-- LunaCON CON to Lunatic translator
-- requires LPeg, http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html

local lpeg = require("lpeg")


-- If/else nesting is problematic in CON: because a dangling 'else' is attached
-- to the outermost 'if', I think there's no way of linearizing its (recursive)
-- pattern, so the "too many pending calls/choices" is unavoidable in general.
-- This limit is of course still arbitrary, but writing if/else cascades
-- in CON isn't pretty either (though sometimes necessary because nested switches
-- don't work?)
-- See also:  http://lua-users.org/lists/lua-l/2010-03/msg00086.html
lpeg.setmaxstack(1024);


local Pat, Set, Range, Var = lpeg.P, lpeg.S, lpeg.R, lpeg.V


---- All keywords pattern -- needed for CON syntax
local con_keyword = require("con_lang")


local function match_until(matchsp, untilsp)  -- (!untilsp matchsp)* in PEG
    -- sp: string or pattern
    return (matchsp - Pat(untilsp))^0
end


----==== patterns ====----

---- basic ones
-- Windows, *nix and Mac newlines all exist in the wild!
local newline = "\r"*Pat("\n")^-1 + "\n"
local EOF = Pat(-1)
local anychar = Pat(1)
-- comments
local comment = "/*" * match_until(anychar, "*/") * "*/"
local linecomment = "//" * match_until(anychar, newline)
local whitespace = Var("whitespace")
local sp0 = whitespace^0
-- This "WS+" pattern matches EOF too, so that a forgotten newline at EOF is
-- properly handled
local sp1 = whitespace^1 + EOF
local alpha = Range("AZ", "az")  -- locale?
local alphanum = alpha + Range("09")
--local alnumtok = alphanum + Set("{}/\\*-_.")  -- see isaltok() in gamedef.c

--- basic lexical elements ("tokens")
local t_number = (Pat("0x") + "0X")*Range("09", "af", "AF")^1 + Range("09")^1
-- Valid identifier names are disjunct from keywords!
-- XXX: CON is more permissive with identifier name characters:
local t_identifier = Var("t_identifier")
-- This one matches keywords, too:
local t_identifier_all = Var("t_identifier_all")
local t_define = Var("t_define")
local t_filename = (anychar-Set(" \t\r\n"))^1 --alnumtok^1  -- XXX
local t_newline_term_str = match_until(anychar, newline)

-- new-style inline arrays and structures:
local t_arrayexp = Var("t_arrayexp")

-- defines and constants can take the place of vars that are only read:
local t_rvar = t_arrayexp + t_define
-- not so with written-to vars:
local t_wvar = t_arrayexp + t_identifier


---- helper patterns / pattern constructing functions
local maybe_quoted_filename = ('"' * t_filename * '"' + t_filename)
-- empty string is handled too; we must not eat the newline then!
local newline_term_string = (#newline + EOF) + (whitespace-newline)^1 * t_newline_term_str


-- (sp1 * t_define) repeated exactly n times
local function n_defines(n)  -- works well only for small n
    local pat = Pat(true)
    for i=1,n do
        pat = sp1 * t_define * pat
    end
    return pat
end


local D, R, W, I = -1, -2, -3, -4;

-- Generic command pattern, types given by varargs.
-- The command name to be matched is attached later.
-- Example:
--  "command" writtenvar readvar def def:  gencmd(W,R,D,D)
--    -->  sp1 * t_wvar * sp1 * t_rvar * sp1 * t_define * sp1 * t_define
--  "command_with_no_args":  gencmd()
--    --> Pat(true)
local function cmd(...)
    local pat = Pat(true)
    local vartypes = {...}

    for i=1,#vartypes do
        assert(vartypes[i] < 0)

        if (vartypes[i] == D) then
            pat = pat * sp1 * t_define
        elseif (vartypes[i] == R) then
            pat = pat * sp1 * t_rvar
        elseif (vartypes[i] == W) then
            pat = pat * sp1 * t_wvar
        else  -- I
            assert(vartypes[i] == I)
            pat = pat * sp1 * t_identifier
        end
    end

    return pat
end


-- The command names will be attached to the front of the patterns later!

