Run a command on every match of a search (not on the line)

Question

I am trying to run a command on every occurrence of a search match. So, If i have some thing like this where a search match matches only these two anchor tags,

.................. <a src="****" ></a>
......... <a src="****"></a>

I want to run a command that changes it to,

.................. <a class = "bodyclass" src="****" ></a>
......... <a class="bodyclass" src="****"></a>

So, how can I run a command on all the search matches? The only way I can think of is to go to the search match and do a :execute 'normal! Wiclass="bodyclass" ' to insert the class in the tag.

I am not looking for g command here as that operates on the lines and not on the matches directly unless there is a way I can get this functionality with g itself.

Any ideas ?

Answer 1

You can use the expression register, see :h sub-replace-expression:

:s/search/\=MyFunction(submatch(0))/

The submatch() function can also be used directly inside the function, which would make the syntax even simpler:

:s/search/\=MyFunction()/

---

To give a concrete example of the latter variant, consider the following Vim function:

function! MyFunction()
  return 'x' . submatch(0) . 'y'
endfunction

And the following text:

this is a test
this is a second test
this is a third test

Now do

:%s/search/\=MyFunction()/

in the text buffer, and the result should be:

this is a xtesty
this is a second xtesty
this is a third xtesty