/*
 * Copyright 2002-2018 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
 *
 *      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.
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package org.springframework.expression.spel.ast;

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

import org.springframework.asm.MethodVisitor;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Operation;
import org.springframework.expression.TypeConverter;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.ExpressionState;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.NumberUtils;

The plus operator will:
  • add numbers
  • concatenate strings

It can be used as a unary operator for numbers. The standard promotions are performed when the operand types vary (double+int=double). For other options it defers to the registered overloader.

Author:Andy Clement, Juergen Hoeller, Ivo Smid, Giovanni Dall'Oglio Risso
Since:3.0
/** * The plus operator will: * <ul> * <li>add numbers * <li>concatenate strings * </ul> * * <p>It can be used as a unary operator for numbers. * The standard promotions are performed when the operand types vary (double+int=double). * For other options it defers to the registered overloader. * * @author Andy Clement * @author Juergen Hoeller * @author Ivo Smid * @author Giovanni Dall'Oglio Risso * @since 3.0 */
public class OpPlus extends Operator { public OpPlus(int pos, SpelNodeImpl... operands) { super("+", pos, operands); Assert.notEmpty(operands, "Operands must not be empty"); } @Override public TypedValue getValueInternal(ExpressionState state) throws EvaluationException { SpelNodeImpl leftOp = getLeftOperand(); if (this.children.length < 2) { // if only one operand, then this is unary plus Object operandOne = leftOp.getValueInternal(state).getValue(); if (operandOne instanceof Number) { if (operandOne instanceof Double) { this.exitTypeDescriptor = "D"; } else if (operandOne instanceof Float) { this.exitTypeDescriptor = "F"; } else if (operandOne instanceof Long) { this.exitTypeDescriptor = "J"; } else if (operandOne instanceof Integer) { this.exitTypeDescriptor = "I"; } return new TypedValue(operandOne); } return state.operate(Operation.ADD, operandOne, null); } TypedValue operandOneValue = leftOp.getValueInternal(state); Object leftOperand = operandOneValue.getValue(); TypedValue operandTwoValue = getRightOperand().getValueInternal(state); Object rightOperand = operandTwoValue.getValue(); if (leftOperand instanceof Number && rightOperand instanceof Number) { Number leftNumber = (Number) leftOperand; Number rightNumber = (Number) rightOperand; if (leftNumber instanceof BigDecimal || rightNumber instanceof BigDecimal) { BigDecimal leftBigDecimal = NumberUtils.convertNumberToTargetClass(leftNumber, BigDecimal.class); BigDecimal rightBigDecimal = NumberUtils.convertNumberToTargetClass(rightNumber, BigDecimal.class); return new TypedValue(leftBigDecimal.add(rightBigDecimal)); } else if (leftNumber instanceof Double || rightNumber instanceof Double) { this.exitTypeDescriptor = "D"; return new TypedValue(leftNumber.doubleValue() + rightNumber.doubleValue()); } else if (leftNumber instanceof Float || rightNumber instanceof Float) { this.exitTypeDescriptor = "F"; return new TypedValue(leftNumber.floatValue() + rightNumber.floatValue()); } else if (leftNumber instanceof BigInteger || rightNumber instanceof BigInteger) { BigInteger leftBigInteger = NumberUtils.convertNumberToTargetClass(leftNumber, BigInteger.class); BigInteger rightBigInteger = NumberUtils.convertNumberToTargetClass(rightNumber, BigInteger.class); return new TypedValue(leftBigInteger.add(rightBigInteger)); } else if (leftNumber instanceof Long || rightNumber instanceof Long) { this.exitTypeDescriptor = "J"; return new TypedValue(leftNumber.longValue() + rightNumber.longValue()); } else if (CodeFlow.isIntegerForNumericOp(leftNumber) || CodeFlow.isIntegerForNumericOp(rightNumber)) { this.exitTypeDescriptor = "I"; return new TypedValue(leftNumber.intValue() + rightNumber.intValue()); } else { // Unknown Number subtypes -> best guess is double addition return new