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use std::env;
pub fn split_on(s:&str,c:char)->(&str,&str){
match s.find(c){
Some(n)=>{
let (lt,rt) = s.split_at(n);
let rt = &rt[1..];
(lt,rt)
},
None=>(s,"")
}
}
pub fn replace(s:&str,f:&Fn(&str)->String)->String{
let mut res = "".to_string();
let mut depth = 0;
let mut midepth = 0; let mut esc = false;
let mut temp = "".to_string();
for c in s.chars(){
if esc {
res.push(c) ;
esc = false;
continue;
}
if c == '\\'{
esc = true;
continue;
}
if c == '{' {
if depth == 0 {
temp = "".to_string();
}else{
temp.push('{');
}
depth +=1;
if midepth < depth {midepth +=1}
continue;
}
if depth == 0 {
res.push(c);
continue;
}
if c == '}' {
depth -=1;
if depth == 0{
if midepth >1 {
temp = replace(&temp,f);
}
res.push_str(&f(&temp));
continue;
}
}
temp.push(c);
}
if depth > 1 {
temp = replace(&temp,f);
}
if depth > 0 {
res.push_str(&f(&temp));
}
return res;
}
pub fn env(s:&str)->String{
match env::var_os(s) {
Some(ros)=> match ros.to_str(){
Some(res)=>String::from(res),
None=>String::from(""),
},
None => String::from(""),
}
}
pub fn env_replace(s:&str)->String{
replace(s,&env)
}