Change tdop.py to use util.ParseError, so we get location information.

Exposed this error:

$ bin/osh -n ~/git/wild/books/wicked_cool_shell_scripts_2e/12/unscramble
Line 19 of '/home/andy/git/wild/books/wicked_cool_shell_scripts_2e/12/unscramble'
    for (( val=1; $val < $len ; ))
                                ^
Token can't be used in prefix position

core/tdop.py

@@ -10,15 +10,12 @@
from osh import ast_ as ast
from osh.lex import LexMode

p_die = util.p_die

arith_expr_e = ast.arith_expr_e
word_e = ast.word_e


class TdopParseError(Exception):
  pass


def Assert(s, expected, tree):
  """Used for tests."""
  print(s)
@@ -75,8 +72,8 @@ def ToLValue(node):
        node.left.tag == arith_expr_e.ArithVarRef):
      return ast.LhsIndexedName(node.left.name, node.right)

  # TODO: parse error context here.
  raise TdopParseError("Can't assign to %r" % node)
  # TODO: Location information needs token instead of op_id.
  p_die("Can't assign to %r", node)


#
@@ -86,7 +83,7 @@ def ToLValue(node):

def NullError(p, t, bp):
  # TODO: I need position information
  raise TdopParseError("Token %s can't be used in prefix position" % t)
  p_die("Token can't be used in prefix position", word=t)


def NullConstant(p, w, bp):
@@ -124,7 +121,7 @@ def NullPrefixOp(p, w, bp):

def LeftError(p, t, left, rbp):
  # Hm is this not called because of binding power?
  raise TdopParseError("Token %s can't be used in infix position" % t)
  p_die("Token can't be used in infix position", word=t)


def LeftBinaryOp(p, w, left, rbp):
@@ -201,7 +198,7 @@ def LookupNud(self, token):
    try:
      nud = self.nud_lookup[token]
    except KeyError:
      raise TdopParseError('No nud for token %r' % token)
      raise AssertionError('No nud for token %r' % token)
    return nud

  def LookupLed(self, token):
@@ -244,7 +241,7 @@ def Eat(self, token_type):
    """ Eat()? """
    if not self.AtToken(token_type):
      t = IdName(token_type)
      raise TdopParseError('TDOP expected %s, got %s' % (t, self.cur_word))
      p_die('Parser expected %s, got %s', t, self.cur_word, word=self.cur_word)

    self.Next()

@@ -254,10 +251,7 @@ def Next(self):
    if self.cur_word is None:
      error_stack = self.w_parser.Error()
      self.error_stack.extend(error_stack)
      self.AddErrorContext('Error reading arith word in ArithParser',
          word=self.cur_word)
      #return False
      raise TdopParseError()  # use exceptions for now
      p_die('Error reading arith word in ArithParser')
    self.op_id = word.ArithId(self.cur_word)
    return True

@@ -268,7 +262,7 @@ def ParseUntil(self, rbp):
    """
    # TODO: use Kind.Eof
    if self.op_id in (Id.Eof_Real, Id.Eof_RParen, Id.Eof_Backtick):
      raise TdopParseError('Unexpected end of input')
      p_die('Unexpected end of input')

    t = self.cur_word
    self.Next()  # skip over the token, e.g. ! ~ + -
@@ -281,7 +275,7 @@ def ParseUntil(self, rbp):
      try:
        left_info = self._Led(word.ArithId(t))
      except KeyError:
        raise TdopParseError('Invalid token %s' % t)
        raise AssertionError('Invalid token %s' % t)

      # Examples:
      # If we see 1*2+  , rbp = 27 and lbp = 25, so stop.
@@ -297,12 +291,10 @@ def ParseUntil(self, rbp):

  def Parse(self):
    try:
      self.Next()  # can raise TdopParseError
      self.Next()  # may raise ParseError
      node = self.ParseUntil(0)
    except TdopParseError as e:
      # TODO: attribute to token or word
      err = util.ParseError(str(e))
      self.error_stack.append(err)
    except util.ParseError as e:
      self.error_stack.append(e)
      return None
    return node