com.github.wreulicke.bean.validation.ASMNotNullInstrumentation.java Source code

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Here is the source code for com.github.wreulicke.bean.validation.ASMNotNullInstrumentation.java

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/**
 * MIT License
 *
 * Copyright (c) 2017 Wreulicke
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.github.wreulicke.bean.validation;

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.reflect.Modifier;
import java.security.ProtectionDomain;
import java.util.List;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.TypeReference;
import org.objectweb.asm.tree.AnnotationNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.LdcInsnNode;
import org.objectweb.asm.tree.LocalVariableNode;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.TypeAnnotationNode;
import org.objectweb.asm.tree.VarInsnNode;

public class ASMNotNullInstrumentation implements ClassFileTransformer {
    @Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
            ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_FRAMES + ClassWriter.COMPUTE_MAXS);
        ClassReader reader = new ClassReader(classfileBuffer);
        ClassNode node = new ClassNode();
        reader.accept(node, ClassReader.EXPAND_FRAMES);
        new InnerNotNullInstrumentation(node).visit();
        node.accept(writer);
        return writer.toByteArray();
    }

    private static class InnerNotNullInstrumentation {
        ClassNode node;

        public InnerNotNullInstrumentation(ClassNode node) {
            this.node = node;
        }

        public void visit() {
            @SuppressWarnings("unchecked")
            List<MethodNode> nodes = node.methods;
            nodes.forEach(this::accept);
        }

        @SuppressWarnings("unchecked")
        public void accept(MethodNode method) {
            InsnList insnList = new InsnList();

            List<TypeAnnotationNode> typeAnnotations = method.visibleTypeAnnotations;
            if (typeAnnotations != null) {
                typeAnnotations.stream().filter((annotation) -> {
                    return new TypeReference(annotation.typeRef).getSort() == TypeReference.METHOD_RECEIVER
                            && "Ljavax/validation/constraints/NotNull;".equals(annotation.desc);
                }).findFirst().ifPresent((annotation) -> {
                    insnList.add(new VarInsnNode(Opcodes.ALOAD, 0));
                    insnList.add(new LdcInsnNode("this is required"));
                    insnList.add(new MethodInsnNode(Opcodes.INVOKESTATIC, "java/util/Objects", "requireNonNull",
                            "(Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;", false));
                });
            }
            List<AnnotationNode>[] parameters = method.visibleParameterAnnotations;
            if (parameters != null) {
                for (int i = 0; i < parameters.length; i++) {
                    final int index = i + (Modifier.isStatic(method.access) ? 0 : 1);
                    List<AnnotationNode> annotations = parameters[i];
                    annotations.stream().map((annnotation) -> annnotation.desc)
                            .filter("Ljavax/validation/constraints/NotNull;"::equals).findFirst()
                            .ifPresent((found) -> {
                                LocalVariableNode localVar = (LocalVariableNode) method.localVariables.get(index);
                                insnList.add(new VarInsnNode(Opcodes.ALOAD, index));
                                insnList.add(new LdcInsnNode(localVar.name + " is required"));
                                insnList.add(new MethodInsnNode(Opcodes.INVOKESTATIC, "java/util/Objects",
                                        "requireNonNull",
                                        "(Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;", false));
                            });
                    ;
                }
            }
            method.instructions.insert(insnList);
            method.visitMaxs(method.maxStack, method.maxLocals);
        }
    }
}