Java tutorial
/* * Copyright 2012-2015 Institut National des Sciences Appliques de Lyon (INSA-Lyon) * * 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 fr.insalyon.citi.golo.compiler; import fr.insalyon.citi.golo.compiler.ir.Union; import org.objectweb.asm.ClassWriter; import org.objectweb.asm.Label; import org.objectweb.asm.MethodVisitor; import java.util.Collection; import java.util.LinkedList; import java.util.Map; import java.util.HashMap; import static fr.insalyon.citi.golo.compiler.JavaBytecodeUtils.loadInteger; import static org.objectweb.asm.ClassWriter.COMPUTE_FRAMES; import static org.objectweb.asm.ClassWriter.COMPUTE_MAXS; import static org.objectweb.asm.Opcodes.*; class JavaBytecodeUnionGenerator { public Collection<CodeGenerationResult> compile(Union union, String sourceFilename) { LinkedList<CodeGenerationResult> results = new LinkedList<>(); ClassWriter classWriter = new ClassWriter(COMPUTE_FRAMES | COMPUTE_MAXS); classWriter.visitSource(sourceFilename, null); classWriter.visit(V1_8, ACC_PUBLIC | ACC_SUPER | ACC_ABSTRACT, union.getPackageAndClass().toJVMType(), null, "java/lang/Object", null); makeDefaultConstructor(classWriter, "java/lang/Object"); HashMap<String, PackageAndClass> staticFields = new HashMap<>(); for (Union.Value value : union.getValues()) { results.add(makeUnionValue(classWriter, sourceFilename, value)); if (value.hasMembers()) { makeStaticFactory(classWriter, value); } else { staticFields.put(value.getName(), value.getPackageAndClass()); } } initStaticFields(classWriter, union.getPackageAndClass(), staticFields); classWriter.visitEnd(); results.addFirst(new CodeGenerationResult(classWriter.toByteArray(), union.getPackageAndClass())); return results; } private void initStaticFields(ClassWriter cw, PackageAndClass unionType, Map<String, PackageAndClass> staticFields) { MethodVisitor mv = cw.visitMethod(ACC_STATIC, "<clinit>", "()V", null, null); mv.visitCode(); for (String attr : staticFields.keySet()) { mv.visitTypeInsn(NEW, staticFields.get(attr).toJVMType()); mv.visitInsn(DUP); mv.visitMethodInsn(INVOKESPECIAL, staticFields.get(attr).toJVMType(), "<init>", "()V", false); mv.visitFieldInsn(PUTSTATIC, unionType.toJVMType(), attr, unionType.toJVMRef()); } mv.visitInsn(RETURN); mv.visitMaxs(0, 0); mv.visitEnd(); } private void makeStaticFactory(ClassWriter cw, Union.Value value) { MethodVisitor mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC, value.getName(), argsSignature(value.getMembers().size()) + value.getUnion().getPackageAndClass().toJVMRef(), null, null); mv.visitCode(); mv.visitTypeInsn(NEW, value.getPackageAndClass().toJVMType()); mv.visitInsn(DUP); for (int i = 0; i < value.getMembers().size(); i++) { mv.visitVarInsn(ALOAD, i); } mv.visitMethodInsn(INVOKESPECIAL, value.getPackageAndClass().toJVMType(), "<init>", argsSignature(value.getMembers().size()) + "V", false); mv.visitInsn(ARETURN); mv.visitMaxs(0, 0); mv.visitEnd(); } private void makeDefaultConstructor(ClassWriter classWriter, String superCls) { MethodVisitor visitor = classWriter.visitMethod(ACC_PROTECTED, "<init>", "()V", null, null); visitor.visitCode(); visitor.visitVarInsn(ALOAD, 0); visitor.visitMethodInsn(INVOKESPECIAL, superCls, "<init>", "()V", false); visitor.visitInsn(RETURN); visitor.visitMaxs(0, 0); visitor.visitEnd(); } private void makeToString(ClassWriter classWriter, Union.Value value) { MethodVisitor visitor = classWriter.visitMethod(ACC_PUBLIC, "toString", "()Ljava/lang/String;", null, null); visitor.visitCode(); if (!value.hasMembers()) { visitor.visitLdcInsn( "union " + value.getUnion().getPackageAndClass().className() + "." + value.getName()); } else { visitor.visitTypeInsn(NEW, "java/lang/StringBuilder"); visitor.visitInsn(DUP); visitor.visitLdcInsn( "union " + value.getUnion().getPackageAndClass().className() + "." + value.getName() + "{"); visitor.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "(Ljava/lang/String;)V", false); visitor.visitVarInsn(ASTORE, 1); boolean first = true; for (String member : value.getMembers()) { visitor.visitVarInsn(ALOAD, 1); visitor.visitLdcInsn((first ? "" : ", ") + member + "="); visitor.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false); visitor.visitInsn(POP); visitor.visitVarInsn(ALOAD, 1); visitor.visitVarInsn(ALOAD, 0); visitor.visitFieldInsn(GETFIELD, value.getPackageAndClass().toJVMType(), member, "Ljava/lang/Object;"); visitor.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/Object;)Ljava/lang/StringBuilder;", false); visitor.visitInsn(POP); first = false; } visitor.visitVarInsn(ALOAD, 1); visitor.visitLdcInsn("}"); visitor.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false); visitor.visitInsn(POP); visitor.visitVarInsn(ALOAD, 1); visitor.