feat: 初始提交 LeonOS 实现

添加 LeonOS 的基本实现，包括：
- 核心 API 模块（colors, disk, gps, keys, multishell, parallel, rednet, redstone, settings, vector）
- 命令行程序（about, alias, bg, clear, copy, delete, edit, fg, help, list, lua, mkdir, move, paint, peripherals, programs, reboot, set, shutdown, threads）
- 系统启动脚本和包管理
- 文档（README.md, LICENSE）
- 开发工具（devbin）和更新程序

实现功能：
- 完整的线程管理系统
- 兼容 ComputerCraft 的 API 设计
- 改进的 shell 和命令补全系统
- 多标签终端支持
- 设置管理系统

data/computercraft/lua/rom/modules/main/cc/audio/dfpwm.lua

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+--[[-
+Provides utilities for converting between streams of DFPWM audio data and a list of amplitudes.
+
+DFPWM (Dynamic Filter Pulse Width Modulation) is an audio codec designed by GreaseMonkey. It's a relatively compact
+format compared to raw PCM data, only using 1 bit per sample, but is simple enough to simple enough to encode and decode
+in real time.
+
+Typically DFPWM audio is read from @{fs.BinaryReadHandle|the filesystem} or a @{http.Response|a web request} as a
+string, and converted a format suitable for @{speaker.playAudio}.
+
+## Encoding and decoding files
+This modules exposes two key functions, @{make_decoder} and @{make_encoder}, which construct a new decoder or encoder.
+The returned encoder/decoder is itself a function, which converts between the two kinds of data.
+
+These encoders and decoders have lots of hidden state, so you should be careful to use the same encoder or decoder for
+a specific audio stream. Typically you will want to create a decoder for each stream of audio you read, and an encoder
+for each one you write.
+
+## Converting audio to DFPWM
+DFPWM is not a popular file format and so standard audio processing tools will not have an option to export to it.
+Instead, you can convert audio files online using [music.madefor.cc] or with the [LionRay Wav Converter][LionRay] Java
+application.
+
+[music.madefor.cc]: https://music.madefor.cc/ "DFPWM audio converter for Computronics and CC: Tweaked"
+[LionRay]: https://github.com/gamax92/LionRay/ "LionRay Wav Converter "
+
+@see guide!speaker_audio Gives a more general introduction to audio processing and the speaker.
+@see speaker.playAudio To play the decoded audio data.
+@usage Reads "data/example.dfpwm" in chunks, decodes them and then doubles the speed of the audio. The resulting audio
+is then re-encoded and saved to "speedy.dfpwm". This processed audio can then be played with the `speaker` program.
+
+```lua
+local dfpwm = require("cc.audio.dfpwm")
+
+local encoder = dfpwm.make_encoder()
+local decoder = dfpwm.make_decoder()
+
+local out = fs.open("speedy.dfpwm", "wb")
+for input in io.lines("data/example.dfpwm", 16 * 1024 * 2) do
+  local decoded = decoder(input)
+  local output = {}
+
+  -- Read two samples at once and take the average.
+  for i = 1, #decoded, 2 do
+    local value_1, value_2 = decoded[i], decoded[i + 1]
+    output[(i + 1) / 2] = (value_1 + value_2) / 2
+  end
+
+  out.write(encoder(output))
+
+  sleep(0) -- This program takes a while to run, so we need to make sure we yield.
+end
+out.close()
+```
+]]
+
+local expect = require "cc.expect".expect
+
+local char, byte, floor, band, rshift = string.char, string.byte, math.floor, bit32.band, bit32.arshift
+
+local PREC = 10
+local PREC_POW = 2 ^ PREC
+local PREC_POW_HALF = 2 ^ (PREC - 1)
+local STRENGTH_MIN = 2 ^ (PREC - 8 + 1)
+
+local function make_predictor()
+    local charge, strength, previous_bit = 0, 0, false
+
+    return function(current_bit)
+        local target = current_bit and 127 or -128
+
+        local next_charge = charge + floor((strength * (target - charge) + PREC_POW_HALF) / PREC_POW)
+        if next_charge == charge and next_charge ~= target then
+            next_charge = next_charge + (current_bit and 1 or -1)
+        end
+
+        local z = current_bit == previous_bit and PREC_POW - 1 or 0
+        local next_strength = strength
+        if next_strength ~= z then next_strength = next_strength + (current_bit == previous_bit and 1 or -1) end
+        if next_strength < STRENGTH_MIN then next_strength = STRENGTH_MIN end
+
+        charge, strength, previous_bit = next_charge, next_strength, current_bit
+        return charge
+    end
+end
+
+--[[- Create a new encoder for converting PCM audio data into DFPWM.
+
+The returned encoder is itself a function. This function accepts a table of amplitude data between -128 and 127 and
+returns the encoded DFPWM data.
+
+:::caution Reusing encoders
+Encoders have lots of internal state which tracks the state of the current stream. If you reuse an encoder for multiple
+streams, or use different encoders for the same stream, the resulting audio may not sound correct.
+:::
+
+@treturn function(pcm: { number... }):string The encoder function
+@see encode A helper function for encoding an entire file of audio at once.
+]]
+local function make_encoder()
+    local predictor = make_predictor()
+    local previous_charge = 0
+
+    return function(input)
+        expect(1, input, "table")
+
+        local output, output_n = {}, 0
+        for i = 1, #input, 8 do
+            local this_byte = 0
+            for j = 0, 7 do
+                local inp_charge = floor(input[i + j] or 0)
+                if inp_charge > 127 or inp_charge < -128 then
+                    error(("Amplitude at position %d was %d, but should be between -128 and 127"):format(i + j, inp_charge), 2)
+                end
+
+                local current_bit = inp_charge > previous_charge or (inp_charge == previous_charge and inp_charge == 127)
+                this_byte = floor(this_byte / 2) + (current_bit and 128 or 0)
+
+                previous_charge = predictor(current_bit)
+            end
+
+            output_n = output_n + 1
+            output[output_n] = char(this_byte)
+        end
+
+        return table.concat(output, "", 1, output_n)
+    end
+end
+
+--[[- Create a new decoder for converting DFPWM into PCM audio data.
+
+The returned decoder is itself a function. This function accepts a string and returns a table of amplitudes, each value
+between -128 and 127.
+
+:::caution Reusing decoders
+Decoders have lots of internal state which tracks the state of the current stream. If you reuse an decoder for multiple
+streams, or use different decoders for the same stream, the resulting audio may not sound correct.
+:::
+
+@treturn function(dfpwm: string):{ number... } The encoder function
+@see decode A helper function for decoding an entire file of audio at once.
+
+@usage Reads "data/example.dfpwm" in blocks of 16KiB (the speaker can accept a maximum of 128×1024 samples), decodes
+them and then plays them through the speaker.
+
+```lua {data-peripheral=speaker}
+local dfpwm = require "cc.audio.dfpwm"
+local speaker = peripheral.find("speaker")
+
+local decoder = dfpwm.make_decoder()
+for input in io.lines("data/example.dfpwm", 16 * 1024) do
+  local decoded = decoder(input)
+  while not speaker.playAudio(decoded) do
+    os.pullEvent("speaker_audio_empty")
+  end
+end
+```
+]]
+local function make_decoder()
+    local predictor = make_predictor()
+    local low_pass_charge = 0
+    local previous_charge, previous_bit = 0, false
+
+    return function (input, output)
+        expect(1, input, "string")
+
+        local output, output_n = {}, 0
+        for i = 1, #input do
+            local input_byte = byte(input, i)
+            for _ = 1, 8 do
+                local current_bit = band(input_byte, 1) ~= 0
+                local charge = predictor(current_bit)
+
+                local antijerk = charge
+                if current_bit ~= previous_bit then
+                    antijerk = floor((charge + previous_charge + 1) / 2)
+                end
+
+                previous_charge, previous_bit = charge, current_bit
+
+                low_pass_charge = low_pass_charge + floor(((antijerk - low_pass_charge) * 140 + 0x80) / 256)
+
+                output_n = output_n + 1
+                output[output_n] = low_pass_charge
+
+                input_byte = rshift(input_byte, 1)
+            end
+        end
+
+        return output
+    end
+end
+
+--[[- A convenience function for decoding a complete file of audio at once.
+
+This should only be used for short files. For larger files, one should read the file in chunks and process it using
+@{make_decoder}.
+
+@tparam string input The DFPWM data to convert.
+@treturn { number... } The produced amplitude data.
+@see make_decoder
+]]
+local function decode(input)
+    expect(1, input, "string")
+    return make_decoder()(input)
+end
+
+--[[- A convenience function for encoding a complete file of audio at once.
+
+This should only be used for complete pieces of audio. If you are writing writing multiple chunks to the same place,
+you should use an encoder returned by @{make_encoder} instead.
+
+@tparam { number... } input The table of amplitude data.
+@treturn string The encoded DFPWM data.
+@see make_encoder
+]]
+local function encode(input)
+    expect(1, input, "table")
+    return make_encoder()(input)
+end
+
+return {
+    make_encoder = make_encoder,
+    encode = encode,
+
+    make_decoder = make_decoder,
+    decode = decode,
+}

data/computercraft/lua/rom/modules/main/cc/completion.lua

@@ -0,0 +1,45 @@
+-- cc.completion
+
+local expect = require("cc.expect").expect
+local settings = require("settings")
+local peripheral = require("peripheral")
+
+local c = {}
+
+-- choices and options!
+-- extension: add_space can be a table of booleans
+function c.choice(text, choices, add_space)
+  expect(1, text, "string")
+  expect(2, choices, "table")
+  expect(3, add_space, "boolean", "table", "nil")
+
+  local options = {}
+
+  for i=1, #choices, 1 do
+    local add = add_space
+    if type(add_space) == "table" then
+      add = add_space[i] or add_space[1]
+    end
+
+    if choices[i]:sub(0, #text) == text then
+      options[#options+1] = choices[i]:sub(#text+1) .. (add and " " or "")
+    end
+  end
+
+  return options
+end
+
+function c.peripheral(text, add_space)
+  return c.choice(text, peripheral.getNames(), add_space)
+end
+
+local sides = {"front", "back", "top", "bottom", "left", "right"}
+function c.side(text, add_space)
+  return c.choice(text, sides, add_space)
+end
+
+function c.setting(text, add_space)
+  return c.choice(text, settings.getNames(), add_space)
+end
+
+return c

