repl.coffee

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repl.coffee

fs = require 'fs'
path = require 'path'
vm = require 'vm'
nodeREPL = require 'repl'
CoffeeScript = require './coffee-script'
{merge, updateSyntaxError} = require './helpers'

replDefaults =
  prompt: 'coffee> ',
  historyFile: path.join process.env.HOME, '.coffee_history' if process.env.HOME
  historyMaxInputSize: 10240
  eval: (input, context, filename, cb) ->

XXX: multiline hack.

    input = input.replace /\uFF00/g, '\n'

¶

Node’s REPL sends the input ending with a newline and then wrapped in parens. Unwrap all that.
```
    input = input.replace /^$([\s\S]*)\n$$/m, '$1'
```

Require AST nodes to do some AST manipulation.

    {Block, Assign, Value, Literal} = require './nodes'

    try

¶

Generate the AST of the clean input.
```
      ast = CoffeeScript.nodes input
```

Add assignment to _ variable to force the input to be an expression.

      ast = new Block [
        new Assign (new Value new Literal '_'), ast, '='
      ]
      js = ast.compile bare: yes, locals: Object.keys(context)
      result = if context is global
        vm.runInThisContext js, filename 
      else
        vm.runInContext js, context, filename
      cb null, result
    catch err

AST’s compile does not add source code information to syntax errors.

      updateSyntaxError err, input
      cb err

addMultilineHandler = (repl) ->
  {rli, inputStream, outputStream} = repl

  multiline =
    enabled: off
    initialPrompt: repl.prompt.replace /^[^> ]*/, (x) -> x.replace /./g, '-'
    prompt: repl.prompt.replace /^[^> ]*>?/, (x) -> x.replace /./g, '.'
    buffer: ''

Proxy node’s line listener

  nodeLineListener = rli.listeners('line')[0]
  rli.removeListener 'line', nodeLineListener
  rli.on 'line', (cmd) ->
    if multiline.enabled
      multiline.buffer += "#{cmd}\n"
      rli.setPrompt multiline.prompt
      rli.prompt true
    else
      nodeLineListener cmd
    return

Handle Ctrl-v

  inputStream.on 'keypress', (char, key) ->
    return unless key and key.ctrl and not key.meta and not key.shift and key.name is 'v'
    if multiline.enabled

allow arbitrarily switching between modes any time before multiple lines are entered

      unless multiline.buffer.match /\n/
        multiline.enabled = not multiline.enabled
        rli.setPrompt repl.prompt
        rli.prompt true
        return

no-op unless the current line is empty

      return if rli.line? and not rli.line.match /^\s*$/

eval, print, loop

      multiline.enabled = not multiline.enabled
      rli.line = ''
      rli.cursor = 0
      rli.output.cursorTo 0
      rli.output.clearLine 1

XXX: multiline hack

      multiline.buffer = multiline.buffer.replace /\n/g, '\uFF00'
      rli.emit 'line', multiline.buffer
      multiline.buffer = ''
    else
      multiline.enabled = not multiline.enabled
      rli.setPrompt multiline.initialPrompt
      rli.prompt true
    return

Store and load command history from a file

addHistory = (repl, filename, maxSize) ->
  lastLine = null
  try

Get file info and at most maxSize of command history

    stat = fs.statSync filename
    size = Math.min maxSize, stat.size

Read last size bytes from the file

    readFd = fs.openSync filename, 'r'
    buffer = new Buffer(size)
    fs.readSync readFd, buffer, 0, size, stat.size - size

Set the history on the interpreter

    repl.rli.history = buffer.toString().split('\n').reverse()

¶

If the history file was truncated we should pop off a potential partial line
```
    repl.rli.history.pop() if stat.size > maxSize
```

Shift off the final blank newline

    repl.rli.history.shift() if repl.rli.history[0] is ''
    repl.rli.historyIndex = -1
    lastLine = repl.rli.history[0]

  fd = fs.openSync filename, 'a'

  repl.rli.addListener 'line', (code) ->
    if code and code.length and code isnt '.history' and lastLine isnt code

Save the latest command in the file

      fs.write fd, "#{code}\n"
      lastLine = code

  repl.rli.on 'exit', -> fs.close fd

Add a command to show the history stack

  repl.commands['.history'] =
    help: 'Show command history'
    action: ->
      repl.outputStream.write "#{repl.rli.history[..].reverse().join '\n'}\n"
      repl.displayPrompt()

module.exports =
  start: (opts = {}) ->
    [major, minor, build] = process.versions.node.split('.').map (n) -> parseInt(n)

    if major is 0 and minor < 8
      console.warn "Node 0.8.0+ required for CoffeeScript REPL"
      process.exit 1

    CoffeeScript.register()
    process.argv = ['coffee'].concat process.argv[2..]
    opts = merge replDefaults, opts
    repl = nodeREPL.start opts
    repl.on 'exit', -> repl.outputStream.write '\n'
    addMultilineHandler repl
    addHistory repl, opts.historyFile, opts.historyMaxInputSize if opts.historyFile
    repl