001/*
002 * Copyright 2002-2014 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.expression.spel;
018
019import org.springframework.asm.MethodVisitor;
020import org.springframework.asm.Opcodes;
021import org.springframework.expression.PropertyAccessor;
022
023/**
024 * A compilable property accessor is able to generate bytecode that represents
025 * the access operation, facilitating compilation to bytecode of expressions
026 * that use the accessor.
027 *
028 * @author Andy Clement
029 * @since 4.1
030 */
031public interface CompilablePropertyAccessor extends PropertyAccessor, Opcodes {
032
033        /**
034         * Return {@code true} if this property accessor is currently suitable for compilation.
035         */
036        boolean isCompilable();
037
038        /**
039         * Return the type of the accessed property - may only be known once an access has occurred.
040         */
041        Class<?> getPropertyType();
042
043        /**
044         * Generate the bytecode the performs the access operation into the specified MethodVisitor
045         * using context information from the codeflow where necessary.
046         * @param propertyName the name of the property
047         * @param mv the Asm method visitor into which code should be generated
048         * @param cf the current state of the expression compiler
049         */
050        void generateCode(String propertyName, MethodVisitor mv, CodeFlow cf);
051
052}