C preprocessor in Lua

loadHeader.lua

local function split(str, sep)
    local retval = {}
    for m in str:gmatch("([^" .. sep .. "]+)") do table.insert(retval, m) end
    return retval
end

local function dirname(str)
	if str:match(".-/.-") then return string.gsub(str, "^(.*)/.*$", "%1")
    else return "" end
end

local function createMacro(params, definition)
    local n = #params
    for i,v in ipairs(params) do params[i] = v:gsub("^%s*", ""):gsub("%s*$", "") end
    return function(...)
        local retval = definition
        local args = {...}
        for i = 1, n do
            if args[i] == nil then error("Not enough arguments to macro (expected " .. n .. ", got " .. i-1 .. ")")
            elseif type(args[i]) ~= nil then args[i] = tostring(args[i]) end
            retval = retval:gsub("(.)" .. params[i] .. "%s*##%s*", "%1" .. args[i])
                           :gsub("^" .. params[i] .. "%s*##%s*", args[i])
                           :gsub("(.)##(.)", "%1%2")
                           :gsub("#" .. params[i] .. "([^%w_])", '"' .. args[i] .. '"%1')
                           :gsub("#" .. params[i] .. "$", '"' .. args[i] .. '"')
                           :gsub("([^%w_])" .. params[i] .. "([^%w_])", "%1" .. args[i] .. "%2")
                           :gsub("^" .. params[i] .. "([^%w_])", args[i] .. "%1")
                           :gsub("([^%w_])" .. params[i] .. "$", "%1" .. args[i])
                           :gsub("^" .. params[i] .. "%", args[i])
        end
        return retval
    end
end

local function countGsub(t, str, m, r)
    local ret, a = str:gsub(m, r)
    t.n = t.n + a
    if a > 0 then table.insert(t.m, {m, r}) end
    return ret
end

local function macroExpansion(retval, defines)
    local p = {n = 0, m = {}}
    local start = tonumber(os.date "%s")
    local loops = 0
    repeat
        p.n = 0
        p.m = {}
        for k,v in pairs(defines) do if k ~= v then
            if type(v) == "function" then
                local function replacer(argstr, a)
                    if a ~= nil then
                        local retval = argstr
                        argstr = a
                        a = retval
                    else a = "" end
                    local args = {"", n = 1}
                    local plevel, slevel, clevel, dq, sq, escape = 0, 0, 0, false, false, false
                    for c in argstr:match("^%((.+)%)$"):gmatch "." do
                        if c == '(' then plevel = plevel + 1
                        elseif c == ')' and plevel > 0 then plevel = plevel - 1
                        elseif c == '[' then slevel = slevel + 1
                        elseif c == ']' and slevel > 0 then slevel = slevel - 1
                        elseif c == '{' then clevel = clevel + 1
                        elseif c == '}' and clevel > 0 then clevel = clevel - 1
                        elseif c == '"' and not (dq and escape) then dq = not dq
                        elseif c == "'" and not (sq and escape) then sq = not sq end
                        if c == ',' and plevel == 0 and slevel == 0 and clevel == 0 and not dq and not sq then
                            args.n = args.n + 1
                            args[args.n] = ""
                        else args[args.n] = args[args.n] .. c end
                        escape = c == '\\' and (dq or sq)
                    end
                    for i = 1, args.n do args[args.n] = args[args.n]:gsub("^%s*", ""):gsub("%s*^", "") end
                    return a .. v(unpack(args))
                end
                retval = countGsub(p, countGsub(p, retval, "([^%w_])" .. k .. "%s*(%b())", replacer), "^" .. k .. "%s*(%b())", replacer)
            elseif type(v) ~= "table" then
                retval = countGsub(p, countGsub(p, countGsub(p, countGsub(p, retval,
                            "([^%w_])" .. k .. "([^%w_])", "%1" .. v .. "%2"),
                            "^" .. k .. "([^%w_])", v .. "%1"),
                            "([^%w_])" .. k .. "$", "%1" .. v),
                            "^" .. k .. "$", v)
            end
        end end
        loops = loops + 1
        if tonumber(os.date "%s") - start > 1 then
            for i,v in ipairs(p.m) do print(v[1], v[2]) end
            error("Too long without yielding: " .. loops .. ", " .. p.n .. ": " .. retval)
        end
    until p.n == 0
    return retval
end