--== Top level CON commands ==--
-- XXX: many of these are also allowed inside actors/states/events in CON.
local Co = {
    --- 1. Preprocessor
    include = sp1 * maybe_quoted_filename,
    includedefault = cmd(),
    define = cmd(I,D),
    --define = sp1 * t_identifier * sp1 * t_define,

    --- 2. Defines and Meta-Settings
    dynamicremap = cmd(),
    setcfgname = sp1 * t_filename,
    setdefname = sp1 * t_filename,
    setgamename = newline_term_string,

    precache = cmd(D,D,D),
    scriptsize = cmd(D),  -- unused
    cheatkeys = cmd(D,D),

    definecheat = newline_term_string,  -- XXX: actually tricker syntax (TS)
    definegamefuncname = newline_term_string,  -- XXX: TS?
    definegametype = n_defines(2) * newline_term_string,
    definelevelname = n_defines(2) * newline_term_string,  -- XXX: TS
    defineskillname = sp1 * t_define * newline_term_string,
    definevolumename = sp1 * t_define * newline_term_string,

    definequote = sp1 * t_define * newline_term_string,
    defineprojectile = cmd(D,D,D),
    definesound = sp1 * t_define * sp1 * maybe_quoted_filename * n_defines(5),  -- XXX: TS

    -- XXX: need to see how that behaves with e.g. stuff like gamevar.ogg:
    music = sp1 * t_define * match_until(sp1 * t_filename, con_keyword),

    --- 3. Game Settings
    -- gamestartup has 25/29 fixed defines, depending on 1.3D/1.5 version:
    gamestartup = (sp1 * t_define)^25,
    spritenopal = cmd(D),
    spritenoshade = cmd(D),
    spritenvg = cmd(D),
    spriteshadow = cmd(D),

    spriteflags = cmd(D,D),  -- also see inner

    --- 4. Game Variables / Arrays
    gamevar = cmd(I,D,D),
    gamearray = cmd(I,D),

    --- 5. Top level commands that are also run-time commands
    action = sp1 * t_identifier * (sp1 * t_define)^-5,
    ai = sp1 * t_identifier * (sp1 * t_define)^0,
    move = sp1 * t_identifier * (sp1 * t_define)^-2,

    --- 6. Deprecated TLCs
    betaname = newline_term_string,
    enhanced = cmd(D),
}


--== Run time CON commands ==--
--- 1. Gamevar Operators
local varop = cmd(W,D)
local varvarop = cmd(W,R)

-- Allow nesting... stuff like
--   ifvarl actorvar[sprite[THISACTOR].owner].burning 0
-- is kinda breaking the classic "no array nesting" rules
-- (if there ever were any) and making our life harder else.
local arraypat = sp0 * "[" * sp0 * t_rvar * sp0 * "]"

-- Have to bite the bullet here and list actor/player members with second parameters,
-- even though it's ugly to make it part of the syntax.  Also, stuff like
--   actor[xxx].loogiex parm2 x
-- will be wrongly accepted at the parsing stage because we don't discriminate between
-- actor and player (but it will be rejected later).
local parm2memberpat = (Pat("htg_t") + "loogiex" + "loogiey" + "ammo_amount" +
                        "weaprecs" + "gotweapon" + "pals" + "max_ammo_amount") * sp0 * t_rvar
-- The member name must match keywords, too (_all), because e.g. cstat is a member
-- of sprite[].
local memberpat = sp0 * "." * sp0 * (parm2memberpat + t_identifier_all)

local getstructcmd =  -- get<structname>[<idx>].<member> (<parm2>)? <<var>>
    -- existence of a second parameter is determined later
-- This is wrong,  (sp1 id)? will match (sp1 wvar) if there's no 2nd param:
--    arraypat * memberpat * (sp1 * t_identifier)^-1 * sp1 * t_wvar
    arraypat * memberpat * sp1 * (t_rvar * sp1 * t_wvar + t_wvar)

local setstructcmd =  -- set<structname>[<idx>].<member> (<parm2>)? <var>
    -- existence of a second parameter is determined later
    arraypat * memberpat * sp1 * (t_rvar * sp1 * t_rvar + t_rvar)

local getperxvarcmd =  -- get<actor/player>var[<idx>].<member> <<var>>
    arraypat * memberpat * sp1 * t_wvar

local setperxvarcmd = -- set<actor/player>var[<idx>].<member> <var>
    arraypat * memberpat * sp1 * t_rvar


local Ci = {
    -- these can appear anywhere in the script
    ["break"] = cmd(),
    ["return"] = cmd(),

