Vim: How to number paragraphs automatically and how to refer to this numbering? - vim

Question

Let us say I have the following three paragraphs of text (separated
from each other by empty lines—number 3 and 7, here):
This is my first paragraph line 1
This is my first paragraph line 2
This is my second paragraph line 4
This is my second paragraph line 5
This is my second paragraph line 6
This is my third paragraph line 8
This is my third paragraph line 9
Question 1: How can I number these paragraphs automatically,
to obtain this result:
1 This is my first paragraph line 1
This is my first paragraph line 2
2 This is my second paragraph line 4
This is my second paragraph line 5
This is my second paragraph line 6
3 This is my third paragraph line 8
This is my third paragraph line 9
(I succeeded to do this, but only via a clumsy macro.)
Question 2: Is it possible to refer to these paragraphs? For
instance, is it possible to index a text file as answered (by Prince
Goulash and Herbert Sitz) in the earlier question, but this time
with the paragraph numbers and not the line numbers?
Thanks in advance.

Answer 1

Here's one way to do the ref numbers, with a pair of functions:
function! MakeRefMarkers()
" Remove spaces from empty lines:
%s/^ \+$//
" Mark all spots for ref number:
%s/^\_$\_.\zs\(\s\|\S\)/_parref_/
" Initialize ref val:
let s:i = 0
" Replace with ref nums:
%s/^_parref_/\=GetRef()/
endfunction
function! GetRef()
let s:i += 1
return s:i . '. '
endfunction
Then just do it by calling MakeRefMarkers(). It doesn't remove existing ref numbers if they're there, that would require another step. And it doesn't catch first paragraph if it's first line in file (i.e, without preceding blank line). But it does handle situations where there's more than one blank line between paragraphs.

Answer 2

Question One
Here is a function to enumerate paragraphs. Simply do :call EnumeratePara() anywhere in your file. The variable indent can be adjusted as you wish. Let me know if anything needs correcting or explaining.
function! EnumeratePara()
let indent = 5
let lnum = 1
let para = 1
let next_is_new_para = 1
while lnum <= line("$")
let this = getline(lnum)
if this =~ "^ *$"
let next_is_new_para=1
elseif next_is_new_para == 1 && this !~ "^ *$"
call cursor(lnum, 1)
sil exe "normal i" . para . repeat(" ", indent-len(para))
let para+=1
let next_is_new_para = 0
else
call cursor(lnum, 1)
sil exe "normal i" . repeat(" ", indent)
endif
let lnum += 1
endwhile
endfunction
Question Two
This isn't a very elegant approach, but it seems to work. First of all, here's a function that maps each line in the file to a paragraph number:
function! MapLinesToParagraphs()
let lnum = 1
let para_lines = []
let next_is_new_para = 1
let current_para = 0
while lnum <= line("$")
let this = getline(lnum)
if this =~ "^ *$"
let next_is_new_para = 1
elseif next_is_new_para == 1
let current_para += 1
let next_is_new_para = 0
endif
call add(para_lines, current_para)
let lnum += 1
endwhile
return para_lines
endfunction
So that para_lines[i] will give the paragraph of line i.
Now we can use the existing IndexByWord() function, and use MapLinesToParagraph() to convert the line numbers into paragraph numbers before we return them:
function! IndexByParagraph(wordlist)
let temp_dict = {}
let para_lines = MapLinesToParagraphs()
for word in a:wordlist
redir => result
sil! exe ':g/' . word . '/#'
redir END
let tmp_list = split(strtrans(result), "\\^\# *")
let res_list = []
call map(tmp_list, 'add(res_list, str2nr(matchstr(v:val, "^[0-9]*")))')
call map(res_list, 'para_lines[v:val]')
let temp_dict[word] = res_list
endfor
let result_list = []
for key in sort(keys(temp_dict))
call add(result_list, key . ' : ' . string(temp_dict[key])[1:-2])
endfor
return join(result_list, "\n")
endfunction
I have not tested these functions very thoroughly, but they seem to work okay, at least in your example text. Let me know how you get on!

Answer 3

Both problems could be solved much easier than it is suggested
by the other two answers.
1. In order to solve the first problem of numbering paragraphs,
the following two steps are ample.
Indent the paragraphs (using tabs, here):
:v/^\s*$/s/^/\t/
Insert paragraph numbering (see also my answer to
the question on substitution with counter):
:let n=[0] | %s/^\s*\n\zs\ze\s*\S\|\%1l/\=map(n,'v:val+1')
2. The second problem of creating index requires some scripting in
order to be solved by Vim means only. Below is the listing of a small
function, WordParIndex() that is supposed to be run after paragraphs
are numbered according to the first problem's description.
function! WordParIndex()
let [p, fq] = [0, {}]
let [i, n] = [1, line('$')]
while i <= n
let l = getline(i)
if l !~ '^\s*$'
let [p; ws] = ([p] + split(l, '\s\+'))[l=~'^\S':]
for w in ws
let t = get(fq, w, [p])
let fq[w] = t[-1] != p ? t + [p] : t
endfor
endif
let i += 1
endwhile
return fq
endfunction
The return value of the WordParIndex() function is the target index
dictionary. To append its text representation at the end of a buffer,
run
:call map(WordParIndex(), 'append(line("$"),v:key.": ".join(v:val,","))')

Answer 4

My approach would be macro based:
Yank the number "0" somehow and move to the start of the first paragraph.
Record a macro to
Indent the paragraph with >}
Paste the stored number at the correct position p
Increment the number by one with <ctrl>-a
Yank the pasted number with yiw
Move to the next paragraph with }l or /^\S
Execute the macro as many times as needed to reach the end of the document.
The method of pasting a number, incrementing it, and then reyanking it inside a macro is quite a useful technique that comes in handy whenever you need to number things. And it's simple enough to just do it in a throw-away fashion. I mainly use it for carpet logging, but it has other uses as your question demonstrates.