-- -- $Id: re.lua,v 1.44 2013/03/26 20:11:40 roberto Exp $

-- -- imported functions and modules
-- local tonumber, type, print, error = tonumber, type, print, error
-- local setmetatable = setmetatable
-- local m = require"lpeg"

-- -- 'm' will be used to parse expressions, and 'mm' will be used to
-- -- create expressions; that is, 're' runs on 'm', creating patterns
-- -- on 'mm'
-- local mm = m

-- -- pattern's metatable
-- local mt = getmetatable(mm.P(0))



-- -- No more global accesses after this point
-- local version = _VERSION
-- if version == "Lua 5.2" then _ENV = nil end


-- local any = m.P(1)


-- -- Pre-defined names
-- local Predef = { nl = m.P"\n" }


-- local mem
-- local fmem
-- local gmem


-- local function updatelocale ()
--   mm.locale(Predef)
--   Predef.a = Predef.alpha
--   Predef.c = Predef.cntrl
--   Predef.d = Predef.digit
--   Predef.g = Predef.graph
--   Predef.l = Predef.lower
--   Predef.p = Predef.punct
--   Predef.s = Predef.space
--   Predef.u = Predef.upper
--   Predef.w = Predef.alnum
--   Predef.x = Predef.xdigit
--   Predef.A = any - Predef.a
--   Predef.C = any - Predef.c
--   Predef.D = any - Predef.d
--   Predef.G = any - Predef.g
--   Predef.L = any - Predef.l
--   Predef.P = any - Predef.p
--   Predef.S = any - Predef.s
--   Predef.U = any - Predef.u
--   Predef.W = any - Predef.w
--   Predef.X = any - Predef.x
--   mem = {}    -- restart memoization
--   fmem = {}
--   gmem = {}
--   local mt = {__mode = "v"}
--   setmetatable(mem, mt)
--   setmetatable(fmem, mt)
--   setmetatable(gmem, mt)
-- end


-- updatelocale()



-- local I = m.P(function (s,i) print(i, s:sub(1, i-1)); return i end)


-- local function getdef (id, defs)
--   local c = defs and defs[id]
--   if not c then LogError("undefined name: " .. id) end
--   return c
-- end


-- local function patt_error (s, i)
--   local msg = (#s < i + 20) and s:sub(i)
--                              or s:sub(i,i+20) .. "..."
--   msg = ("pattern error near '%s'"):format(msg)
--   LogError(msg, 2)
-- end

-- local function mult (p, n)
--   local np = mm.P(true)
--   while n >= 1 do
--     if n%2 >= 1 then np = np * p end
--     p = p * p
--     n = n/2
--   end
--   return np
-- end

-- local function equalcap (s, i, c)
--   if type(c) ~= "string" then return nil end
--   local e = #c + i
--   if s:sub(i, e - 1) == c then return e else return nil end
-- end


-- local S = (Predef.space + "--" * (any - Predef.nl)^0)^0

-- local name = m.R("AZ", "az", "__") * m.R("AZ", "az", "__", "09")^0

-- local arrow = S * "<-"

-- local seq_follow = m.P"/" + ")" + "}" + ":}" + "~}" + "|}" + (name * arrow) + -1

-- name = m.C(name)


-- -- a defined name only have meaning in a given environment
-- local Def = name * m.Carg(1)

-- local num = m.C(m.R"09"^1) * S / tonumber

-- local String = "'" * m.C((any - "'")^0) * "'" +
--                '"' * m.C((any - '"')^0) * '"'


-- local defined = "%" * Def / function (c,Defs)
--   local cat =  Defs and Defs[c] or Predef[c]
--   if not cat then LogError ("name '" .. c .. "' undefined") end
--   return cat
-- end

-- local Range = m.Cs(any * (m.P"-"/"") * (any - "]")) / mm.R

-- local item = defined + Range + m.C(any)

-- local Class =
--     "["
--   * (m.C(m.P"^"^-1))    -- optional complement symbol
--   * m.Cf(item * (item - "]")^0, mt.__add) /
--                           function (c, p) return c == "^" and any - p or p end
--   * "]"

-- local function adddef (t, k, exp)
--   if t[k] then
--     LogError("'"..k.."' already defined as a rule")
--   else
--     t[k] = exp
--   end
--   return t
-- end

