paste_into_c_string.vim

" paste_into_c_string.vim
"

function! EscapeText(text)

    let l:escaped_text = a:text

    " Map characters to named C backslash escapes. Normally, single-quoted
    " strings don't require double-backslashing, but these are necessary
    " to make the substitute() call below work properly.
    "
    let l:charmap = {
    \   '"'     : '\\"',
    \   "'"     : '\\''',
    \   "\n"    : '\\n',
    \   "\r"    : '\\r',
    \   "\b"    : '\\b',
    \   "\t"    : '\\t',
    \   "\x07"  : '\\a',
    \   "\x0B"  : '\\v',
    \   "\f"    : '\\f',
    \   }

    " Escape any existing backslashes in the text first, before
    " generating new ones. (Vim dictionaries iterate in arbitrary order,
    " so this step can't be combined with the items() loop below.)
    "
    let l:escaped_text = substitute(l:escaped_text, "\\", '\\\', 'g')

    " Replace actual returns, newlines, tabs, etc., with their escaped
    " representations.
    "
    for [original, escaped] in items(charmap)
        let l:escaped_text = substitute(l:escaped_text, original, escaped, 'g')
    endfor

    " Replace any other character that isn't a letter, number,
    " punctuation, or space with a 3-digit octal escape sequence. (Octal
    " is used instead of hex, since octal escapes terminate after 3
    " digits. C allows hex escapes of any length, so it's possible for
    " them to run up against subsequent characters that might be valid
    " hex digits.)
    "
    let l:escaped_text = substitute(l:escaped_text,
    \   '\([^[:alnum:][:punct:] ]\)',
    \   '\="\\o" . printf("%03o",char2nr(submatch(1)))',
    \   'g')

    return l:escaped_text

endfunction


function! PasteEscapedRegister(where)

    " Remember current register name, contents, and type,
    " so they can be restored once we're done.
    "
    let l:save_reg_name     = v:register
    let l:save_reg_contents = getreg(l:save_reg_name, 1)
    let l:save_reg_type     = getregtype(l:save_reg_name)

    echo "register: [" . l:save_reg_name . "] type: [" . l:save_reg_type . "]"

    " Replace the contents of the register with the escaped text, and set the
    " type to characterwise (so pasting into an existing double-quoted string,
    " for example, will work as expected).
    "
    call setreg(l:save_reg_name, EscapeText(getreg(l:save_reg_name)), "c")

    " Build the appropriate Normal-mode paste command.
    "
    let l:cmd = 'normal! "' . l:save_reg_name . (a:where == "before" ? "P" : "p")

    " Insert the escaped register contents.
    "
    exec l:cmd

    " Restore the register to its original value and type.
    "
    call setreg(l:save_reg_name, l:save_reg_contents, l:save_reg_type)

endfunction

" Define keymaps to paste escaped text before or after the cursor.
"
nmap <Leader>P :call PasteEscapedRegister("before")<cr>
nmap <Leader>p :call PasteEscapedRegister("after")<cr>

" end paste_into_c_string.vim