local function loadHeader(path, incpath, defines)
    defines = defines or {}
    defines.debugLocation = defines.debugLocation or {}
    incpath = incpath or {}
    local ifLevels = {n = 0, [0] = true}
    local elseSkips = {}
    local comment = false
    local retval = ""
    local lines = {}
    --for line in io.lines(path) do table.insert(lines, line) end
    local filein = io.open(path, "r")
    for line in filein:read("*a"):gmatch "[^\r\n]+" do table.insert(lines, line) end
    filein:close()
    local lineno = 1
    while lineno <= #lines do
        local line = lines[lineno]
        while line:match "\\%s*$" do
            repeat lineno = lineno + 1 until lines[lineno]:gsub("^%s*", ""):gsub("%s*$", "") ~= ""
            line = line:gsub("\\%s*$", "") .. lines[lineno]
        end
        if not comment or line:find "%*/" then
            if comment then line = line:gsub(".-%*/", "") end
            local shouldComment = line:find "/%*" ~= nil and line:find "%*/" == nil
            line = line:gsub("//.*$", ""):gsub("/%*.*%*/", ""):gsub("/%*.*$", "")
            if line:match "^%s*#" then
                local cmd, tokens = line:match "^%s*#%s*(%S+)%s*(.*)"
                tokens = tokens:gsub("%s*$", "")
                if cmd == "ifdef" then
                    ifLevels[ifLevels.n+1] = ifLevels[ifLevels.n] and defines[tokens:match "^(%S+)"] ~= nil
                    elseSkips[ifLevels.n+1] = ifLevels[ifLevels.n+1] == true
                    ifLevels.n = ifLevels.n + 1
                elseif cmd == "ifndef" then
                    ifLevels[ifLevels.n+1] = ifLevels[ifLevels.n] and defines[tokens:match "^(%S+)"] == nil
                    elseSkips[ifLevels.n+1] = ifLevels[ifLevels.n+1] == true
                    ifLevels.n = ifLevels.n + 1
                elseif cmd == "if" then
                    if ifLevels[ifLevels.n] then
                        local str = "return " .. tokens:gsub("!=", "~="):gsub("!", " not "):gsub("&&", " and "):gsub("||", " or "):gsub("defined(%b())", function(a) return "defined('" .. a:sub(2, -2) .. "')" end):gsub("defined%s+([%w_]+)", "defined '%1'"):gsub("(%d+)U?L?L?", "%1"):gsub("(0x%x+)U?L?L?", "%1"):gsub("(0b[01]+)U?L?L?", "%1"):gsub("(0[0-7]+)U?L?L?", "%1"):gsub("([%d%.]+)f", "%1"):gsub("?([^():]+):", " and %1 or "):gsub("?([^():]*%b()[^():]*):", " and %1 or ")
                        local fn, err = loadstring(str)
                        if not fn then error(path .. "[" .. str .. "]" .. lineno .. err) end
                        setfenv(fn, setmetatable({defined = function(name) return defines[name] ~= nil end}, {__index = defines}))
                        local ok, res = pcall(fn)
                        --if not ok then print(path .. "[" .. str .. "]" .. lineno .. res) res = ok end
                        ifLevels[ifLevels.n+1] = res
                        elseSkips[ifLevels.n+1] = ifLevels[ifLevels.n+1] == true
                    else
                        ifLevels[ifLevels.n+1] = false
                        elseSkips[ifLevels.n+1] = false
                    end
                    ifLevels.n = ifLevels.n + 1
                elseif cmd == "elif" then
                    if ifLevels[ifLevels.n-1] and not elseSkips[ifLevels.n] then
                        local str = "return " .. tokens:gsub("!=", "~="):gsub("!", " not "):gsub("&&", " and "):gsub("||", " or "):gsub("defined(%b())", function(a) return "defined('" .. a:sub(2, -2) .. "')" end):gsub("defined%s+([%w_]+)", "defined '%1'"):gsub("(%d+)U?L?L?", "%1"):gsub("(0x%x+)U?L?L?", "%1"):gsub("(0b[01]+)U?L?L?", "%1"):gsub("(0[0-7]+)U?L?L?", "%1"):gsub("([%d%.]+)f", "%1"):gsub("?([^():]+):", " and %1 or "):gsub("?([^():]*%b()[^():]*):", " and %1 or ")
                        local fn, err = loadstring(str)
                        if not fn then error(path .. "[" .. str .. "]" .. lineno .. err) end
                        setfenv(fn, setmetatable({defined = function(name) return defines[name] ~= nil end}, {__index = defines}))
                        local ok, res = pcall(fn)
                        --if not ok then print(path .. "[" .. str .. "]" .. lineno .. res) res = ok end
                        ifLevels[ifLevels.n] = res
