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--[[
Licensed according to the included 'LICENSE' document
Author: Thomas Harning Jr <harningt@gmail.com>
]]
local string_char = require("string").char
local pairs = pairs
local jsonutil = require("json.util")
local util_merge = jsonutil.merge
local _ENV = nil
local normalEncodingMap = {
['"'] = '\\"',
['\\'] = '\\\\',
['/'] = '\\/',
['\b'] = '\\b',
['\f'] = '\\f',
['\n'] = '\\n',
['\r'] = '\\r',
['\t'] = '\\t',
['\v'] = '\\v' -- not in official spec, on report, removing
}
local xEncodingMap = {}
for char, encoded in pairs(normalEncodingMap) do
xEncodingMap[char] = encoded
end
-- Pre-encode the control characters to speed up encoding...
-- NOTE: UTF-8 may not work out right w/ JavaScript
-- JavaScript uses 2 bytes after a \u... yet UTF-8 is a
-- byte-stream encoding, not pairs of bytes (it does encode
-- some letters > 1 byte, but base case is 1)
for i = 0, 255 do
local c = string_char(i)
if c:match('[%z\1-\031\128-\255]') and not normalEncodingMap[c] then
-- WARN: UTF8 specializes values >= 0x80 as parts of sequences...
-- without \x encoding, do not allow encoding > 7F
normalEncodingMap[c] = ('\\u%.4X'):format(i)
xEncodingMap[c] = ('\\x%.2X'):format(i)
end
end
local defaultOptions = {
xEncode = false, -- Encode single-bytes as \xXX
processor = nil, -- Simple processor for the string prior to quoting
-- / is not required to be quoted but it helps with certain decoding
-- Required encoded characters, " \, and 00-1F (0 - 31)
encodeSet = '\\"/%z\1-\031',
encodeSetAppend = nil -- Chars to append to the default set
}
local modeOptions = {}
local function mergeOptions(options, mode)
jsonutil.doOptionMerge(options, false, 'strings', defaultOptions, mode and modeOptions[mode])
end
local function getEncoder(options)
options = options and util_merge({}, defaultOptions, options) or defaultOptions
local encodeSet = options.encodeSet
if options.encodeSetAppend then
encodeSet = encodeSet .. options.encodeSetAppend
end
local encodingMap = options.xEncode and xEncodingMap or normalEncodingMap
local encodeString
if options.processor then
local processor = options.processor
encodeString = function(s, state)
return '"' .. processor(s:gsub('[' .. encodeSet .. ']', encodingMap)) .. '"'
end
else
encodeString = function(s, state)
return '"' .. s:gsub('[' .. encodeSet .. ']', encodingMap) .. '"'
end
end
return {
string = encodeString
}
end
local strings = {
mergeOptions = mergeOptions,
getEncoder = getEncoder
}
return strings
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