Initial commit

LICENSE

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+Copyright (c) 2015 rxi
+
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# ![json.lua](https://cloud.githubusercontent.com/assets/3920290/9207222/24413cbe-4064-11e5-874e-7e2deeb5f8cb.png)  
+A minimal JSON library for Lua
+
+
+## Features
+* Pure Lua implementation
+* Tiny: around 250sloc, 7kb
+* Proper error messages, *eg:* `expected '}' or ',' at line 203 col 30`
+
+
+## Usage
+The [json.lua](json.lua?raw=1) file should be dropped into an existing project
+and required by it:
+```lua
+json = require "json"
+```
+The library provides the following functions:
+
+#### json.encode(value)
+Returns a string representing `value` encoded in JSON.
+```lua
+json.encode({ 1, 2, 3, { x = 10 } }) -- Returns '[1,2,3,{"x":10}]'
+```
+
+#### json.decode(str)
+Returns a value representing the decoded JSON string.
+```lua
+json.decode('[1,2,3,{"x":10}]') -- Returns { 1, 2, 3, { x = 10 } }
+```
+
+## Notes
+* UTF-16 surrogate pairs are not supported
+* Tables with the key `1` set are treated as arrays when encoding
+* `null` values contained within an array or object are converted to `nil` and
+  are therefore lost upon decoding
+* *Pretty* encoding is not supported, `json.encode()` only encodes to a compact
+  format
+
+
+## License
+This library is free software; you can redistribute it and/or modify it under
+the terms of the MIT license. See [LICENSE](LICENSE) for details.
+

