text: /**
   * 历史记录堆栈管理类
   * @class
   */
  class History {
  	index = -1;
  
  	schemaList = [];
  
  	constructor(schema) {
  		this.schema = schema;
  	}
  
  	/**
  	 * @param  {} data
  	 */
  	push(data) {
  		if(this.index!==-1&&this.index<(this.schemaList.length-1)){// 删除后面会被覆盖的历史记录
  			this.schemaList.splice(this.index+1,this.schemaList.length-this.index-1);
  		}
  		this.schemaList.push(JSON.stringify(data).trim(" "));
  		this.index++;
  		this.schema.editor.fire("change");
  	}
  
  	pop(){
  		this.schemaList.pop();
  		this.index--;
  		this.schema.editor.fire("change");
  	}
  
  	/**
  	 * @param  {} index
  	 * @param  {} data
  	 */
  	replace(index, data) {
  		this.schemaList[this.index + index] = data;
  	}
  
  	// 重做
  	redo() {
  		this.schema.data = JSON.parse(this.schemaList[++this.index]);
  		this.schema.editor.fire("change");
  	}
  
  	// 撤销
  	undo() {
  		this.schema.data = JSON.parse(this.schemaList[--this.index]);
  		this.schema.editor.fire("change");
  	}
  
  	clear(){
  		this.schemaList = [];
  		this.index = -1;
  	}
  }
  export default History;
  