data/computercraft/lua/rom/modules/main/cc/expect.lua

@@ -0,0 +1,50 @@
+-- cc.expect
+
+local _expect = {}
+
+local function checkType(index, valueType, value, ...)
+  local expected = table.pack(...)
+  local isType = false
+
+  for i=1, expected.n, 1 do
+    if type(value) == expected[i] then
+      isType = true
+      break
+    end
+  end
+
+  if not isType then
+    error(string.format("bad %s %s (%s expected, got %s)", valueType,
+      index, table.concat(expected, " or "), type(value)), 3)
+  end
+
+  return value
+end
+
+function _expect.expect(index, value, ...)
+  return checkType(("#%d"):format(index), "argument", value, ...)
+end
+
+function _expect.field(tbl, index, ...)
+  _expect.expect(1, tbl, "table")
+  _expect.expect(2, index, "string")
+  return checkType(("%q"):format(index), "field", tbl[index], ...)
+end
+
+function _expect.range(num, min, max)
+  _expect.expect(1, num, "number")
+  _expect.expect(2, min, "number", "nil")
+  _expect.expect(3, max, "number", "nil")
+  min = min or -math.huge
+  max = max or math.huge
+  if num < min or num > max then
+    error(("number outside of range (expected %d to be within %d and %d")
+      :format(num, min, max), 2)
+  end
+end
+
+setmetatable(_expect, {__call = function(_, ...)
+  return _expect.expect(...)
+end})
+
+return _expect

data/computercraft/lua/rom/modules/main/cc/http/gist.lua

@@ -0,0 +1,293 @@
+--- gist.lua - Gist client for ComputerCraft
+-- Made by JackMacWindows for LeonOS-PC and CC: Tweaked
+--
+-- @module cc.http.gist
+
+local textutils = require("textutils")
+local settings = require("settings")
+local expect = require("cc.expect").expect
+local colors = require("colors")
+local write = require("rc").write
+local term = require("term")
+local http = require("http")
+local read = term.read
+
+local gist = {}
+
+local function emptyfn() end -- to reduce memory/speed footprint when using empty functions
+
+-- Internal functions
+
+local function getGistFile(data)
+    if not data.truncated then return data.content else
+        local handle = http.get(data.raw_url)
+        if not handle then error("Could not connect to api.github.com.") end
+        if handle.getResponseCode() ~= 200 then
+            handle.close()
+            error("Failed to download file data.")
+        end
+        local d = handle.readAll()
+        handle.close()
+        return d
+    end
+end
+
+local function setTextColor(c) if term.isColor() then term.setTextColor(c) elseif c == colors.white or c == colors.yellow then term.setTextColor(colors.white) else term.setTextColor(colors.lightGray) end end
+
+local function requestAuth(headers, interactive)
+    if settings.get("gist.id") ~= nil then
+        headers.Authorization = "token " .. settings.get("gist.id")
+        return true
+    elseif interactive then
+        setTextColor(colors.yellow)
+        write("You need to add a Personal Access Token (PAK) to upload Gists. Follow the instructions at ")
+        setTextColor(colors.blue)
+        write("https://tinyurl.com/GitHubPAK")
+        setTextColor(colors.yellow)
+        write(" to generate one. Make sure to check the '")
+        setTextColor(colors.blue)
+        write("gist")
+        setTextColor(colors.yellow)
+        print("' checkbox on step 7 (under 'Select scopes'). Once done, paste it here.")
+        setTextColor(colors.lime)
+        write("PAK: ")
+        setTextColor(colors.white)
+        local pak = read()
+        if pak == nil or pak == "" then error("Invalid PAK, please try again.") end
+        settings.set("gist.id", pak)
+        settings.save(".settings")
+        headers.Authorization = "token " .. pak
+        return true
+    end
+    return false
+end
+
+-- User API - this can be loaded with require "cc.http.gist"
+
+-- ID can be either just the gist ID or a gist ID followed by a slash and a file name
+-- (This also includes Gist URLs)
+-- * If a file name is specified, retrieves that file
+-- * Otherwise, if there's only one file, retrieves that file
+-- * Otherwise, if there's a file named 'init.lua', retrieves 'init.lua'
+-- * Otherwise, if there's more than one file but only one *.lua file, retrieves the Lua file
+-- * Otherwise, retrieves the first Lua file alphabetically (with a warning)
+-- * Otherwise, fails
+
+--- Retrieves one file from a Gist using the specified ID.
+-- @tparam string id The Gist ID to download from. See above comments for more details.
+-- @tparam[opt] function progress A function to use to report status messages.
+-- @treturn string|nil The contents of the specified Gist file, or nil on error.
+-- @treturn string|nil The name of the file that was chosen to be downloaded, or a message on error.
+function gist.get(id, progress)
+    expect(1, id, "string")
+    expect(2, progress, "function", "nil")
+    progress = progress or emptyfn
+    local file
+    if id:find("https?://") then id = id:gsub("https?://[^/]+/", ""):gsub("^[^/]*[^/%x]+[^/]*/", "") end
+    if id:find("/") ~= nil then id, file = id:match("^([0-9A-Fa-f:]+)/(.+)$") end
+    if id == nil or not id:match("^[0-9A-Fa-f][0-9A-Fa-f:]+[0-9A-Fa-f]$") then error("bad argument #1 to 'get' (invalid ID)", 2) end
+    if id:find(":") ~= nil then id = id:gsub(":", "/") end
+    progress("Connecting to api.github.com... ")
+    local handle = http.get("https://api.github.com/gists/" .. id)
+    if handle == nil then
+        progress("Failed.\n")
+        return nil, "Failed to connect"
+    end
+    local meta = textutils.unserializeJSON(handle.readAll())
+    local code = handle.getResponseCode()
+    handle.close()
+    if code ~= 200 then
+        progress("Failed.\n")
+        return nil, "Invalid response code (" .. code .. ")" .. (meta and ": " .. meta.message or "")
+    end
+    if meta == nil or meta.files == nil then
+        progress("Failed.\n")
+        return nil, meta and "GitHub API error: " .. meta.message or "Error parsing JSON"
+    end
+    progress("Success.\n")
+    if file then return getGistFile(meta.files[file]), file
+    elseif next(meta.files, next(meta.files)) == nil then return getGistFile(meta.files[next(meta.files)]), next(meta.files)
+    elseif meta.files["init.lua"] ~= nil then return getGistFile(meta.files["init.lua"]), "init.lua"
+    else
+        local luaFiles = {}
+        for k in pairs(meta.files) do if k:match("%.lua$") then table.insert(luaFiles, k) end end
+        table.sort(luaFiles)
+        if #luaFiles == 0 then
+            progress("Error: Could not find any Lua files to download!\n")
+            return nil, "Could not find any Lua files to download"
+        end
+        if #luaFiles > 1 then progress("Warning: More than one Lua file detected, downloading the first one alphabetically.\n") end
+        return getGistFile(meta.files[luaFiles[1]]), luaFiles[1]
+    end
+end
+
+--- Runs a specified Gist. This is a wrapper for convenience.
+-- @tparam string id The Gist ID to download from. See above comments for more details.
+-- @tparam[opt] function progress A function to use to report status messages. If
+-- this is not a function, it will be used as an argument to the script.
+-- @tparam[opt] any ... Any arguments to pass to the script.
+-- @treturn any Any results returned from the script.
+function gist.run(id, progress, ...)
+    expect(1, id, "string")
+    local args = table.pack(...)
+    if type(progress) ~= "function" and progress ~= nil then
+        table.insert(args, 1, progress)
+        progress = nil
+    end
+    local data, name = gist.get(id, progress)
+    if data == nil then return end
+    local fn, err = load(data, name, "t", _ENV)
+    if fn == nil then error(err) end
+    local retval = table.pack(pcall(fn, table.unpack(args)))
+    if not retval[1] then error(retval[2]) end
+    return table.unpack(retval, 2)
+end
+
+--- Retrieves a table of all files from a Gist.
+-- @tparam string id The Gist ID to download.
+-- @tparam[opt] function progress A function to use to report status messages.
+-- @treturn table|nil A key-value list of all files in the Gist, or nil on error.
+-- @treturn string|nil If an error occurred, a string describing the error.
+function gist.getAll(id, progress)
+    expect(1, id, "string")
+    expect(2, progress, "function", "nil")
+    progress = progress or emptyfn
+    if id:find("https?://") then id = id:gsub("https?://[^/]+/", ""):gsub("^[^/]*[^/%x]+[^/]*/", "") end
+    if id:find("/") ~= nil then id = id:match("^([0-9A-Fa-f:]+)/.*$") end
+    if id == nil or not id:match("^[0-9A-Fa-f][0-9A-Fa-f:]+[0-9A-Fa-f]$") then error("bad argument #1 to 'getAll' (invalid ID)", 2) end
+    if id:find(":") ~= nil then id = id:gsub(":", "/") end
+    progress("Connecting to api.github.com... ")
+    local handle = http.get("https://api.github.com/gists/" .. id)
+    if handle == nil then progress("Failed.\n") return nil, "Failed to connect" end
+    local meta = textutils.unserializeJSON(handle.readAll())
+    local code = handle.getResponseCode()
+    handle.close()
+    if code ~= 200 then
+        progress("Failed.\n")
+        return nil, "Invalid response code (" .. code .. ")" .. (meta and ": " .. meta.message or "")
+    end
+    if meta == nil or meta.files == nil then
+        progress("Failed.\n")
+        return nil, meta and meta.message and "GitHub API error: " .. meta.message or "Error parsing JSON"
+    end
+    progress("Success.\n")
+    local retval = {}
+    for k, v in pairs(meta.files) do retval[k] = getGistFile(v) end
+    return retval
+end
+
+--- Returns some information about a Gist.
+-- @tparam string id The Gist ID to get info about.
+-- @tparam[opt] function progress A function to use to report status messages.
+-- @treturn table|nil A table of information about the Gist. The table may
+-- contain the following entries:
+--  - description: The description for the Gist.
+--  - author: The username of the author of the Gist.
+--  - revisionCount: The number of revisions that have been made to the Gist.
+--  - files: A list of all file names in the Gist, sorted alphabetically.
+-- @treturn string|nil If an error occurred, a string describing the error.
+function gist.info(id, progress)
+    expect(1, id, "string")
+    expect(2, progress, "function", "nil")
+    progress = progress or emptyfn
+    if id:find("https?://") then id = id:gsub("https?://[^/]+/", ""):gsub("^[^/]*[^/%x]+[^/]*/", "") end
+    if id:find("/") ~= nil then id = id:match("^([0-9A-Fa-f:]+)/.*$") end
+    if id == nil or not id:match("^[0-9A-Fa-f][0-9A-Fa-f:]+[0-9A-Fa-f]$") then error("bad argument #1 to 'info' (invalid ID)", 2) end
+    if id:find(":") ~= nil then id = id:gsub(":", "/") end
+    progress("Connecting to api.github.com... ")
+    local handle = http.get("https://api.github.com/gists/" .. id)
+    if handle == nil then progress("Failed.\n") return nil, "Failed to connect" end
+    local meta = textutils.unserializeJSON(handle.readAll())
+    local code = handle.getResponseCode()
+    handle.close()
+    if code ~= 200 then
+        progress("Failed.\n")
+        return nil, "Invalid response code (" .. code .. ")" .. (meta and ": " .. meta.message or "")
+    end
+    if meta == nil or meta.files == nil then
+        progress("Failed.\n")
+        return nil, meta and meta.message and "GitHub API error: " .. meta.message or "Error parsing JSON"
+    end
+    local f = {}
+    for k in pairs(meta.files) do table.insert(f, k) end
+    table.sort(f)
+    progress("Success.\n")
+    return { description = meta.description, author = meta.owner.login, revisionCount = #meta.history, files = f }
+end
+
+--- Uploads a list of files to Gist, updating a previous Gist if desired.
+-- @tparam table files The files to upload to Gist. This table should be
+-- structured with a key as file name and a string with the file contents. If
+-- updating a Gist, files can be deleted by setting the data to textutils.json_null.
+-- @tparam[opt] string description The description of the Gist. This is required
+-- when updating a Gist, but is optional when uploading a Gist for the first
+-- time. If you don't want to change the description when updating, you can get
+-- the current description with gist.info() and pass in the description field.
+-- @tparam[opt] string id The ID of the Gist to update. If nil, a new Gist will
+-- be created.
+-- @tparam[opt] boolean interactive Set this to true to allow asking for a PAK
+-- if one is not available in the settings. If this is not specified, this
+-- function will return nil if gist.id is not available in the settings.
+-- @treturn string|nil The ID of the Gist, or nil on error.
+-- @treturn string|nil The URL of the Gist, or a string on error.
+function gist.put(files, description, id, interactive)
+    expect(1, files, "table")
+    expect(3, id, "string", "nil")
+    expect(2, description, "string", id == nil and "nil" or nil)
+    expect(4, interactive, "boolean", "nil")
+    if id then
+        if id:find("https?://") then id = id:gsub("https?://[^/]+/", ""):gsub("^[^/]*[^/%x]+[^/]*/", "") end
+        if id:find("/") ~= nil then id = id:match("^([0-9A-Fa-f:]+)/.*$") end
+        if id == nil or not id:match("^[0-9A-Fa-f][0-9A-Fa-f:]+[0-9A-Fa-f]$") then error("bad argument #3 to 'put' (invalid ID)", 2) end
+        if id:find(":") ~= nil then id = id:gsub(":", "/") end
+    end
+    local data = { files = {}, public = true, description = description }
+    for k, v in pairs(files) do if v == textutils.json_null then data.files[k] = v else data.files[k] = { content = v } end end
+    local headers = { ["Content-Type"] = "application/json" }
+    if not requestAuth(headers, interactive) then return nil, "Authentication required" end
+    if interactive then write("Connecting to api.github.com... ") end
+    local handle
+    if id then handle = http.post{ url = "https://api.github.com/gists/" .. id, body = textutils.serializeJSON(data):gsub("\n", "n"), headers = headers, method = "PATCH" }
+    else handle = http.post("https://api.github.com/gists", textutils.serializeJSON(data):gsub("\n", "n"), headers) end
+    if handle == nil then if interactive then print("Failed.") end return nil, "Could not connect" end
+    local resp = textutils.unserializeJSON(handle.readAll())
+    if handle.getResponseCode() ~= 201 and handle.getResponseCode() ~= 200 or resp == nil then
+        if interactive then print("Failed: " .. handle.getResponseCode() .. ": " .. (resp and resp.message or "Unknown error")) end
+        handle.close()
+        return nil, "Failed: " .. handle.getResponseCode() .. ": " .. (resp and resp.message or "Unknown error")
+    end
+    handle.close()
+    if interactive then print("Success.") end
+    return resp.id, resp.html_url
+end
+
+--- Deletes a Gist.
+-- @tparam string id The Gist ID to delete.
+-- @tparam[opt] boolean interactive Set this to true to allow asking for a PAK
+-- if one is not available in the settings. If this is not specified, this
+-- function will return false if gist.id is not available in the settings.
+-- @treturn boolean Whether the request succeeded.
+-- @treturn string|nil If an error occurred, a message describing the error.
+function gist.delete(id, interactive)
+    expect(1, id, "string")
+    expect(2, interactive, "boolean", "nil")
+    if id:find("https?://") then id = id:gsub("https?://[^/]+/", ""):gsub("^[^/]*[^/%x]+[^/]*/", "") end
+    if id:find("/") ~= nil or id:find(":") ~= nil then id = id:match("^([0-9A-Fa-f]+)") end
+    if id == nil or not id:match("^[0-9A-Fa-f][0-9A-Fa-f:]+[0-9A-Fa-f]$") then error("bad argument #1 to 'delete' (invalid ID)", 2) end
+    local headers = {}
+    if not requestAuth(headers, interactive) then return false, "Authentication required" end
+    if interactive then write("Connecting to api.github.com... ") end
+    local handle = http.post{ url = "https://api.github.com/gists/" .. id, headers = headers, method = "DELETE" }
+    if handle == nil then if interactive then print("Failed.") end return false, "Could not connect" end
+    if handle.getResponseCode() ~= 204 then
+        local resp = textutils.unserializeJSON(handle.readAll())
+        if interactive then print("Failed: " .. handle.getResponseCode() .. ": " .. (resp and resp.message or "Unknown error")) end
+        handle.close()
+        return false, "Failed: " .. handle.getResponseCode() .. ": " .. (resp and resp.message or "Unknown error")
+    end
+    handle.close()
+    if interactive then print("Success.") end
+    return true
+end
+
+return gist