TypedValue(leftNumber.doubleValue() + rightNumber.doubleValue()); } } if (leftOperand instanceof String && rightOperand instanceof String) { this.exitTypeDescriptor = "Ljava/lang/String"; return new TypedValue((String) leftOperand + rightOperand); } if (leftOperand instanceof String) { return new TypedValue( leftOperand + (rightOperand == null ? "null" : convertTypedValueToString(operandTwoValue, state))); } if (rightOperand instanceof String) { return new TypedValue( (leftOperand == null ? "null" : convertTypedValueToString(operandOneValue, state)) + rightOperand); } return state.operate(Operation.ADD, leftOperand, rightOperand); } @Override public String toStringAST() { if (this.children.length < 2) { // unary plus return "+" + getLeftOperand().toStringAST(); } return super.toStringAST(); } @Override public SpelNodeImpl getRightOperand() { if (this.children.length < 2) { throw new IllegalStateException("No right operand"); } return this.children[1]; }
Convert operand value to string using registered converter or using toString method.
Params:
  • value – typed value to be converted
  • state – expression state
Returns:TypedValue instance converted to String
/** * Convert operand value to string using registered converter or using * {@code toString} method. * @param value typed value to be converted * @param state expression state * @return {@code TypedValue} instance converted to {@code String} */
private static String convertTypedValueToString(TypedValue value, ExpressionState state) { TypeConverter typeConverter = state.getEvaluationContext().getTypeConverter(); TypeDescriptor typeDescriptor = TypeDescriptor.valueOf(String.class); if (typeConverter.canConvert(value.getTypeDescriptor(), typeDescriptor)) { return String.valueOf(typeConverter.convertValue(value.getValue(), value.getTypeDescriptor(), typeDescriptor)); } return String.valueOf(value.getValue()); } @Override public boolean isCompilable() { if (!getLeftOperand().isCompilable()) { return false; } if (this.children.length > 1) { if (!getRightOperand().isCompilable()) { return false; } } return (this.exitTypeDescriptor != null); }
Walk through a possible tree of nodes that combine strings and append them all to the same (on stack) StringBuilder.
/** * Walk through a possible tree of nodes that combine strings and append * them all to the same (on stack) StringBuilder. */
private void walk(MethodVisitor mv, CodeFlow cf, @Nullable SpelNodeImpl operand) { if (operand instanceof OpPlus) { OpPlus plus = (OpPlus)operand; walk(mv, cf, plus.getLeftOperand()); walk(mv, cf, plus.getRightOperand()); } else if (operand != null) { cf.enterCompilationScope(); operand.generateCode(mv,cf); if (!"Ljava/lang/String".equals(cf.lastDescriptor())) { mv.visitTypeInsn(CHECKCAST, "java/lang/String"); } cf.exitCompilationScope(); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false); } } @Override public void generateCode(MethodVisitor mv, CodeFlow cf) { if ("Ljava/lang/String".equals(this.exitTypeDescriptor)) { mv.visitTypeInsn(NEW, "java/lang/StringBuilder"); mv.visitInsn(DUP); mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "()V", false); walk(mv, cf, getLeftOperand()); walk(mv, cf, getRightOperand()); mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false); } else { this.children[0].generateCode(mv, cf); String leftDesc = this.children[0].exitTypeDescriptor; String exitDesc = this.exitTypeDescriptor; Assert.state(exitDesc != null, "No exit type descriptor"); char targetDesc = exitDesc.charAt(0); CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, leftDesc, targetDesc); if (this.children.length > 1) { cf.enterCompilationScope(); this.children[1].generateCode(mv, cf); String rightDesc = this.children[1].exitTypeDescriptor; cf.exitCompilationScope(); CodeFlow.insertNumericUnboxOrPrimitiveTypeCoercion(mv, rightDesc, targetDesc); switch (targetDesc) { case 'I': mv.visitInsn(IADD); break; case 'J': mv.visitInsn(LADD); break; case 'F': mv.visitInsn(FADD); break; case 'D': mv.visitInsn(DADD); break; default: throw new IllegalStateException( "Unrecognized exit type descriptor: '" + this.exitTypeDescriptor + "'"); } } } cf.pushDescriptor(this.exitTypeDescriptor); } }