                        elseSkips[ifLevels.n] = elseSkips[ifLevels.n] or ifLevels[ifLevels.n] == true
                    else
                        ifLevels[ifLevels.n] = false
                    end
                elseif cmd == "else" then
                    if elseSkips[ifLevels.n] or not ifLevels[ifLevels.n-1] then
                        ifLevels[ifLevels.n] = false
                        elseSkips[ifLevels.n] = false
                    else
                        ifLevels[ifLevels.n] = not ifLevels[ifLevels.n]
                        elseSkips[ifLevels.n] = true
                    end
                elseif cmd == "endif" and ifLevels.n > 0 then
                    ifLevels[ifLevels.n] = nil
                    ifLevels.n = ifLevels.n - 1
                elseif cmd == "error" and ifLevels[ifLevels.n] then
                    error(path .. ": " .. lineno .. ": " .. tokens)
                elseif cmd == "warning" and ifLevels[ifLevels.n] then
                    print(path .. ": " .. lineno .. ": Warning: " .. tokens)
                elseif cmd == "include" and ifLevels[ifLevels.n] then
                    if tokens:find '<' then
                        local ppath = tokens:match("(%b<>)"):sub(2, -2)
                        local found = false
                        for _,v in ipairs(incpath) do
                            local file = io.open(v .. "/" .. ppath, "r")
                            if file then
                                file:close()
                                retval = retval .. "\n" .. loadHeader(v .. "/" .. ppath, incpath, defines)
                                found = true
                                break
                            end
                        end
                        if not found then error("Could not find header " .. ppath) end
                    elseif tokens:find '"' then
                        local ppath = tokens:match("(%b\"\")"):sub(2, -2)
                        local found = false
                        for _,v in ipairs(incpath) do
                            local file = io.open(v .. "/" .. ppath, "r")
                            if file then
                                file:close()
                                retval = retval .. "\n" .. loadHeader(v .. "/" .. ppath, incpath, defines)
                                found = true
                                break
                            end
                        end
                        if not found then
                            local file = io.open(dirname(path) .. "/" .. ppath, "r")
                            if file then
                                file:close()
                                retval = retval .. "\n" .. loadHeader(dirname(path) .. "/" .. ppath, incpath, defines)
                            else error("Could not find local header " .. ppath) end
                        end
                    else error("Invalid include path: " .. tokens) end
                elseif cmd == "define" and ifLevels[ifLevels.n] then
                    local name, value
                    if tokens:match "^[^%s(]+%(" then name, value = tokens:match "^([^(]+%b())%S*%s*(.*)"
                    else name, value = tokens:match "^(%S+)%s*(.*)" end
                    if name ~= nil and value == nil then value = "" end
                    if name:find "%(" then defines[name:match "^[^(]+"] = createMacro(split(name:match("%b()"):sub(2, -2), ","), value)
                    else defines[name] = tonumber(value:gsub("(%d+)U?L?L?", "%1"):gsub("(0x%x+)U?L?L?", "%1"):gsub("(0b[01]+)U?L?L?", "%1"):gsub("(0[0-7]+)U?L?L?", "%1"):gsub("([%d%.]+)f", "%1"), nil) or value end
                    defines.debugLocation[name:find "%(" and name:match "^[^(]+" or name] = path .. ":" .. lineno
                elseif cmd == "undef" and ifLevels[ifLevels.n] then
                    defines[tokens:match "^(%S+)"] = nil
                end
            elseif ifLevels[ifLevels.n] and line:gsub("^%s*", ""):gsub("%s*$", "") ~= "" then
                retval = retval .. "\n" .. macroExpansion(line, defines)
            end
            comment = shouldComment
        end
        lineno = lineno + 1
    end
    return retval
end

return loadHeader