171 lines
4.7 KiB
CoffeeScript
171 lines
4.7 KiB
CoffeeScript
{car, cdr, cons, nil, nilp, pairp, vectorToList, list} = require 'cons-lists/lists'
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{inspect} = require "util"
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{Comment, Symbol} = require "../chapter5/reader_types"
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NEWLINES = ["\n", "\r", "\x0B", "\x0C"]
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WHITESPACE = [" ", "\t"].concat(NEWLINES)
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EOF = new (class Eof)()
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EOO = new (class Eoo)()
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class ReadError extends Error
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name: 'LispInterpreterError'
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constructor: (@message) ->
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class Source
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constructor: (@inStream) ->
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@index = 0
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@max = @inStream.length - 1
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@line = 0
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@column = 0
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peek: -> @inStream[@index]
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position: -> [@line, @column]
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next: ->
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c = @peek()
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return EOF if @done()
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@index++
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[@line, @column] = if @peek() in NEWLINES then [@line + 1, 0] else [@line, @column + 1]
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c
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done: -> @index > @max
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# IO -> IO
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skipWS = (inStream) ->
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while inStream.peek() in WHITESPACE then inStream.next()
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readMaybeNumber = (symbol) ->
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if symbol[0] == '+'
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return readMaybeNumber symbol.substr(1)
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if symbol[0] == '-'
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ret = readMaybeNumber symbol.substr(1)
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return if ret? then -1 * ret else undefined
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if symbol.search(/^0x[0-9a-fA-F]+$/) > -1
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return parseInt(symbol, 16)
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if symbol.search(/^0[0-9a-fA-F]+$/) > -1
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return parseInt(symbol, 8)
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if symbol.search(/^[0-9]+$/) > -1
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return parseInt(symbol, 10)
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if symbol.search(/^nil$/) > -1
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return nil
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undefined
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# (Delim, TypeName) -> IO -> (IO, Node) | Errorfor
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makeReadPair = (delim, type) ->
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# IO -> (IO, Node) | Error
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(inStream) ->
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inStream.next()
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skipWS inStream
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if inStream.peek() == delim
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inStream.next() unless inStream.done()
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return if type then cons((new Symbol type), nil) else nil
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# IO -> (IO, Node) | Error
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dotted = false
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readEachPair = (inStream) =>
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obj = @read inStream, true, null, true
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if inStream.peek() == delim
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if dotted then return obj
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return cons obj, nil
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return obj if obj instanceof ReadError
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if inStream.done() then return new ReadError "Unexpected end of input"
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if dotted then return new ReadError "More than one symbol after dot in list"
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if @acc(obj) instanceof Symbol and @acc(obj).name == '.'
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dotted = true
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return readEachPair inStream
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cons obj, readEachPair inStream
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obj = readEachPair(inStream)
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inStream.next()
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if type then cons((new Symbol type), obj) else obj
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# Type -> IO -> IO, Node
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class Reader
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prefixReader = (type) ->
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# IO -> IO, Node
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(inStream) ->
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inStream.next()
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obj = @read inStream, true, null, true
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return obj if obj instanceof ReadError
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cons((new Symbol type), obj)
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"acc": (obj) -> obj
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"symbol": (inStream) ->
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symbol = (until (inStream.done() or @[inStream.peek()]? or inStream.peek() in WHITESPACE)
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inStream.next()).join ''
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number = readMaybeNumber symbol
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if number?
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return number
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new Symbol symbol
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"read": (inStream, eofErrorP = false, eofError = EOF, recursiveP = false, keepComments = false) ->
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inStream = if inStream instanceof Source then inStream else new Source inStream
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c = inStream.peek()
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# (IO, Char) -> (IO, Node) | Error
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matcher = (inStream, c) =>
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if inStream.done()
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return if recursiveP then (new ReadError 'EOF while processing nested object') else nil
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if c in WHITESPACE
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inStream.next()
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return nil
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if c == ';'
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return readComment(inStream)
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ret = if @[c]? then @[c](inStream) else @symbol(inStream)
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skipWS inStream
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ret
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while true
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form = matcher inStream, c
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skip = (not nilp form) and (form instanceof Comment) and not keepComments
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break if (not skip and not nilp form) or inStream.done()
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c = inStream.peek()
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null
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form
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'(': makeReadPair ')', null
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'[': makeReadPair ']', 'vector'
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'{': makeReadPair('}', 'record', (res) ->
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res.length % 2 == 0 and true or mkerr "record key without value")
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'"': (inStream) ->
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inStream.next()
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s = until inStream.peek() == '"' or inStream.done()
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if inStream.peek() == '\\'
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inStream.next()
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inStream.next()
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return (new ReadError "end of file seen before end of string") if inStream.done()
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inStream.next()
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s.join ''
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')': (inStream) -> new ReadError "Closing paren encountered"
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']': (inStream) -> new ReadError "Closing bracket encountered"
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'}': (inStream) -> new ReadError "Closing curly without corresponding opening."
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"`": prefixReader 'back-quote'
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"'": prefixReader 'quote'
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",": prefixReader 'unquote'
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";": (inStream) ->
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r = (while inStream.peek() != "\n" and not inStream.done()
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inStream.next()).join("")
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inStream.next() if not inStream.done()
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new Comment r
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exports.Source = Source
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exports.ReadError = ReadError
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exports.Reader = Reader
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reader = new Reader()
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exports.read = -> reader.read.apply(reader, arguments)
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