--- Perl Compatible Regular Expressions
-- \n\n
-- One of Lua's quirks is its string patterns. While they have great performance
-- and are tightly integrated into the Lua interpreter, they are very different
-- in syntax and not as powerful as standard regular expressions.  So we have
-- integrated Perl compatible regular expressions into Lua using PCRE and a
-- modified version of the Lua PCRE library written by Reuben Thomas and Shmuel
-- Zeigerman. These are the same sort of regular expressions used by Nmap
-- version detection.  The main modification to their library is that the NSE
-- version only supports PCRE expressions instead of both PCRE and POSIX
-- patterns. In order to maintain a high script execution speed, the library
-- interfacing with PCRE is kept very thin. It is not integrated as seamlessly
-- as the Lua string pattern API. This allows script authors to decide when to
-- use PCRE expressions versus Lua patterns.  The use of PCRE involves a
-- separate pattern compilation step, which saves execution time when patterns
-- are reused.  Compiled patterns can be cached in the NSE registry and reused
-- by other scripts.
-- \n\n
-- The documentation for this module is derived from that supplied by the PCRE
-- Lua lib.
-- \n\n
-- Warning: PCRE has a history of security vulnerabilities allowing attackers
-- who are able to compile arbitrary regular expressions to execute arbitrary
-- code.  More such vulnerabilities may be discovered in the future.  These have
-- never affected Nmap because it doesn't give attackers any control over the
-- regular expressions it uses.  Similarly, NSE scripts should never build
-- regular expressions with untrusted network input.  Matching hardcoded regular
-- expressions against the untrusted input is fine.
-- @author Reuben Thomas
-- @author Shmuel Zeigerman

module "pcre"

--- Returns a compiled regular expression.
-- \n\n
-- The resulting compiled regular expression is ready to be matched against
-- strings. Compiled regular expressions are subject to Lua's garbage
-- collection.
-- \n\n
-- The compilation flags are set bitwise. If you want to set the 3rd
-- (corresponding to the number 4) and the 1st (corresponding to 1) bit for
-- example you would pass the number 5 as a second argument. The compilation
-- flags accepted are those of the PCRE C library. These include flags for case
-- insensitive matching (1), matching line beginnings (^) and endings ($) even
-- in multiline strings (i.e. strings containing newlines) (2) and a flag for
-- matching across line boundaries (4). No compilation flags yield a default
-- value of 0.
-- @param pattern a string describing the pattern, such as "^foo$".
-- @param flags a number describing which compilation flags are set.
-- @param locale a string describing the locale which should be used to compile
-- the regular expression (optional). The value is a string which is passed to
-- the C standard library function setlocale.  For more information on this
-- argument refer to the documentation of setlocale.
-- @usage my_regex = pcre.new("pcre-pattern",0,"C")
function pcre.new(pattern, flags, locale)

--- Returns a table of the available PCRE option flags (numbers) keyed by their
-- names (strings).
-- \n\n
-- Possible names of the available strings can be retrieved from the
-- documentation of the PCRE library used to link against Nmap. The key is the
-- option name in the manual minus the PCRE prefix. PCRE_CASELESS becomes
-- CASELESS for example.
function pcre.flags()

--- Returns the version of the PCRE library in use as a string.
-- \n\n
-- For example "6.4 05-Sep-2005".
function pcre.version()

--- Matches a string against a compiled regular expression.
-- \n\n
-- Returns the start point and the end point of the first match of the compiled
-- regular expression pcre_obj in the string.
-- @param string the string to match against.
-- @param start where to start the match in the string (optional).
-- @param flags execution flags (optional).
-- @return nil if no match, otherwise the start point of the first match.
-- @return the end point of the first match.
-- @return a table which contains false in the positions where the pattern did
-- not match. If named sub-patterns were used, the table also contains substring
-- matches keyed by their sub-pattern name.
-- @usage
-- s = pcre_obj:match("string to be searched", 0,0);\n
-- if(s) code_to_be_done_on_match end
function pcre_obj:match(string, start, flags)

--- Matches a string against a compiled regular expression, returning positions
-- of substring matches.
-- \n\n
-- This function is like match() except that a table returned as a third result
-- contains offsets of substring matches rather than substring matches
-- themselves. That table will not contain string keys, even if named
-- sub-patterns are used.  For example, if the whole match is at offsets 10, 20
-- and substring matches are at offsets 12, 14 and 16, 19 then the function
-- returns the following: 10, 20, {12,14,16,19}
-- @param string the string to match against.
-- @param start where to start the match in the string (optional).
-- @param flags execution flags (optional).
-- @return a table which contains a list of substring match start and end
-- positions.
function pcre_obj:exec(string, start, flags)

--- Matches a string against a regular expression multiple times.
-- \n\n
-- Tries to match the regular expression pcre_obj against string up to n times
-- (or as many as possible if n is either not given or is not a positive
-- number), subject to the execution flags ef. Each time there is a match, func
-- is called as func(m, t), where m is the matched string and t is a table of
-- substring matches. This table contains false in the positions where the
-- corresponding sub-pattern did not match. If named sub-patterns are used then
-- the table also contains substring matches keyed by their correspondent
-- sub-pattern names (strings).  If func returns a true value, then gmatch
-- immediately returns; gmatch returns the number of matches made.
-- @param string the string to match against.
-- @param n the maximum number of matches to do (optional).
-- @param ef execution flags (optional).
-- @return the number of matches made.
function pcre_obj:gmatch(string, func, n, ef)