Replace a block of code with another

Question

How can I replace a block of code with another, akin to query-replace/query-replace-regexp?

For example:

Replacing the following block:

for(A) {
  if(B) {
     s1;
  } else {
     C;
  }
}

with

for(M) {
  if(N) {
    s1;
  } else {
     O;
  }
}

Answer 1

You could use iedit for that.

image source: iedit github repository

You should select your block of code and activate iedit-mode (C-;) to edit it.

When Iedit mode is turned on, all the occurrences of the current region in the buffer (possibly narrowed) or a region are highlighted. If one occurrence is modified, the change are propagated to all other occurrences simultaneously.

If region is not active, ‘iedit-default-occurrence’ is called to get an occurrence candidate, according to the thing at point. It might be url, email address, markup tag or current symbol(or word).

In the above two situations, with digit prefix argument 0, only occurrences in current function are matched. This is good for renaming refactoring in programming.

After install iedit-mode from MELPA, I encourage you to read the full help (C-h f iedit-mode).

Answer 2

The query-replace-regexp does the job.