data/computercraft/lua/rom/modules/main/cc/pretty.lua

@@ -0,0 +1,523 @@
+--[[- Provides a "pretty printer", for rendering data structures in an
+aesthetically pleasing manner.
+
+In order to display something using @{cc.pretty}, you build up a series of
+@{Doc|documents}. These behave a little bit like strings; you can concatenate
+them together and then print them to the screen.
+
+However, documents also allow you to control how they should be printed. There
+are several functions (such as @{nest} and @{group}) which allow you to control
+the "layout" of the document. When you come to display the document, the 'best'
+(most compact) layout is used.
+
+The structure of this module is based on [A Prettier Printer][prettier].
+
+[prettier]: https://homepages.inf.ed.ac.uk/wadler/papers/prettier/prettier.pdf "A Prettier Printer"
+
+@module cc.pretty
+@since 1.87.0
+@usage Print a table to the terminal
+
+    local pretty = require "cc.pretty"
+    pretty.pretty_print({ 1, 2, 3 })
+
+@usage Build a custom document and display it
+
+    local pretty = require "cc.pretty"
+    pretty.print(pretty.group(pretty.text("hello") .. pretty.space_line .. pretty.text("world")))
+]]
+
+local _expect = require "cc.expect"
+local expect, field = _expect.expect, _expect.field
+
+local term = require("term")
+local type, getmetatable, setmetatable, colours, str_write, tostring = type, getmetatable, setmetatable, require("colours"), require("rc").write, tostring
+local debug_info, debug_local = debug.getinfo, debug.getlocal
+
+--- @{table.insert} alternative, but with the length stored inline.
+local function append(out, value)
+    local n = out.n + 1
+    out[n], out.n = value, n
+end
+
+--- A document containing formatted text, with multiple possible layouts.
+--
+-- Documents effectively represent a sequence of strings in alternative layouts,
+-- which we will try to print in the most compact form necessary.
+--
+-- @type Doc
+local Doc = { }
+
+local function mk_doc(tbl) return setmetatable(tbl, Doc) end
+
+--- An empty document.
+local empty = mk_doc({ tag = "nil" })
+
+--- A document with a single space in it.
+local space = mk_doc({ tag = "text", text = " " })
+
+--- A line break. When collapsed with @{group}, this will be replaced with @{empty}.
+local line = mk_doc({ tag = "line", flat = empty })
+
+--- A line break. When collapsed with @{group}, this will be replaced with @{space}.
+local space_line = mk_doc({ tag = "line", flat = space })
+
+local text_cache = { [""] = empty, [" "] = space, ["\n"] = space_line }
+
+local function mk_text(text, colour)
+    return text_cache[text] or setmetatable({ tag = "text", text = text, colour = colour }, Doc)
+end
+
+--- Create a new document from a string.
+--
+-- If your string contains multiple lines, @{group} will flatten the string
+-- into a single line, with spaces between each line.
+--
+-- @tparam      string text   The string to construct a new document with.
+-- @tparam[opt] number colour The colour this text should be printed with. If not given, we default to the current
+-- colour.
+-- @treturn Doc The document with the provided text.
+-- @usage Write some blue text.
+--
+--     local pretty = require "cc.pretty"
+--     pretty.print(pretty.text("Hello!", colours.blue))
+local function text(text, colour)
+    expect(1, text, "string")
+    expect(2, colour, "number", "nil")
+
+    local cached = text_cache[text]
+    if cached then return cached end
+
+    local new_line = text:find("\n", 1)
+    if not new_line then return mk_text(text, colour) end
+
+    -- Split the string by "\n". With a micro-optimisation to skip empty strings.
+    local doc = setmetatable({ tag = "concat", n = 0 }, Doc)
+    if new_line ~= 1 then append(doc, mk_text(text:sub(1, new_line - 1), colour)) end
+
+    new_line = new_line + 1
+    while true do
+        local next_line = text:find("\n", new_line)
+        append(doc, space_line)
+        if not next_line then
+            if new_line <= #text then append(doc, mk_text(text:sub(new_line), colour)) end
+            return doc
+        else
+            if new_line <= next_line - 1 then
+                append(doc, mk_text(text:sub(new_line, next_line - 1), colour))
+            end
+            new_line = next_line + 1
+        end
+    end
+end
+
+--- Concatenate several documents together. This behaves very similar to string concatenation.
+--
+-- @tparam Doc|string ... The documents to concatenate.
+-- @treturn Doc The concatenated documents.
+-- @usage
+--     local pretty = require "cc.pretty"
+--     local doc1, doc2 = pretty.text("doc1"), pretty.text("doc2")
+--     print(pretty.concat(doc1, " - ", doc2))
+--     print(doc1 .. " - " .. doc2) -- Also supports ..
+local function concat(...)
+    local args = table.pack(...)
+    for i = 1, args.n do
+        if type(args[i]) == "string" then args[i] = text(args[i]) end
+        if getmetatable(args[i]) ~= Doc then expect(i, args[i], "document") end
+    end
+
+    if args.n == 0 then return empty end
+    if args.n == 1 then return args[1] end
+
+    args.tag = "concat"
+    return setmetatable(args, Doc)
+end
+
+Doc.__concat = concat --- @local
+
+--- Indent later lines of the given document with the given number of spaces.
+--
+-- For instance, nesting the document
+-- ```txt
+-- foo
+-- bar
+-- ```
+-- by two spaces will produce
+-- ```txt
+-- foo
+--   bar
+-- ```
+--
+-- @tparam number depth The number of spaces with which the document should be indented.
+-- @tparam Doc    doc   The document to indent.
+-- @treturn Doc The nested document.
+-- @usage
+--     local pretty = require "cc.pretty"
+--     print(pretty.nest(2, pretty.text("foo\nbar")))
+local function nest(depth, doc)
+    expect(1, depth, "number")
+    if getmetatable(doc) ~= Doc then expect(2, doc, "document") end
+    if depth <= 0 then error("depth must be a positive number", 2) end
+
+    return setmetatable({ tag = "nest", depth = depth, doc }, Doc)
+end
+
+local function flatten(doc)
+    if doc.flat then return doc.flat end
+
+    local kind = doc.tag
+    if kind == "nil" or kind == "text" then
+        return doc
+    elseif kind == "concat" then
+        local out = setmetatable({ tag = "concat", n = doc.n }, Doc)
+        for i = 1, doc.n do out[i] = flatten(doc[i]) end
+        doc.flat, out.flat = out, out -- cache the flattened node
+        return out
+    elseif kind == "nest" then
+        return flatten(doc[1])
+    elseif kind == "group" then
+        return doc[1]
+    else
+        error("Unknown doc " .. kind)
+    end
+end
+
+--- Builds a document which is displayed on a single line if there is enough
+-- room, or as normal if not.
+--
+-- @tparam Doc doc The document to group.
+-- @treturn Doc The grouped document.
+-- @usage Uses group to show things being displayed on one or multiple lines.
+--
+--     local pretty = require "cc.pretty"
+--     local doc = pretty.group("Hello" .. pretty.space_line .. "World")
+--     print(pretty.render(doc, 5)) -- On multiple lines
+--     print(pretty.render(doc, 20)) -- Collapsed onto one.
+local function group(doc)
+    if getmetatable(doc) ~= Doc then expect(1, doc, "document") end
+
+    if doc.tag == "group" then return doc end -- Skip if already grouped.
+
+    local flattened = flatten(doc)
+    if flattened == doc then return doc end -- Also skip if flattening does nothing.
+    return setmetatable({ tag = "group", flattened, doc }, Doc)
+end
+
+local function get_remaining(doc, width)
+    local kind = doc.tag
+    if kind == "nil" or kind == "line" then
+        return width
+    elseif kind == "text" then
+        return width - #doc.text
+    elseif kind == "concat" then
+        for i = 1, doc.n do
+            width = get_remaining(doc[i], width)
+            if width < 0 then break end
+        end
+        return width
+    elseif kind == "group" or kind == "nest" then
+        return get_remaining(kind[1])
+    else
+        error("Unknown doc " .. kind)
+    end
+end
+
+--- Display a document on the terminal.
+--
+-- @tparam          Doc     doc         The document to render
+-- @tparam[opt=0.6] number  ribbon_frac The maximum fraction of the width that we should write in.
+local function write(doc, ribbon_frac)
+    if getmetatable(doc) ~= Doc then expect(1, doc, "document") end
+    expect(2, ribbon_frac, "number", "nil")
+
+    local term = term
+    local width, height = term.getSize()
+    local ribbon_width = (ribbon_frac or 0.6) * width
+    if ribbon_width < 0 then ribbon_width = 0 end
+    if ribbon_width > width then ribbon_width = width end
+
+    local def_colour = term.getTextColour()
+    local current_colour = def_colour
+
+    local function go(doc, indent, col)
+        local kind = doc.tag
+        if kind == "nil" then
+            return col
+        elseif kind == "text" then
+            local doc_colour = doc.colour or def_colour
+            if doc_colour ~= current_colour then
+                term.setTextColour(doc_colour)
+                current_colour = doc_colour
+            end
+
+            str_write(doc.text)
+
+            return col + #doc.text
+        elseif kind == "line" then
+            local _, y = term.getCursorPos()
+            if y < height then
+                term.setCursorPos(indent + 1, y + 1)
+            else
+                term.scroll(1)
+                term.setCursorPos(indent + 1, height)
