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--[[
Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
]]--
--[[ Lua LPEG grammar based on https://github.com/xolox/lua-lxsh/ ]]
local lpeg = require "lpeg"
local P = lpeg.P
local R = lpeg.R
local S = lpeg.S
local D = R '09' -- Digits
local I = R('AZ', 'az', '\127\255') + '_' -- Identifiers
local B = -(I + D) -- Word boundary
local EOS = -lpeg.P(1) -- end of string
-- Pattern for long strings and long comments.
local longstring = #(P '[[' + (P '[' * P '=' ^ 0 * '[')) * P(function(input, index)
local level = input:match('^%[(=*)%[', index)
if level then
local _, last = input:find(']' .. level .. ']', index, true)
if last then
return last + 1
end
end
end)
-- String literals.
local singlequoted = P "'" * ((1 - S "'\r\n\f\\") + (P '\\' * 1)) ^ 0 * "'"
local doublequoted = P '"' * ((1 - S '"\r\n\f\\') + (P '\\' * 1)) ^ 0 * '"'
-- Comments.
local eol = P '\r\n' + '\n'
local line = (1 - S '\r\n\f') ^ 0 * eol ^ -1
local singleline = P '--' * line
local multiline = P '--' * longstring
-- Numbers.
local sign = S '+-' ^ -1
local decimal = D ^ 1
local hexadecimal = P '0' * S 'xX' * R('09', 'AF', 'af') ^ 1
local float = D ^ 1 * P '.' * D ^ 0 + P '.' * D ^ 1
local maybeexp = (float + decimal) * (S 'eE' * sign * D ^ 1) ^ -1
local function compile_keywords(keywords)
local list = {}
for word in keywords:gmatch('%S+') do
list[#list + 1] = word
end
-- Sort by length
table.sort(list, function(a, b)
return #a > #b
end)
local pattern
for _, word in ipairs(list) do
local p = lpeg.P(word)
pattern = pattern and (pattern + p) or p
end
local AB = B + EOS -- ending boundary
return pattern * AB
end
-- Identifiers
local ident = I * (I + D) ^ 0
local expr = ('.' * ident) ^ 0
local patterns = {
{ 'whitespace', S '\r\n\f\t\v ' ^ 1 },
{ 'constant', (P 'true' + 'false' + 'nil') * B },
{ 'string', singlequoted + doublequoted + longstring },
{ 'comment', multiline + singleline },
{ 'number', hexadecimal + maybeexp },
{ 'operator', P 'not' + '...' + 'and' + '..' + '~=' + '==' + '>=' + '<='
+ 'or' + S ']{=>^[<;)*(%}+-:,/.#' },
{ 'keyword', compile_keywords([[
break do else elseif end for function if in local repeat return then until while
]]) },
{ 'identifier', lpeg.Cmt(ident,
function(input, index)
return expr:match(input, index)
end)
},
{ 'error', 1 },
}
local compiled
local function compile_patterns()
if not compiled then
local function process(elt)
local n, grammar = elt[1], elt[2]
return lpeg.Cc(n) * lpeg.P(grammar) * lpeg.Cp()
end
local any = process(patterns[1])
for i = 2, #patterns do
any = any + process(patterns[i])
end
compiled = any
end
return compiled
end
local function sync(token, lnum, cnum)
local lastidx
lnum, cnum = lnum or 1, cnum or 1
if token:find '\n' then
for i in token:gmatch '()\n' do
lnum = lnum + 1
lastidx = i
end
cnum = #token - lastidx + 1
else
cnum = cnum + #token
end
return lnum, cnum
end
local exports = {}
exports.gmatch = function(input)
local parser = compile_patterns()
local index, lnum, cnum = 1, 1, 1
return function()
local kind, after = parser:match(input, index)
if kind and after then
local text = input:sub(index, after - 1)
local oldlnum, oldcnum = lnum, cnum
index = after
lnum, cnum = sync(text, lnum, cnum)
return kind, text, oldlnum, oldcnum
end
end
end
exports.lex_to_table = function(input)
local out = {}
for kind, text, lnum, cnum in exports.gmatch(input) do
out[#out + 1] = { kind, text, lnum, cnum }
end
return out
end
return exports
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