Wednesday, April 8, 2015

StructuralCodeConstraintException

com.sun.org.apache.bcel.internal.verifier.exc.StructuralCodeConstraintException

StructuralCodeConstraintException is described in the javadoc comments as:

Instances of this class are thrown by BCEL's class file verifier 'JustIce' when a class file to verify does not pass the verification pass 3 because of a violation of a structural constraint as described in the Java Virtual Machine Specification, 2nd edition, 4.8.2, pages 137-139. Note that the notion of a 'structural' constraint is somewhat misleading. Structural constraints are constraints on relationships between Java virtual machine instructions. These are the constraints where data-flow analysis is needed to verify if they hold. The data flow analysis of pass 3 is called pass 3b in JustIce.
version: $Id: StructuralCodeConstraintException.java,v 1.1.1.1 2001/10/29 20:00:34 jvanzyl Exp $ author: Enver Haase

Where is this exception thrown?

Following, is a list of exception messages cross-referenced to the source code responsible for throwing them. Click on the method link to view the code and see how the exception is thrown.

How is this exception thrown?

The following sub-sections identify where this exception is thrown, and how (or why) the code is throwing the exception.

Any source code quoted in this section is subject to the Java Research License unless stated otherwise.

com.sun.org.apache.bcel.internal.verifier.structurals.LocalVariables.merge(LocalVariables, int)

/**
  * Merges a single local variable.
  *
  * @see #merge(LocalVariables)
  */
private void merge(LocalVariables lv, int i) {
    if ((!(locals[i] instanceof UninitializedObjectType)) && (lv.locals[i] instanceof UninitializedObjectType)) {
        throw new StructuralCodeConstraintException('Backwards branch with an uninitialized object in the local variables detected.');
    }
    if ((!(locals[i].equals(lv.locals[i]))) && (locals[i] instanceof UninitializedObjectType) && (lv.locals[i] instanceof UninitializedObjectType)) {
        throw new StructuralCodeConstraintException('Backwards branch with an uninitialized object in the local variables detected.');
    }
    if (locals[i] instanceof UninitializedObjectType) {
        if (!(lv.locals[i] instanceof UninitializedObjectType)) {
            locals[i] = ((UninitializedObjectType) locals[i]).getInitialized();
        }
    }
    if ((locals[i] instanceof ReferenceType) && (lv.locals[i] instanceof ReferenceType)) {
        if (!locals[i].equals(lv.locals[i])) {
            Type sup = ((ReferenceType) locals[i]).firstCommonSuperclass((ReferenceType) (lv.locals[i]));
            if (sup != null) {
                locals[i] = sup;
            } else {
                throw new AssertionViolatedException('Could not load all the super classes of '' + locals[i] + '' and '' + lv.locals[i] + ''.');
            }
        }
    } else {
        if (!(locals[i].equals(lv.locals[i]))) {
            locals[i] = Type.UNKNOWN;
        }
    }
}

Source: "Java SE Downloads: Java SE 6 JDK Source Code", at: http://www.oracle.com/technetwork/java/javase/downloads/index.html

com.sun.org.apache.bcel.internal.verifier.structurals.OperandStack.merge(OperandStack)

/**
  * Merges another stack state into this instance's stack state.
  * See the Java Virtual Machine Specification, Second Edition, page 146: 4.9.2
  * for details.
  */
public void merge(OperandStack s) {
    if ((slotsUsed() != s.slotsUsed()) || (size() != s.size())) throw new StructuralCodeConstraintException('Cannot merge stacks of different size:\nOperandStack A:\n' + this + '\nOperandStack B:\n' + s);
    for (int i = 0; i < size(); i++) {
        if ((!(stack.get(i) instanceof UninitializedObjectType)) && (s.stack.get(i) instanceof UninitializedObjectType)) {
            throw new StructuralCodeConstraintException('Backwards branch with an uninitialized object on the stack detected.');
        }
        if ((!(stack.get(i).equals(s.stack.get(i)))) && (stack.get(i) instanceof UninitializedObjectType) && (!(s.stack.get(i) instanceof UninitializedObjectType))) {
            throw new StructuralCodeConstraintException('Backwards branch with an uninitialized object on the stack detected.');
        }
        if (stack.get(i) instanceof UninitializedObjectType) {
            if (!(s.stack.get(i) instanceof UninitializedObjectType)) {
                stack.set(i, ((UninitializedObjectType) (stack.get(i))).getInitialized());
            }
        }
        if (!stack.get(i).equals(s.stack.get(i))) {
            if ((stack.get(i) instanceof ReferenceType) && (s.stack.get(i) instanceof ReferenceType)) {
                stack.set(i, ((ReferenceType) stack.get(i)).firstCommonSuperclass((ReferenceType) (s.stack.get(i))));
            } else {
                throw new StructuralCodeConstraintException('Cannot merge stacks of different types:\nStack A:\n' + this + '\nStack B:\n' + s);
            }
        }
    }
}

Source: "Java SE Downloads: Java SE 6 JDK Source Code", at: http://www.oracle.com/technetwork/java/javase/downloads/index.html

com.sun.org.apache.bcel.internal.verifier.structurals.InstConstraintVisitor.constraintViolated(Instruction, String)

/**
   * This method is called by the visitXXX() to notify the acceptor of this InstConstraintVisitor
   * that a constraint violation has occured. This is done by throwing an instance of a
   * StructuralCodeConstraintException.
   * @throws com.sun.org.apache.bcel.internal.verifier.exc.StructuralCodeConstraintException always.
   */
private void constraintViolated(Instruction violator, String description) {
    String fq_classname = violator.getClass().getName();
    throw new StructuralCodeConstraintException('Instruction ' + fq_classname.substring(fq_classname.lastIndexOf('.') + 1) + ' constraint violated: ' + description);
}

Source: "Java SE Downloads: Java SE 6 JDK Source Code", at: http://www.oracle.com/technetwork/java/javase/downloads/index.html

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