Scala example source code file (SimpleVerifier.java)

This example Scala source code file (SimpleVerifier.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

asm, basicvalue, class, classloader, error, internal, list, lnull, override, simpleverifier, type

The SimpleVerifier.java Scala example source code

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package scala.tools.asm.tree.analysis;

import java.util.List;

import scala.tools.asm.Type;

/**
 * An extended {@link BasicVerifier} that performs more precise verifications.
 * This verifier computes exact class types, instead of using a single "object
 * reference" type (as done in the {@link BasicVerifier}).
 *
 * @author Eric Bruneton
 * @author Bing Ran
 */
public class SimpleVerifier extends BasicVerifier {

    /**
     * The class that is verified.
     */
    private final Type currentClass;

    /**
     * The super class of the class that is verified.
     */
    private final Type currentSuperClass;

    /**
     * The interfaces implemented by the class that is verified.
     */
    private final List<Type> currentClassInterfaces;

    /**
     * If the class that is verified is an interface.
     */
    private final boolean isInterface;

    /**
     * The loader to use for referenced classes.
     */
    private ClassLoader loader = getClass().getClassLoader();

    /**
     * Constructs a new {@link SimpleVerifier}.
     */
    public SimpleVerifier() {
        this(null, null, false);
    }

    /**
     * Constructs a new {@link SimpleVerifier} to verify a specific class. This
     * class will not be loaded into the JVM since it may be incorrect.
     *
     * @param currentClass
     *            the class that is verified.
     * @param currentSuperClass
     *            the super class of the class that is verified.
     * @param isInterface
     *            if the class that is verified is an interface.
     */
    public SimpleVerifier(final Type currentClass,
            final Type currentSuperClass, final boolean isInterface) {
        this(currentClass, currentSuperClass, null, isInterface);
    }

    /**
     * Constructs a new {@link SimpleVerifier} to verify a specific class. This
     * class will not be loaded into the JVM since it may be incorrect.
     *
     * @param currentClass
     *            the class that is verified.
     * @param currentSuperClass
     *            the super class of the class that is verified.
     * @param currentClassInterfaces
     *            the interfaces implemented by the class that is verified.
     * @param isInterface
     *            if the class that is verified is an interface.
     */
    public SimpleVerifier(final Type currentClass,
            final Type currentSuperClass,
            final List<Type> currentClassInterfaces, final boolean isInterface) {
        this(ASM4, currentClass, currentSuperClass, currentClassInterfaces,
                isInterface);
    }

    protected SimpleVerifier(final int api, final Type currentClass,
            final Type currentSuperClass,
            final List<Type> currentClassInterfaces, final boolean isInterface) {
        super(api);
        this.currentClass = currentClass;
        this.currentSuperClass = currentSuperClass;
        this.currentClassInterfaces = currentClassInterfaces;
        this.isInterface = isInterface;
    }

    /**
     * Set the <code>ClassLoader</code> which will be used to load referenced
     * classes. This is useful if you are verifying multiple interdependent
     * classes.
     *
     * @param loader
     *            a <code>ClassLoader</code> to use
     */
    public void setClassLoader(final ClassLoader loader) {
        this.loader = loader;
    }

    @Override
    public BasicValue newValue(final Type type) {
        if (type == null) {
            return BasicValue.UNINITIALIZED_VALUE;
        }

        boolean isArray = type.getSort() == Type.ARRAY;
        if (isArray) {
            switch (type.getElementType().getSort()) {
            case Type.BOOLEAN:
            case Type.CHAR:
            case Type.BYTE:
            case Type.SHORT:
                return new BasicValue(type);
            }
        }

        BasicValue v = super.newValue(type);
        if (BasicValue.REFERENCE_VALUE.equals(v)) {
            if (isArray) {
                v = newValue(type.getElementType());
                String desc = v.getType().getDescriptor();
                for (int i = 0; i < type.getDimensions(); ++i) {
                    desc = '[' + desc;
                }
                v = new BasicValue(Type.getType(desc));
            } else {
                v = new BasicValue(type);
            }
        }
        return v;
    }

    @Override
    protected boolean isArrayValue(final BasicValue value) {
        Type t = value.getType();
        return t != null
                && ("Lnull;".equals(t.getDescriptor()) || t.getSort() == Type.ARRAY);
    }