    state = cmd(I),

    --- 1. get*, set*
    getactor = getstructcmd,
    getinput = getstructcmd,
    getplayer = getstructcmd,
    getprojectile = getstructcmd,
    getsector = getstructcmd,
    getthisprojectile = getstructcmd,
    gettspr = getstructcmd,
    -- NOTE: {get,set}userdef is the only struct that can be accessed without
    -- an "array part", e.g.  H266mod has "setuserdef .weaponswitch 0" (space
    -- between keyword and "." is mandatory)
    getuserdef = (arraypat + sp1) * memberpat * sp1 * (t_rvar * sp1 * t_wvar + t_wvar),
--    getuserdef = getstructcmd,
    getwall = getstructcmd,

    getactorvar = getperxvarcmd,
    getplayervar = getperxvarcmd,

    setactor = setstructcmd,
    setinput = setstructcmd,
    setplayer = setstructcmd,
    setprojectile = setstructcmd,
    setsector = setstructcmd,
    setthisprojectile = setstructcmd,
    settspr = setstructcmd,
    setuserdef = (arraypat + sp1) * memberpat * sp1 * (t_rvar * sp1 * t_wvar + t_rvar),
--    setuserdef = setstructcmd,
    setwall = setstructcmd,

    setactorvar = setperxvarcmd,
    setplayervar = setperxvarcmd,

    setsprite = cmd(R,R,R,R),

    setvarvar = varvarop,
    addvarvar = varvarop,
    subvarvar = varvarop,
    mulvarvar = varvarop,
    divvarvar = varvarop,
    modvarvar = varvarop,
    andvarvar = varvarop,
    orvarvar = varvarop,
    xorvarvar = varvarop,
    randvarvar = varvarop,

    setvar = varop,
    addvar = varop,
    subvar = varop,
    mulvar = varop,
    divvar = varop,
    modvar = varop,
    andvar = varop,
    orvar = varop,
    xorvar = varop,
    randvar = varop,
    shiftvarl = varop,
    shiftvarr = varop,

    --- 2. Math operations
    sqrt = cmd(R,W),
    calchypotenuse = cmd(W,R,R),
    sin = cmd(W,R),
    cos = cmd(W,R),
    mulscale = cmd(W,R,R,R),
    getangle = cmd(W,R,R),
    getincangle = cmd(W,R,R),

    --- 3. Actors
    -- These three need more attention (different kind of labels; move
    -- additionally may accept 0 or 1):
    action = cmd(D),
    ai = cmd(D),
    move = sp1 * t_define * (sp1 * t_define)^0,

    cactor = cmd(D),
    count = cmd(D),
    cstator = cmd(D),
    cstat = cmd(D),
    clipdist = cmd(D),
    sizeto = cmd(D,D),
    sizeat = cmd(D,D),
    strength = cmd(D),
    addstrength = cmd(D),
    spritepal = cmd(D),

    hitradius = cmd(D,D,D,D,D),
    hitradiusvar = cmd(R,R,R,R,R),

    -- some commands taking read vars
    eshootvar = cmd(R),
    espawnvar = cmd(R),
    qspawnvar = cmd(R),
    eqspawnvar = cmd(R),
    operaterespawns = cmd(R),
    operatemasterswitches = cmd(R),
    checkactivatormotion = cmd(R),
    time = cmd(R),  -- no-op
    inittimer = cmd(R),
    lockplayer = cmd(R),
    shootvar = cmd(R),
    quake = cmd(R),
    jump = cmd(R),
    cmenu = cmd(R),
    soundvar = cmd(R),
    globalsoundvar = cmd(R),
    stopsoundvar = cmd(R),
    soundoncevar = cmd(R),
    angoffvar = cmd(R),
    checkavailweapon = cmd(R),
    checkavailinven = cmd(R),
    guniqhudid = cmd(R),
    savegamevar = cmd(R),
    readgamevar = cmd(R),
    userquote = cmd(R),
    echo = cmd(R),
    starttrackvar = cmd(R),
    clearmapstate = cmd(R),
    activatecheat = cmd(R),
    setgamepalette = cmd(R),

    -- some commands taking defines
    addammo = cmd(D,D),  -- exec SPECIAL HANDLING!
    addweapon = cmd(D,D),  -- exec SPECIAL HANDLING!
    debris = cmd(D,D),
    addinventory = cmd(D,D),
    guts = cmd(D,D),

