raze/polymer/eduke32/source/lunatic/lunacon.lua

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

local lpeg = require("lpeg")

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


---- All keywords pattern -- needed for CON syntax
local con_keyword = dofile("con_lang.lua")


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


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

---- basic ones
local newline = Pat("\n")  -- need to do stuff on newline later...
local anychar = Pat(1)
-- comments
local comment = "/*" * match_until(anychar, "*/") * "*/"
local linecomment = "//" * match_until(anychar, newline)
local whitespace = Var("whitespace")
local sp0 = whitespace^0
local sp1 = whitespace^1 -- + (-1)  -- matches EOF, too
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 = Range("09")^1 + (Pat("0x") + "0X")*Range("09", "af")^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)
local newline_term_string = (whitespace-newline)^1 * t_newline_term_str  -- XXX: empty string?


-- (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 = {...}

    local spat = ""
    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 ==--
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 = 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 * (sp1 * t_define)^-4,
    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)

-- t_define is t_rvar without t_arrayexp, actually, so that no nesting is allowed:
local arraypat = sp0 * "[" * sp0 * t_define * sp0 * "]"
-- The member name must match keywords, too (_all), because e.g. cstat is a member
-- of sprite[]
local memberpat = sp0 * "." * sp0 * 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
-- XXX: This is still wrong.
    arraypat * memberpat * sp1 * (t_identifier * 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_identifier * 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,
    getsprite = getstructcmd,
    getthisprojectile = getstructcmd,
    gettspr = getstructcmd,
    getuserdef = getstructcmd,
    getwall = getstructcmd,

    getactorvar = getperxvarcmd,
    getplayervar = getperxvarcmd,

    setactor = setstructcmd,
    setinput = setstructcmd,
    setplayer = setstructcmd,
    setprojectile = setstructcmd,
    setsector = setstructcmd,
    setsprite = setstructcmd,
    setthisprojectile = setstructcmd,
    settspr = setstructcmd,
    setuserdef = setstructcmd,
    setwall = setstructcmd,

    setactorvar = setperxvarcmd,
    setplayervar = setperxvarcmd,

    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),
    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),
    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(),
    mikesnd = cmd(),
    nullop = cmd(),
    operate = cmd(),
    pkick = cmd(),
    pstomp = cmd(),
    resetactioncount = cmd(),
    resetcount = cmd(),
    resetplayer = cmd(),
    respawnhitag = cmd(),
    tip = cmd(),
    tossweapon = cmd(),
    wackplayer = cmd(),

    -- sprite searching
    findplayer = cmd(D,D),
    findotherplayer = cmd(D,D),
    findnearspritezvar = cmd(D,R,R,W),
    findnearspritez = cmd(D,D,D,W),
    findnearspritevar = cmd(D,R,W),
    findnearsprite3dvar = cmd(D,R,W),
    findnearsprite3d = cmd(D,D,W),
    findnearsprite = cmd(D,D,W),
    findnearactorzvar = cmd(D,R,R,W),
    findnearactorz = cmd(D,D,D,W),
    findnearactorvar = cmd(D,R,W),
    findnearactor3dvar = cmd(D,R,W),
    findnearactor3d = cmd(D,D,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,
    setarray = sp1 * t_identifier * arraypat * sp1 * t_rvar,

    activatebysector = cmd(R,R),
    addlog = cmd(),
    addlogvar = cmd(R),
    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),
    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(W,R,R,R,R,R,R,R,R,R,R,R),  -- 1W 11R
    minitext = cmd(R,R,R,R,R),

    ldist = cmd(W),
    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),
    operatesectors = cmd(R),
    palfrom = (sp1 * t_define)^-4,

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

    ifp = (sp1 * t_define)^1,

    ifclient = cmd(),
    ifserver = cmd(),
    ifonwater = cmd(),
    ifinwater = cmd(),
    ifactornotstayput = cmd(),
    ifactorsound = cmd(),
    ifcansee = cmd(),
    ifhitweapon = cmd(),
    ifsquished = cmd(),
    ifdead = cmd(),
    ifcanshoottarget = cmd(),
    ifhitspace = cmd(),
    ifoutside = cmd(),
    ifmultiplayer = cmd(),
    ifinspace = cmd(),
    ifbulletnear = cmd(),
    ifrespawn = cmd(),
    ifinouterspace = cmd(),
    ifnotmoving = cmd(),
    ifawayfromwall = cmd(),
    ifcanseetarget = cmd(),
    ifnosounds = cmd(),

    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),

    ifactorsound = cmd(R,R),
    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),
}


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

    if (doit==nil or doit) then
        pat = lpeg.Cmt(pat, function (subj, pos, a) print(pos..":"..a); return true; end)
    end
    return pat
end

-- These are tracers for specific patterns which can be disabled
-- if desired.
local function Keyw(kwname) return TraceFunc(kwname, false) end
local function Stmt(cmdpat) return TraceFunc(cmdpat, false) end


-- attach the command names at the front!
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.
function all_alt_pattern(...)
    local pat = Pat(false)
    local args = {...}
    for argi=1,#args do
        local pattab = args[argi]
        for cmdname,cmdpat in pairs(pattab) do
            pat = pat + cmdpat
        end
    end
    return pat
end

-- actor ORGANTIC is greeting!
local function warn_on_lonely_else(subj, pos)
    print(pos..": warning: found `else' with no `if'")
    return true
end

-- About prefixes: I think it's not a problem 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.
local con_outer_command = all_alt_pattern(Co)
local con_inner_command = all_alt_pattern(Ci)
local con_if_begs = all_alt_pattern(Cif)

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

-- 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)


--- 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 + (-1)))^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
    whitespace = Set(" \t\r") + newline + Set("(),;") + comment + linecomment,

    t_identifier_all = Range("AZ", "az", "__") * Range("AZ", "az", "__", "09")^0,
    -- 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 = -(con_keyword * (sp1 + "[")) * t_identifier_all,
    t_define = Pat("-")^-1 * sp0 * (t_identifier + t_number),

    t_arrayexp = t_identifier * arraypat * memberpat^-1,

    switch_stmt = Keyw("switch") * (sp1 * (Var("case") + Var("default")))^0 * sp1 * "endswitch",
    case = Keyw("case") * sp1 * t_define * sp0 * Pat(":")^-1 * sp1 * stmt_list_or_eps * "break",
    default = Keyw("default") * sp0 * Pat(":")^-1 * sp1 * stmt_list_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("{") * sp0 * "}"
              + 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 string = require("string")

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 has less than 2 elements, returns nil.
local function bsearch(tab, searchelt)
--    printf("bsearch(tab, %d)", searchelt)
    local l, r = 1, #tab
    local i

    if (r <= 1) then
        return
    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

---=== stand-alone: ===---
if (not EDUKE32_LUNATIC) then
    local io = require("io")

    local filename = arg[1]
    assert(filename)

    local contents = io.open(filename):read("*all")
    local idx = lpeg.match(Grammar, contents)

    -- newlineidxs will contain the 1-based file offsets to "\n" characters
    local newlineidxs = {}
    for i in string.gmatch(contents, "()\n") do
        newlineidxs[#newlineidxs+1] = i
    end
    newlineidxs[#newlineidxs+1] = #contents+1  -- dummy newline

    if (not idx) then
        print("Match failed.")
        return
    end

    if (idx == #contents+1) then
        print("Matched whole contents.")
        return
    end

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

    local i = bsearch(newlineidxs, idx)
    local bi, ei = newlineidxs[i]+1, newlineidxs[i+1]-1
    printf("Line goes from %d to %d", bi, ei)
    print(string.sub(contents, bi, ei))
end