Add option to update indent after exchange

doc/exchange.txt

@@ -75,6 +75,14 @@ g:exchange_no_mappings ~
 
 If this variable is defined, the default mappings will not be created.
 
+                                                *g:exchange_indent*
+g:exchange_indent ~
+
+If this variable is defined and non-zero, linewise exchanges will swap
+indents. Alternatively, setting the option to '==' will re-indent the
+exchanged text with |==|. This behavior can be configured per buffer by
+setting b:exchange_indent.
+
 ISSUES AND TODO                                 *exchange-issues*
                                                 *exchange-todo*
 

plugin/exchange.vim

@@ -20,6 +20,20 @@ function! s:exchange(x, y, reverse, expand)
 		silent exe "normal! `[" . a:x[1] . "`]\"zp"
 	endif
 
+	if exists("b:exchange_indent") ? (b:exchange_indent !~ 0) :
+			\ (exists("g:exchange_indent") && (g:exchange_indent !~ 0))
+		let xlines = 1 + a:x[3][1] - a:x[2][1]
+		let xindent = matchstr(getline(nextnonblank(a:x[2][1])), '^\s*')
+		let ylines = 1 + a:y[3][1] - a:y[2][1]
+		let yindent = matchstr(getline(nextnonblank(a:y[2][1])), '^\s*')
+		if a:y[1] ==# 'V'
+			call s:reindent(a:x[2][1], ylines, yindent)
+		endif
+		if a:x[1] ==# 'V'
+			call s:reindent(a:y[2][1] - xlines + ylines, xlines, xindent)
+		endif
+	endif
+
 	if a:reverse
 		call cursor(a:x[2][1], a:x[2][2])
 	else
@@ -33,6 +47,40 @@ function! s:exchange(x, y, reverse, expand)
 	call s:restore_reg('+', reg_plus)
 endfunction
 
+function! s:reindent(start, lines, new_indent)
+	if g:exchange_indent == '=='
+		let lnum = nextnonblank(a:start)
+		let line = getline(lnum)
+		execute "silent normal! " . lnum . "G=="
+		let new_indent = matchstr(getline(lnum), '^\s*')
+		call setline(a:start, line)
+	else
+		let new_indent = a:new_indent
+	endif
+	let indent = matchstr(getline(nextnonblank(a:start)), '^\s*')
+	if strdisplaywidth(new_indent) > strdisplaywidth(indent)
+		for lnum in range(a:start, a:start + a:lines - 1)
+			if lnum =~ '\S'
+				call setline(lnum, new_indent . getline(lnum)[len(indent):])
+			endif
+		endfor
+	elseif strdisplaywidth(new_indent) < strdisplaywidth(indent)
+		let can_dedent = 1
+		for lnum in range(a:start, a:start + a:lines - 1)
+			if stridx(getline(lnum), new_indent) != 0 && nextnonblank(lnum) == lnum
+				let can_dedent = 0
+			endif
+		endfor
+		if can_dedent
+			for lnum in range(a:start, a:start + a:lines - 1)
+				if stridx(getline(lnum), new_indent) == 0
+					call setline(lnum, new_indent . getline(lnum)[len(indent):])
+				endif
+			endfor
+		endif
+	endif
+endfunction
+
 function! s:exchange_get(type, vis)
 	let reg = s:save_reg('"')
 	let reg_star = s:save_reg('*')