+            end
+
+            return indent
+        elseif kind == "concat" then
+            for i = 1, doc.n do col = go(doc[i], indent, col) end
+            return col
+        elseif kind == "nest" then
+            return go(doc[1], indent + doc.depth, col)
+        elseif kind == "group" then
+            if get_remaining(doc[1], math.min(width, ribbon_width + indent) - col) >= 0 then
+                return go(doc[1], indent, col)
+            else
+                return go(doc[2], indent, col)
+            end
+        else
+            error("Unknown doc " .. kind)
+        end
+    end
+
+    local col = math.max(term.getCursorPos() - 1, 0)
+    go(doc, 0, col)
+    if current_colour ~= def_colour then term.setTextColour(def_colour) end
+end
+
+--- Display a document on the terminal with a trailing new line.
+--
+-- @tparam          Doc     doc         The document to render.
+-- @tparam[opt=0.6] number  ribbon_frac The maximum fraction of the width that we should write in.
+local function print(doc, ribbon_frac)
+    if getmetatable(doc) ~= Doc then expect(1, doc, "document") end
+    expect(2, ribbon_frac, "number", "nil")
+    write(doc, ribbon_frac)
+    str_write("\n")
+end
+
+--- Render a document, converting it into a string.
+--
+-- @tparam          Doc     doc         The document to render.
+-- @tparam[opt]     number  width       The maximum width of this document. Note that long strings will not be wrapped to
+-- fit this width - it is only used for finding the best layout.
+-- @tparam[opt=0.6] number  ribbon_frac The maximum fraction of the width that we should write in.
+-- @treturn string The rendered document as a string.
+local function render(doc, width, ribbon_frac)
+    if getmetatable(doc) ~= Doc then expect(1, doc, "document") end
+    expect(2, width, "number", "nil")
+    expect(3, ribbon_frac, "number", "nil")
+
+    local ribbon_width
+    if width then
+        ribbon_width = (ribbon_frac or 0.6) * width
+        if ribbon_width < 0 then ribbon_width = 0 end
+        if ribbon_width > width then ribbon_width = width end
+    end
+
+    local out = { n = 0 }
+    local function go(doc, indent, col)
+        local kind = doc.tag
+        if kind == "nil" then
+            return col
+        elseif kind == "text" then
+            append(out, doc.text)
+            return col + #doc.text
+        elseif kind == "line" then
+            append(out, "\n" .. (" "):rep(indent))
+            return indent
+        elseif kind == "concat" then
+            for i = 1, doc.n do col = go(doc[i], indent, col) end
+            return col
+        elseif kind == "nest" then
+            return go(doc[1], indent + doc.depth, col)
+        elseif kind == "group" then
+            if not width or get_remaining(doc[1], math.min(width, ribbon_width + indent) - col) >= 0 then
+                return go(doc[1], indent, col)
+            else
+                return go(doc[2], indent, col)
+            end
+        else
+            error("Unknown doc " .. kind)
+        end
+    end
+
+    go(doc, 0, 0)
+    return table.concat(out, "", 1, out.n)
+end
+
+Doc.__tostring = render --- @local
+
+local keywords = {
+    ["and"] = true, ["break"] = true, ["do"] = true, ["else"] = true,
+    ["elseif"] = true, ["end"] = true, ["false"] = true, ["for"] = true,
+    ["function"] = true, ["if"] = true, ["in"] = true, ["local"] = true,
+    ["nil"] = true, ["not"] = true, ["or"] = true, ["repeat"] = true, ["return"] = true,
+    ["then"] = true, ["true"] = true, ["until"] = true, ["while"] = true,
+  }
+
+local comma = text(",")
+local braces = text("{}")
+local obrace, cbrace = text("{"), text("}")
+local obracket, cbracket = text("["), text("] = ")
+
+local function key_compare(a, b)
+    local ta, tb = type(a), type(b)
+
+    if ta == "string" then return tb ~= "string" or a < b
+    elseif tb == "string" then return false
+    end
+
+    if ta == "number" then return tb ~= "number" or a < b end
+    return false
+end
+
+local function show_function(fn, options)
+    local info = debug_info and debug_info(fn, "Su")
+
+    -- Include function source position if available
+    local name
+    if options.function_source and info and info.short_src and info.linedefined and info.linedefined >= 1 then
+        name = "function<" .. info.short_src .. ":" .. info.linedefined .. ">"
+    else
+        name = tostring(fn)
+    end
+
+    -- Include arguments if a Lua function and if available. Lua will report "C"
+    -- functions as variadic.
+    if options.function_args and info and info.what == "Lua" and info.nparams and debug_local then
+        local args = {}
+        for i = 1, info.nparams do args[i] = debug_local(fn, i) or "?" end
+        if info.isvararg then args[#args + 1] = "..." end
+        name = name .. "(" .. table.concat(args, ", ") .. ")"
+    end
+
+    return name
+end
+
+local function pretty_impl(obj, options, tracking)
+    local obj_type = type(obj)
+    if obj_type == "string" then
+        local formatted = ("%q"):format(obj):gsub("\\\n", "\\n")
+        return text(formatted, colours.red)
+    elseif obj_type == "number" then
+        return text(tostring(obj), colours.magenta)
+    elseif obj_type == "function" then
+        return text(show_function(obj, options), colours.lightGrey)
+    elseif obj_type ~= "table" or tracking[obj] then
+        return text(tostring(obj), colours.lightGrey)
+    elseif getmetatable(obj) ~= nil and getmetatable(obj).__tostring then
+        return text(tostring(obj))
+    elseif next(obj) == nil then
+        return braces
+    else
+        tracking[obj] = true
+        local doc = setmetatable({ tag = "concat", n = 1, space_line }, Doc)
+
+        local length, keys, keysn = #obj, {}, 1
+        for k in pairs(obj) do
+            if type(k) ~= "number" or k % 1 ~= 0 or k < 1 or k > length then
+                keys[keysn], keysn = k, keysn + 1
+            end
+        end
+        table.sort(keys, key_compare)
+
+        for i = 1, length do
+            if i > 1 then append(doc, comma) append(doc, space_line) end
+            append(doc, pretty_impl(obj[i], options, tracking))
+        end
+
+        for i = 1, keysn - 1 do
+            if i > 1 or length >= 1 then append(doc, comma) append(doc, space_line) end
+
+            local k = keys[i]
+            local v = obj[k]
+            if type(k) == "string" and not keywords[k] and k:match("^[%a_][%a%d_]*$") then
+                append(doc, text(k .. " = "))
+                append(doc, pretty_impl(v, options, tracking))
+            else
+                append(doc, obracket)
+                append(doc, pretty_impl(k, options, tracking))
+                append(doc, cbracket)
+                append(doc, pretty_impl(v, options, tracking))
+            end
+        end
+
+        tracking[obj] = nil
+        return group(concat(obrace, nest(2, concat(table.unpack(doc, 1, doc.n))), space_line, cbrace))
+    end
+end
+
+--- Pretty-print an arbitrary object, converting it into a document.
+--
+-- This can then be rendered with @{write} or @{print}.
+--
+-- @param obj The object to pretty-print.
+-- @tparam[opt] { function_args = boolean, function_source = boolean } options
+-- Controls how various properties are displayed.
+--  - `function_args`: Show the arguments to a function if known (`false` by default).
+--  - `function_source`: Show where the function was defined, instead of
+--    `function: xxxxxxxx` (`false` by default).
+-- @treturn Doc The object formatted as a document.
+-- @changed 1.88.0 Added `options` argument.
+-- @usage Display a table on the screen
+--
+--     local pretty = require "cc.pretty"
+--     pretty.print(pretty.pretty({ 1, 2, 3 }))
+-- @see pretty_print for a shorthand to prettify and print an object.
+local function pretty(obj, options)
+    expect(2, options, "table", "nil")
+    options = options or {}
+
+    local actual_options = {
+        function_source = field(options, "function_source", "boolean", "nil") or false,
+        function_args = field(options, "function_args", "boolean", "nil") or false,
+    }
+    return pretty_impl(obj, actual_options, {})
+end
+
+--[[- A shortcut for calling @{pretty} and @{print} together.
+
+@param obj The object to pretty-print.
+@tparam[opt] { function_args = boolean, function_source = boolean } options
+Controls how various properties are displayed.
+ - `function_args`: Show the arguments to a function if known (`false` by default).
+ - `function_source`: Show where the function was defined, instead of
+   `function: xxxxxxxx` (`false` by default).
+@tparam[opt=0.6] number ribbon_frac The maximum fraction of the width that we should write in.
+
+@usage Display a table on the screen.
+
+    local pretty = require "cc.pretty"
+    pretty.pretty_print({ 1, 2, 3 })
+
+@see pretty
+@see print
+@since 1.99
+]]
+local function pretty_print(obj, options, ribbon_frac)
+    expect(2, options, "table", "nil")
+    options = options or {}
+    expect(3, ribbon_frac, "number", "nil")
+
+    return print(pretty(obj, options), ribbon_frac)
+end
+
+return {
+    empty = empty,
+    space = space,
+    line = line,
+    space_line = space_line,
+    text = text,
+    concat = concat,
+    nest = nest,
+    group = group,
+
+    write = write,
+    print = print,
+    render = render,
+
+    pretty = pretty,
+
+    pretty_print = pretty_print,
+}

