详解nodejs模板引擎制作

string = "hello {}".format("郭璞") # hello 郭璞
string = "hello {username}".format(username="郭璞") # hello 郭璞

function create_function(){
  var func_body = "var time = new Date(); console.log('创建时间：'+time);";
  var func = new Function('', func_body);
  func();
}
create_function();

E:\Code\Nodejs\learn\my-work\string>node one.js
创建时间：Tue Jun 13 2017 15:40:15 GMT+0800 (中国标准时间)

E:\Code\Nodejs\learn\my-work\string>

function create_function_with_parameters() {
  var param1 = "郭璞";
  var param2 = "辽宁大连";
  var func_body = "console.log('Hello '+param1+', welcome to '+param2+'!' );";
  var func = new Function('param1', 'param2', func_body);
  func(param1, param2);
}
create_function_with_parameters();

E:\Code\Nodejs\learn\my-work\string>node one.js
Hello 郭璞, welcome to 辽宁大连!

E:\Code\Nodejs\learn\my-work\string>

var pattern1 = /{{([\s\S]+?)}}/gi;
// 或者
var pattern2 = /{%([\s\S]+?)%}/gi;

function test1(){
  var tpl = "Hello {{visitorname}}, Welcome to {{worldname}}!";
  var data = {
    visitorname: "游客",
    worldname: "冰雹工作室"
  };
  var pattern = /{{([\s\S]+?)}}/gi;
  var result = tpl.replace(pattern, (match, tuple)=>{
    return data[tuple];
  });

  console.log("渲染后的数据为：\n", result);
}

E:\Code\Nodejs\learn\my-work\string>node one.js
渲染后的数据为：
 Hello 游客, Welcome to 冰雹工作室!

E:\Code\Nodejs\learn\my-work\string>

function test2(){
  var tpl = "I'm {{user.name}}, and I come from {{user.address}}";
  var user = {name: "郭璞", address: "辽宁大连"};
  console.log(user.name);
  var pattern = /{{([\s\S]+?)}}/gi;
  var result = tpl.replace(pattern, function(match, tuple, offset){
    return eval(''+tuple);
  });
  console.log(result);

}

E:\Code\Nodejs\learn\my-work\string>node one.js
郭璞
I'm 郭璞, and I come from 辽宁大连

E:\Code\Nodejs\learn\my-work\string>

function test3(){
  var tpl = "I am {} of {} years old, and I come from {user.address}.";
  var name = '郭璞';
  var index = 0;
  var paramindex = 0;
  // var parameters = [{name: '郭璞'}, {'age': 22}, {address: '辽宁大连'}];
  var parameters = ['郭璞', 22, {user: {address: '辽宁大连'}}];
  console.log(parameters[2]);
  var result = tpl.replace(/{([\s\S])*?}/gi, function(match, tuple, offset){
    console.log('match:', match);
    console.log('tuple: ', tuple);
    tpl = tpl.slice(index, offset);
    index = offset + match.length;
    paramindex += 1;

    var temp = parameters[paramindex-1];
    if(match.length > 2){
      // 使用tuple不能正确获取到标记中相关的变量名，故用match来代替.
      match = match.slice(1, match.length-1);
      return eval('parameters[paramindex-1].'+match);
    }else{
      return temp;
    }
    // return parameters[paramindex-1];
  });
  console.log(result);
}

E:\Code\Nodejs\learn\my-work\string>node one.js
{ user: { address: '辽宁大连' } }
match: {}
tuple: undefined
match: {}
tuple: undefined
match: {user.address}
tuple: s
******* s
I am 郭璞 of 22 years old, and I come from 辽宁大连.

E:\Code\Nodejs\learn\my-work\string>

/**
 * 通过正则表达式和Function语法创建一个简单的模板引擎。
 */

const pattern = /{{([\s\S]+?)}}|{%([\s\S]+?)%}|$/img;

function template(text, params, name) {
  // 声明最终要返回的解析好的文本串,也就是构造Function所需的函数体部分。
  var func_body = '';
  // 函数体里面最终效果是返回一个代表了解析完成的字符串的变量，因此要声明一个出来
  func_body += 'var parsedstr="";';
  func_body += 'parsedstr+="';
  var index = 0;
  // 开始正则匹配，根据捕获到的元组进行剖析
  text.replace(pattern, function (matchedtext, interpolate, evaluate, offset) {
    // 匹配到正常的HTML文本，则直接添加到func_body中即可
    func_body += text.slice(index, offset);

    // 如果是evaluate类型的文本，则作为代码进行拼接
    if (evaluate) {
      func_body += '";' + evaluate + 'parsedstr+="';
    }

    // 匹配到interpolate类型的文本，则作为变量值进行替换
    if (interpolate) {
      func_body += '"+' + interpolate + '+"';
    }

    // 更新偏移量index，让程序向后移动
    index = offset + matchedtext.length;
    // 貌似返回值没什么用吧
    return matchedtext;
  });

  // 完成函数体的构建之后就可以调用Function的语法实现渲染函数的构建了
  func_body += '"; return parsedstr;';

  return new Function('obj', 'name', func_body)(params, name);
}

function test() {
  var obj = [
    { text: '张三' },
    { text: '李四' },
    { text: '王五' },
    { text: '赵六' },
    { text: '韩七' },
    { text: '王八' }
  ];
  var name = '郭璞';


  var fs = require('fs');
  // var rawtext = fs.readFileSync('index.html').toString('utf8');
  var rawtext = '<ul>{%for(var i in obj){%}<li>{{ obj[i].text }}</li>
{%}%}</ul>';
  console.log("源文件：", rawtext);
  var result = template(rawtext, obj);
  console.log("渲染后文件：", result, name);
  fs.writeFileSync('rendered.html', result);
  console.log('渲染完毕，请查看rendered.html文件')
}

test();

<ul>
  <li>张三</li><br>
  <li>李四</li><br>
  <li>王五</li><br>
  <li>赵六</li><br>
  <li>韩七</li><br>
  <li>王八</li><br></ul>