org.mvel2.optimizers.impl.asm.ProducesBytecode Maven / Gradle / Ivy
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TBEL is a powerful expression language for ThingsBoard platform user-defined functions.
Original implementation is based on MVEL.
/**
* MVEL 2.0
* Copyright (C) 2007 The Codehaus
* Mike Brock, Dhanji Prasanna, John Graham, Mark Proctor
*
* 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 org.mvel2.optimizers.impl.asm;
import org.mvel2.asm.MethodVisitor;
import org.mvel2.integration.VariableResolverFactory;
/**
* A {@link org.mvel2.integration.PropertyHandler} that implements this class advertises the to the
* {@link ASMAccessorOptimizer} that it is able to generate bytecode for it's custom resolvers.
*
* The two methods defined by this interface (one for get, and one for set accessors) are passed an
* ASM MethodVistor object. It is to be assumed by the implementor that the JIT has already produced
* the necessary bytecode up until this point. The implementor most only implement the necessary bytecode
* instructions to retrieve the property, leaving the resultant value on the stack. DO NOT implement
* bytecode that calls a return instruction such as ARETURN. This will be done automatically by the JIT.
*
* See the following example:
*
* public void produceBytecodeGet(MethodVisitor mv, String propertyName, VariableResolverFactory variableResolverFactory) {
* mv.visitTypeInsn(CHECKCAST, "org/mvel/tests/main/res/SampleBean");
* mv.visitLdcInsn(propertyName);
* mv.visitMethodInsn(INVOKEVIRTUAL, "org/mvel/tests/main/res/SampleBean", "getProperty", "(Ljava/lang/String;)Ljava/lang/Object;");
* }
*
* This example (correctly) presumes that the property of interest exists on the stack, and simply performs the necessary
* CHECKCAST, and call to the needed method in the accessor to translate the property call.
*
* This is taken from a working example which you can examine in the MVEL unit tests.
* The class is: org.mvel.tests.main.res.SampleBeanAccessor
*/
public interface ProducesBytecode {
public void produceBytecodeGet(MethodVisitor mv, String propertyName, VariableResolverFactory factory);
public void produceBytecodePut(MethodVisitor mv, String propertyName, VariableResolverFactory factory);
}