apb.processors.NotNullClassInstrumenter.java Source code

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Here is the source code for apb.processors.NotNullClassInstrumenter.java

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// Copyright 2008-2009 Emilio Lopez-Gabeiras
//
// 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 apb.processors;

import java.util.ArrayList;
import java.util.List;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.ClassAdapter;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodAdapter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
//
// User: emilio
// Date: Oct 27, 2009
// Time: 4:01:57 PM

class NotNullClassInstrumenter extends ClassAdapter {
    //~ Instance fields ......................................................................................

    private boolean isModified;

    private String className;

    //~ Constructors .........................................................................................

    public NotNullClassInstrumenter(ClassVisitor classVisitor) {
        super(classVisitor);
        isModified = false;
    }

    //~ Methods ..............................................................................................

    public boolean isModified() {
        return isModified;
    }

    public void visit(int version, int access, String name, String signature, String superName,
            String[] interfaces) {
        super.visit(version, access, name, signature, superName, interfaces);
        className = name;
    }

    public void visitInnerClass(String name, String outerName, String innerName, int access) {
        super.visitInnerClass(name, outerName, innerName, access);
    }

    public MethodVisitor visitMethod(final int access, final String name, String desc, String signature,
            String[] exceptions) {
        final Type[] args = Type.getArgumentTypes(desc);
        final Type returnType = Type.getReturnType(desc);

        MethodVisitor v = cv.visitMethod(access, name, desc, signature, exceptions);
        return new MethodAdapter(v) {
            @Override
            public AnnotationVisitor visitParameterAnnotation(int parameter, String anno, boolean visible) {
                final AnnotationVisitor result = mv.visitParameterAnnotation(parameter, anno, visible);

                if (NotNullClassInstrumenter.isReferenceType(args[parameter])
                        && anno.equals(NOT_NULL_ANNOATATION_SIGNATURE)) {
                    notNullParams.add(parameter);
                }

                return result;
            }

            @Override
            public AnnotationVisitor visitAnnotation(String anno, boolean isRuntime) {
                final AnnotationVisitor av = mv.visitAnnotation(anno, isRuntime);

                if (isReferenceType(returnType) && anno.equals(NOT_NULL_ANNOATATION_SIGNATURE)) {
                    isResultNotNull = true;
                }

                return av;
            }

            @Override
            public void visitCode() {
                if (isResultNotNull || !notNullParams.isEmpty()) {
                    startGeneratedCodeLabel = new Label();
                    mv.visitLabel(startGeneratedCodeLabel);
                }

                for (int nullParam : notNullParams) {
                    int var = (access & 8) != 0 ? 0 : 1;

                    for (int i = 0; i < nullParam; i++) {
                        var += args[i].getSize();
                    }

                    mv.visitVarInsn(Opcodes.ALOAD, var);
                    Label end = new Label();
                    mv.visitJumpInsn(Opcodes.IFNONNULL, end);
                    generateThrow(
                            ILLEGAL_STATE_EXCEPTION_SIGNATURE, "Argument " + nullParam
                                    + " for @NotNull parameter of " + className + "." + name + " must not be null",
                            end);
                }

                if (isResultNotNull) {
                    final Label codeStart = new Label();
                    mv.visitJumpInsn(Opcodes.GOTO, codeStart);
                    throwLabel = new Label();
                    mv.visitLabel(throwLabel);
                    generateThrow(ILLEGAL_STATE_EXCEPTION_SIGNATURE,
                            "@NotNull method " + className + "." + name + " must not return null", codeStart);
                }
            }

            @Override
            public void visitLocalVariable(String name, String desc, String signature, Label start, Label end,
                    int index) {
                boolean isStatic = (access & 8) != 0;
                boolean isParameter = isStatic ? index < args.length : index <= args.length;
                mv.visitLocalVariable(name, desc, signature,
                        !isParameter || startGeneratedCodeLabel == null ? start : startGeneratedCodeLabel, end,
                        index);
            }

            public void visitInsn(int opcode) {
                if (opcode == Opcodes.ARETURN && isResultNotNull) {
                    mv.visitInsn(Opcodes.DUP);
                    mv.visitJumpInsn(Opcodes.IFNULL, throwLabel);
                }

                mv.visitInsn(opcode);
            }

            private void generateThrow(String exceptionClass, String descr, Label end) {
                mv.visitTypeInsn(Opcodes.NEW, exceptionClass);
                mv.visitInsn(Opcodes.DUP);
                mv.visitLdcInsn(descr);

                final String exceptionParamClass = "(Ljava/lang/String;)V";
                mv.visitMethodInsn(Opcodes.INVOKESPECIAL, exceptionClass, "<init>", exceptionParamClass);
                mv.visitInsn(Opcodes.ATHROW);
                mv.visitLabel(end);
                isModified = true;
            }

            private final List<Integer> notNullParams = new ArrayList<Integer>();
            private boolean isResultNotNull = false;
            public Label throwLabel;
            private Label startGeneratedCodeLabel;
        };
    }

    private static boolean isReferenceType(Type type) {
        return type.getSort() == 10 || type.getSort() == 9;
    }

    //~ Static fields/initializers ...........................................................................

    private static final String NOT_NULL_ANNOATATION_SIGNATURE = "Lorg/jetbrains/annotations/NotNull;";
    private static final String ILLEGAL_STATE_EXCEPTION_SIGNATURE = "java/lang/IllegalArgumentException";
}