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125 lines
3.5 KiB
CoffeeScript
125 lines
3.5 KiB
CoffeeScript
# A very simple Read-Eval-Print-Loop. Compiles one line at a time to JavaScript
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# and evaluates it. Good for simple tests, or poking around the **Node.js** API.
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# Using it looks like this:
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#
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# coffee> console.log "#{num} bottles of beer" for num in [99..1]
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# Require the **coffee-script** module to get access to the compiler.
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CoffeeScript = require './coffee-script'
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readline = require 'readline'
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{inspect} = require 'util'
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{Script} = require 'vm'
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Module = require 'module'
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# REPL Setup
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# Config
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REPL_PROMPT = 'coffee> '
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REPL_PROMPT_CONTINUATION = '......> '
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enableColours = no
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unless process.platform is 'win32'
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enableColours = not process.env.NODE_DISABLE_COLORS
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# Start by opening up `stdin` and `stdout`.
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stdin = process.openStdin()
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stdout = process.stdout
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# Log an error.
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error = (err) ->
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stdout.write (err.stack or err.toString()) + '\n'
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# The current backlog of multi-line code.
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backlog = ''
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# The main REPL function. **run** is called every time a line of code is entered.
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# Attempt to evaluate the command. If there's an exception, print it out instead
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# of exiting.
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run = (buffer) ->
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if !buffer.toString().trim() and !backlog
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repl.prompt()
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return
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code = backlog += buffer
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if code[code.length - 1] is '\\'
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backlog = "#{backlog[...-1]}\n"
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repl.setPrompt REPL_PROMPT_CONTINUATION
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repl.prompt()
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return
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repl.setPrompt REPL_PROMPT
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backlog = ''
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try
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_ = global._
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returnValue = CoffeeScript.eval "_=(#{code}\n)", {
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filename: 'repl'
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modulename: 'repl'
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}
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if returnValue is undefined
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global._ = _
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process.stdout.write inspect(returnValue, no, 2, enableColours) + '\n'
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catch err
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error err
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repl.prompt()
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## Autocompletion
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# Regexes to match complete-able bits of text.
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ACCESSOR = /\s*([\w\.]+)(?:\.(\w*))$/
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SIMPLEVAR = /(\w+)$/i
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# Returns a list of completions, and the completed text.
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autocomplete = (text) ->
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completeAttribute(text) or completeVariable(text) or [[], text]
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# Attempt to autocomplete a chained dotted attribute: `one.two.three`.
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completeAttribute = (text) ->
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if match = text.match ACCESSOR
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[all, obj, prefix] = match
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try
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val = Script.runInThisContext obj
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catch error
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return
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completions = getCompletions prefix, Object.getOwnPropertyNames Object val
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[completions, prefix]
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# Attempt to autocomplete an in-scope free variable: `one`.
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completeVariable = (text) ->
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free = text.match(SIMPLEVAR)?[1]
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free = "" if text is ""
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if free?
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vars = Script.runInThisContext 'Object.getOwnPropertyNames(Object(this))'
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keywords = (r for r in CoffeeScript.RESERVED when r[..1] isnt '__')
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possibilities = vars.concat keywords
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completions = getCompletions free, possibilities
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[completions, free]
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# Return elements of candidates for which `prefix` is a prefix.
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getCompletions = (prefix, candidates) ->
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(el for el in candidates when el.indexOf(prefix) is 0)
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# Make sure that uncaught exceptions don't kill the REPL.
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process.on 'uncaughtException', error
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# Create the REPL by listening to **stdin**.
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if readline.createInterface.length < 3
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repl = readline.createInterface stdin, autocomplete
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stdin.on 'data', (buffer) -> repl.write buffer
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else
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repl = readline.createInterface stdin, stdout, autocomplete
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repl.on 'attemptClose', ->
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if backlog
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backlog = ''
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process.stdout.write '\n'
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repl.setPrompt REPL_PROMPT
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repl.prompt()
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else
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repl.close()
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repl.on 'close', ->
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process.stdout.write '\n'
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stdin.destroy()
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repl.on 'line', run
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repl.setPrompt REPL_PROMPT
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repl.prompt()
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