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 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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package org.springframework.expression.spel.ast;

import java.math.BigDecimal;
import java.math.BigInteger;

import org.springframework.expression.EvaluationException;
import org.springframework.expression.Operation;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.expression.spel.SpelEvaluationException;
import org.springframework.expression.spel.SpelMessage;
import org.springframework.util.Assert;

Decrement operator. Can be used in a prefix or postfix form. This will throw appropriate exceptions if the operand in question does not support decrement.
Author:Andy Clement, Juergen Hoeller, Giovanni Dall'Oglio Risso
Since:3.2
/** * Decrement operator. Can be used in a prefix or postfix form. This will throw * appropriate exceptions if the operand in question does not support decrement. * * @author Andy Clement * @author Juergen Hoeller * @author Giovanni Dall'Oglio Risso * @since 3.2 */
public class OpDec extends Operator { private final boolean postfix; // false means prefix public OpDec(int startPos, int endPos, boolean postfix, SpelNodeImpl... operands) { super("--", startPos, endPos, operands); this.postfix = postfix; Assert.notEmpty(operands, "Operands must not be empty"); } @Override public TypedValue getValueInternal(ExpressionState state) throws EvaluationException { SpelNodeImpl operand = getLeftOperand(); // The operand is going to be read and then assigned to, we don't want to evaluate it twice. ValueRef lvalue = operand.getValueRef(state); TypedValue operandTypedValue = lvalue.getValue(); //operand.getValueInternal(state); Object operandValue = operandTypedValue.getValue(); TypedValue returnValue = operandTypedValue; TypedValue newValue = null; if (operandValue instanceof Number) { Number op1 = (Number) operandValue; if (op1 instanceof BigDecimal) { newValue = new TypedValue(((BigDecimal) op1).subtract(BigDecimal.ONE), operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Double) { newValue = new TypedValue(op1.doubleValue() - 1.0d, operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Float) { newValue = new TypedValue(op1.floatValue() - 1.0f, operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof BigInteger) { newValue = new TypedValue(((BigInteger) op1).subtract(BigInteger.ONE), operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Long) { newValue = new TypedValue(op1.longValue() - 1L, operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Integer) { newValue = new TypedValue(op1.intValue() - 1, operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Short) { newValue = new TypedValue(op1.shortValue() - (short) 1, operandTypedValue.getTypeDescriptor()); } else if (op1 instanceof Byte) { newValue = new TypedValue(op1.byteValue() - (byte) 1, operandTypedValue.getTypeDescriptor()); } else { // Unknown Number subtype -> best guess is double decrement newValue = new TypedValue(op1.doubleValue() - 1.0d, operandTypedValue.getTypeDescriptor()); } } if (newValue == null) { try { newValue = state.operate(Operation.SUBTRACT, returnValue.getValue(), 1); } catch (SpelEvaluationException ex) { if (ex.getMessageCode() == SpelMessage.OPERATOR_NOT_SUPPORTED_BETWEEN_TYPES) { // This means the operand is not decrementable throw new SpelEvaluationException(operand.getStartPosition(), SpelMessage.OPERAND_NOT_DECREMENTABLE, operand.toStringAST()); } else { throw ex; } } } // set the new value try { lvalue.setValue(newValue.getValue()); } catch (SpelEvaluationException see) { // if unable to set the value the operand is not writable (e.g. 1-- ) if (see.getMessageCode() == SpelMessage.SETVALUE_NOT_SUPPORTED) { throw new SpelEvaluationException(operand.getStartPosition(), SpelMessage.OPERAND_NOT_DECREMENTABLE); } else { throw see; } } if (!this.postfix) { // the return value is the new value, not the original value returnValue = newValue; } return returnValue; } @Override public String toStringAST() { return getLeftOperand().toStringAST() + "--"; } @Override public SpelNodeImpl getRightOperand() { throw new IllegalStateException("No right operand"); } }