    -- cont'd
    addkills = cmd(D),
    addphealth = cmd(D),
    angoff = cmd(D),
    debug = cmd(D),
    endofgame = cmd(D),
    eqspawn = cmd(D),
    espawn = cmd(D),
    globalsound = cmd(D),
    lotsofglass = cmd(D),
    mail = cmd(D),
    money = cmd(D),
    paper = cmd(D),
    qspawn = cmd(D),
    quote = cmd(D),
    savenn = cmd(D),
    save = cmd(D),
    sleeptime = cmd(D),
    soundonce = cmd(D),
    sound = cmd(D),
    spawn = cmd(D),
    stopsound = cmd(D),

    eshoot = cmd(D),
    ezshoot = cmd(R,D),
    ezshootvar = cmd(R,R),
    shoot = cmd(D),
    zshoot = cmd(R,D),
    zshootvar = cmd(R,R),

    fall = cmd(),
    flash = cmd(),
    getlastpal = cmd(),
    insertspriteq = cmd(),
    killit = cmd(),  -- exec SPECIAL HANDLING!
    mikesnd = cmd(),
    nullop = cmd(),
    pkick = cmd(),
    pstomp = cmd(),
    resetactioncount = cmd(),
    resetcount = cmd(),
    resetplayer = cmd(),  -- exec SPECIAL HANDLING!
    respawnhitag = cmd(),
    tip = cmd(),
    tossweapon = cmd(),
    wackplayer = cmd(),

    -- player/sprite searching
    findplayer = cmd(W),
    findotherplayer = cmd(W),
    findnearspritezvar = cmd(D,R,R,W),
    findnearspritez = cmd(D,D,D,W),
    findnearsprite3dvar = cmd(D,R,W),
    findnearsprite3d = cmd(D,D,W),
    findnearspritevar = cmd(D,R,W),
    findnearsprite = cmd(D,D,W),
    findnearactorzvar = cmd(D,R,R,W),
    findnearactorz = cmd(D,D,D,W),
    findnearactor3dvar = cmd(D,R,W),
    findnearactor3d = cmd(D,D,W),
    findnearactorvar = cmd(D,R,W),
    findnearactor = cmd(D,D,W),

    -- quotes
    qsprintf = sp1 * t_rvar * sp1 * t_rvar * (sp1 * t_rvar)^-32,
    qgetsysstr = cmd(R,R),
    qstrcat = cmd(R,R),
    qstrcpy = cmd(R,R),
    qstrlen = cmd(R,R),
    qstrncat = cmd(R,R),
    qsubstr = cmd(R,R),

    -- array stuff
    copy = sp1 * t_identifier * arraypat * sp1 * t_identifier * arraypat * sp1 * t_rvar,
    setarray = sp1 * t_identifier * arraypat * sp1 * t_rvar,

    activatebysector = cmd(R,R),
    addlogvar = cmd(R),
--    addlog = cmd(),  -- must come after addlogvar
    addweaponvar = cmd(R,R),  -- exec SPECIAL HANDLING!
    cansee = cmd(R,R,R,R,R,R,R,R,W),
    canseespr = cmd(R,R,W),
    changespritesect = cmd(R,R),
    changespritestat = cmd(R,R),
    clipmove = cmd(W,W,W,R,W,R,R,R,R,R,R),
    clipmovenoslide = cmd(W,W,W,R,W,R,R,R,R,R,R),
    displayrand = cmd(W),
    displayrandvar = cmd(W,D),
    displayrandvarvar = cmd(W,R),
    dist = cmd(W,R,R),
    dragpoint = cmd(R,R,R),
    hitscan = cmd(R,R,R,R,R,R,R,W,W,W,W,W,W,R), -- 7R 6W 1R

    -- screen text and numbers display
    gametext = cmd(R,R,R,R,R,R,R,R,R,R,R),  -- 11 R
    gametextz = cmd(R,R,R,R,R,R,R,R,R,R,R,R),  -- 12 R
    digitalnumber = cmd(R,R,R,R,R,R,R,R,R,R,R),  -- 11R
    digitalnumberz = cmd(R,R,R,R,R,R,R,R,R,R,R,R),  -- 12R
    minitext = cmd(R,R,R,R,R),

    ldist = cmd(W,R,R),
    lineintersect = cmd(R,R,R,R,R,R,R,R,R,R,W,W,W,W),  -- 10R 4W
    rayintersect = cmd(R,R,R,R,R,R,R,R,R,R,W,W,W,W),  -- 10R 4W
    loadmapstate = cmd(),
    savemapstate = cmd(),
    movesprite = cmd(R,R,R,R,R,W),
    neartag = cmd(R,R,R,R,R,W,W,W,W,R,R),
    operateactivators = cmd(R,R),
    operatesectors = cmd(R,R),
    palfrom = (sp1 * t_define)^-4,

