org.jsimpledb.JField Maven / Gradle / Ivy
Show all versions of jsimpledb-main Show documentation
/*
* Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
*/
package org.jsimpledb;
import java.lang.reflect.Method;
import java.util.Arrays;
import org.jsimpledb.core.ObjId;
import org.jsimpledb.schema.SchemaField;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
/**
* Represents a field in a Java model object.
*/
public abstract class JField extends JSchemaObject {
final Method getter;
JSchemaObject parent;
boolean requiresDefaultValidation;
JField(JSimpleDB jdb, String name, int storageId, String description, Method getter) {
super(jdb, name, storageId, description);
this.getter = getter;
}
void calculateRequiresDefaultValidation() {
this.requiresDefaultValidation = this.getter != null && Util.requiresDefaultValidation(this.getter);
}
/**
* Determine if this instance and the given instance are effectively the same.
*
*
* This is used to handle the case where a field is declared via abstract methods in multiple
* supertypes, but not declared in the model class itself.
*/
boolean isSameAs(JField that) {
if (!(this.name != null ? this.name.equals(that.name) : that.name == null))
return false;
if (this.storageId != that.storageId)
return false;
if (!this.description.equals(that.description))
return false;
if (!this.getClass().equals(that.getClass()))
return false;
if (!this.getter.getReturnType().equals(that.getter.getReturnType()))
return false;
if (!Arrays.equals(this.getter.getParameterTypes(), that.getter.getParameterTypes()))
return false;
return true;
}
@Override
abstract SchemaField toSchemaItem(JSimpleDB jdb);
/**
* Get the getter method associated with this field.
*
* @return field property getter method, or null if this field is a sub-field of a complex field
*/
public Method getGetter() {
return this.getter;
}
/**
* Get the Java value of this field in the given Java model object.
* Does not alter the schema version of the object.
*
* @param jobj object containing this field
* @throws org.jsimpledb.core.DeletedObjectException if {@code jobj} does not exist in its associated {@link JTransaction}
* @throws org.jsimpledb.kv.StaleTransactionException if the {@link JTransaction} associated with {@code jobj}
* is no longer usable
* @return this field's value in {@code jobj}
* @throws IllegalArgumentException if {@code jobj} is null
*/
public abstract Object getValue(JObject jobj);
/**
* Apply visitor pattern.
*
* @param target target to invoke
* @param visit return type
* @return value from the method of {@code target} corresponding to this instance's type
* @throws NullPointerException if {@code target} is null
*/
public abstract R visit(JFieldSwitch target);
/**
* Create a {@link JFieldInfo} instance that corresponds to this instance.
*/
abstract JFieldInfo toJFieldInfo();
// Bytecode generation
boolean hasClassInitializerBytecode() {
return false;
}
void outputClassInitializerBytecode(ClassGenerator generator, MethodVisitor mv) {
throw new UnsupportedOperationException();
}
void outputFields(ClassGenerator generator, ClassWriter cw) {
}
abstract void outputMethods(ClassGenerator generator, ClassWriter cw);
void outputCachedValueField(ClassGenerator generator, ClassWriter cw) {
final FieldVisitor valueField = cw.visitField(Opcodes.ACC_PRIVATE,
this.getCachedValueFieldName(), Type.getDescriptor(this.getCachedValueFieldType()), null, null);
valueField.visitEnd();
}
void outputCachedValueGetterMethod(ClassGenerator generator, ClassWriter cw, Method fieldReaderMethod) {
final MethodVisitor mv = generator.startMethod(cw, this.getter);
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitFieldInsn(Opcodes.GETFIELD, generator.getClassName(),
this.getCachedValueFieldName(), Type.getDescriptor(this.getCachedValueFieldType()));
mv.visitInsn(Opcodes.DUP);
final Label valueReady = new Label();
mv.visitJumpInsn(Opcodes.IFNONNULL, valueReady);
mv.visitInsn(Opcodes.POP);
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitFieldInsn(Opcodes.GETFIELD, generator.getClassName(),
ClassGenerator.TX_FIELD_NAME, Type.getDescriptor(JTransaction.class));
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitFieldInsn(Opcodes.GETFIELD, generator.getClassName(),
ClassGenerator.ID_FIELD_NAME, Type.getDescriptor(ObjId.class));
mv.visitLdcInsn(this.storageId);
mv.visitInsn(Opcodes.ICONST_1); // i.e., true
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, Type.getInternalName(JTransaction.class),
fieldReaderMethod.getName(), Type.getMethodDescriptor(fieldReaderMethod), false);
mv.visitTypeInsn(Opcodes.CHECKCAST, Type.getInternalName(this.getCachedValueFieldType()));
mv.visitInsn(Opcodes.DUP);
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitInsn(Opcodes.SWAP);
mv.visitFieldInsn(Opcodes.PUTFIELD, generator.getClassName(),
this.getCachedValueFieldName(), Type.getDescriptor(this.getCachedValueFieldType()));
mv.visitLabel(valueReady);
mv.visitFrame(Opcodes.F_SAME1, 0, new Object[0], 1, new String[] { Type.getInternalName(this.getCachedValueFieldType()) });
mv.visitInsn(Opcodes.ARETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
private String getCachedValueFieldName() {
return ClassGenerator.JFIELD_FIELD_PREFIX + this.storageId;
}
private Class getCachedValueFieldType() {
return this.getter.getReturnType();
}
}