spring OpEQ 源码

spring OpEQ 代码

文件路径：/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpEQ.java

/*
 * Copyright 2002-2019 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.expression.spel.ast;

import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.support.BooleanTypedValue;

/**
 * Implements the equality operator.
 *
 * @author Andy Clement
 * @since 3.0
 */
public class OpEQ extends Operator {

	public OpEQ(int startPos, int endPos, SpelNodeImpl... operands) {
		super("==", startPos, endPos, operands);
		this.exitTypeDescriptor = "Z";
	}


	@Override
	public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
		Object left = getLeftOperand().getValueInternal(state).getValue();
		Object right = getRightOperand().getValueInternal(state).getValue();
		this.leftActualDescriptor = CodeFlow.toDescriptorFromObject(left);
		this.rightActualDescriptor = CodeFlow.toDescriptorFromObject(right);
		return BooleanTypedValue.forValue(equalityCheck(state.getEvaluationContext(), left, right));
	}

	// This check is different to the one in the other numeric operators (OpLt/etc)
	// because it allows for simple object comparison
	@Override
	public boolean isCompilable() {
		SpelNodeImpl left = getLeftOperand();
		SpelNodeImpl right = getRightOperand();
		if (!left.isCompilable() || !right.isCompilable()) {
			return false;
		}

		String leftDesc = left.exitTypeDescriptor;
		String rightDesc = right.exitTypeDescriptor;
		DescriptorComparison dc = DescriptorComparison.checkNumericCompatibility(leftDesc,
				rightDesc, this.leftActualDescriptor, this.rightActualDescriptor);
		return (!dc.areNumbers || dc.areCompatible);
	}

	@Override
	public void generateCode(MethodVisitor mv, CodeFlow cf) {
		cf.loadEvaluationContext(mv);
		String leftDesc = getLeftOperand().exitTypeDescriptor;
		String rightDesc = getRightOperand().exitTypeDescriptor;
		boolean leftPrim = CodeFlow.isPrimitive(leftDesc);
		boolean rightPrim = CodeFlow.isPrimitive(rightDesc);

		cf.enterCompilationScope();
		getLeftOperand().generateCode(mv, cf);
		cf.exitCompilationScope();
		if (leftPrim) {
			CodeFlow.insertBoxIfNecessary(mv, leftDesc.charAt(0));
		}
		cf.enterCompilationScope();
		getRightOperand().generateCode(mv, cf);
		cf.exitCompilationScope();
		if (rightPrim) {
			CodeFlow.insertBoxIfNecessary(mv, rightDesc.charAt(0));
		}

		String operatorClassName = Operator.class.getName().replace('.', '/');
		String evaluationContextClassName = EvaluationContext.class.getName().replace('.', '/');
		mv.visitMethodInsn(INVOKESTATIC, operatorClassName, "equalityCheck",
				"(L" + evaluationContextClassName + ";Ljava/lang/Object;Ljava/lang/Object;)Z", false);
		cf.pushDescriptor("Z");
	}

}

相关信息

spring 源码目录

相关文章

spring Assign 源码

spring AstUtils 源码

spring BeanReference 源码

spring BooleanLiteral 源码

spring CompoundExpression 源码

spring ConstructorReference 源码

spring Elvis 源码

spring FloatLiteral 源码

spring FormatHelper 源码

spring FunctionReference 源码