data/computercraft/lua/rom/modules/main/cc/shell/completion.lua

@@ -0,0 +1,113 @@
+-- cc.shell.completion
+-- XXX incompatible: functions do not accept a 'shell' argument
+
+local completion = require("cc.completion")
+local expect = require("cc.expect").expect
+local shell = require("shell")
+local fs = require("fs")
+
+local c = {}
+
+function c.file(text)
+  expect(1, text, "string")
+  return fs.complete(text, shell.dir(), true, false)
+end
+
+function c.dir(text)
+  expect(1, text, "string")
+  return fs.complete(text, shell.dir(), false)
+end
+
+function c.dirOrFile(text, previous, add_space)
+  expect(1, text, "string")
+  expect(2, previous, "table")
+  expect(3, add_space, "boolean", "nil")
+  local completed = fs.complete(text, shell.dir(), true, true)
+
+  if add_space then
+    for i=1, #completed, 1 do
+      completed[i] = completed[i] .. " "
+    end
+  end
+
+  return completed
+end
+
+function c.program(text, add_space)
+  expect(1, text, "string")
+  expect(2, add_space, "boolean", "table", "nil")
+  local progs = shell.programs()
+  local files = c.file(text)
+
+  local seen = {}
+  for i=1, #files, 1 do
+    local full = text..files[i]
+    if fs.isDir(full) and full:sub(-1) ~= "/" then
+      full = full .. "/"
+    end
+    if not seen[full] then
+      progs[#progs+1] = full
+    end
+    seen[full] = true
+  end
+
+  table.sort(progs, function(a,b) return #a < #b end)
+
+  return completion.choice(text, progs, add_space)
+end
+
+function c.programWithArgs(text, previous, starting)
+  expect(1, text, "string")
+  expect(2, previous, "table")
+  expect(3, starting, "number")
+
+  if not previous[starting] then
+    return shell.completeProgram(text)
+  end
+
+  local command = previous[starting]
+  command = shell.aliases()[command] or command
+  local complete = shell.getCompletionInfo()[command]
+
+  if complete then
+    return complete(#previous - starting + 1, text,
+      {table.unpack(previous, starting)})
+  end
+end
+
+for k,v in pairs(completion) do
+  c[k] = function(text, _, ...) return v(text, ...) end
+end
+
+function c.build(...)
+  local args = table.pack(...)
+
+  for i=1, args.n, 1 do
+    expect(i, args[i], "function", "table", "nil")
+  end
+
+  return function(index, current, previous)
+    local complete
+    if args.n < index then
+      if type(args[args.n]) == "table" and args[args.n].many then
+        complete = args[args.n]
+      end
+
+    else
+      complete = args[index]
+    end
+
+    if not complete then
+      return {}
+    end
+
+    if type(complete) == "function" then
+      return complete(current, previous)
+
+    elseif type(complete) == "table" then
+      return complete[1](current, previous, table.unpack(complete, 2))
+    end
+  end
+end
+
+return c

data/computercraft/lua/rom/modules/main/cc/strings.lua

@@ -0,0 +1,133 @@
+-- cc.strings
+
+local term = require("term")
+local expectlib = require("cc.expect")
+local expect = expectlib.expect
+local field = expectlib.field
+local strings = {}
+
+local function count(...)
+  local tab = table.pack(...)
+  local n = 0
+
+  for i=1, tab.n, 1 do
+    if tab[i] then n = n + 1 end
+  end
+
+  return n
+end
+
+function strings.splitElements(text, limit)
+  expect(1, text, "string")
+  expect(2, limit, "number", "nil")
+
+  local tokens = {}
+
+  while #text > 0 do
+    local ws = text:match("^[ \t]+")
+    local nl = text:match("^\n+")
+    local sep = text:match("^[%-%+%*]")
+    local word = text:match("^[^ \t\n%-%+%*]+")
+
+    if count(ws, nl, sep, word) > 1 then
+      error(("Edge case: %q, %q, %q, %q"):format(ws, nl, sep, word), 0)
+    end
+
+    local token = ws or nl or sep or word
+    text = text:sub(#token + 1)
+
+    while #token > 0 do
+      local ttext = token:sub(1, limit or 65535)
+      token = token:sub(#ttext + 1)
+
+      tokens[#tokens+1] = { text = ttext, type = ws and "ws" or nl and "nl"
+        or sep and "word" or word and "word" }
+    end
+  end
+
+  return tokens
+end
+
+function strings.wrappedWriteElements(elements, width, doHalves, handler)
+  expect(1, elements, "table")
+  expect(2, width, "number")
+  expect(3, doHalves, "boolean", "nil")
+  expect(4, handler, "table")
+
+  field(handler, "newline", "function")
+  field(handler, "append", "function")
+  field(handler, "getX", "function")
+
+  for i=1, #elements, 1 do
+    local e = elements[i]
+
+    if e.type == "nl" then
+      for _=1, #e.text do handler.newline() end
+
+    elseif e.type == "ws" then
+      local x = handler.getX()
+
+      if x + #e.text > width + 1 then
+        handler.newline()
+
+      else
+        handler.append(e.text)
+      end
+
+    elseif e.type == "word" then
+      local x = handler.getX()
+      local half = math.ceil(#e.text / 2)
+
+      if x + #e.text > width + 1 then
+        if doHalves and x + half < width and #e.text > width/2 then
+          local halfText = e.text:sub(1, math.floor(#e.text / 2)) .. "-"
+          e.text = e.text:sub(#halfText)
+          handler.append(halfText)
+          handler.newline()
+
+        elseif x > 1 then
+          handler.newline()
+        end
+      end
+
+      handler.append(e.text)
+    end
+  end
+end
+
+function strings.wrap(text, width, doHalves)
+  expect(1, text, "string")
+  expect(2, width, "number", "nil")
+  expect(3, doHalves, "boolean", "nil")
+
+  width = width or term.getSize()
+
+  local lines = { "" }
+  local elements = strings.splitElements(text, width)
+
+  strings.wrappedWriteElements(elements, width, doHalves, {
+    newline = function()
+      lines[#lines+1] = ""
+    end,
+
+    append = function(newText)
+      lines[#lines] = lines[#lines] .. newText
+    end,
+
+    getX = function()
+      return #lines[#lines]
+    end
+  })
+
+  return lines
+end
+
+function strings.ensure_width(line, width)
+  expect(1, line, "string")
+  expect(2, width, "number", "nil")
+  width = width or term.getSize()
+
+  return (line .. (" "):rep(width - #line)):sub(1, width)
+end
+
+return strings

