/**
 +-----------------------------------------
 * jsonDB 	基於json數據格式構建的數據模型
 +-----------------------------------------
 * @description		對json數據檢索，刪除，查詢和更新
 * @author	戚銀(web程序員)	[email protected]
 * @date 2014年6月28日
 * @version	0.1
 * @blog http://blog.csdn.net/thinkercode/
 +-----------------------------------------
 * 簡單介紹：
 * jsonDB是js的一個類庫，是基於json數據格式構建的數據
 * 模型實現對json數據增刪改查。
 
jsonDB的構建源自於HTML5
 * 本地存儲的一個應用需求，能夠通過sql對json數據進行增
 * 刪改查，同一時候該類庫提供強大的where檢索條件，數據排序，
 * limit查詢條件限制等數據庫基本功能。
通過jsonDB能夠輕
 * 松維護一個庫/表或多個庫/表。而無需額外實現json的數據
 * 的維護等，在該類庫完好以後為簡化sql操作，基於jsonDB核
 * 心模塊擴展了連貫操作模型，簡化對jsonDB的操作以及sql語
 * 句出錯的概率。
 +-----------------------------------------
 * 當前版本號的不足：
 * 1.無法支持查詢字段運算
 * 2.不支持對沒有選取的查詢字段排序
 * 3.僅僅支持單個字段排序，無法進行組合排序操作
 * 4.update、delete語句不支持order by子句。導致limit子句功能弱化
 * 5.編寫where條件是必須使用()包括where條件
 * 6.無法選取深層次的字段作為返回字段
 * 7.沒有錯誤或異常解決方式
 * 8.不支持外部擴展
 +-----------------------------------------
 * jsonDB的使用：
 * jsonDB會提供一個具體的使用手冊，當中包括大量演示樣例
 * jsonDB還有非常多能夠使用的技巧並沒有一一包括在手冊中
 * 期望強大的網友一起挖掘jsonDB的潛在使用技巧。並分享給大家
 * 假設使用中發現問題能夠隨時發送郵件，或者通過博客留言等方式一起探討
 * 同一時候鑒於自己實力有限，期望發動網友一起擴展jsonDB。
 * 能在未來前端應用中奉獻一份力量
 +-----------------------------------------
 */
(function(window,undefined){
	_jsonDB = window.jsonDB,
	_history = null,
	DBCore = {},
	Database = {},
	DBExpand = {};


	/**
	 * [jsonDB 初始化模型。支持定義本地數據庫和數據表]
	 * @param  mixed data 	數據
	 * @param  string dbName	數據庫名字
	 * @return jsonDB
	 */
	var jsonDB = function(data,dbName){

		//創建數據庫或者數據表
		if(data){
			dbName = dbName || 'json_db';
			eval('Database.'+ dbName +'= data');
		}

		return jsonDB.fn.init();
	}

	jsonDB.fn = jsonDB.prototype = {
		//初始化插件
		init : function (alias){
			if(alias){
				_history = window[alias];
				window[alias] = jsonDB();
			}
			return this;
		},

		query : function(sql){
			var type = sql.match(/^(\w+)/);
			switch(type[0]){
				case 'select' :
				case 'delete' : 
				case 'update' :
					return eval('DBCore.fn.'+ type[0] +'(sql+" ")');
				break;
				default :
					return false;
				break;
			}
		},

		insert : function(data,dbName){
			if(data){
				dbName = dbName || 'json_db';
				eval('Database.'+ dbName +'.push(data)');
			}
			return this;
		},

		findAll : function(dbName){
			if(dbName){
				return eval('Database.'+ dbName);
			}
			return Database;
		}
	};

	/**
	 * [DBExpand 數據庫核心功能擴展]
	 */
	DBExpand = DBExpand.prototype = {
		sqlParam : {
			fields : '*',
			table : 'json_db',
			where : null,
			order : null,
			limit : null,
		},

		add : function(data){
			return this.insert(data,this.sqlParam.table);
		},

		select : function(){
			var sql = 'select '+this.sqlParam.fields+' from '+this.sqlParam.table;
			if(this.sqlParam.where){
				sql += ' where '+this.sqlParam.where;
			}
			if(this.sqlParam.order){
				sql += ' order by '+this.sqlParam.order;
			}
			if(this.sqlParam.limit){
				sql += ' limit '+this.sqlParam.limit;
			}

			this.clear();
			return this.query(sql);
		},

		update : function(data){
			if(data.length<1){
				return false;
			}

			var sql = 'update '+this.sqlParam.table+' set '+data;
			if(this.sqlParam.where){
				sql += ' where '+this.sqlParam.where;
			}
			if(this.sqlParam.limit){
				sql += ' limit '+this.sqlParam.limit;
			}
			this.clear();
			return this.query(sql);
		},

