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types = require "./types.coffee"
_symbol = types._symbol
class Reader
constructor: (@tokens) -> @position = 0
next: -> @tokens[@position++]
peek: -> @tokens[@position]
skip: ->
@position++
@
tokenize = (str) ->
re = /[\s,]*(~@|[\[\]{}()'`~^@]|"(?:\\.|[^\\"])*"|;.*|[^\s\[\]{}('"`,;)]*)/g
results = []
while (match = re.exec(str)[1]) != ""
continue if match[0] == ';'
results.push(match)
results
read_atom = (rdr) ->
token = rdr.next()
if token.match /^-?[0-9]+$/ then parseInt token,10
else if token.match /^-?[0-9][0-9.]*$/ then parseFloat token,10
else if token[0] == '"'
token.slice(1, token.length-1)
.replace(/\\"/g, '"')
.replace(/\\n/g, "\n")
else if token[0] == ':' then types._keyword(token[1..])
else if token == "nil" then null
else if token == "true" then true
else if token == "false" then false
else _symbol(token)
read_list = (rdr, start='(', end=')') ->
ast = []
token = rdr.next()
throw new Error "expected '" + start + "'" if token != start
while (token = rdr.peek()) != end
throw new Error "expected '" + end + "', got EOF" if !token
ast.push read_form rdr
rdr.next()
ast
read_vector = (rdr) ->
types._vector(read_list(rdr, '[', ']')...)
read_hash_map = (rdr) ->
types._hash_map(read_list(rdr, '{', '}')...)
read_form = (rdr) ->
token = rdr.peek()
switch token
when '\'' then [_symbol('quote'), read_form(rdr.skip())]
when '`' then [_symbol('quasiquote'), read_form(rdr.skip())]
when '~' then [_symbol('unquote'), read_form(rdr.skip())]
when '~@' then [_symbol('splice-unquote'), read_form(rdr.skip())]
when '^'
meta = read_form(rdr.skip())
[_symbol('with-meta'), read_form(rdr), meta]
when '@' then [_symbol('deref'), read_form(rdr.skip())]
# list
when ')' then throw new Error "unexpected ')'"
when '(' then read_list(rdr)
# vector
when ']' then throw new Error "unexpected ']'"
when '[' then read_vector(rdr)
# hash-map
when '}' then throw new Error "unexpected '}'"
when '{' then read_hash_map(rdr)
# atom
else read_atom(rdr)
exports.BlankException = BlankException = (msg) -> null
exports.read_str = read_str = (str) ->
tokens = tokenize(str)
throw new BlankException() if tokens.length == 0
read_form(new Reader(tokens))
#console.log read_str "(1 \"two\" three)"
#console.log read_str "[1 2 3]"
#console.log read_str '{"abc" 123 "def" 456}'
# vim: ts=2:sw=2
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