ref: b7d6be96fcc372886415e8fd55e3febff8340b95
dir: /re.lua/
-- $Id: re.lua $
-- 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 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)
error(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 function getdef (id, defs)
local c = defs and defs[id]
if not c then error("undefined name: " .. id) end
return c
end
-- match a name and return a group of its corresponding definition
-- and 'f' (to be folded in 'Suffix')
local function defwithfunc (f)
return m.Cg(Def / getdef * m.Cc(f))
end
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 error ("name '" .. c .. "' undefined") end
return cat
end
local Range = m.Cs(any * (m.P"-"/"") * (any - "]")) / mm.R
local item = (defined + Range + m.C(any)) / m.P
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
error("'"..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
error("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)
+ defwithfunc(mt.__div)
)
+ "=>" * S * defwithfunc(m.Cmt)
+ "~>" * S * defwithfunc(m.Cf)
) * 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 error("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 _G.re = re end
return re