    -- must come after all other operate* commands
--    operate = cmd(),

    myos = cmd(R,R,R,R,R),
    myosx = cmd(R,R,R,R,R),
    myospal = cmd(R,R,R,R,R,R),
    myospalx = cmd(R,R,R,R,R,R),

    headspritesect = cmd(R,R),
    headspritestat = cmd(R,R),
    nextspritesect = cmd(R,R),
    nextspritestat = cmd(R,R),
    prevspritesect = cmd(R,R),
    prevspritestat = cmd(R,R),

    readarrayfromfile = cmd(I,D),
    writearraytofile = cmd(I,D),

    redefinequote = sp1 * t_define * newline_term_string,
    resizearray = cmd(I,R),
    getarraysize = cmd(I,W),
    rotatepoint = cmd(R,R,R,R,R,W,W),
    rotatesprite = cmd(R,R,R,R,R,R,R,R,R,R,R,R),  -- 12R
    rotatesprite16 = cmd(R,R,R,R,R,R,R,R,R,R,R,R),  -- 12R
    sectorofwall = cmd(W,R,R),
    sectclearinterpolation = cmd(R),
    sectsetinterpolation = cmd(R),

    sectgethitag = cmd(),
    sectgetlotag = cmd(),
    spgethitag = cmd(),
    spgetlotag = cmd(),

    showview = cmd(R,R,R,R,R,R,R,R,R,R),  -- 10R
    showviewunbiased = cmd(R,R,R,R,R,R,R,R,R,R),  -- 10R
    smaxammo = cmd(R,R),
    gmaxammo = cmd(R,W),
    spriteflags = cmd(R),  -- also see outer
    ssp = cmd(R,R),
    startlevel = cmd(R,R),
    starttrack = cmd(D),
    stopactorsound = cmd(R,R),
    stopallsounds = cmd(),
    updatesector = cmd(R,R,W),
    updatesectorz = cmd(R,R,R,W),

    getactorangle = cmd(W),
    setactorangle = cmd(R),
    getplayerangle = cmd(W),
    setplayerangle = cmd(R),
    getangletotarget = cmd(W),

    getceilzofslope = cmd(R,R,R,W),
    getflorzofslope = cmd(R,R,R,W),
    getcurraddress = cmd(W),  -- XXX
    getkeyname = cmd(R,R,R),
    getpname = cmd(R,R),
    gettextureceiling = cmd(),
    gettexturefloor = cmd(),
    getticks = cmd(W),
    gettimedate = cmd(W,W,W,W,W,W,W,W),
    getzrange = cmd(R,R,R,R,W,W,W,W,R,R),

    setactorsoundpitch = cmd(R,R,R),
    setaspect = cmd(R,R),
}

local Cif = {
    -- XXX: ai, action, move/def labels
    ifai = cmd(D),
    ifaction = cmd(D),
    ifmove = cmd(D),

    ifrnd = cmd(D),
    ifpdistl = cmd(D),
    ifpdistg = cmd(D),
    ifwasweapon = cmd(D),
    ifactioncount = cmd(D),
    ifcount = cmd(D),
    ifactor = cmd(D),
    ifstrength = cmd(D),
    ifspawnedby = cmd(D),
    ifgapzl = cmd(D),
    iffloordistl = cmd(D),
    ifceilingdistl = cmd(D),
    ifphealthl = cmd(D),
    ifspritepal = cmd(D),
    ifgotweaponce = cmd(D),
    ifangdiffl = cmd(D),
    ifsound = cmd(D),
    ifpinventory = cmd(D,D),

    ifvarl = cmd(R,D),
    ifvarg = cmd(R,D),
    ifvare = cmd(R,D),
    ifvarn = cmd(R,D),
    ifvarand = cmd(R,D),
    ifvaror = cmd(R,D),
    ifvarxor = cmd(R,D),
    ifvareither = cmd(R,D),

    ifvarvarg = cmd(R,R),
    ifvarvarl = cmd(R,R),
    ifvarvare = cmd(R,R),
    ifvarvarn = cmd(R,R),
    ifvarvarand = cmd(R,R),
    ifvarvaror = cmd(R,R),
    ifvarvarxor = cmd(R,R),
    ifvarvareither = cmd(R,R),