		delete : function(){
			if(this.sqlParam.where.length<1){
				return false;
			}

			var sql = 'delete from '+this.sqlParam.table;
			if(this.sqlParam.where){
				sql += ' where '+this.sqlParam.where;
			}
			if(this.sqlParam.limit){
				sql += ' limit '+this.sqlParam.limit;
			}
			this.clear();
			return this.query(sql);
		},

		drop : function(dbName){
			//創建數據庫或者數據表
			if(data){
				dbName = dbName || 'json_db';
				eval('Database.'+ dbName +'= null');
			}
			return this;
		},

		field : function(fields){
			if(typeof fields == 'object'){
				this.sqlParam.fields = fields.join(',');
			}else{
				this.sqlParam.fields = fields;
			}
			return this;
		},

		table : function(table){
			this.sqlParam.table = table;
			return this;
		},

		where : function(where){
			this.sqlParam.where = '('+where+')';
			return this;
		},

		order : function(order){
			this.sqlParam.order = order;
			return this;
		},
		
		limit : function(limit){
			this.sqlParam.limit = limit;
			return this;
		},

		clear : function(){
			this.sqlParam.fields = '*';
			this.sqlParam.where = null;
			this.sqlParam.order = null;
			this.sqlParam.limit = null;
		}
	}

	/**
	 * [DBCore 數據庫核心]
	 */
	DBCore.fn = DBCore.prototype = {
		SqlRegExp : {
			fields: '([a-z0-9_\\,\\.\\s\\*]*?\\s+)',
			from : '(from\\s+([a-z0-9_\\.]+)\\s*)?',
			where : '(?:where\\s+(\\(.*\\))\\s*)?
 
',
			order : '(?:order\\s+by\\s+([a-z0-9_\\,\\.]+))?
\\s+(asc|desc|ascnum|descnum)?\\s*',
			limit : '(?:limit\\s+([0-9\\,]+))?',
			set : '(set\\s+(.*?)\\s+)',
			table : '(([a-z0-9_\\.]*?)\\s*)?',
		},

		select : function(sql){
			var params = {fields:["*"], from:"json_db", where:"", orderby:[], order: "asc", limit:[]},
			SqlRegExp = this.SqlRegExp,
			reg = '^(select)\\s+'+SqlRegExp.fields + SqlRegExp.from + SqlRegExp.where + SqlRegExp.order + SqlRegExp.limit,
			sqlReg = new RegExp(reg,'i'),
			sqlFields = sql.match(sqlReg),
			options = {
				fields: sqlFields[2].replace(' ','').split(','), 
				from: (sqlFields[4] == undefined) ? 'json_db' : sqlFields[4],
				where: (sqlFields[5] == undefined) ? "true" : sqlFields[5].replace(/([^\>\<\!\=])=([^\>\<\!\=])/gi,'$1 == $2').replace(/\sand\s/gi,' && ').replace(/\sor\s/gi,' || ').replace(/`/gi,''),
				orderby: (sqlFields[6] == undefined) ?
 
 []:sqlFields[6].replace(' ','').split(','),
				order: (sqlFields[7] == undefined) ? "asc" : sqlFields[7],
				limit: (sqlFields[8] == undefined) ?
 [] : sqlFields[8].replace(' ','').split(',')
			};
			
			for(i in options){
				params[i] = options[i];
			}

			var result = [];
			result =  this.filter(params,function(data){
				if(options.fields.length == 0 || options.fields[0] == "*"){
					return data;
				}
						
				var result = {};
				for(var i in options.fields){
					result[options.fields[i]] = data[options.fields[i]];
				}		
				return result;
			});
			result =  this.orderBy(result,options);
			result =  this.limit(result,options);
			return result;
		},

		update : function(sql){
			var params = {from:"json_db", where:"", limit:[], set:[]},
			SqlRegExp = this.SqlRegExp,
			reg = '^(update)\\s+'+ SqlRegExp.table + SqlRegExp.set + SqlRegExp.where + SqlRegExp.limit,
			sqlReg = new RegExp(reg,'i'),
			sqlFields = sql.match(sqlReg),
			options = {
				from: (sqlFields[3] == undefined) ? 'json_db' : sqlFields[3],
				set: (sqlFields[5] == undefined) ? [] : sqlFields[5].replace(' ','').split(','),
				where: (sqlFields[6] == undefined) ? "true" : sqlFields[6].replace(/([^\>\<\!\=])=([^\>\<\!\=])/gi,'$1 == $2').replace(/\sand\s/gi,' && ').replace(/\sor\s/gi,' || ').replace(/`/gi,''),
				limit: (sqlFields[7] == undefined) ?
 [] : sqlFields[7].replace(' ','').split(',')
			};
			
