@inheritDoc}
     * @since 1.5
     */
    @Override
    public Type[] getGenericParameterTypes() {
        return super.getGenericParameterTypes();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Class<?>[] getExceptionTypes() {
        return exceptionTypes.length == 0 ? exceptionTypes : exceptionTypes.clone();
    }

    /**
     * {@inheritDoc}
     * @throws GenericSignatureFormatError {@inheritDoc}
     * @throws TypeNotPresentException {@inheritDoc}
     * @throws MalformedParameterizedTypeException {@inheritDoc}
     * @since 1.5
     */
    @Override
    public Type[] getGenericExceptionTypes() {
        return super.getGenericExceptionTypes();
    }

    /**
     * Compares this {@code Constructor} against the specified object.
     * Returns true if the objects are the same.  Two {@code Constructor} objects are
     * the same if they were declared by the same class and have the
     * same formal parameter types.
     */
    public boolean equals(Object obj) {
        if (obj instanceof Constructor<?> other) {
            if (getDeclaringClass() == other.getDeclaringClass()) {
                return equalParamTypes(parameterTypes, other.parameterTypes);
            }
        }
        return false;
    }

    /**
     * Returns a hashcode for this {@code Constructor}. The hashcode is
     * the same as the hashcode for the underlying constructor's
     * declaring class name.
     */
    public int hashCode() {
        return getDeclaringClass().getName().hashCode();
    }

    /**
     * Returns a string describing this {@code Constructor}.  The string is
     * formatted as the constructor access modifiers, if any,
     * followed by the fully-qualified name of the declaring class,
     * followed by a parenthesized, comma-separated list of the
     * constructor's formal parameter types.  For example:
     * <pre>{@code
     *    public java.util.HashMap(int,float)
     * }</pre>
     *
     * <p>If the constructor is declared to throw exceptions, the
     * parameter list is followed by a space, followed by the word
     * "{@code throws}" followed by a comma-separated list of the
     * thrown exception types.
     *
     * <p>The only possible modifiers for constructors are the access
     * modifiers {@code public}, {@code protected} or
     * {@code private}.  Only one of these may appear, or none if the
     * constructor has default (package) access.
     *
     * @return a string describing this {@code Constructor}
     * @jls 8.8.3 Constructor Modifiers
     * @jls 8.9.2 Enum Body Declarations
     */
    public String toString() {
        return sharedToString(Modifier.constructorModifiers(),
                              false,
                              parameterTypes,
                              exceptionTypes);
    }

    @Override
    void specificToStringHeader(StringBuilder sb) {
        sb.append(getDeclaringClass().getTypeName());
    }

    @Override
    String toShortString() {
        StringBuilder sb = new StringBuilder("constructor ");
        sb.append(getDeclaringClass().getTypeName());
        sb.append('(');
        StringJoiner sj = new StringJoiner(",");
        for (Class<?> parameterType : getSharedParameterTypes()) {
            sj.add(parameterType.getTypeName());
        }
        sb.append(sj);
        sb.append(')');
        return sb.toString();
    }

    /**
     * Returns a string describing this {@code Constructor},
     * including type parameters.  The string is formatted as the
     * constructor access modifiers, if any, followed by an
     * angle-bracketed comma separated list of the constructor's type
     * parameters, if any, including  informative bounds of the
     * type parameters, if any, followed by the fully-qualified name of the
     * declaring class, followed by a parenthesized, comma-separated
     * list of the constructor's generic formal parameter types.
     *
     * If this constructor was declared to take a variable number of
     * arguments, instead of denoting the last parameter as
     * "<code><i>Type</i>[]</code>", it is denoted as
     * "<code><i>Type</i>...</code>".
     *
     * A space is used to separate access modifiers from one another
     * and from the type parameters or class name.  If there are no
     * type parameters, the type parameter list is elided; if the type
     * parameter list is present, a space separates the list from the
     * class name.  If the constructor is declared to throw
     * exceptions, the parameter list is followed by a space, followed
     * by the word "{@code throws}" followed by a
     * comma-separated list of the generic thrown exception types.
     *
     * <p>The only possible modifiers for constructors are the access
     * modifiers {@code public}, {@code protected} or
     * {@code private}.  Only one of these may appear, or none if the
     * constructor has default (package) access.
     *
     * @return a string describing this {@code Constructor},
     * include type parameters
     *
     * @since 1.5
     * @jls 8.8.3 Constructor Modifiers
     * @jls 8.9.2 Enum Body Declarations
     */
    @Override
    public String toGenericString() {
        return sharedToGenericString(Modifier.constructorModifiers(), false);
    }