    ifactorsound = cmd(R,R),

    ifp = (sp1 * t_define)^1,
    ifsquished = cmd(),
    ifserver = cmd(),
    ifrespawn = cmd(),
    ifoutside = cmd(),
    ifonwater = cmd(),
    ifnotmoving = cmd(),
    ifnosounds = cmd(),
    ifmultiplayer = cmd(),
    ifinwater = cmd(),
    ifinspace = cmd(),
    ifinouterspace = cmd(),
    ifhitweapon = cmd(),
    ifhitspace = cmd(),
    ifdead = cmd(),
    ifclient = cmd(),
    ifcanshoottarget = cmd(),
    ifcanseetarget = cmd(),
--    ifcansee = cmd(),
    ifbulletnear = cmd(),
    ifawayfromwall = cmd(),
    ifactornotstayput = cmd(),
}


----==== Tracing and reporting ====----
local string = require("string")

-- newlineidxs will contain the 1-based file offsets to "\n" characters
local newlineidxs = {}

local function printf(fmt, ...)
    print(string.format(fmt, ...))
end

-- Returns index into the sorted table tab such that
--   tab[index] <= searchelt < tab[index+1].
-- Preconditions:
--  tab[i] < tab[i+1] for 1 <= i < #tab
--  tab[1] <= searchelt < tab[#tab]
-- If #tab is less than 2, returns 0. This plays nicely with newline index
-- tables like { [0]=0, [1]=len+1 }, e.g. if the file doesn't contain any.
local function bsearch(tab, searchelt)
--    printf("bsearch(tab, %d)", searchelt)
    local l, r = 1, #tab
    local i

    if (r < 2) then
        return 0
    end

    while (l ~= r) do
        i = l + math.ceil((r-l)/2)  -- l < i <= r
        assert(l < i and i <= r)
        local elt = tab[i]
--        printf("l=%d tab[%d]=%d r=%d", l, i, elt, r)

        if (searchelt == elt) then
            return i
        end

        if (searchelt < elt) then
            r = i-1
        else  -- (searchelt > elt)
            l = i
        end
    end

--    printf("return tab[%d]=%d", l, tab[l])
    return l
end

local function getlinecol(pos)
    local line = bsearch(newlineidxs, pos)
    assert(line and newlineidxs[line]<=pos and pos<newlineidxs[line+1])
    local col = pos-newlineidxs[line]
    return line+1, col-1
end

-- Last keyword position, for error diagnosis.
local g_lastkwpos = nil
local g_lastkw = nil
local g_badids = {}  -- maps bad id strings to 'true'

-- A generic trace function, prints a position together with the match content
-- A non-existing 'doit' means 'true'.
local function TraceFunc(pat, label, doit)
    pat = Pat(pat)

    if (doit==nil or doit) then
        local function tfunc(subj, pos, a)
            local line, col = getlinecol(pos)
            printf("%d,%d:%s: %s", line, col, label, a)
            return true
        end
        pat = lpeg.Cmt(pat, tfunc)
    elseif (label=="kw") then  -- HACK
        local function tfunc(subj, pos, a)
            g_lastkwpos = pos
            g_lastkw = a
            return true
        end
        -- XXX: is there a better way?
        pat = lpeg.Cmt(pat, tfunc)
    end

    return pat
end

local function BadIdentFunc(pat)
    local function tfunc(subj, pos, a)
        if (not g_badids[a]) then
            local line, col = getlinecol(pos)
            printf("%d,%d: warning: bad identifier: %s", line, col, a)
            g_badids[a] = true
        end
        return true
    end
    return lpeg.Cmt(Pat(pat), tfunc)
end

-- These are tracers for specific patterns which can be disabled
-- if desired.
local function Keyw(kwname) return TraceFunc(kwname, "kw", false) end
local function NotKeyw(text) return TraceFunc(text, "!kw", false) end
local function Ident(idname) return TraceFunc(idname, "id", false) end
local function BadIdent(idname) return BadIdentFunc(idname) end
local function Stmt(cmdpat) return TraceFunc(cmdpat, "st", false) end

--local function Temp(kwname) return TraceFunc(kwname, "temp", true) end
--Ci["myosx"] = Temp(Ci["myosx"])

