potatOS/minify/Scope.lua

local var_count = 0
local util = require'Util'
local lookupify = util.lookupify
local Keywords = lookupify{
	'and', 'break', 'do', 'else', 'elseif',
	'end', 'false', 'for', 'function', 'goto', 'if',
	'in', 'local', 'nil', 'not', 'or', 'repeat',
	'return', 'then', 'true', 'until', 'while',
};

local Scope = {
	new = function(self, parent)
		local s = {
			Parent = parent,
			Locals = { },
			Globals = { },
			oldLocalNamesMap = { },
			oldGlobalNamesMap = { },
			Children = { },
		}
		
		if parent then
			table.insert(parent.Children, s)
		end
		
		return setmetatable(s, { __index = self })
	end,
	
	AddLocal = function(self, v)
		table.insert(self.Locals, v)
	end,
	
	AddGlobal = function(self, v)
		table.insert(self.Globals, v)
	end,
	
	CreateLocal = function(self, name)
		local v
		v = self:GetLocal(name)
		if v then return v end
		v = { }
		v.Scope = self
		v.Name = name
		v.IsGlobal = false
		v.CanRename = true
		v.References = 1
		self:AddLocal(v)
		return v
	end,
	
	GetLocal = function(self, name)
		for k, var in pairs(self.Locals) do
			if var.Name == name then return var end
		end
		
		if self.Parent then
			return self.Parent:GetLocal(name)
		end
	end,
	
	GetOldLocal = function(self, name)
		if self.oldLocalNamesMap[name] then
			return self.oldLocalNamesMap[name]
		end
		return self:GetLocal(name)
	end,
	
	mapLocal = function(self, name, var)
		self.oldLocalNamesMap[name] = var
	end,
	
	GetOldGlobal = function(self, name)
		if self.oldGlobalNamesMap[name] then
			return self.oldGlobalNamesMap[name]
		end
		return self:GetGlobal(name)
	end,
	
	mapGlobal = function(self, name, var)
		self.oldGlobalNamesMap[name] = var
	end,
	
	GetOldVariable = function(self, name)
		return self:GetOldLocal(name) or self:GetOldGlobal(name)
	end,
	
	RenameLocal = function(self, oldName, newName)
		oldName = type(oldName) == 'string' and oldName or oldName.Name
		local found = false
		local var = self:GetLocal(oldName)
		if var then
			var.Name = newName
			self:mapLocal(oldName, var)
			found = true
		end
		if not found and self.Parent then
			self.Parent:RenameLocal(oldName, newName)
		end
	end,
	
	RenameGlobal = function(self, oldName, newName)
		oldName = type(oldName) == 'string' and oldName or oldName.Name
		local found = false
		local var = self:GetGlobal(oldName)
		if var then
			var.Name = newName
			self:mapGlobal(oldName, var)
			found = true
		end
		if not found and self.Parent then
			self.Parent:RenameGlobal(oldName, newName)
		end
	end,
	
	RenameVariable = function(self, oldName, newName)
		oldName = type(oldName) == 'string' and oldName or oldName.Name
		if self:GetLocal(oldName) then
			self:RenameLocal(oldName, newName)
		else
			self:RenameGlobal(oldName, newName)
		end
	end,
	
	GetAllVariables = function(self)
		local ret = self:getVars(true) -- down
		for k, v in pairs(self:getVars(false)) do -- up
			table.insert(ret, v)
		end
		return ret
	end,
	
	getVars = function(self, top)
		local ret = { }
		if top then
			for k, v in pairs(self.Children) do
				for k2, v2 in pairs(v:getVars(true)) do
					table.insert(ret, v2)
				end
			end
		else
			for k, v in pairs(self.Locals) do
				table.insert(ret, v)
			end
			for k, v in pairs(self.Globals) do
				table.insert(ret, v)
			end
			if self.Parent then
				for k, v in pairs(self.Parent:getVars(false)) do
					table.insert(ret, v)
				end
			end
		end
		return ret
	end,
	
	CreateGlobal = function(self, name)
		local v
		v = self:GetGlobal(name)
		if v then return v end
		v = { }
		v.Scope = self
		v.Name = name
		v.IsGlobal = true
		v.CanRename = true
		v.References = 1
		self:AddGlobal(v)
		return v
	end, 
	
	GetGlobal = function(self, name)
		for k, v in pairs(self.Globals) do
			if v.Name == name then return v end
		end
		
		if self.Parent then
			return self.Parent:GetGlobal(name)
		end
	end,
	
	GetVariable = function(self, name)
		return self:GetLocal(name) or self:GetGlobal(name)
	end,
	
	ObfuscateLocals = function(self, recommendedMaxLength, validNameChars)
		recommendedMaxLength = recommendedMaxLength or 7
		local chars = validNameChars or "QWERTYUIOPASDFGHJKLZXCVBNMqwertyuioplkjhgfdsazxcvbnm_"
		--local chars2 = validNameChars or "QWERTYUIOPASDFGHJKLZXCVBNMqwertyuioplkjhgfdsazxcvbnm_1234567890"
		for _, var in pairs(self.Locals) do
			local id = ""
			local tries = 0
			--[[
			repeat
				local n = math.random(1, #chars)
				id = id .. chars:sub(n, n)
				for i = 1, math.random(0, tries > 5 and 30 or recommendedMaxLength) do
					local n = math.random(1, #chars2)
					id = id .. chars2:sub(n, n)
				end
				tries = tries + 1
			until not self:GetVariable(id)]]
			local id
			repeat
				local n = var_count
				id = ""
				repeat
					local x = n % #chars
					id = id .. chars:sub(x + 1, x + 1)
					n = math.floor(n / #chars)
				until n == 0
				var_count = var_count + 1
			until not Keywords[id]
			self:RenameLocal(var.Name, id)
		end
	end,
}

return Scope