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-- lib/lace/lex.lua
--
-- Lua Access Control Engine -- Ruleset lexer
--
-- Copyright 2012 Daniel Silverstone <dsilvers@digital-scurf.org>
--
-- For Licence terms, see COPYING
--
local sio = require "luxio.simple"
local function lex_one_line(line)
local r = {}
local acc = ""
local c
local escaping = false
local quoting = false
local spos, cpos = 1, 0
while #line > 0 do
c, line = line:match("^(.)(.*)$")
cpos = cpos + 1
if escaping then
if quoting then
if c == "n" then
acc = acc .. "\n"
elseif c == "t" then
acc = acc .. "\t"
else
acc = acc .. c
end
else
acc = acc .. c
end
escaping = false
else
if c == "'" and quoting == false then
-- Start single quotes
quoting = c
elseif c == '"' and quoting == false then
-- Start double quotes
quoting = c
elseif c == "'" and quoting == c then
-- End single quotes
quoting = false
elseif c == '"' and quoting == c then
-- End double quotes
quoting = false
elseif c == "\\" then
-- A backslash, entering escaping mode
escaping = true
elseif quoting then
-- Within quotes, so accumulate
acc = acc .. c
elseif c == " " or c == "\t" then
-- A space (or tab) and not quoting, so clear the accumulator
if acc ~= "" then
r[#r+1] = { spos = spos, epos = cpos - 1, str = acc }
spos = cpos + 1
elseif cpos == spos then
-- Increment the start position since we've not found a word yet
spos = spos + 1
end
acc = ""
else
acc = acc .. c
end
end
end
if acc ~= "" then
r[#r+1] = { spos = spos, epos = cpos, str = acc }
end
local warnings = {}
if quoting then
warnings[#warnings+1] = "Un-terminated quoted string"
end
if escaping then
warnings[#warnings+1] = "Un-used escape at end"
end
return r, warnings
end
local function lex_a_ruleset(ruleset, sourcename)
local lines = {}
local ret = { source = sourcename, lines = lines }
local n = 1
local warn
if ruleset:match("[^\n]$") then
ruleset = ruleset .. "\n"
end
for oneline in ruleset:gmatch("([^\n]*)\n") do
local linetab = { original = oneline }
if oneline:match("^[ \t]*#") or
oneline:match("^[ \t]*//") or
oneline:match("^[ \t]*%-%-") then
linetab.type = "comment"
elseif oneline:match("^[ \t]*$") then
linetab.type = "whitespace"
else
linetab.type = "rule"
linetab.content, warn = lex_one_line(oneline)
if #warn > 0 then
linetab.warnings = warn
end
end
lines[n] = linetab
n = n + 1
end
return ret
end
local function lex_a_file(filename)
local fh, err = sio.open(filename, "r")
if not fh then
return nil, "Unable to open " .. tostring(filename) .. ": " .. tostring(err)
end
local ruleset = fh:read("*a")
fh:close()
return lex_a_ruleset(ruleset, "@" .. filename)
end
return {
file = lex_a_file,
string = lex_a_ruleset,
}
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