----==== Translator continued ====----
-- attach the command names at the front!
local function attachnames(kwtab)
    for cmdname,cmdpat in pairs(kwtab) do
        kwtab[cmdname] = Keyw(cmdname) * cmdpat
    end
end

attachnames(Co)
attachnames(Ci)
attachnames(Cif)


-- Takes one or more tables and +'s all its patterns together in the order of
-- appearance.
-- The tables must map command names to their patterns.
local function all_alt_pattern(...)
    local pat = Pat(false)
    local args = {...}
    for argi=1,#args do
        local pattab = args[argi]
        -- NOTE: pairs() iterates in undefined order!
        -- We can't handle prefix-problematic commands this way here.
        for cmdname,cmdpat in pairs(pattab) do
            pat = cmdpat + pat
        end
    end
    return pat
end

-- actor ORGANTIC is greeting!
local function warn_on_lonely_else(subj, pos)
    local line, col = getlinecol(pos)
    printf("%d,%d: warning: found `else' with no `if'", line, col)
    return true
end

-- NOTE: The indented text is not true, e.g. addlog vs. addlogvar:
-- since 'addlog' has no args, it will get matched given an 'addlogvar' in the subject:
--   About prefixes: I think it's not a problem *here* if e.g. "getactor" comes
--   before "getactorvar", because the pattern for the former will fail
--   eventually in the ordered choice if fed with the latter.  However, it DOES
--   matter in the keyword list, see NotKeyw() trace function and comment in
--   con_lang.lua.
-- Do we have more of them?  Yes.
--  operate/operate*
--  ifcansee/ifcanseetarget
local con_outer_command = all_alt_pattern(Co)
-- Empty-arged commands that are prefixes of others must come last:
local con_inner_command = all_alt_pattern(Ci) + "addlog" + "operate"
local con_if_begs = all_alt_pattern(Cif) + "ifcansee"

local lone_else = lpeg.Cmt("else" * sp1, warn_on_lonely_else)

local stmt_list = Var("stmt_list")
-- possibly empty statement list:
local stmt_list_or_eps = (stmt_list * sp1)^-1
local stmt_list_nosp_or_eps = (stmt_list * (sp1 * stmt_list)^0)^-1

-- common to all three: <name/tilenum> [<strength> [<action> [<move> [<ai>... ]]]]
local common_actor_end = sp1 * t_define * sp1 * (t_define * sp1)^0 * stmt_list_or_eps * "enda"

--== block delimiters (no recursion) ==--
local Cb = {
    -- actor (...)
    actor = common_actor_end,
    -- eventloadactor (...)
    eventloadactor = common_actor_end,
    -- useractor <actortype> (...)
    useractor = sp1 * t_define * common_actor_end,

    onevent = sp1 * t_define * sp1 * stmt_list_or_eps * "endevent",

    state = sp1 * t_identifier * sp1 * stmt_list_or_eps * "ends",
}

attachnames(Cb)


local t_good_identifier = Range("AZ", "az", "__") * Range("AZ", "az", "__", "09")^0

-- CON isaltok also has chars in "{}.", but these could potentially
-- interfere with *CON* syntax.  The "]" is so that the number in array[80]
-- isn't considered a broken identifier.
-- "-" is somewhat problematic, but we allow it only as 2nd and up character, so
-- there's no ambiguity with unary minus.  (Commands must be separated by spaces
-- in CON, so a trailing "-" is "OK", too.)
-- This is broken in itself, so we ought to make a compatibility/modern CON switch.
local t_broken_identifier = BadIdent(-((t_number + t_good_identifier) * (sp1 + Set("[]:"))) *
                                     (alphanum + Set("_/\\*")) * (alphanum + Set("_/\\*-"))^0)

--- The final grammar!
local Grammar = Pat{
    -- The starting symbol.
    -- A translation unit is a (possibly empty) sequence of outer CON
    -- commands, separated by at least one whitespace which may be
    -- omitted at the EOF.
    sp0 * ((con_outer_command + all_alt_pattern(Cb)) * sp1)^0,