data/computercraft/lua/rom/modules/main/edit/syntax.lua

@@ -0,0 +1,198 @@
+-- A simple, fairly clever method of tokenizing code.
+-- Each token is defined by a set of rules.  These rules are
+-- accordingly defined in the relevant syntax definition file.
+-- A rule takes the form of a triplet of functions:
+--  - The first function takes a single character, and returns
+--    whether that character is valid as part of the corresponding
+--    token.
+--  - The second function takes a single character and the current
+--    token, and returns whether that character is valid as part
+--    of the token.  This allows flexible implementations of highly
+--    language-specific features such as strings.
+--  - The third function takes only a token, and returns whether
+--    that token is valid.
+--
+-- Multiple tokens may be evaluated in parallel and the longest is returned.
+
+local lib = {}
+
+local syntenv = {
+  char = function(str)
+    return {
+      function(c)
+        return c == str:sub(1,1)
+      end,
+      function(tk, c)
+        return tk .. c == str:sub(1, #tk + 1)
+      end,
+      function(tk)
+        return tk == str
+      end
+    }
+  end,
+  print = print,
+  string = string, table = table,
+  pairs = pairs, ipairs = ipairs,
+  tonumber = tonumber, math = math,
+  globalenv = _G, type = type,
+}
+
+-- basic ""reader""
+local function reader(text)
+  local chars = {}
+  for c in text:gmatch(".") do
+    chars[#chars+1] = c
+  end
+
+  local i = 0
+  return {
+    advance = function()
+      i = i + 1
+      return chars[i]
+    end,
+    backpedal = function()
+      i = math.max(0, i - 1)
+    end
+  }
+end
+
+-- Takes a file and returns a builder.
+function lib.new(file)
+  local definitions = assert(loadfile(file, "t", syntenv))()
+
+  for _, _defs in pairs(definitions) do
+    for i, ent in pairs(_defs) do
+      if type(ent) == "string" then
+        _defs[i] = syntenv.char(ent)
+      end
+    end
+  end
+
+  return function(text)
+    local read = reader(text)
+    local possibilities = {}
+    local aux = ""
+
+    -- find and return the most likely (aka, longest) token and its class
+    local function most_likely()
+      -- if there are no possibilities, then ...
+      if #possibilities == 0 then
+        -- ... if the aux value has some characters, return that ...
+        if #aux > 0 then
+          local result = aux
+          aux = ""
+          return result
+        else
+          -- ... otherwise return nil.
+          return nil
+        end
+      end
+
+      local former_longest, new_longest = 0, 0
+
+      -- remove all invalid possibilites
+      for i=#possibilities, 1, -1 do
+        if not possibilities[i].valid(possibilities[i].token) then
+          former_longest = math.max(#possibilities[i].token, former_longest)
+          table.remove(possibilities, i)
+        else
+          new_longest = math.max(#possibilities[i].token, new_longest)
+        end
+      end
+
+      if former_longest > new_longest then
+        for _=new_longest, former_longest - 1 do
+          read.backpedal()
+        end
+      end
+
+      -- sort possibilities by length - and deprioritize whitespace/word
+      table.sort(possibilities, function(a, b)
+        return #a.token > #b.token
+            or (#a.token == #b.token and b.class == "word")
+            or b.class == "whitespace"
+      end)
+
+      if #possibilities == 0 then
+        --read.backpedal()
+        return most_likely()
+      end
+
+      -- grab the first (longest) one
+      local token, class = possibilities[1].token, possibilities[1].class
+      -- reset possibilities
+      possibilities = {}
+
+      aux = ""
+
+      -- return it
+      return token, class
+    end
+
+    -- return an iterator!
+    return function()
+      while true do
+        local c = read.advance()
+
+        -- if no character, return the most likely token
+        if not c then return most_likely() end
+
+        if #possibilities == 0 then
+          -- if no current possibilities, then go through and check for them
+          for class, defs in pairs(definitions) do
+            for _, funcs in pairs(defs) do
+              if funcs[1](c) then
+                -- if the token is valid, add it here
+                possibilities[#possibilities+1] = {
+                  check = funcs[2], class = class, token = c,
+                  valid = funcs[3] or function()return true end, active = true
+                }
+              end
+            end
+          end
+
+          -- if there are now some possibilities, return whatever the "aux"
+          -- value was
+          if #possibilities > 0 then
+            if #aux > 0 then
+              local temp = aux--:sub(1,-2)
+              aux = ""
+              return temp
+            end
+            aux = c
+          else
+            -- otherwise, add c to the aux value
+            aux = aux .. c
+          end
+        else
+          aux = aux .. c
+          -- whether any possibilities matched
+          local valid_for_any = false
+
+          for _, p in ipairs(possibilities) do
+            -- 'active' is roughly equal to whether the last character matched
+            if p.active then
+              -- if valid, set valid_for_any to true and add c to its valid
+              if p.check(p.token, c) then
+                valid_for_any = true
+                p.token = p.token .. c
+              else
+                -- otherwise, disable it from future checks
+                p.active = false
+              end
+            end
+          end
+
+          -- if nothing was valid, retract the current character
+          -- and return the most likely token
+          if not valid_for_any then
+            read.backpedal()
+            return most_likely()
+          end
+        end
+      end
+    end
+  end
+end
+
+return lib

data/computercraft/lua/rom/modules/main/edit/syntax/lua.lua

@@ -0,0 +1,152 @@
+local syn = {
+  whitespace = {
+    {
+      function(c)
+        return c:match("[ \n\r\t]")
+      end,
+      function()
+        return false
+      end,
+      function(c)
+        return c:match("^[ \n\r\t]+")
+      end
+    },
+  },
+  word = {
+    {
+      function(c)
+        return not not c:match("[a-zA-Z_]")
+      end,
+      function(_, c)
+        return not not c:match("[a-zA-Z_0-9]")
+      end
+    }
+  },
+  keyword = {
+    "const", "close", "local", "while", "for", "repeat", "until", "do", "if",
+    "in", "else", "elseif", "and", "or", "not", "then", "end", "return",
+    "goto", "break",
+  },
+  builtin = {
+    "function",
+  },
+  separator = {
+    ",", "(", ")", "{", "}", "[", "]",
+  },
+  operator = {
+    "+", "-", "/", "*", "//", "==", ">>", "<<", ">", "<", "=", "&",
+    "|", "^", "%", "~", "...", "..", "~=", "#", ".", ":"
+  },
+  boolean = {
+    "true", "false", "nil"
+  },
+  comment = {
+    {
+      function(c)
+        return c == "-"
+      end,
+      function(t,c)
+        if t == "-" and c ~= "-" then return false end
+        return c ~= "\n"
+      end,
+      function(t)
+        return #t > 1
+      end
+    },
+    {
+      function(c)
+        return c == "-"
+      end,
+      function(t,c)
+        if t == "-" and c == "-" then return true
+        elseif t == "--" and c == "[" then return true
+        elseif t == "--[" and c == "=" and c == "[" then return true
+        elseif t:match("^%-%-%[(=*)$") and c == "=" and c == "[" then
+          return true
+        end
+        local eqs = t:match("^%-%-%[(=*)")
+        if not eqs then
+          return false
+        else
+          if #t == #eqs + 3 and c == "[" then return true end
+          if t:sub(-(#eqs+2)) == "]"..eqs.."]" then
+            return false
+          else
+            return true
+          end
+        end
+      end,
+      function(t)
+        return #t > 3
+      end
+    }
+  },
+  string = {
+    {
+      function(c)
+        return c == "'" or c == '"'
+      end,
+      function(t, c)
+        local first = t:sub(1,1)
+        local last = t:sub(#t)
+        local penultimate = t:sub(-2, -2)
+        if #t == 1 then return true end
+        if first == last and penultimate ~= "\\" then return false end
+        return true
+      end
+    },
+    {
+      function(c)
+        return c == "["
+      end,
+      function(t,c)
+        if t == "[" then
+          return c == "=" or c == "["
+        elseif t:match("^%[(=*)$") and (c == "=" or c == "[") then
+          return true
+        end
+        local eqs = t:match("^%[(=*)")
+        if not eqs then
+          return false
+        else
+          if #t == #eqs + 3 and c == "[" then return true end
+          if t:sub(-(#eqs+2)) == "]"..eqs.."]" then
+            return false
+          else
+            return true
+          end
+        end
+      end,
+      function(t)
+        return #t > 2
+      end
+    }
+  },
+  number = {
+    {
+      function(c)
+        return not not tonumber(c)
+      end,
+      function(t, c)
+        return not not tonumber(t .. c .. "0")
+      end
+    }
+  }
+}
+
+local seen = {}
+local function add(k, v)
+  if not v then return end
+  if seen[v] then return end
+  seen[v] = true
+  for _k, _v in pairs(v) do
+    syn.builtin[#syn.builtin+1] = char((k and k.."." or "").._k)
+    if type(_v) == "table" then
+      add((k and k.."." or "").._k, _v)
+    end
+  end
+end
+
+add(nil, globalenv)
+
+return syn

data/computercraft/lua/rom/modules/main/rc/copy.lua

@@ -0,0 +1,36 @@
+-- rc.copy - table copier
+
+-- from https://lua-users.org/wiki/CopyTable
+local function deepcopy(orig, copies, dont_copy)
+  copies = copies or {}
+  local orig_type = type(orig)
+  local copy
+
+  if orig_type == 'table' and not dont_copy[orig] then
+    if copies[orig] then
+      copy = copies[orig]
+    else
+      copy = {}
+      copies[orig] = copy
+
+      for orig_key, orig_value in next, orig, nil do
+        copy[deepcopy(orig_key, copies, dont_copy)] = deepcopy(orig_value,
+          copies, dont_copy)
+      end
+
+      setmetatable(copy, deepcopy(getmetatable(orig), copies, dont_copy))
+    end
+  else -- number, string, boolean, etc
+    copy = orig
+  end
+
+  return copy
+end
+
+return { copy = function(original, ...)
+  local dont_copy = {}
+  for _, thing in pairs({...}) do
+    dont_copy[thing] = true
+  end
+  return deepcopy(original, nil, dont_copy)
+end }

