pcre.lua

local ffi = require("ffi")
local pcre = ffi.load("pcre")

ffi.cdef([[
typedef struct real_pcre pcre;
typedef struct pcre_extra pcre_extra;
typedef const char * PCRE_SPTR;

static const int PCRE_STUDY_JIT_COMPILE = 0x0001;

pcre *pcre_compile(const char *, int, const char **, int *,
                   const unsigned char *);
pcre_extra *pcre_study(const pcre *, int, const char **);
int pcre_exec(const pcre *, const pcre_extra *, PCRE_SPTR,
              int, int, int, int *, int);
void pcre_free_study(pcre_extra *);
void (*pcre_free)(void *);
]])

local function pcre_compile(pattern, options)
	local err = ffi.new("const char *[1]")
	local erroffset = ffi.new("int[1]")

	local res = pcre.pcre_compile(pattern, options, err, erroffset, nil)
	if err[0] ~= nil then
		error("error in regular expression at character "..erroffset..": "..ffi.string(err[0]))
	end
	ffi.gc(res, pcre.pcre_free)

	return res
end

local function pcre_study(regex)
	local err = ffi.new("const char *[1]")

	local res = pcre.pcre_study(regex, pcre.PCRE_STUDY_JIT_COMPILE, err)
	if err[0] ~= nil then
		error("error studying regular expression: "..ffi.string(err[0]))
	end
	ffi.gc(res, pcre.pcre_free_study)

	return res
end

local function pcre_exec(regex, regex_extra, str)
	local rc = pcre.pcre_exec(regex, regex_extra, str, #str, 0, 0, nil, 0)
	return rc
end

local Regex = {}
Regex.__index = Regex

function compile(pattern)
	local r = setmetatable({}, Regex)
	r:_init(pattern)
	return r
end

function Regex:_init(pattern)
	self.pattern = pattern
	self._pcre = pcre_compile(pattern, 0)
	self._pcre_extra = pcre_study(self._pcre)
end

function Regex:match(str)
	return pcre_exec(self._pcre, self._pcre_extra, str)
end

return {
	compile = compile
}