Equal out bracket types

Question

Based on THIS question.

Given a string, replace each bracket ()[]{}<> with a bracket of the appropriate type so that the brackets match, and the nested brackets cycle as follows:

1. Outermost ones are ()
2. Directly inside of () should be []
3. Directly inside of [] should be {}
4. Directly inside of {} should be <>
5. Directly inside of <> will be () again (cycles)

All non-bracket chars must remain exactly as they are. Open brackets may only be replaced with open brackets of some type, and close brackets with close brackets.

The input will always make this possible. This means its brackets matched correctly if their type is ignored. So, {ab<)c] is a valid input, but ab)(cd or ab((cd are not.

Examples:

2#jd {¤>. = 2#jd (¤).
abcdef    = abcdef
(3×5+(4-1)) = (3×5+[4-1])
<<<>><<>><<<<<<>>>>>>> = ([{}][{}][{<([{}])>}])

The use of native transforming of input this way (auto syntax of language) is not allowed.

As always: shortest code wins.

Answer 1

JavaScript (ES6), 79 bytes

s=>s.replace(/./g,c=>~(p=l.indexOf(c))?l[p&4?--k&3|4:k++&3]:c,l='([{<)]}>',k=0)

Test cases

let f =

s=>s.replace(/./g,c=>~(p=l.indexOf(c))?l[p&4?--k&3|4:k++&3]:c,l='([{<)]}>',k=0)

console.log(f("2#jd {¤>."));
console.log(f("abcdef"));
console.log(f("(3×5+(4-1))"));
console.log(f("<<<>><<>><<<<<<>>>>>>>"));

Answer 2

Lex, 132 bytes

%{
int i,o[4]={40,91,123,60};
%}
%%
[[({<] {putchar(o[i++&3]);}
[])}>] {putchar(o[--i&3]+2-!(i&3));}
%%
yywrap(){}
main(){yylex();}

Answer 3

Java, 155 bytes

a->{String s="([{<)]}>";for(int i=0,j=0,k;i<a.length;i++){k=s.indexOf(a[i]);if(k>3){a[i]=s.charAt(--j%4+4);}else if(k>-1){a[i]=s.charAt(j++%4);}}return a;}

Lambda that takes a char[] as it's single argument. We loop through the array, storing it's position in our string of brackets (s) in a variable (k). We check if it's an opening or closing bracket (s.indexAt()), and replace it with the appropriate bracket based on it's level of nesting (s.charAt()), looping appropriately with %4

Answer 4

Haskell, 126 bytes

b="([{<"
d=")]}>"
y=cycle
(!)=elem
f(e:c)n(x:r)|x!b=y b!!n:f(y d!!n:e:c)(n+1)r|x!d=e:f c(n-1)r|1<3=x:f(e:c)n r
f c n s=s
f" "0

Try it on ideone. Usage:

*Main> f" "0 "<<<>><<>><<<<<<>>>>>>>"
"([{}][{}][{<([{}])>}])"

Explanation

f takes three arguments: A string that works as stack for closing brackets, an int n for counting the nesting-depth and the input string.

f c n "" = ""                            -- base case for recursion: input string is empty
f (e:c) n (x:r)                          -- for the current char x
   | elem x "([{<" =                     -- check if it is an opening bracket
       (cycle "([{<")!!n :               --   if so, replace it with a bracket of the current nesting depth
           f ((cycle ")]}>")!!n : e : c) --   push the matching closing bracket on the stack
               (n+1) r                   --   increase depth level and check the next char
   | elem x ")]}>" =                     -- if x is a closing bracket
       e :                               --   replace it by the closing bracket from on top of the stack
           f c (n-1) r                   --   decrement depth level and check the next char
   | otherwise     = x : f (e:c) n r     -- otherwise keep x and check the next char