浅析Prototype的模板类 Template

var str = #{what} may have gone, but there is a time of #{how};
var object = {
what : Swallows,
how : return
}
var template_1 = new Template(str);
var result = template_1.evaluate(object);

console.log(result:,result);
//输出：Swallows may have gone, but there is a time of return

<script type="text/javascript">
var object = {
what : {
name : Swallows
},
how : return
}
</script>

<script type="text/javascript">
var str = #{what.name} may have gone, but there is a time of #{how};
//或者str = #{what[name]} may have gone, but there is a time of #{how};
var object = {
what : {
name : Swallows
},
how : return
}
var template_1 = new Template(str);
var result = template_1.evaluate(object);

console.log(result:,result);
//输出：Swallows may have gone, but there is a time of return
</script>

<script type="text/javascript">
function gsub(str,pattern, replacement){
var result = ,
source = str,
match;
//下面的每一次匹配都是分成三段来操作的
//相当于 $` $& $
while(source.length > 0){
match = source.match(pattern);
if(match){
result += source.slice(0, match.index);
result += replacement(match);
source = source.slice(match.index + match[0].length);
}else{
result += source;
source = ;
}
}
return result;
}
</script>

<script type="text/javascript">
console.log(gsub(there is a time of #{how},/(^|.|\r|\n)(#\{(.*?)\})/,function{
return demo;
}))
//输出there is a time ofdemo
</script>

<script type="text/javascript">
var Template = function(template, pattern){
this.template = template.toString();
this.pattern = pattern || Template.Pattern;
};
Template.Pattern = /(^|.|\r|\n)(#\{(.*?)\})/;
Template.prototype.evaluate = function(object){}
</script>

var str = \\#{what} may have gone, but there is a time of \\#{how};
var object = {
what : Swallows,
how : return
}

Template.prototype.evaluate = function(object){
//gsub(str,pattern, replacement)
return gsub(this.template,this.pattern,function(match){
var before = match[1];//这里的match[1]就是Template.Pattern中(^|.|\r|\n)匹配的部分
var content = match[2];//这里的match[1]就是Template.Pattern中(#\{(.*?)\})匹配的部分
var expr = match[3];//这里的match[1]就是Template.Pattern中(.*?)匹配的部分
//示例：
//对于 s#{what} 来说before=s,content=#{what},expr=what

//第一、object是一个空对象，那么我们直接删除需要替换的部分
if(object == null){
return (match[1] + );
}
//第二、转义部分直接保留
if (before == \\){
return content;
}

//除了上面的两种情况，下面是正常的替换流程 。
var ctx = object;

//下面这个正则我在前面说过，是为了匹配嵌套对象的 。看最后面的(\.|\[|$)是为了确定有没有嵌套的子对象匹配 。
//#{what.name}中的.
//或者#{what[name]}中的[
//也就是下面的match[3]

var pattern = /^([^.[]+|\[((?:.*?[^\\])?)\])(\.|\[|$)/;
match = pattern.exec(expr);

while (match != null) {
if(/^\[/.test(match[1])){
var comp = match[2].replace(/\\\\]/g, ]);
}else{
var comp = match[1];
}
ctx = ctx[comp];//如果ctx[comp]是一个字符串，那么下面一步就可以收工了，如果ctx[comp]还是一个对象，那么抱歉，加班继续干吧 。

if (null == ctx || == match[3]){//需要替换的不是object的嵌套子对象，那么就直接中断循环 。替换成功，下班 。
break;
}

//下面的仅仅是为了剥离出来关键字，其他操作用在循环里面再来一次 。
if([ == match[3]){
expr = expr.substring(match[1].length)
}else{
expr = expr.substring(match[0].length)
}
match = pattern.exec(expr);
}

return before + ctx;
});
};