gistfile1.lua

function string.wrap(text,cols)
	-- takes one or more lines of text and wraps them at punctuation, whilst preserving the (tab or space) indentation
	cols = cols or tonumber(string.match(io.popen("stty size"):read()," (%d*)")) -- sh doesn't seem to export $COLUMNS
	local output = {} -- more memory efficient than constantly concatenating
	local offset,char,indent,indents,wrapped
	local function IndexString (text) local temp = {} for i=1,#text do  temp[string.sub(text,i,i)]=true end return temp end -- this just makes it easier to write the values as a string on the next line
	local punctuation = IndexString [[ ,.;:!?"[]{}()]]
	-- iterate over each line
	for line in string.gmatch(text.."\n","(.-)\n") do
		-- determine indentation
		indent = ""
		indents = 0
		for char,position in string.gmatch(line,"(%s)()") do
			if position > (#indent + 2) then break end
			indent = indent .. char
			if char == "\t" then indents = indents + 8 -- assuming the terminal displays tabs as 8 spaces
			else indents = indents + 1 end
		end
		-- check each line
		if #line + indents - #indent < cols then
			-- doesn't need to be wrapped, so output unchanged
			table.insert(output,line)
		else
			-- does need to be wrapped
			-- work backwards from the wrap point to find punctuation
			offset = cols - indents
			while offset > 0 do
				char = string.sub(line,offset,offset)
				if punctuation[char] then break end
				offset = offset - 1
			end
			-- output the trimmed line
			table.insert(output,string.sub(line,1,offset))
			table.insert(output,"\n")
			-- determine if the wrapped line also needs wrapping
			wrapped = indent..string.sub(line,offset+1)
			if #wrapped + indents - #indent > cols then
				-- does need wrapping as well, so call self with new value
				table.insert(output,string.wrap(wrapped,cols))
			else
				-- output the wrapped line
				table.insert(output,wrapped)
			end
		end
		table.insert(output,"\n")
	end
	table.remove(output,#output) -- removes the final linebreak we added initially
	return table.concat(output)
end