    @Override
    void specificToGenericStringHeader(StringBuilder sb) {
        specificToStringHeader(sb);
    }

    /**
     * Uses the constructor represented by this {@code Constructor} object to
     * create and initialize a new instance of the constructor's
     * declaring class, with the specified initialization parameters.
     * Individual parameters are automatically unwrapped to match
     * primitive formal parameters, and both primitive and reference
     * parameters are subject to method invocation conversions as necessary.
     *
     * <p>If the number of formal parameters required by the underlying constructor
     * is 0, the supplied {@code initargs} array may be of length 0 or null.
     *
     * <p>If the constructor's declaring class is an inner class in a
     * non-static context, the first argument to the constructor needs
     * to be the enclosing instance; see section {@jls 15.9.3} of
     * <cite>The Java Language Specification</cite>.
     *
     * <p>If the required access and argument checks succeed and the
     * instantiation will proceed, the constructor's declaring class
     * is initialized if it has not already been initialized.
     *
     * <p>If the constructor completes normally, returns the newly
     * created and initialized instance.
     *
     * @param initargs array of objects to be passed as arguments to
     * the constructor call; values of primitive types are wrapped in
     * a wrapper object of the appropriate type (e.g. a {@code float}
     * in a {@link java.lang.Float Float})
     *
     * @return a new object created by calling the constructor
     * this object represents
     *
     * @throws    IllegalAccessException    if this {@code Constructor} object
     *              is enforcing Java language access control and the underlying
     *              constructor is inaccessible.
     * @throws    IllegalArgumentException  if the number of actual
     *              and formal parameters differ; if an unwrapping
     *              conversion for primitive arguments fails; or if,
     *              after possible unwrapping, a parameter value
     *              cannot be converted to the corresponding formal
     *              parameter type by a method invocation conversion; if
     *              this constructor pertains to an enum class.
     * @throws    InstantiationException    if the class that declares the
     *              underlying constructor represents an abstract class.
     * @throws    InvocationTargetException if the underlying constructor
     *              throws an exception.
     * @throws    ExceptionInInitializerError if the initialization provoked
     *              by this method fails.
     */
    @CallerSensitive
    @ForceInline // to ensure Reflection.getCallerClass optimization
    public T newInstance(Object ... initargs)
        throws InstantiationException, IllegalAccessException,
               IllegalArgumentException, InvocationTargetException
    {
        Class<?> caller = override ? null : Reflection.getCallerClass();
        return newInstanceWithCaller(initargs, !override, caller);
    }

    /* package-private */
    T newInstanceWithCaller(Object[] args, boolean checkAccess, Class<?> caller)
        throws InstantiationException, IllegalAccessException,
               InvocationTargetException
    {
        if (checkAccess)
            checkAccess(caller, clazz, clazz, modifiers);

        ConstructorAccessor ca = constructorAccessor;   // read @Stable
        if (ca == null) {
            ca = acquireConstructorAccessor();
        }
        @SuppressWarnings("unchecked")
        T inst = (T) ca.newInstance(args);
        return inst;
    }

    /**
     * {@inheritDoc}
     * @since 1.5
     * @jls 8.4.1 Formal Parameters
     */
    @Override
    public boolean isVarArgs() {
        return super.isVarArgs();
    }

    /**
     * {@inheritDoc}
     * @jls 13.1 The Form of a Binary
     * @jvms 4.6 Methods
     * @since 1.5
     * @see <a
     * href="{@docRoot}/java.base/java/lang/reflect/package-summary.html#LanguageJvmModel">Java
     * programming language and JVM modeling in core reflection</a>
     */
    @Override
    public boolean isSynthetic() {
        return super.isSynthetic();
    }

    // NOTE that there is no synchronization used here. It is correct
    // (though not efficient) to generate more than one
    // ConstructorAccessor for a given Constructor. However, avoiding
    // synchronization will probably make the implementation more
    // scalable.
    private ConstructorAccessor acquireConstructorAccessor() {

