JWebAssembly/src/de/inetsoftware/classparser/MethodInfo.java

/*
   Copyright 2011 - 2020 Volker Berlin (i-net software)

   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 de.inetsoftware.classparser;

import java.io.DataInputStream;
import java.io.IOException;
import java.util.Collections;
import java.util.Map;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import de.inetsoftware.classparser.Attributes.AttributeInfo;

/**
 * @author Volker Berlin
 */
public class MethodInfo implements Member {

    private final int          accessFlags;

    private final String       name;

    private String             description;

    private final Attributes   attributes;

    private final ConstantPool constantPool;

    private Code               code;

    private Exceptions         exceptions;

    private ClassFile          classFile;

    private Map<String,Map<String,Object>> annotations;

    /**
     * Read the method_info structure http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.6
     * http://docs.oracle.com/javase/specs/jvms/se5.0/html/ClassFile.doc.html#1513
     *
     * @param input
     *            the stream of the class file
     * @param constantPool
     *            the ConstantPool of the class
     * @param classFile
     *            the declaring class file
     * @throws IOException
     *             if an I/O error occurs
     */
    MethodInfo( DataInputStream input, ConstantPool constantPool, ClassFile classFile ) throws IOException {
        this.accessFlags = input.readUnsignedShort();
        this.name = (String)constantPool.get( input.readUnsignedShort() );
        this.description = (String)constantPool.get( input.readUnsignedShort() );
        this.constantPool = constantPool;
        this.attributes = new Attributes( input, constantPool );
        this.classFile = classFile;
    }

    /**
     * Get the declaring class file of the method
     * @return the ClassFile
     */
    public ClassFile getDeclaringClassFile() {
        return classFile;
    }

    /**
     * Get the access flags of the method.
     * http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.6-200-A
     * http://docs.oracle.com/javase/specs/jvms/se5.0/html/ClassFile.doc.html#1522
     *
     * @return the flags
     */
    public int getAccessFlags() {
        return accessFlags;
    }

    /**
     * If the method is a static method.
     * http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.6-200-A
     * http://docs.oracle.com/javase/specs/jvms/se5.0/html/ClassFile.doc.html#1522
     * @return true, if static
     * @see #getAccessFlags()
     */
    public boolean isStatic() {
        return (accessFlags & 0x0008) > 0;
    }

    /**
     * If the method is abstract
     * 
     * @return true, if abstract
     */
    public boolean isAbstract() {
        return (accessFlags & 0x0400) > 0;
    }

    /**
     * @return the name
     */
    @Override
    public String getName() {
        return name;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getClassName() {
        return getDeclaringClassFile().getThisClass().getName();
    }

    /**
     * @return the attributes
     */
    public Attributes getAttributes() {
        return attributes;
    }

    public Code getCode() throws IOException {
        if( code != null ){
            return code;
        }
        AttributeInfo data = attributes.get( "Code" );
        if( data != null ) {
            code = new Code( data.getDataInputStream(), constantPool );
        }
        return code;
    }


    /**
     * Get the signature of the method without generic types.
     */
    @Override
    public String getType() {
        return description;
    }

    /**
     * Get the signature of the method with generic types.
     * 
     * @return the signature
     * @throws IOException
     *             if an I/O error occurs
     */
    public String getSignature() throws IOException {
        AttributeInfo info = getAttributes().get( "Signature" );
        if( info != null ) {
            int idx = info.getDataInputStream().readShort();
            return (String)constantPool.get( idx );
        } else {
            return description;
        }
    }

    public Exceptions getExceptions() throws IOException {
        if( exceptions != null ) {
            return exceptions;
        }
        AttributeInfo data = attributes.get( "Exceptions" );
        if( data != null ) {
            exceptions = new Exceptions( data.getDataInputStream(), constantPool );
        }
        return exceptions;
    }

    /**
     * Get a single annotation or null
     * 
     * @param annotation
     *            the class name of the annotation
     * @return the value or null if not exists
     * @throws IOException
     *             if any I/O error occur
     */
    @Nullable
    public Map<String, Object> getAnnotation( String annotation ) throws IOException {
        if( annotations == null ) {
            AttributeInfo data = attributes.get( "RuntimeInvisibleAnnotations" );
            if( data != null ) {
                annotations =  Annotations.read( data.getDataInputStream(), constantPool );
            } else {
                annotations = Collections.emptyMap();
            }
        }
        return annotations.get( annotation );
    }

    /**
     * Get the constant pool of the the current class.
     * @return the constant pool
     */
    public ConstantPool getConstantPool() {
        return constantPool;
    }

    /**
     * Replace the reference to the ClassFile
     * 
     * @param origClassName
     *            the class name that should be replaced.
     * @param classFile
     *            the new value
     */
    void setDeclaringClassFile( @Nonnull String origClassName, @Nonnull ClassFile classFile ) {
        description = description.replace( 'L' + origClassName + ';', 'L' + classFile.getThisClass().getName() + ';' );
        this.classFile = classFile;
    }
}