json.lua

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+--
+-- json.lua
+--
+-- Copyright (c) 2015 rxi
+--
+-- This library is free software; you can redistribute it and/or modify it
+-- under the terms of the MIT license. See LICENSE for details.
+--
+
+local json = { _version = "0.0.0" }
+
+-------------------------------------------------------------------------------
+-- Encode
+-------------------------------------------------------------------------------
+
+local loadstring = loadstring or load
+local encode
+
+local escape_char_map = {
+  [ "\\" ] = "\\\\",
+  [ "\"" ] = "\\\"",
+  [ "\b" ] = "\\b",
+  [ "\f" ] = "\\f",
+  [ "\n" ] = "\\n",
+  [ "\r" ] = "\\r",
+  [ "\t" ] = "\\t",
+}
+
+local function escape_char(c)
+  return escape_char_map[c] or string.format("\\u%04x", c:byte())
+end
+
+
+local function encode_nil(val)
+  return "null"
+end 
+
+
+local function encode_table(val, stack)
+  local res = {}
+  stack = stack or {}
+
+  -- Circular reference?
+  if stack[val] then error("circular reference") end
+
+  stack[val] = true
+
+  if val[1] ~= nil then
+    -- Treat as an array
+    for i, v in ipairs(val) do
+      table.insert(res, encode(v, stack))
+    end
+    stack[val] = nil
+    return "[" .. table.concat(res, ",") .. "]"
+
+  else
+    -- Treat as an object
+    for k, v in pairs(val) do
+      local t = type(k)
+      if t ~= "string" then
+        error("expected key of type 'string', got '" .. t .. "'")
+      end
+      table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
+    end
+    stack[val] = nil
+    return "{" .. table.concat(res, ",") .. "}"
+  end
+end
+
+
+local function encode_string(val)
+  return '"' .. val:gsub('[%z\1-\31\\"]', escape_char) .. '"'
+end
+
+
+local function encode_number(val)
+  -- Check for NaN, -inf and inf
+  if val ~= val or val <= -math.huge or val >= math.huge then
+    error("unexpected number value '" .. tostring(val) .. "'")
+  end
+  return tostring(val)
+end
+
+
+local type_func_map = {
+  [ "nil"     ] = encode_nil,
+  [ "table"   ] = encode_table,
+  [ "string"  ] = encode_string,
+  [ "number"  ] = encode_number,
+  [ "boolean" ] = tostring,
+}
+
+
+encode = function(val, stack)
+  local t = type(val)
+  local f = type_func_map[t]
+  if f then
+    return f(val, stack)
+  end
+  error("unexpected type '" .. t .. "'")
+end
+
+
+function json.encode(val)
+  return ( encode(val) )
+end
+
+
+-------------------------------------------------------------------------------
+-- Decode
+-------------------------------------------------------------------------------
+
+local parse
+
+local function create_set(...) 
+  local res = {}
+  for i = 1, select("#", ...) do
+    res[ select(i, ...) ] = true
+  end
+  return res
+end
+
+local space_chars   = create_set(" ", "\t", "\r", "\n")
+local delim_chars   = create_set(" ", "\t", "\r", "\n", "]", "}", ",")
+local escape_chars  = create_set("\\", "/", '"', "b", "f", "n", "r", "t", "u")
+local keywords      = create_set("true", "false", "null")
+
+
+local function next_char(str, idx, set, negate)
+  for i = idx, #str do
+    if set[str:sub(i, i)] ~= negate then
+      return i
+    end
+  end
+  return #str + 1
+end
+
+
+local function decode_error(str, idx, msg)
+  local line_count = 1
+  local col_count = 1
+  for i = 1, idx - 1 do
+    col_count = col_count + 1
+    if str:sub(i, i) == "\n" then
+      line_count = line_count + 1
+      col_count = 1
+    end
+  end
+  error( string.format("%s at line %d col %d", msg, line_count, col_count) )
+end
+
+
+local function parse_unicode_escape(s)
+  local n = tonumber( s:sub(3), 16 )
+  if n <= 0x7f then
+    return string.char(n)
+  elseif n <= 0x7ff then
+    return string.char(n / 64 + 192, n % 64 + 128)
+  end
+  return string.char(n / 4096 + 224, n % 4096 / 64 + 128, n % 64 + 128)
+end
+
+
+local function parse_string(str, i, chr)
+  local has_unicode_escape = false
+  local last
+  for j = i + 1, #str do
+    local x = str:sub(j, j)
+
+    if x == "\n" then
+      decode_error(str, j, "unexpected new line in string")
+    end
+
+    if last == "\\" then
+      if x == "u" then 
+        local hex = str:sub(j + 1, j + 5)
+        if not hex:find("%x%x%x%x") then
+          decode_error(str, j, "invalid unicode escape in string")
+        end
+        if hex:find("^[dD][89aAbB]") then
+          decode_error(str, j, "unsupported utf-16 surrogate pair in string")
+        end
+        has_unicode_escape = true
+      end
+      if not escape_chars[x] then
+        decode_error(str, j, "invalid escape char '" .. x .. "' in string")
+      end
+
+    elseif x == '"' then
+      local s = str:sub(i, j)
+      if has_unicode_escape then 
+        s = s:gsub("\\u....", parse_unicode_escape)
+      end
+      return loadstring( "return " .. s )(), j + 1
+    end
+    last = x
+  end
+  decode_error(str, i, "expected closing quote for string")
+end
+
+
+local function parse_number(str, i, chr)
+  local x = next_char(str, i, delim_chars)
+  local s = str:sub(i, x - 1)
+  local n = tonumber(s)
+  if not n then
+    decode_error(str, i, "invalid number '" .. s .. "'")
+  end
+  return n, x
+end
+
+
+local function parse_keyword(str, i, chr)
+  local x = next_char(str, i, delim_chars)
+  local word = str:sub(i, x - 1)
+  if not keywords[word] then
+    decode_error(str, i, "invalid keyword '" .. word .. "'")
+  end
+  return (chr == "t") and true or (chr == "f") and false, x
+end
+
+
+local function parse_array(str, i, chr)
+  local res = {}
+  local n = 1
+  i = i + 1
+  while 1 do
+    local x
+    i = next_char(str, i, space_chars, true)
+    -- Empty / end of array?
+    if str:sub(i, i) == "]" then 
+      i = i + 1
+      break
+    end
+    -- Read token
+    x, i = parse(str, i)
+    res[n] = x
+    n = n + 1
+    -- Next token 
+    i = next_char(str, i, space_chars, true)
+    chr = str:sub(i, i)
+    i = i + 1
+    if chr == "]" then break end
+    if chr ~= "," then decode_error(str, i, "expected ']' or ','") end
+  end
+  return res, i
+end
+
+
+local function parse_object(str, i, chr)
+  local res = {}
+  i = i + 1
+  while 1 do
+    local key, val
+    i = next_char(str, i, space_chars, true)
+    -- Empty / end of object?
+    if str:sub(i, i) == "}" then 
+      i = i + 1
+      break
+    end
+    -- Read key
+    key, i = parse(str, i)
+    -- Read ':' delimiter
+    i = next_char(str, i, space_chars, true)
+    if str:sub(i, i) ~= ":" then
+      decode_error(str, i, "expected ':' after key")
+    end
+    i = next_char(str, i + 1, space_chars, true)
+    -- Read value
+    val, i = parse(str, i)
+    -- Set
+    res[key] = val
+    -- Next token
+    i = next_char(str, i, space_chars, true)
+    chr = str:sub(i, i)
+    i = i + 1
+    if chr == "}" then break end
+    if chr ~= "," then decode_error(str, i, "expected '}' or ','") end
+  end
+  return res, i
+end
+
+
+local char_func_map = {
+  [ '"' ] = parse_string,
+  [ "0" ] = parse_number,
+  [ "1" ] = parse_number,
+  [ "2" ] = parse_number,
+  [ "3" ] = parse_number,
+  [ "4" ] = parse_number,
+  [ "5" ] = parse_number,
+  [ "6" ] = parse_number,
+  [ "7" ] = parse_number,
+  [ "8" ] = parse_number,
+  [ "9" ] = parse_number,
+  [ "." ] = parse_number,
+  [ "-" ] = parse_number,
+  [ "t" ] = parse_keyword,
+  [ "f" ] = parse_keyword,
+  [ "n" ] = parse_keyword,
+  [ "[" ] = parse_array,
+  [ "{" ] = parse_object,
+}
+
+
+parse = function(str, idx)
+  local chr = str:sub(idx, idx)
+  local f = char_func_map[chr]
+  if f then
+    return f(str, idx, chr)
+  else
+    decode_error(str, idx, "unexpected character '" .. chr .. "'")
+  end
+end
+
+
+function json.decode(str)
+  return ( parse(str, next_char(str, 1, space_chars, true)) )
+end
+
+
+return json