    -- Deps.  These appear here because we're hitting a limit with LPeg else:
    -- http://lua-users.org/lists/lua-l/2008-11/msg00462.html
    -- NOTE: NW demo (NWSNOW.CON) contains a Ctrl-Z char (decimal 26)
    whitespace = Set(" \t\r\26") + newline + Set("(),;") + comment + linecomment,

    t_identifier_all = t_broken_identifier + t_good_identifier,
    -- NOTE: -con_keyword alone would be wrong, e.g. "state breakobject":
    -- NOTE 2: The + "[" is so that stuff like
    --   getactor[THISACTOR].x x
    --   getactor[THISACTOR].y y
    -- is parsed correctly.  (Compared with this:)
    --   getactor[THISACTOR].x x
    --   getactor [THISACTOR].y y
    -- This is in need of cleanup!
    t_identifier = -NotKeyw(con_keyword * (sp1 + "[")) * Ident(t_identifier_all),
    t_define = (Pat("-") * sp0)^-1 * (t_identifier + t_number),

    t_arrayexp = t_identifier * arraypat * memberpat^-1,

    -- SWITCH
    switch_stmt = Keyw("switch") * sp1 * t_rvar *
        (Var("case_block") + Var("default_block"))^0 * sp1 * "endswitch",

    -- NOTE: some old DNWMD has "case: PIGCOP".  I don't think I'll allow that.
    case_block = (sp1 * Keyw("case") * sp1 * t_define * (sp0*":")^-1)^1 * sp1 *
        stmt_list_nosp_or_eps, -- * "break",

    default_block = sp1 * Keyw("default") * (sp0*":"*sp0 + sp1) * stmt_list_nosp_or_eps,  -- * "break",

    -- The "lone" if statement is tested first, so that a potential dangling "else" is
    -- attached to the outermost possible "if", as done by CON
    if_stmt = con_if_begs * sp1 * Var("single_stmt") * -(sp1 * Pat("else"))
        + con_if_begs * sp1 * Var("single_stmt") * sp1 * "else" * sp1 * Var("single_stmt"),

    while_stmt = Keyw("whilevarvarn") * sp1 * t_rvar * sp1 * t_rvar * sp1 * Var("single_stmt")
        + Keyw("whilevarn") * sp1 * t_rvar * sp1 * t_define * sp1 * Var("single_stmt"),

    -- TODO: some sp1 --> sp0?
    single_stmt = Stmt(
        lone_else^-1 *
            ( Keyw("{") * sp1 * "}"  -- space separation of commands in CON is for a reason!
              + Keyw("{") * sp1 * stmt_list * sp1 * "}"
              + (con_inner_command + Var("switch_stmt") + Var("if_stmt") + Var("while_stmt"))
--              + lpeg.Cmt(t_newline_term_str, function (subj, curpos) print("Error at "..curpos) end)
            )),

    -- a non-empty statement/command list
    stmt_list = Var("single_stmt") * (sp1 * Var("single_stmt"))^0,
}


local math = require("math")

local function setup_newlineidxs(contents)
    newlineidxs = {}
    for i in string.gmatch(contents, "()\n") do
        newlineidxs[#newlineidxs+1] = i
    end
    if (#newlineidxs == 0) then
        -- try CR only (old Mac)
        for i in string.gmatch(contents, "()\r") do
            newlineidxs[#newlineidxs+1] = i
        end
--        if (#newlineidxs > 0) then print('CR-only lineends detected.') end
    end
    -- dummy newlines at beginning and end
    newlineidxs[#newlineidxs+1] = #contents+1
    newlineidxs[0] = 0
end


---=== EXPORTED FUNCTIONS ===---

local function parse(contents)
    setup_newlineidxs(contents)

    g_badids = {}
    g_lastkw = nil
    g_lastkwpos = nil

    local idx = lpeg.match(Grammar, contents)

    if (not idx) then
        print("Match failed.")
    elseif (idx == #contents+1) then
        print("Matched whole contents.")
    else
        local i, col = getlinecol(idx)
        local bi, ei = newlineidxs[i-1]+1, newlineidxs[i]-1

        printf("Match succeeded up to %d (line %d, col %d; len=%d)",
               idx, i, col, #contents)

--        printf("Line goes from %d to %d", bi, ei)
        print(string.sub(contents, bi, ei))

        if (g_lastkwpos) then
            i, col = getlinecol(g_lastkwpos)
            printf("Last keyword was at line %d, col %d: %s", i, col, g_lastkw)
        end
    end
end


if (not _EDUKE32_LUNATIC) then
    --- stand-alone
    local io = require("io")

    for argi=1,#arg do
        local filename = arg[argi]
        printf("\n---- Parsing file \"%s\"", filename);

        local contents = io.open(filename):read("*all")
        parse(contents)
    end
else
    --- embedded
    return { parse=parse }
end