lua: refactor complete-filename plugin

There are probably more things to simplify but at least this makes
it easier to see what exactly is different between `<C-x><C-f>` and
`<C-x><C-o>`.

Some differences were removed:
* whitespace in range is treated the same for both actions
* empty range will expand to files in CWD for both actions

closes martanne#1146: Complete file name and file path swapped in doc

lua/plugins/complete-filename.lua

@@ -1,56 +1,51 @@
--- complete file path at primary selection location using vis-complete(1)
-
-vis:map(vis.modes.INSERT, "<C-x><C-f>", function()
+local complete_filename = function(expand)
 	local win = vis.win
 	local file = win.file
 	local pos = win.selection.pos
 	if not pos then return end
+
 	-- TODO do something clever here
 	local range = file:text_object_longword(pos > 0 and pos-1 or pos);
 	if not range then return end
 	if range.finish > pos then range.finish = pos end
-	if range.start == range.finish then return end
+
 	local prefix = file:content(range)
 	if not prefix then return end
-	-- Strip leading delimiters for some languages
-	local _, j = string.find(prefix, "[[(<'\"]+")
-	if j then prefix = prefix:sub(j + 1) end
-	local cmd = string.format("vis-complete --file '%s'", prefix:gsub("'", "'\\''"))
-	local status, out, err = vis:pipe(file, { start = 0, finish = 0 }, cmd)
-	if status ~= 0 or not out then
-		if err then vis:info(err) end
-		return
-	end
-	file:insert(pos, out)
-	win.selection.pos = pos + #out
-end, "Complete file path")
 
--- complete file path at primary selection location using vis-open(1)
+	-- Strip leading delimiters for some progamming languages
+	local _, j = prefix:find("[[(<'\"]+")
+	if not expand and j then prefix = prefix:sub(j + 1) end
 
-vis:map(vis.modes.INSERT, "<C-x><C-o>", function()
-	local win = vis.win
-	local file = win.file
-	local pos = win.selection.pos
-	if not pos then return end
-	-- TODO do something clever here
-	local range = file:text_object_longword(pos > 0 and pos-1 or pos);
-	if not range then return end
-	if range.finish > pos then range.finish = pos end
-	local prefix = file:content(range)
-	if not prefix then return end
 	if prefix:match("^%s*$") then
 		prefix = ""
 		range.start = pos
 		range.finish = pos
 	end
-	local cmd = string.format("vis-open -- '%s'*", prefix:gsub("'", "'\\''"))
-	local status, out, err = vis:pipe(file, { start = 0, finish = 0 }, cmd)
+
+	local cmdfmt = "vis-complete --file '%s'"
+	if expand then cmdfmt = "vis-open -- '%s'*" end
+	local status, out, err = vis:pipe(cmdfmt:format(prefix:gsub("'", "'\\''")))
 	if status ~= 0 or not out then
 		if err then vis:info(err) end
 		return
 	end
 	out = out:gsub("\n$", "")
-	file:delete(range)
-	file:insert(range.start, out)
-	win.selection.pos = range.start + #out
+
+	if expand then
+		file:delete(range)
+		pos = range.start
+	end
+
+	file:insert(pos, out)
+	win.selection.pos = pos + #out
+end
+
+-- complete file path at primary selection location using vis-complete(1)
+vis:map(vis.modes.INSERT, "<C-x><C-f>", function()
+	complete_filename(false);
 end, "Complete file name")
+
+-- complete file path at primary selection location using vis-open(1)
+vis:map(vis.modes.INSERT, "<C-x><C-o>", function()
+	complete_filename(true);
+end, "Complete file name (expands path)")