/**
* Copyright (c) 2011-2017, James Zhan 詹波 (jfinal@126.com).
*
* 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.util.LinkedHashMap;
import java.util.Map.Entry;
import com.jfinal.template.stat.Scope;
/**
* Map
*
* 1:定义 map 常量
* {k1:123, k2:"abc", 'k3':true, "k4":[1,2,3], k5:1+2}
* 如上所示,map定义的 key 可以为 String 或者 id 标识符,而右侧的 value 可以是任意的常量与表达式
*
* 2:取值
* 先将 Map 常量赋值给某个变量: #set(map = {...})
* map['k1']
* map["k1"]
* map[expr]
* map.get("k1")
* map.k1
*
* 如上所示,当以下标方式取值时,下标参数可以是 string 与 expr,而 expr 求值以后的值必须也为 string类型
* 当用 map.k1 这类 field 字段取值形式时,则是使用 id 标识符,而不是 string 形参数
*
* 注意:即便是定义的时候 key 用的是 id 标识符,但在取值时也要用 string 类型下标参数或 expr 求值后为 string
* 定义时 key 可以使用 id 标识符是为了书写方便,本质上仍然是 string
*
* 3:可创建空 map,如: #(map = {})
*/
public class Map extends Expr {
private LinkedHashMap<Object, Expr> map;
public Map(LinkedHashMap<Object, Expr> map) {
this.map = map;
}
public Object eval(Scope scope) {
LinkedHashMap<Object, Object> valueMap = new LinkedHashMap<Object, Object>(map.size());
for (Entry<Object, Expr> e : map.entrySet()) {
valueMap.put(e.getKey(), e.getValue().eval(scope));
}
return valueMap;
}
}