        // First check to see if one has been created yet, and take it
        // if so.
        Constructor<?> root = this.root;
        ConstructorAccessor tmp = root == null ? null : root.getConstructorAccessor();
        if (tmp != null) {
            constructorAccessor = tmp;
        } else {
            // Otherwise fabricate one and propagate it up to the root
            // Ensure the declaring class is not an Enum class.
            if ((clazz.getModifiers() & Modifier.ENUM) != 0)
                throw new IllegalArgumentException("Cannot reflectively create enum objects");

            tmp = reflectionFactory.newConstructorAccessor(this);
            // set the constructor accessor only if it's not using native implementation
            if (VM.isJavaLangInvokeInited())
                setConstructorAccessor(tmp);
        }

        return tmp;
    }

    // Returns ConstructorAccessor for this Constructor object, not
    // looking up the chain to the root
    ConstructorAccessor getConstructorAccessor() {
        return constructorAccessor;
    }

    // Sets the ConstructorAccessor for this Constructor object and
    // (recursively) its root
    void setConstructorAccessor(ConstructorAccessor accessor) {
        constructorAccessor = accessor;
        // Propagate up
        Constructor<?> root = this.root;
        if (root != null) {
            root.setConstructorAccessor(accessor);
        }
    }

    int getSlot() {
        return slot;
    }

    String getSignature() {
        return signature;
    }

    byte[] getRawAnnotations() {
        return annotations;
    }

    byte[] getRawParameterAnnotations() {
        return parameterAnnotations;
    }


    /**
     * {@inheritDoc}
     *
     * @throws NullPointerException  {@inheritDoc}
     * @since 1.5
     */
    @Override
    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
        return super.getAnnotation(annotationClass);
    }

    /**
     * {@inheritDoc}
     * @since 1.5
     */
    @Override
    public Annotation[] getDeclaredAnnotations()  {
        return super.getDeclaredAnnotations();
    }

    /**
     * {@inheritDoc}
     * @since 1.5
     */
    @Override
    public Annotation[][] getParameterAnnotations() {
        return sharedGetParameterAnnotations(parameterTypes, parameterAnnotations);
    }

    @Override
    boolean handleParameterNumberMismatch(int resultLength, Class<?>[] parameterTypes) {
        int numParameters = parameterTypes.length;
        Class<?> declaringClass = getDeclaringClass();
        if (declaringClass.isEnum()) {
            return resultLength + 2 == numParameters &&
                    parameterTypes[0] == String.class &&
                    parameterTypes[1] == int.class;
        } else if (
            declaringClass.isAnonymousClass() ||
            declaringClass.isLocalClass() )
            return false; // Can't do reliable parameter counting
        else {
            if (declaringClass.isMemberClass() &&
                ((declaringClass.getModifiers() & Modifier.STATIC) == 0)  &&
                resultLength + 1 == numParameters) {
                return true;
            } else {
                throw new AnnotationFormatError(
                          "Parameter annotations don't match number of parameters");
            }
        }
    }

    /**
     * {@inheritDoc}
     * @since 1.8
     */
    @Override
    public AnnotatedType getAnnotatedReturnType() {
        return getAnnotatedReturnType0(getDeclaringClass());
    }

    /**
     * {@inheritDoc}
     * @since 1.8
     */
    @Override
    public AnnotatedType getAnnotatedReceiverType() {
        Class<?> thisDeclClass = getDeclaringClass();
        Class<?> enclosingClass = thisDeclClass.getEnclosingClass();

        if (enclosingClass == null) {
            // A Constructor for a top-level class
            return null;
        }

        Class<?> outerDeclaringClass = thisDeclClass.getDeclaringClass();
        if (outerDeclaringClass == null) {
            // A constructor for a local or anonymous class
            return null;
        }

        // Either static nested or inner class
        if (Modifier.isStatic(thisDeclClass.getModifiers())) {
            // static nested
            return null;
        }

        // A Constructor for an inner class
        return TypeAnnotationParser.buildAnnotatedType(getTypeAnnotationBytes0(),
                SharedSecrets.getJavaLangAccess().
                    getConstantPool(thisDeclClass),
                this,
                thisDeclClass,
                parameterize(enclosingClass),
                TypeAnnotation.TypeAnnotationTarget.METHOD_RECEIVER);
    }
}