[Minor] Add lpeg re module

2 files changed, 268 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cf4223840..dc4a37ca6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1379,6 +1379,7 @@ INSTALL(FILES "contrib/lua-fun/fun.lua" DESTINATION ${LUALIBDIR})
 INSTALL(FILES "contrib/lua-argparse/argparse.lua" DESTINATION ${LUALIBDIR})
 INSTALL(FILES "contrib/lua-tableshape/tableshape.lua" DESTINATION ${LUALIBDIR})
 INSTALL(FILES "contrib/lua-lupa/lupa.lua" DESTINATION ${LUALIBDIR})
+INSTALL(FILES "contrib/lua-lpeg/lpegre.lua" DESTINATION ${LUALIBDIR})
 
 IF(ENABLE_TORCH MATCHES "ON")
 	INSTALL(FILES "contrib/lua-moses/moses.lua" DESTINATION ${LUALIBDIR})
diff --git a/contrib/lua-lpeg/lpegre.lua b/contrib/lua-lpeg/lpegre.lua
new file mode 100644
index 000000000..3bb8af7d4
--- /dev/null
+++ b/contrib/lua-lpeg/lpegre.lua
@@ -0,0 +1,267 @@
+-- $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