    @Override
    protected BasicValue getElementValue(final BasicValue objectArrayValue)
            throws AnalyzerException {
        Type arrayType = objectArrayValue.getType();
        if (arrayType != null) {
            if (arrayType.getSort() == Type.ARRAY) {
                return newValue(Type.getType(arrayType.getDescriptor()
                        .substring(1)));
            } else if ("Lnull;".equals(arrayType.getDescriptor())) {
                return objectArrayValue;
            }
        }
        throw new Error("Internal error");
    }

    @Override
    protected boolean isSubTypeOf(final BasicValue value,
            final BasicValue expected) {
        Type expectedType = expected.getType();
        Type type = value.getType();
        switch (expectedType.getSort()) {
        case Type.INT:
        case Type.FLOAT:
        case Type.LONG:
        case Type.DOUBLE:
            return type.equals(expectedType);
        case Type.ARRAY:
        case Type.OBJECT:
            if ("Lnull;".equals(type.getDescriptor())) {
                return true;
            } else if (type.getSort() == Type.OBJECT
                    || type.getSort() == Type.ARRAY) {
                return isAssignableFrom(expectedType, type);
            } else {
                return false;
            }
        default:
            throw new Error("Internal error");
        }
    }

    @Override
    public BasicValue merge(final BasicValue v, final BasicValue w) {
        if (!v.equals(w)) {
            Type t = v.getType();
            Type u = w.getType();
            if (t != null
                    && (t.getSort() == Type.OBJECT || t.getSort() == Type.ARRAY)) {
                if (u != null
                        && (u.getSort() == Type.OBJECT || u.getSort() == Type.ARRAY)) {
                    if ("Lnull;".equals(t.getDescriptor())) {
                        return w;
                    }
                    if ("Lnull;".equals(u.getDescriptor())) {
                        return v;
                    }
                    if (isAssignableFrom(t, u)) {
                        return v;
                    }
                    if (isAssignableFrom(u, t)) {
                        return w;
                    }
                    // TODO case of array classes of the same dimension
                    // TODO should we look also for a common super interface?
                    // problem: there may be several possible common super
                    // interfaces
                    do {
                        if (t == null || isInterface(t)) {
                            return BasicValue.REFERENCE_VALUE;
                        }
                        t = getSuperClass(t);
                        if (isAssignableFrom(t, u)) {
                            return newValue(t);
                        }
                    } while (true);
                }
            }
            return BasicValue.UNINITIALIZED_VALUE;
        }
        return v;
    }

    protected boolean isInterface(final Type t) {
        if (currentClass != null && t.equals(currentClass)) {
            return isInterface;
        }
        return getClass(t).isInterface();
    }

    protected Type getSuperClass(final Type t) {
        if (currentClass != null && t.equals(currentClass)) {
            return currentSuperClass;
        }
        Class<?> c = getClass(t).getSuperclass();
        return c == null ? null : Type.getType(c);
    }

    protected boolean isAssignableFrom(final Type t, final Type u) {
        if (t.equals(u)) {
            return true;
        }
        if (currentClass != null && t.equals(currentClass)) {
            if (getSuperClass(u) == null) {
                return false;
            } else {
                if (isInterface) {
                    return u.getSort() == Type.OBJECT
                            || u.getSort() == Type.ARRAY;
                }
                return isAssignableFrom(t, getSuperClass(u));
            }
        }
        if (currentClass != null && u.equals(currentClass)) {
            if (isAssignableFrom(t, currentSuperClass)) {
                return true;
            }
            if (currentClassInterfaces != null) {
                for (int i = 0; i < currentClassInterfaces.size(); ++i) {
                    Type v = currentClassInterfaces.get(i);
                    if (isAssignableFrom(t, v)) {
                        return true;
                    }
                }
            }
            return false;
        }
        Class<?> tc = getClass(t);
        if (tc.isInterface()) {
            tc = Object.class;
        }
        return tc.isAssignableFrom(getClass(u));
    }

    protected Class<?> getClass(final Type t) {
        try {
            if (t.getSort() == Type.ARRAY) {
                return Class.forName(t.getDescriptor().replace('/', '.'),
                        false, loader);
            }
            return Class.forName(t.getClassName(), false, loader);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e.toString());
        }
    }
}