data/computercraft/lua/rom/modules/main/rc/io.lua

@@ -0,0 +1,231 @@
+-- rc.io
+
+local expect = require("cc.expect").expect
+local thread = require("rc.thread")
+local colors = require("colors")
+local term = require("term")
+local fs = require("fs")
+local rc = require("rc")
+
+local io = {}
+
+local _file = {}
+function _file:read(...)
+  local args = table.pack(...)
+  local ret = {}
+
+  if args.n == 0 then
+    args[1] = "l"
+    args.n = 1
+  end
+
+  if not (self.handle.read and pcall(self.handle.read, 0)) then
+    return nil, "bad file descriptor"
+  end
+
+  if self.handle.flush then self.handle.flush() end
+
+  for i=1, args.n, 1 do
+    local format = args[i]
+    if format:sub(1,1) == "*" then
+      format = format:sub(2)
+    end
+
+    if format == "a" then
+      ret[#ret+1] = self.handle.readAll()
+
+    elseif format == "l" or format == "L" then
+      ret[#ret+1] = self.handle.readLine(format == "L")
+
+    elseif type(format) == "number" then
+      ret[#ret+1] = self.handle.read(format)
+
+    else
+      error("invalid format '"..format.."'", 2)
+    end
+  end
+
+  return table.unpack(ret, 1, args.n)
+end
+
+function _file:lines(...)
+  local formats = {...}
+  if #formats == 0 then
+    formats[1] = "l"
+  end
+  return function()
+    return self:read(table.unpack(formats))
+  end
+end
+
+function _file:write(...)
+  local args = table.pack(...)
+
+  if not (self.handle.write and pcall(self.handle.write, "")) then
+    return nil, "bad file descriptor"
+  end
+
+  for i=1, args.n, 1 do
+    self.handle.write(args[i])
+  end
+
+  return self
+end
+
+function _file:seek(whence, offset)
+  expect(1, whence, "string", "nil")
+  expect(2, offset, "number", "nil")
+  if self.handle.seek then
+    return self.handle.seek(whence, offset)
+  else
+    return nil, "bad file descriptor"
+  end
+end
+
+function _file:flush()
+  if self.handle.flush then self.handle.flush() end
+  return self
+end
+
+function _file:close()
+  self.closed = true
+  pcall(self.handle.close)
+end
+
+local function iofile(handle)
+  return setmetatable({handle = handle, closed = false}, {__index = _file})
+end
+
+local stdin_rbuf = ""
+io.stdin = iofile {
+  read = function(n)
+    while #stdin_rbuf < n do
+      stdin_rbuf = stdin_rbuf .. term.read() .. "\n"
+    end
+    local ret = stdin_rbuf:sub(1, n)
+    stdin_rbuf = stdin_rbuf:sub(#ret+1)
+    return ret
+  end,
+
+  readLine = function(trail)
+    local nl = stdin_rbuf:find("\n")
+
+    if nl then
+      local ret = stdin_rbuf:sub(1, nl+1)
+      if not trail then ret = ret:sub(1, -2) end
+      stdin_rbuf = stdin_rbuf:sub(#ret+1)
+      return ret
+
+    else
+      return stdin_rbuf .. term.read() .. (trail and "\n" or "")
+    end
+  end
+}
+
+io.stdout = iofile {
+  write = rc.write
+}
+
+io.stderr = iofile {
+  write = function(text)
+    local old = term.getTextColor()
+    term.setTextColor(colors.red)
+    rc.write(text)
+    term.setTextColor(old)
+  end
+}
+
+function io.open(file, mode)
+  expect(1, file, "string")
+  expect(2, mode, "string", "nil")
+
+  mode = (mode or "r"):match("[rwa]") .. "b"
+
+  local handle, err = fs.open(file, mode)
+  if not handle then
+    return nil, err
+  end
+
+  return iofile(handle)
+end
+
+function io.input(file)
+  expect(1, file, "string", "table", "nil")
+  local vars = thread.vars()
+  if type(file) == "string" then file = assert(io.open(file, "r")) end
+  if file then vars.input = file end
+  return vars.input or io.stdin
+end
+
+function io.output(file)
+  expect(1, file, "string", "table", "nil")
+  local vars = thread.vars()
+  if type(file) == "string" then file = assert(io.open(file, "w")) end
+  if file then vars.output = file end
+  return vars.output or io.stdout
+end
+
+function io.read(...)
+  return io.input():read(...)
+end
+
+function io.write(...)
+  return io.output():write(...)
+end
+
+function io.flush(file)
+  expect(1, file, "table", "nil")
+  return (file or io.output):flush()
+end
+
+function io.close(file)
+  expect(1, file, "table", "nil")
+  return (file or io.output):close()
+end
+
+function io.lines(file, ...)
+  expect(1, file, "string", "nil")
+  if file then file = assert(io.open(file, "r")) end
+  local formats = table.pack(...)
+  return (file or io.stdin):lines(table.unpack(formats, 1, formats.n))
+end
+
+function io.type(obj)
+  if type(obj) == "table" then
+    local is_file = true
+    for k, v in pairs(_file) do
+      if (not obj[k]) or v ~= obj[k] then
+        is_file = false
+      end
+    end
+
+    if is_file then
+      return obj.closed and "closed file" or "file"
+    end
+  end
+end
+
+-- loadfile and dofile here as well
+function _G.loadfile(file, mode, env)
+  expect(1, file, "string")
+  expect(2, mode, "string", "nil")
+  expect(3, env, "table", "nil")
+  local handle, err = io.open(file, "r")
+  if not handle then
+    return nil, file .. ": " .. err
+  end
+  local data = handle:read("a")
+  handle:close()
+  return load(data, "="..file, mode or "bt", env)
+end
+
+function _G.dofile(file, ...)
+  expect(1, file, "string")
+  local func, err = loadfile(file)
+  if not func then
+    error(err)
+  end
+  return func(...)
+end
+
+return io

data/computercraft/lua/rom/modules/main/rc/json.lua

@@ -0,0 +1,388 @@
+--
+-- json.lua
+--
+-- Copyright (c) 2020 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.
+--
+
+local json = { _version = "0.1.2" }
+
+-------------------------------------------------------------------------------
+-- Encode
+-------------------------------------------------------------------------------
+
+local encode
+
+local escape_char_map = {
+  [ "\\" ] = "\\",
+  [ "\"" ] = "\"",
+  [ "\b" ] = "b",
+  [ "\f" ] = "f",
+  [ "\n" ] = "n",
+  [ "\r" ] = "r",
+  [ "\t" ] = "t",
+}
+
+local escape_char_map_inv = { [ "/" ] = "/" }
+for k, v in pairs(escape_char_map) do
+  escape_char_map_inv[v] = k
+end
+
+
+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 rawget(val, 1) ~= nil or next(val) == nil then
+    -- Treat as array -- check keys are valid and it is not sparse
+    local n = 0
+    for k in pairs(val) do
+      if type(k) ~= "number" then
+        error("invalid table: mixed or invalid key types")
+      end
+      n = n + 1
+    end
+    if n ~= #val then
+      error("invalid table: sparse array")
+    end
+    -- Encode
+    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
+      if type(k) ~= "string" then
+        error("invalid table: mixed or invalid key types")
+      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 string.format("%.14g", 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 literals      = create_set("true", "false", "null")
+
+local literal_map = {
+  [ "true"  ] = true,
+  [ "false" ] = false,
+  [ "null"  ] = nil,
+}
+
+
+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 codepoint_to_utf8(n)
+  -- http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=iws-appendixa
+  local f = math.floor
+  if n <= 0x7f then
+    return string.char(n)
+  elseif n <= 0x7ff then
+    return string.char(f(n / 64) + 192, n % 64 + 128)
+  elseif n <= 0xffff then
+    return string.char(f(n / 4096) + 224, f(n % 4096 / 64) + 128, n % 64 + 128)
+  elseif n <= 0x10ffff then
+    return string.char(f(n / 262144) + 240, f(n % 262144 / 4096) + 128,
+                       f(n % 4096 / 64) + 128, n % 64 + 128)
+  end
+  error( string.format("invalid unicode codepoint '%x'", n) )
+end
+
+
+local function parse_unicode_escape(s)
+  local n1 = tonumber( s:sub(1, 4),  16 )
+  local n2 = tonumber( s:sub(7, 10), 16 )
+   -- Surrogate pair?
+  if n2 then
+    return codepoint_to_utf8((n1 - 0xd800) * 0x400 + (n2 - 0xdc00) + 0x10000)
+  else
+    return codepoint_to_utf8(n1)
+  end
+end
+
+
+local function parse_string(str, i)
+  local res = ""
+  local j = i + 1
+  local k = j
+
+  while j <= #str do
+    local x = str:byte(j)
+
+    if x < 32 then
+      decode_error(str, j, "control character in string")
+
+    elseif x == 92 then -- `\`: Escape
+      res = res .. str:sub(k, j - 1)
+      j = j + 1
+      local c = str:sub(j, j)
+      if c == "u" then
+        local hex = str:match("^[dD][89aAbB]%x%x\\u%x%x%x%x", j + 1)
+                 or str:match("^%x%x%x%x", j + 1)
+                 or decode_error(str, j - 1, "invalid unicode escape in string")
+        res = res .. parse_unicode_escape(hex)
+        j = j + #hex
+      else
+        if not escape_chars[c] then
+          decode_error(str, j - 1, "invalid escape char '" .. c .. "' in string")
+        end
+        res = res .. escape_char_map_inv[c]
+      end
+      k = j + 1
+
+    elseif x == 34 then -- `"`: End of string
+      res = res .. str:sub(k, j - 1)
+      return res, j + 1
+    end
+
+    j = j + 1
+  end
+
+  decode_error(str, i, "expected closing quote for string")
+end
+
+
+local function parse_number(str, i)
+  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_literal(str, i)
+  local x = next_char(str, i, delim_chars)
+  local word = str:sub(i, x - 1)
+  if not literals[word] then
+    decode_error(str, i, "invalid literal '" .. word .. "'")
+  end
+  return literal_map[word], x
+end
+
+
+local function parse_array(str, i)
+  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)
+    local 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)
+  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
+    if str:sub(i, i) ~= '"' then
+      decode_error(str, i, "expected string for key")
+    end
+    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)
+    local 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,
+  [ "t" ] = parse_literal,
+  [ "f" ] = parse_literal,
+  [ "n" ] = parse_literal,
+  [ "[" ] = 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)
+  end
+  decode_error(str, idx, "unexpected character '" .. chr .. "'")
+end
+
+
+function json.decode(str)
+  if type(str) ~= "string" then
+    error("expected argument of type string, got " .. type(str))
+  end
+  local res, idx = parse(str, next_char(str, 1, space_chars, true))
+  idx = next_char(str, idx, space_chars, true)
+  if idx <= #str then
+    decode_error(str, idx, "trailing garbage")
+  end
+  return res
+end
+
+
+return json

