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--
-- (C) 2013-22 - ntop.org
--
--- Simple class for JSON parsing
dirs = ntop.getDirs()
package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
local parseElement
local function skipWhitespaces(content, pos)
local _,nend = content:find("^[ \n\r\t]+", pos)
if (nend ~= nil) then
return nend+1
else
return pos
end
end
local function parseNumber(content, pos)
-- Integer part
local integer_part = content:match('^-?[1-9]%d*', pos)
or content:match("^-?0", pos)
if not integer_part then
return nil
end
-- Decimal part
local lstart = pos + integer_part:len()
local decimal_part = content:match('^%.%d+', i) or ""
lstart = lstart + decimal_part:len()
-- Exponential
local exponent_part = content:match('^[eE][-+]?%d+', i) or ""
lstart = lstart + exponent_part:len()
local full_number_text = integer_part .. decimal_part .. exponent_part
local cnumber = tonumber(full_number_text)
if not cnumber then
return nil
end
return cnumber, lstart
end
local function parseString(content, pos)
if (content:sub(pos, pos) ~= '"') then
return ""
end
local i = pos + 1
local clen = content:len()
local val = ""
while (i <= clen) do
local c = content:sub(i, i)
if (c == '"') then
return val, i+1
end
val = val..c
i = i + 1
end
return ""
end
local function parseObject(content, pos)
if (content:sub(pos, pos) ~= '{') then
return {}, pos
end
local lstart = skipWhitespaces(content, pos+1)
local val = {}
-- Handle empty array
if (content:sub(lstart, lstart) == '}') then
return val, lstart+1
end
local clen = content:len()
while (lstart <= clen) do
local key, nstart = parseString(content, lstart)
lstart = skipWhitespaces(content, nstart)
if (content == nil or lstart == nil or
content:sub(lstart, lstart) ~= ':') then
return {}, lstart
end
lstart = skipWhitespaces(content, lstart+1)
local nval, nstart = parseElement(content, lstart)
val[key] = nval
-- We have key and value, must have a } or a ,
lstart = skipWhitespaces(content, nstart)
if (content == nil or lstart == nil) then
return {}, clen
end
if (content:sub(lstart, lstart) == '}') then
return val, lstart+1
end
if (content:sub(lstart, lstart) ~= ',') then
return {}, lstart
end
lstart = skipWhitespaces(content, lstart+1) -- skip comma
end
return {}, lstart
end
local function parseArray(content, pos)
if (content:sub(pos, pos) ~= '[') then
return {}, pos
end
local lstart = skipWhitespaces(content, pos+1)
local val = {}
-- Handle empty array
if (content:sub(lstart, lstart) == ']') then
return val, lstart+1
end
local idx = 1 -- keep 1 to n convention
local clen = content:len()
while (lstart <= clen) do
local nval, nstart = parseElement(content, lstart)
val[idx] = nval
idx = idx + 1
lstart = skipWhitespaces(content, nstart)
-- Need a ] or a , now
if (content == nil or lstart == nil) then
return {}, clen
end
if (content:sub(lstart, lstart) == ']') then
return val, lstart+1
end
if (content:sub(lstart, lstart) ~= ',') then
return {}, lstart
end
lstart = skipWhitespaces(content, lstart+1)
end
return {}, lstart
end
parseElement = function(content, pos)
pos = skipWhitespaces(content, pos)
if (pos > content:len()) then
return {}, pos
end
if (content:find('^"', pos)) then
return parseString(content, pos)
elseif (content:find('^[-0123456789 ]', pos)) then
return parseNumber(content, pos)
elseif (content:find('^%{', pos)) then
return parseObject(content, pos)
elseif (content:find('^%[', pos)) then
return parseArray(content, pos)
else
return {}, pos
end
end
-- Exposed methods:
-- printTable: prints an indented version of a JSON parsing table
-- parseJSON: creates a table from a JSON
function printTable(tbl, indent)
if (tbl == nil) then return end
if not indent then indent = 0 end
for k, v in pairs(tbl) do
formatting = string.rep(" ", indent) .. k .. ": "
if type(v) == "table" then
io.write(formatting)
printTable(v, indent+1)
elseif type(v) == 'boolean' then
io.write(formatting .. tostring(v).."\n")
else
io.write(formatting .. v.."\n")
end
end
end
function parseJSON(content)
if (content == nil) then return {} end
local table = parseElement(content, 1)
--printTable(table)
return table
end
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