-- local function firstdef (n, r) return adddef({n}, n, r) end


-- local function NT (n, b)
--   if not b then
--     LogError("rule '"..n.."' used outside a grammar")
--   else return mm.V(n)
--   end
-- end


-- local exp = m.P{ "Exp",
--   Exp = S * ( m.V"Grammar"
--             + m.Cf(m.V"Seq" * ("/" * S * m.V"Seq")^0, mt.__add) );
--   Seq = m.Cf(m.Cc(m.P"") * m.V"Prefix"^0 , mt.__mul)
--         * (#seq_follow + patt_error);
--   Prefix = "&" * S * m.V"Prefix" / mt.__len
--          + "!" * S * m.V"Prefix" / mt.__unm
--          + m.V"Suffix";
--   Suffix = m.Cf(m.V"Primary" * S *
--           ( ( m.P"+" * m.Cc(1, mt.__pow)
--             + m.P"*" * m.Cc(0, mt.__pow)
--             + m.P"?" * m.Cc(-1, mt.__pow)
--             + "^" * ( m.Cg(num * m.Cc(mult))
--                     + m.Cg(m.C(m.S"+-" * m.R"09"^1) * m.Cc(mt.__pow))
--                     )
--             + "->" * S * ( m.Cg((String + num) * m.Cc(mt.__div))
--                          + m.P"{}" * m.Cc(nil, m.Ct)
--                          + m.Cg(Def / getdef * m.Cc(mt.__div))
--                          )
--             + "=>" * S * m.Cg(Def / getdef * m.Cc(m.Cmt))
--             ) * S
--           )^0, function (a,b,f) return f(a,b) end );
--   Primary = "(" * m.V"Exp" * ")"
--             + String / mm.P
--             + Class
--             + defined
--             + "{:" * (name * ":" + m.Cc(nil)) * m.V"Exp" * ":}" /
--                      function (n, p) return mm.Cg(p, n) end
--             + "=" * name / function (n) return mm.Cmt(mm.Cb(n), equalcap) end
--             + m.P"{}" / mm.Cp
--             + "{~" * m.V"Exp" * "~}" / mm.Cs
--             + "{|" * m.V"Exp" * "|}" / mm.Ct
--             + "{" * m.V"Exp" * "}" / mm.C
--             + m.P"." * m.Cc(any)
--             + (name * -arrow + "<" * name * ">") * m.Cb("G") / NT;
--   Definition = name * arrow * m.V"Exp";
--   Grammar = m.Cg(m.Cc(true), "G") *
--             m.Cf(m.V"Definition" / firstdef * m.Cg(m.V"Definition")^0,
--               adddef) / mm.P
-- }

-- local pattern = S * m.Cg(m.Cc(false), "G") * exp / mm.P * (-any + patt_error)


-- local function compile (p, defs)
--   if mm.type(p) == "pattern" then return p end   -- already compiled
--   local cp = pattern:match(p, 1, defs)
--   if not cp then LogError("incorrect pattern", 3) end
--   return cp
-- end

-- local function match (s, p, i)
--   local cp = mem[p]
--   if not cp then
--     cp = compile(p)
--     mem[p] = cp
--   end
--   return cp:match(s, i or 1)
-- end

-- local function find (s, p, i)
--   local cp = fmem[p]
--   if not cp then
--     cp = compile(p) / 0
--     cp = mm.P{ mm.Cp() * cp * mm.Cp() + 1 * mm.V(1) }
--     fmem[p] = cp
--   end
--   local i, e = cp:match(s, i or 1)
--   if i then return i, e - 1
--   else return i
--   end
-- end

-- local function gsub (s, p, rep)
--   local g = gmem[p] or {}   -- ensure gmem[p] is not collected while here
--   gmem[p] = g
--   local cp = g[rep]
--   if not cp then
--     cp = compile(p)
--     cp = mm.Cs((cp / rep + 1)^0)
--     g[rep] = cp
--   end
--   return cp:match(s)
-- end


-- -- exported names
-- local re = {
--   compile = compile,
--   match = match,
--   find = find,
--   gsub = gsub,
--   updatelocale = updatelocale,
-- }

-- if version == "Lua 5.1" then
--   --I need this to work with strict.lua, sorry for breaking compatibility.
--   --_G.re = re
-- end

-- return re