Beginnings of a basic HAML subset for Lua

haml.lua

require "tprint"

raw_haml = [[%a
  %b
%a
  %b
    %c]]

-- Generate a list of HAML rules
rules = {}
for rule in raw_haml:gfind("[^\n]+") do
	local spaces, data = rule:match("^(%s*)(.*)$")
	table.insert(rules, {rule = data, depth = spaces:len()/2})
end

table_print(rules)

-- Form a tree representing the HAML
function tree(branches, start, depth, parent)

  branches[0].depth = 0
	local position = start + 1
	while position <= table.maxn(branches) do
	
		if branches[position].depth >= branches[position-1].depth then
			io.write(string.rep("  ", branches[position].depth), position, branches[position].rule, "\n")
			
			local node = { 
				name      = "div",
				attrs     = {},
				classes   = {},
				selector  = "",
				content   = "",
				children  = {}
			}
			
			local scan, haml_rule = 1, branches[position].rule
			while scan <= haml_rule:len() do
				local token_start
				char = haml_rule:sub(scan, scan)
				if char == "%" then
					token_start = haml_rule:find("[%%#.{%s]", scan + 1) or -1
					node.name = haml_rule:sub(scan + 1, token_start - ((token_start == -1) and 0 or 1))
					scan = token_start
				elseif char == "#" then
					token_start = haml_rule:find("[%%#.{%s]", scan + 1) or -1
					node.attrs.id = haml_rule:sub(scan + 1, token_start)
					scan = token_start
				elseif char == "." then
					token_start = haml_rule:find("[%%#.{%s]", scan + 1) or -1
					table.insert(node.classes, haml_rule:sub(scan + 1, token_start - ((token_start == -1) and 0 or 1)))
					scan = token_start
				elseif char == "{" then
					token_start = haml_rule:find("}", scan + 1) or -1
					--io.write("attrs:\t", haml_rule:sub(scan, token_start), "\n")
					attrs = loadstring("return (" .. haml_rule:sub(scan, token_start) .. ")")
					if attrs ~= nil then
						for k,v in pairs(attrs()) do
							node.attrs[k] = v
						end
					end
					dummy, scan = haml_rule:find("}%s+")
					scan = (scan == nil) and (haml_rule:len() + 1) or (scan + 1)
				else
					node.content = (scan == -1) and "" or haml_rule:sub(scan, -1)
					scan = haml_rule:len() + 1
				end
			end
			
			if table.maxn(node.classes) > 0 then
				node.attrs.class = ""
				for i, class in ipairs(node.classes) do
					node.attrs.class = node.attrs.class .. class .. " "
				end
				node.attrs.class = node.attrs.class:sub(1, -2)
			end
			
			table.insert(parent.children, node)
			tree(branches, position, depth+1, node)
		end
		
		position = position + 1
	end
	
end

-- Output HTML from HAML
function html(haml, depth)
	for i, child in ipairs(haml.children) do
		io.write(string.rep("  ", depth), "<", child.name)
		for attr, attr_val in pairs(child.attrs) do
			io.write(" ", attr, '="', attr_val, '"')
		end
		io.write(">\n")
		if child.content ~= "" then
			io.write(string.rep("  ", depth + 1), child.content, "\n")
		end
		html(child, depth + 1)
		io.write(string.rep("  ", depth), "</", child.name, ">\n")
	end
end

root = { children = {} }
tree(rules, 0, 0, root)
--html(root, 0)

--[[haml_delims = "%#."
haml_rule = "%tag#id.class1.class2{href='thing',name='bitch'} zuhhhh"
node.selector = branches[position].rule:match("^(.*)%s*")
			for word in node.selector:gmatch("([.#%%]?[^%s.#%%]+)") do
				if word:sub(1, 1) == '%' then
					node.name = word:sub(2)
				elseif word:sub(1, 1) == '#' then
					node.attrs.id = word:sub(2)
				elseif word:sub(1, 1) == '.' then
					table.insert(node.classes, word:sub(2))
				end
			end]]