macro-italicize.lua

-- italicizes or unitalicizes text [based on style and tags]
-- supports multiple \i tags in a line by switching 0 to 1 and vice versa

script_name="Italicize"
script_description="Italicizes or unitalicizes text"
script_author="unanimated"
script_version="1.61"

function italicize(subs, sel)
	for z, i in ipairs(sel) do
		local l=subs[i]
		text=l.text
		styleref=stylechk(subs,l.style)
		local si=styleref.italic
		if si==false then it="1" else it="0" end
		text=text:gsub("\\i([\\}])","\\i".. 1-it.."%1")
		    if text:match("^{[^}]*\\i%d[^}]*}") then
			text=text:gsub("\\i(%d)", function(num) return "\\i".. 1-num end)
		    else
			if text:match("\\i([01])") then italix=text:match("\\i([01])") end
			if italix==it then text=text:gsub("\\i(%d)", function(num) return "\\i".. 1-num end) end
			text="{\\i"..it.."}"..text
			text=text:gsub("{\\i(%d)}({\\[^}]*)}","%2\\i%1}")
		    end
		l.text=text
		subs[i]=l
	end
	aegisub.set_undo_point(script_name)
	return sel
end

function stylechk(subs,stylename)
    for i=1, #subs do
        if subs[i].class=="style" then
	    style=subs[i]
	    if stylename==style.name then
		styleref=style
		break
	    end
	end
    end
    return styleref
end

aegisub.register_macro(script_name, script_description, italicize)