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false); } visitor.visitInsn(ARETURN); visitor.visitMaxs(0, 0); visitor.visitEnd(); } private CodeGenerationResult makeUnionValue(ClassWriter parentClassWriter, String sourceFilename, Union.Value value) { String unionType = value.getUnion().getPackageAndClass().toJVMType(); String valueType = value.getPackageAndClass().toJVMType(); ClassWriter classWriter = new ClassWriter(COMPUTE_FRAMES | COMPUTE_MAXS); classWriter.visitSource(sourceFilename, null); classWriter.visit(V1_8, ACC_PUBLIC | ACC_SUPER | ACC_FINAL, valueType, null, unionType, null); classWriter.visitInnerClass(valueType, unionType, value.getName(), ACC_PUBLIC | ACC_FINAL | ACC_STATIC); parentClassWriter.visitInnerClass(valueType, unionType, value.getName(), ACC_PUBLIC | ACC_FINAL | ACC_STATIC); for (String member : value.getMembers()) { classWriter.visitField(ACC_PUBLIC | ACC_FINAL, member, "Ljava/lang/Object;", null, null).visitEnd(); } if (value.hasMembers()) { makeValuedConstructor(classWriter, value); makeHashCode(classWriter, value); makeEquals(classWriter, value); } else { makeDefaultConstructor(classWriter, unionType); parentClassWriter.visitField(ACC_PUBLIC | ACC_FINAL | ACC_STATIC, value.getName(), value.getUnion().getPackageAndClass().toJVMRef(), null, null).visitEnd(); } makeToString(classWriter, value); classWriter.visitEnd(); return new CodeGenerationResult(classWriter.toByteArray(), value.getPackageAndClass()); } private void makeEquals(ClassWriter cw, Union.Value value) { String target = value.getPackageAndClass().toJVMType(); MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "equals", "(Ljava/lang/Object;)Z", null, null); Label notSameInstance = new Label(); Label notNull = new Label(); Label sameType = new Label(); Label allAttrsEquals = new Label(); Label attrNotEqual = new Label(); mv.visitCode(); // if (other == this) { return true; } mv.visitVarInsn(ALOAD, 1); mv.visitVarInsn(ALOAD, 0); mv.visitJumpInsn(IF_ACMPNE, notSameInstance); mv.visitInsn(ICONST_1); mv.visitInsn(IRETURN); mv.visitLabel(notSameInstance); // if (other == null) { return false; } mv.visitVarInsn(ALOAD, 1); mv.visitJumpInsn(IFNONNULL, notNull); mv.visitInsn(ICONST_0); mv.visitInsn(IRETURN); mv.visitLabel(notNull); // if (!(other instanceof <value>)) { return false; } mv.visitVarInsn(ALOAD, 1); mv.visitTypeInsn(INSTANCEOF, target); mv.visitJumpInsn(IFNE, sameType); mv.visitInsn(ICONST_0); mv.visitInsn(IRETURN); mv.visitLabel(sameType); // cast other to <value> mv.visitVarInsn(ALOAD, 1); mv.visitTypeInsn(CHECKCAST, target); mv.visitVarInsn(ASTORE, 2); // java.util.Objects.equals(<member>, other.<member>) for (String member : value.getMembers()) { mv.visitVarInsn(ALOAD, 0); mv.visitFieldInsn(GETFIELD, target, member, "Ljava/lang/Object;"); mv.visitVarInsn(ALOAD, 2); mv.visitFieldInsn(GETFIELD, target, member, "Ljava/lang/Object;"); mv.visitMethodInsn(INVOKESTATIC, "java/util/Objects", "equals", "(Ljava/lang/Object;Ljava/lang/Object;)Z", false); mv.visitJumpInsn(IFEQ, attrNotEqual); } mv.visitInsn(ICONST_1); mv.visitJumpInsn(GOTO, allAttrsEquals); mv.visitLabel(attrNotEqual); mv.visitInsn(ICONST_0); mv.visitLabel(allAttrsEquals); mv.visitInsn(IRETURN); mv.visitMaxs(0, 0); mv.visitEnd(); } private void makeHashCode(ClassWriter cw, Union.Value value) { MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "hashCode", "()I", null, null); mv.visitCode(); loadInteger(mv, value.getMembers().size()); mv.visitTypeInsn(ANEWARRAY, "java/lang/Object"); int i = 0; for (String member : value.getMembers()) { mv.visitInsn(DUP); loadInteger(mv, i); mv.visitVarInsn(ALOAD, 0); mv.visitFieldInsn(GETFIELD, value.getPackageAndClass().toJVMType(), member, "Ljava/lang/Object;"); mv.visitInsn(AASTORE); } mv.visitMethodInsn(INVOKESTATIC, "java/util/Objects", "hash", "([Ljava/lang/Object;)I", false); mv.visitInsn(IRETURN); mv.visitMaxs(0, 0); mv.visitEnd(); } private String argsSignature(int membersCount) { StringBuilder signature = new StringBuilder("("); for (int i = 0; i < membersCount; i++) { signature.append("Ljava/lang/Object;"); } signature.append(")"); return signature.toString(); } private void makeValuedConstructor(ClassWriter cw, Union.Value value) { MethodVisitor mv = cw.visitMethod(ACC_PROTECTED, "<init>", argsSignature(value.getMembers().size()) + "V", null, null); mv.visitCode(); mv.visitVarInsn(ALOAD, 0); mv.visitMethodInsn(INVOKESPECIAL, value.getUnion().getPackageAndClass().toJVMType(), "<init>", "()V", false); int idx = 1; for (String member : value.getMembers()) { mv.visitVarInsn(ALOAD, 0); mv.visitVarInsn(ALOAD, idx++); mv.visitFieldInsn(PUTFIELD, value.getPackageAndClass().toJVMType(), member, "Ljava/lang/Object;"); } mv.visitInsn(RETURN); mv.visitMaxs(0, 0); mv.visitEnd(); } }