com.jfinal.template.expr.ast.Logic Maven / Gradle / Ivy

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the jfinal enjoy plugin for normal java program to use sql management function.
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/**
 * Copyright (c) 2011-2017, James Zhan 詹波 ([email protected]).
 *
 * 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 com.jfinal.template.expr.ast;

import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

import com.jfinal.template.TemplateException;
import com.jfinal.template.expr.Sym;
import com.jfinal.template.stat.Location;
import com.jfinal.template.stat.ParseException;
import com.jfinal.template.stat.Scope;

/**
 * Logic
 * 
 * 支持逻辑运算： !  &&  ||
 */
public class Logic extends Expr {
	
	private Sym op;
	private Expr left;		// ! 运算没有 left 参数
	private Expr right;
	
	// 默认为新工作模式
	private static boolean newWorkMode = true;
	/**
	 * 设置为旧工作模式，为了兼容 jfinal 3.3 之前的版本
	 */
	@Deprecated
	public static void setToOldWorkMode() {
		newWorkMode = false;
	}
	
	/**
	 * 构造 || && 结点
	 */
	public Logic(Sym op, Expr left, Expr right, Location location) {
		if (left == null) {
			throw new ParseException("The target of \"" + op.value() + "\" operator on the left side can not be blank", location);
		}
		if (right == null) {
			throw new ParseException("The target of \"" + op.value() + "\" operator on the right side can not be blank", location);
		}
		this.op = op;
		this.left = left;
		this.right = right;
		this.location = location;
	}
	
	/**
	 * 构造 ! 结点，left 为 null
	 */
	public Logic(Sym op, Expr right, Location location) {
		if (right == null) {
			throw new ParseException("The target of \"" + op.value() + "\" operator on the right side can not be blank", location);
		}
		this.op = op;
		this.left = null;
		this.right = right;
		this.location = location;
	}
	
	public Object eval(Scope scope) {
		switch (op) {
		case NOT:
			return evalNot(scope);
		case AND:
			return evalAnd(scope);
		case OR:
			return evalOr(scope);
		default:
			throw new TemplateException("Unsupported operator: " + op.value(), location);
		}
	}
	
	Object evalNot(Scope scope) {
		return ! isTrue(right.eval(scope));
	}
	
	Object evalAnd(Scope scope) {
		return isTrue(left.eval(scope)) && isTrue(right.eval(scope));
	}
	
	Object evalOr(Scope scope) {
		return isTrue(left.eval(scope)) || isTrue(right.eval(scope));
	}
	
	/**
	 * 规则：
	 * 1：null 返回 false
	 * 2：boolean 类型，原值返回
	 * 3：String、StringBuilder 等一切继承自 CharSequence 类的对象，返回 length > 0
	 * 4：其它返回 true
	 * 
	 * 通过 Logic.setToOldWorkMode() 设置，可支持老版本中的以下四个规则：
	 * 1：Number 类型，返回 value != 0
	 * 2：Map、Collection(List被包括在内) 返回 size() > 0
	 * 3：数组，返回 length > 0
	 * 4：Iterator 返回 hasNext() 值
	 */
	public static boolean isTrue(Object v) {
		if (v == null) {
			return false;
		}
		
		if (v instanceof Boolean) {
			return (Boolean)v;
		}
		if (v instanceof CharSequence) {
			return ((CharSequence)v).length() > 0;
		}
		
		// 如果不是新工作模式，则对下面类型进行判断
		if ( !newWorkMode ) {
			if (v instanceof Number) {
				if (v instanceof Double) {
					return ((Number)v).doubleValue() != 0;
				}
				if (v instanceof Float) {
					return ((Number)v).floatValue() != 0;
				}
				return ((Number)v).intValue() != 0;
			}
			
			// 下面四种类型的判断已提供了 shared method 扩展，用法如下：
			// #if(notEmpty(object)) 以及 #if(isEmpty(object))
			if (v instanceof Collection) {
				return ((Collection)v).size() > 0;
			}
			if (v instanceof Map) {
				return ((Map)v).size() > 0;
			}
			if (v.getClass().isArray()) {
				return Array.getLength(v) > 0;
			}
			if (v instanceof Iterator) {
				return ((Iterator)v).hasNext();
			}
		}
		
		return true;
	}
	
	public static boolean isFalse(Object v) {
		return !isTrue(v);
	}
}