VIM: Respect only current code block

Question

I have started working on a huge PHP application that has thousands of lines of code in each file, with lots of huge if blocks, classes, and functions all existing in the same file. I'm not the only dev working on it, so I cannot refactor!

I have tried using the Tags List plugin but it does not really help. Is there any way to have VIM respect only a particular code block, and ignore the rest of the file? I am hoping for some or all of these features:

1. Enable line numbering only for the current code block, starting from 1 at the line containing the opening {, and showing no numbering for lines preceding it or after the closing }.
2. Searching with / would be restricted only to the block in question.

I am thinking along the lines of selecting the current block and editing it in a new buffer when enabling the mode, then replacing the existing block with the edited block when exiting the mode. However, I am having trouble actually implementing this feature. My current version is this:

map <F7> <Esc>mO<C-V>aBy:new<Return>p:set nu<Return>:set ft=php<Return>ggi<?php<Return><Esc>
map <F8> <Esc>ggdd<C-V>aBx:bp<Return>`O<C-V>aBp

However, this has several issues, such as the inability to perform incremental saves.

Answer 1

I would be very surprised if Vim allows the kind of line numbering you ask for.

This plugin (and 1 or 2 similar ones IIRC) allows you to visually select a region of your current file, work on it in another buffer and put everything back in its place in the original file on :w.