vim: escaping strings for substitution (vimscript) - vim

Question

I currently write a substitute function that I often need for programming in vim.
The functions I already wrote look like this and run basically okay for searching and replacing strings which do not have any special characters inside. I already realized to escape the "/" automatically. My question is, how do I have to adapt the escape() function in the line
execute ':silent :argdo %s/' . escape(searchPattern, '/') . '/' . escape(replacePattern, '/') . '/ge'
So that automatically all of the characters that have to be escaped will be escaped?
" MAIN FUNCTION
" inspired by http://vimcasts.org/episodes/project-wide-find-and-replace/
function! SubstituteProjectwide(searchInput)
:set hidden
let cwd = getcwd()
let filename=expand('%:p')
call inputsave()
let searchPattern = input('Search for: ', a:searchInput)
let replacePattern = input('Replace "' . searchPattern . '" with: ')
let filePattern = input('Filepattern: ', cwd . '/**/*.*')
call inputrestore()
execute ':silent :args ' . filePattern
execute ':silent :vimgrep /' . searchPattern . '/g ##'
execute ':silent :Qargs'
execute ':silent :argdo %s/' . escape(searchPattern, '/\') . '/' . escape(replacePattern, '/\') . '/ge'
execute ':silent :edit ' . filename
echo 'Replaced "' . searchPattern . '" with "' . replacePattern . '" in ' . filePattern
endfunction
" VISUAL ENTRYPOINT WITH SELECTED TEXT
function! SubstituteProjectwideVisual()
let v = #*
call SubstituteProjectwide(GetVisualSelectedText())
endfunction
:vnoremap <F6> :call SubstituteProjectwideVisual()<cr>
" NORMAL ENTRYPOINT WIHT WORD UNDER CURSOR
function! SubstituteProjectwideNormal()
let wordUnderCursor = expand("<cword>")
call SubsituteProjectwide(wordUnderCursor)
endfunction
:nnoremap <F6> :call SubstituteProjectwideNormal()<cr>
" GETTING THE FILES WICH CONTAIN SEARCH PATTERN
" copied from http://vimcasts.org/episodes/project-wide-find-and-replace/
command! -nargs=0 -bar Qargs execute 'args' QuickfixFilenames()
function! QuickfixFilenames()
let buffer_numbers = {}
for quickfix_item in getqflist()
let buffer_numbers[quickfix_item['bufnr']] = bufname(quickfix_item['bufnr'])
endfor
return join(map(values(buffer_numbers), 'fnameescape(v:val)'))
endfunction
" GETTING THE CURRENT VISUAL SELECTION
" copied from: https://stackoverflow.com/questions/1533565/how-to-get-visually-selected-text-in-vimscript
function! GetVisualSelectedText()
let [line_start, column_start] = getpos("'<")[1:2]
let [line_end, column_end] = getpos("'>")[1:2]
let lines = getline(line_start, line_end)
if len(lines) == 0
return ''
endif
let lines[-1] = lines[-1][: column_end - (&selection == 'inclusive' ? 1 : 2)]
let lines[0] = lines[0][column_start - 1:]
return join(lines, "\n")
endfunction
UPDATE
I managed to escape many characters like that
escape(searchPattern, ' / \') . '/' . escape(replacePattern, ' / \')
But how do I know which list of characters i have to escape, when it is basically possible, that every character can be inside the search and also the replace string?

Answer 1

To do a literal substitution, specify "very-nomagic" (:help /\V) , and escape the separator (/) and \
in the source.
In the replacement, & and ~ must be escaped, too, if the 'magic' option is set. (\V doesn't work here.)
execute ':silent :argdo %s/\V' . escape(searchPattern, '/\') . '/' . escape(replacePattern, '/\' . (&magic ? '&~' : '')) . '/ge'
Line breaks (if possible) must be changed from ^M to \n:
execute ':silent :argdo %s/\V' . substitute(escape(searchPattern, '/\'),"\n",'\\n','ge') . '/' . escape(replacePattern, '/\' . (&magic ? '&~' : '')) . '/ge'

Answer 2

This doesn't exactly answer your question but is another way of looking at the problem you're trying to solve. I don't entirely follow what the :args setup is doing for you since the quickfix has all of the info you need after the :vimgrep.
I have this in my vimrc:
nnoremap <F3> :vimgrep // $PROJECT_ROOT_DIR/src/**/*.{cpp,h,c,inl,msg}<C-Left><C-Left><Right>
Obviously you'll want to customize the search path, as this focuses on just the above five file extensions in a specific file hierarchy that was configured each time I launched Vim...
Anyway, once you've got that, :cr makes sure you're at the beginning, then do the search&replace you want inside of a macro. You can actually test it out on the first few finds if you want, but then...
qbq Clear the 'b' register.
qa Start recording the 'a' macro'
:%s/this/that/g Start the macro and substitute 'that' for 'this'. (Press enter)
:w|cnf write the file and go to the next one (Press enter)
q Stop recording the 'a' macro.
Then qb#a#bq will run the macro once, saving it in #b. Then just run
(type) #b once more and it'll keep calling itself until it's done.