data/computercraft/lua/rom/modules/main/rc/thread.lua

@@ -0,0 +1,398 @@
+-- New scheduler.
+-- Tabs are integral to the design of this scheduler;  Multishell cannot
+-- be disabled.
+
+local rc = require("rc")
+local fs = require("fs")
+local keys = require("keys")
+local term = require("term")
+local colors = require("colors")
+local window = require("window")
+local expect = require("cc.expect")
+local copy = require("rc.copy").copy
+
+local getfenv
+if rc.lua51 then
+  getfenv = rc.lua51.getfenv
+else
+  getfenv = function() return _ENV or _G end
+end
+
+local tabs = { {} }
+local threads = {}
+local current, wrappedNative
+
+local focused = 1
+
+local api = {}
+
+function api.launchTab(x, name)
+  expect(1, x, "string", "function")
+  name = expect(2, name, "string", "nil") or tostring(x)
+
+  local newTab = {
+    term = window.create(wrappedNative, 1, 1, wrappedNative.getSize()),
+    id = #tabs + 1
+  }
+
+  tabs[newTab.id] = newTab
+
+  local _f = focused
+  focused = newTab.id
+  local id = (type(x) == "string" and api.load or api.spawn)(x, name)
+  focused = _f
+
+  return newTab.id, id
+end
+
+function api.setFocusedTab(f)
+  expect(1, f, "number")
+  if tabs[focused] then focused = f end
+  return not not tabs[f]
+end
+
+function api.getFocusedTab()
+  return focused
+end
+
+function api.getCurrentTab()
+  return current.tab.id
+end
+
+function api.load(file, name)
+  expect(1, file, "string")
+  name = expect(2, name, "string", "nil") or file
+
+  local env = copy(current and current.env or _ENV or _G, package.loaded)
+
+  local func, err = loadfile(file, "t", env)
+  if not func then
+    return nil, err
+  end
+
+  return api.spawn(func, name, tabs[focused])
+end
+
+function api.spawn(func, name, _)
+  expect(1, func, "function")
+  expect(2, name, "string")
+
+  local new = {
+    name = name,
+    coro = coroutine.create(function()
+      assert(xpcall(func, debug.traceback))
+    end),
+    vars = setmetatable({}, {__index = current and current.vars}),
+    env = getfenv(func) or _ENV or _G,
+    tab = _ or tabs[focused],
+    id = #threads + 1,
+    dir = current and current.dir or "/"
+  }
+
+  new.tab[new.id] = true
+  threads[new.id] = new
+
+  new.tab.name = name
+
+  return new.id
+end
+
+function api.exists(id)
+  expect(1, id, "number")
+  return not not threads[id]
+end
+
+function api.id()
+  return current.id
+end
+
+function api.dir()
+  return current.dir or "/"
+end
+
+function api.setDir(dir)
+  expect(1, dir, "string")
+
+  if not fs.exists(dir) then
+    return nil, "that directory does not exist"
+
+  elseif not fs.isDir(dir) then
+    return nil, "not a directory"
+  end
+
+  current.dir = dir
+
+  return true
+end
+
+function api.vars()
+  return current.vars
+end
+
+function api.getTerm()
+  return current and current.tab and current.tab.term or term.native()
+end
+
+function api.setTerm(new)
+  if tabs[focused] then
+    local old = tabs[focused].term
+    tabs[focused].term = new
+    return old
+  end
+end
+
+local w, h
+local function getName(tab)
+  local highest = 0
+
+  for k in pairs(tab) do
+    if type(k) == "number" then highest = math.max(highest, k) end
+  end
+
+  return threads[highest] and threads[highest].name or "???"
+end
+
+function api.info()
+  local running = {}
+  for i, thread in pairs(threads) do
+    running[#running+1] = { id = i, name = thread.name, tab = thread.tab.id }
+  end
+
+  table.sort(running, function(a,b) return a.id < b.id end)
+
+  return running
+end
+
+function api.remove(id)
+  expect(1, id, "number", "nil")
+  threads[id or current.id] = nil
+end
+
+local scroll = 0
+local totalNameLength = 0
+local function redraw()
+  w, h = wrappedNative.getSize()
+
+  wrappedNative.setVisible(false)
+
+  local names = {}
+  totalNameLength = 0
+  for i=1, #tabs, 1 do
+    names[i] = " " .. getName(tabs[i]) .. " "
+    totalNameLength = totalNameLength + #names[i]
+  end
+
+  if #tabs > 1 then
+    local len = -scroll + 1
+    wrappedNative.setCursorPos(1, 1)
+    wrappedNative.setTextColor(colors.black)
+    wrappedNative.setBackgroundColor(colors.gray)
+    wrappedNative.clearLine()
+
+    for i=1, #tabs, 1 do
+      local tab = tabs[i]
+      local name = names[i]
+
+      wrappedNative.setCursorPos(len, 1)
+      len = len + #name
+
+      if i == focused then
+        wrappedNative.setTextColor(colors.yellow)
+        wrappedNative.setBackgroundColor(colors.black)
+        wrappedNative.write(name)
+
+      else
+        wrappedNative.setTextColor(colors.black)
+        wrappedNative.setBackgroundColor(colors.gray)
+        wrappedNative.write(name)
+      end
+
+      tab.term.setVisible(false)
+      tab.term.reposition(1, 2, w, h - 1)
+    end
+
+    if totalNameLength > w-2 then
+      wrappedNative.setTextColor(colors.black)
+      wrappedNative.setBackgroundColor(colors.gray)
+      if scroll > 0 then
+        wrappedNative.setCursorPos(1, 1)
+        wrappedNative.write("<")
+      end
+      if totalNameLength - scroll > w-1 then
+        wrappedNative.setCursorPos(w, 1)
+        wrappedNative.write(">")
+      end
+    end
+
+    tabs[focused].term.setVisible(true)
+
+  elseif #tabs > 0 then
+    local tab = tabs[1]
+    tab.term.reposition(1, 1, w, h)
+    tab.term.setVisible(true)
+  end
+
+  wrappedNative.setVisible(true)
+end
+
+local inputEvents = {
+  key = true,
+  char = true,
+  key_up = true,
+  mouse_up = true,
+  mouse_drag = true,
+  mouse_click = true,
+  mouse_scroll = true,
+  terminate = true,
+}
+
+local altIsDown
+
+local function processEvent(event)
+  if inputEvents[event[1]] then
+    if #event > 3 then -- mouse event
+
+      if #tabs > 1 then
+        if event[4] == 1 then
+          local curX = -scroll
+
+          if event[1] == "mouse_scroll" then
+            scroll = math.max(0, math.min(totalNameLength-w+1,
+              scroll - event[2]))
+            return false
+          end
+
+          for i=1, #tabs, 1 do
+            local tab = tabs[i]
+            curX = curX + #getName(tab) + 2
+
+            if event[3] <= curX then
+              focused = i
+              redraw()
+              break
+            end
+          end
+
+          return false
+
+        else
+          event[4] = event[4] - 1
+        end
+      end
+
+    elseif event[1] == "key" then
+      if event[2] == keys.rightAlt then
+        altIsDown = event[2]
+        return false
+
+      elseif altIsDown then
+        local num = tonumber(keys.getName(event[2]))
+        if num then
+          if tabs[num] then
+            focused = num
+            redraw()
+            return false
+          end
+
+        elseif event[2] == keys.left then
+          focused = math.max(1, focused - 1)
+          redraw()
+          return false
+
+        elseif event[2] == keys.right then
+          focused = math.min(#tabs, focused + 1)
+          redraw()
+          return false
+
+        elseif event[2] == keys.up then
+          scroll = math.max(0, math.min(totalNameLength-w+1,
+            scroll + 1))
+          return false
+
+        elseif event[2] == keys.down then
+          scroll = math.max(0, math.min(totalNameLength-w+1,
+            scroll - 1))
+          return false
+        end
+      end
+
+    elseif event[1] == "key_up" then
+      if event[2] == keys.rightAlt then
+        altIsDown = false
+        return false
+      end
+
+    end
+  end
+
+  return true
+end
+
+local function cleanTabs()
+  for t=#tabs, 1, -1 do
+    local tab = tabs[t]
+
+    local count, removed = 0, 0
+    for i in pairs(tab) do
+      if type(i) == "number" then
+        count = count + 1
+        if not threads[i] then
+          removed = removed + 1
+          tab[i] = nil
+        end
+      end
+    end
+
+    if count == removed then
+      table.remove(tabs, t)
+    end
+  end
+
+  for i=1, #tabs, 1 do
+    tabs[i].id = i
+  end
+
+  focused = math.max(1, math.min(#tabs, focused))
+end
+
+function api.start()
+  api.start = nil
+
+  local _native = term.native()
+  wrappedNative = window.create(_native, 1, 1, _native.getSize())
+  api.launchTab("/rc/programs/shell.lua", "shell")
+
+  rc.pushEvent("init")
+
+  while #tabs > 0 and next(threads) do
+    cleanTabs()
+    redraw()
+    local event = table.pack(coroutine.yield())
+
+    if event[1] == "term_resize" then
+      wrappedNative.reposition(1, 1, _native.getSize())
+    end
+
+    if processEvent(event) then
+      for tid, thread in pairs(threads) do
+        if thread.tab == tabs[focused] or not inputEvents[event[1]] then
+          current = thread
+          local result = table.pack(coroutine.resume(thread.coro,
+            table.unpack(event, 1, event.n)))
+
+          if not result[1] then
+            io.stderr:write(result[2].."\n")
+            threads[tid] = nil
+
+          elseif coroutine.status(thread.coro) == "dead" then
+            threads[tid] = nil
+          end
+        end
+      end
+    end
+  end
+
+  rc.shutdown()
+end
+
+return api