Regex to find if there is only one block of code

Question

My input is a string, I want to validate that there is only one first-level block of code.

Examples :

{ abc }              TRUE
{ a { bc }         


        

Answer 1

In JavaScript what you need to do is strip out all the nested blocks until no nested blocks are left and then check whether there are still multiple blocks:

var r = input.replace(/(['"])(?:(?!\1|\\).|\\.)*\1|\/(?![*/])(?:[^\\/]|\\.)+\/[igm]*|\/\/[^\n]*(?:\n|$)|\/\*(?:[^*]|\*(?!\/))*\*\//gi, '');

if (r.split('{').length != r.split('}').length || r.indexOf('}') < r.indexOf('{')) {
    // ERROR
    continue;
}

while (r.match(/\{[^}]*\{[^{}]*\}/))
    r = r.replace(/(\{[^}]*)\{[^{}]*\}/g, '$1');
if (r.match(/\}.*\{/)
    // FALSE
else
    // TRUE

Working JSFiddle

Be sure to make the regex in the while and the regex in the replace match the same otherwise this might result in infinite loops.

Updated to address ERROR cases and remove anything in comments, strings and regex-literals first after Unihedron asked.