spring OpAnd 源码

spring OpAnd 代码

文件路径：/spring-expression/src/main/java/org/springframework/expression/spel/ast/OpAnd.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.Label;
import org.springframework.asm.MethodVisitor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.expression.spel.support.BooleanTypedValue;
import org.springframework.lang.Nullable;

/**
 * Represents the boolean AND operation.
 *
 * @author Andy Clement
 * @author Mark Fisher
 * @author Oliver Becker
 * @since 3.0
 */
public class OpAnd extends Operator {

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


	@Override
	public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
		if (!getBooleanValue(state, getLeftOperand())) {
			// no need to evaluate right operand
			return BooleanTypedValue.FALSE;
		}
		return BooleanTypedValue.forValue(getBooleanValue(state, getRightOperand()));
	}

	private boolean getBooleanValue(ExpressionState state, SpelNodeImpl operand) {
		try {
			Boolean value = operand.getValue(state, Boolean.class);
			assertValueNotNull(value);
			return value;
		}
		catch (SpelEvaluationException ex) {
			ex.setPosition(operand.getStartPosition());
			throw ex;
		}
	}

	private void assertValueNotNull(@Nullable Boolean value) {
		if (value == null) {
			throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");
		}
	}

	@Override
	public boolean isCompilable() {
		SpelNodeImpl left = getLeftOperand();
		SpelNodeImpl right = getRightOperand();
		return (left.isCompilable() && right.isCompilable() &&
				CodeFlow.isBooleanCompatible(left.exitTypeDescriptor) &&
				CodeFlow.isBooleanCompatible(right.exitTypeDescriptor));
	}

	@Override
	public void generateCode(MethodVisitor mv, CodeFlow cf) {
		// Pseudo: if (!leftOperandValue) { result=false; } else { result=rightOperandValue; }
		Label elseTarget = new Label();
		Label endOfIf = new Label();
		cf.enterCompilationScope();
		getLeftOperand().generateCode(mv, cf);
		cf.unboxBooleanIfNecessary(mv);
		cf.exitCompilationScope();
		mv.visitJumpInsn(IFNE, elseTarget);
		mv.visitLdcInsn(0); // FALSE
		mv.visitJumpInsn(GOTO,endOfIf);
		mv.visitLabel(elseTarget);
		cf.enterCompilationScope();
		getRightOperand().generateCode(mv, cf);
		cf.unboxBooleanIfNecessary(mv);
		cf.exitCompilationScope();
		mv.visitLabel(endOfIf);
		cf.pushDescriptor(this.exitTypeDescriptor);
	}

}

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