			for(i in options){
				params[i] = options[i];
			}
			var jsonData = eval('Database.' + options.from),
			tally = 0,
			extent = this.extent(params),
			setLen = options.set.length,
			affected_rows = 0;

			if(setLen<1){
				return false;
			}

			options.where = options.where || "true";
			for(var i in jsonData){
				with(jsonData[i]){
					if(eval(options.where)){
						if(affected_rows >= extent.start && tally < extent.stop){
							for(var j=0;j<setLen;++j){
								eval(options.set[j]);
							}
							++tally;
						}else if(tally == extent.stop){
							return tally;
						}
						++affected_rows;
					}
				}
			}
			return tally;
		},

		delete : function(sql){
			var params = {from:"json_db", where:"", limit:[]},
			SqlRegExp = this.SqlRegExp,
			reg = '^(delete)\\s+'+ SqlRegExp.from + SqlRegExp.where + SqlRegExp.limit,
			sqlReg = new RegExp(reg,'i'),
			sqlFields = sql.match(sqlReg),
			options = {
				from: (sqlFields[3] == undefined) ? 'json_db' : sqlFields[3],
				where: (sqlFields[4] == undefined) ? "true" : sqlFields[4].replace(/([^\>\<\!\=])=([^\>\<\!\=])/gi,'$1 == $2').replace(/\sand\s/gi,' && ').replace(/\sor\s/gi,' || ').replace(/`/gi,''),
				limit: (sqlFields[5] == undefined) ?
 [] : sqlFields[5].replace(' ','').split(',')
			};
			
			for(i in options){
				params[i] = options[i];
			}

			var jsonData = eval('Database.' + options.from + '.concat()'),
			tally = 0,
			extent = this.extent(params),
			affected_rows = 0;
			
			options.where = options.where || "true";
			for(var i in jsonData){
				with(jsonData[i]){
					if(eval(options.where)){
						if(affected_rows >= extent.start && tally < extent.stop){
							eval('Database.'+options.from+'.splice(i-tally,1)');
							++tally;
						}else if(tally == extent.stop){
							return tally;
						}
						++affected_rows;
					}
				}
			}
			return tally;
		},

		filter : function(options, callback){
			var jsonData = eval('Database.' + options.from),
			result = [],
			index = 0;

			options.where = options.where || "true";
			for(var i in jsonData){
				with(jsonData[i]){
					if(eval(options.where)){
						if(callback){
							result[index++] = callback(jsonData[i]);
						}else{
							result[index++] = jsonData[i];
						}
					}
				}
			}
			
			return result;
		},

		orderBy : function(result,options){
			if(options.orderby.length == 0){
				return result;
			}
	
			result.sort(function(a,b){	
				switch(options.order.toLowerCase()){
					case "desc": return (eval('a.'+ options.orderby[0] +' < b.'+ options.orderby[0]))?
 1:-1;
					case "asc":  return (eval('a.'+ options.orderby[0] +' > b.'+ options.orderby[0]))?
 1:-1;
					case "descnum": return (eval('a.'+ options.orderby[0] +' - b.'+ options.orderby[0]));
					case "ascnum":  return (eval('b.'+ options.orderby[0] +' - a.'+ options.orderby[0]));
				}
			});
			
			return result;
		},

		limit : function(result,options){
			switch(options.limit.length){
				case 0: 
					return result;
				case 1: 
					return result.splice(0,options.limit[0]);
				case 2: 
					return result.splice(options.limit[0],options.limit[1]);
			}
		},

		extent : function(options){
			switch(options.limit.length){
				case 0: 
					return {start:0, stop:9e+99};
				case 1: 
					return {start:0, stop:options.limit[0]};
				case 2: 
					return {start:options.limit[0], stop:options.limit[1]};
			}
		}
	}

	window.jsonDB = jsonDB;

	//追加擴展功能
	jsonDB.fn = jsonDB.prototype =extend(jsonDB.fn,DBExpand);

	//合並對象方法
	function extend(){
		var paramsLen = arguments.length;
		if(paramsLen<1){
			return false;
		}

		var target = arguments[0];
		for(var i=1;i<paramsLen;++i){
			for(var j in arguments[i]){
				target[j] = arguments[i][j];
			}
		}

		return target;
	}
})(window);

源代碼與演示樣例下載：jsonDB.rar

基於json數據格式實現的簡單數據庫——jsonDB