88 lines
1.9 KiB
Lua
88 lines
1.9 KiB
Lua
-- See Copyright Notice in the file lrexlib.h
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-- Convert Lua regex pattern to its PCRE equivalent.
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local t_esc = {
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a = "[:alpha:]",
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A = "[:^alpha:]",
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c = "[:cntrl:]",
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C = "[:^cntrl:]",
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d = "[:digit:]",
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D = "[:^digit:]",
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l = "[:lower:]",
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L = "[:^lower:]",
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p = "[:punct:]",
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P = "[:^punct:]",
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s = "[:space:]",
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S = "[:^space:]",
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u = "[:upper:]",
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U = "[:^upper:]",
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w = "[:alnum:]",
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W = "[:^alnum:]",
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x = "[:xdigit:]",
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X = "[:^xdigit:]",
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z = "\\x00",
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Z = "\\x01-\\xFF",
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}
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local function rep_normal (ch)
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assert (ch ~= "b", "\"%b\" subpattern is not supported")
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assert (ch ~= "0", "invalid capture index")
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local v = t_esc[ch]
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return v and ("[" .. v .. "]") or ("\\" .. ch)
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end
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local function rep_charclass (ch)
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return t_esc[ch] or ("\\" .. ch)
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end
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function pat2pcre (s)
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local ind = 0
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local function getc ()
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ind = ind + 1
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return string.sub (s, ind, ind)
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end
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local function getnum ()
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local num = string.match (s, "^\\(%d%d?%d?)", ind)
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if num then
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ind = ind + #num
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return string.format ("\\x%02X", num)
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end
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end
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local out, state = "", "normal"
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while ind < #s do
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local ch = getc ()
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if state == "normal" then
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if ch == "%" then
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out = out .. rep_normal (getc ())
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elseif ch == "-" then
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out = out .. "*?"
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elseif ch == "." then
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out = out .. "\\C"
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elseif ch == "[" then
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out = out .. ch
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state = "charclass"
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else
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local num = getnum ()
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out = num and (out .. num) or (out .. ch)
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end
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elseif state == "charclass" then
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if ch == "%" then
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out = out .. rep_charclass (getc ())
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elseif ch == "]" then
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out = out .. ch
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state = "normal"
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else
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local num = getnum ()
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out = num and (out .. num) or (out .. ch)
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end
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end
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end
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return out
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end
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return pat2pcre
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