src/java.base/share/classes/java/lang/classfile/MethodSignature.java

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package java.lang.classfile;

import java.lang.classfile.attribute.SignatureAttribute;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.Executable;
import java.lang.reflect.Method;
import java.util.List;

import jdk.internal.classfile.impl.SignaturesImpl;
import jdk.internal.classfile.impl.Util;

import static java.util.Objects.requireNonNull;

/**
 * Models the generic signature of a method or constructor, as defined by JVMS
 * {@jvms 4.7.9.1}.
 *
 * @see Executable
 * @see SignatureAttribute
 * @jls 8.4 Method Declarations
 * @jls 8.8 Constructor Declarations
 * @jvms 4.7.9.1 Signatures
 * @since 24
 */
public sealed interface MethodSignature
        permits SignaturesImpl.MethodSignatureImpl {

    /**
     * {@return the type parameters of this method or constructor, may be empty}
     *
     * @see Executable#getTypeParameters()
     * @jls 8.4.4 Generic Methods
     * @jls 8.8.4 Generic Constructors
     */
    List<Signature.TypeParam> typeParameters();

    /**
     * {@return the signatures of the parameters of this method or constructor,
     * may be empty}  The parameters may differ from those in the method
     * descriptor because some synthetic or implicit parameters are omitted.
     *
     * @see Executable#getGenericParameterTypes()
     * @jls 8.4.1 Formal Parameters
     * @jls 8.8.1 Formal Parameters
     */
    List<Signature> arguments();

    /**
     * {@return the signatures of the return value of this method}  For
     * constructors, this returns a signature representing {@code void}.
     *
     * @see Method#getGenericReturnType()
     * @jls 8.4.5 Method Result
     */
    Signature result();

    /**
     * {@return the signatures of the exceptions thrown by this method or
     * constructor}
     *
     * @see Executable#getGenericExceptionTypes()
     * @jls 8.4.6 Method Throws
     * @jls 8.8.5 Constructor Throws
     */
    List<Signature.ThrowableSig> throwableSignatures();

    /** {@return the raw signature string} */
    String signatureString();

    /**
     * {@return a method signature for a raw method descriptor}  The resulting
     * signature has no type parameter or exception type declared.
     *
     * @param methodDescriptor the method descriptor
     */
    public static MethodSignature of(MethodTypeDesc methodDescriptor) {
        requireNonNull(methodDescriptor);
        return new SignaturesImpl.MethodSignatureImpl(
                List.of(),
                List.of(),
                Signature.of(methodDescriptor.returnType()),
                Util.mappedList(methodDescriptor.parameterList(), Signature::of));
    }

    /**
     * {@return a method signature with no type parameter or exception type}
     * The parameters may differ from those in the method descriptor because
     * some synthetic or implicit parameters are omitted.
     *
     * @param result signature for the return type
     * @param arguments signatures for the method parameters
     */
    public static MethodSignature of(Signature result,
                                     Signature... arguments) {
        return new SignaturesImpl.MethodSignatureImpl(List.of(),
                                                      List.of(),
                                                      requireNonNull(result),
                                                      List.of(arguments));
    }

    /**
     * {@return a method signature}  The parameters may differ from those in
     * the method descriptor because some synthetic or implicit parameters are
     * omitted.
     *
     * @param typeParameters signatures for the type parameters
     * @param exceptions signatures for the exceptions
     * @param result signature for the return type
     * @param arguments signatures for the method parameters
     */
    public static MethodSignature of(List<Signature.TypeParam> typeParameters,
                                     List<Signature.ThrowableSig> exceptions,
                                     Signature result,
                                     Signature... arguments) {
        return new SignaturesImpl.MethodSignatureImpl(
                List.copyOf(requireNonNull(typeParameters)),
                List.copyOf(requireNonNull(exceptions)),
                requireNonNull(result),
                List.of(arguments));
    }

    /**
     * Parses a raw method signature string into a {@code MethodSignature}.
     *
     * @param methodSignature the raw method signature string
     * @return the parsed method signature
     * @throws IllegalArgumentException if the string is not a valid method
     *         signature string
     */
    public static MethodSignature parseFrom(String methodSignature) {
        return new SignaturesImpl(methodSignature).parseMethodSignature();
    }
}