word_parse.py: Change more error cases to use the exception style.

osh/word_parse.py

@@ -141,10 +141,9 @@ def _ReadVarOpArg(self, arg_lex_mode, eof_type=Id.Undefined_Tok,
    self._Next(arg_lex_mode)
    self._Peek()

    w = self._ReadCompoundWord(
        lex_mode=arg_lex_mode, eof_type=eof_type, empty_ok=empty_ok)
    if not w:
      return None
    w = self._ReadCompoundWord(lex_mode=arg_lex_mode, eof_type=eof_type,
                               empty_ok=empty_ok)
    assert w is not None

    # This is for "${s:-}", ${s/a//}, etc.  It is analogous to
    # LooksLikeAssignment where we turn x= into x=''.  It has the same
@@ -895,9 +894,7 @@ def _ReadArrayLiteralPart(self):
    words = []
    while True:
      w = w_parser.ReadWord(lex_mode_e.OUTER)
      if not w:
        self.error_stack.extend(w_parser.Error())
        return None
      assert w is not None

      if w.tag == word_e.TokenWord:
        word_id = word.CommandId(w)
@@ -959,9 +956,7 @@ def _ReadCompoundWord(self, eof_type=Id.Undefined_Tok,
          if t.id == Id.Op_LParen:
            self.lexer.PushHint(Id.Op_RParen, Id.Right_ArrayLiteral)
            part2 = self._ReadArrayLiteralPart()
            if not part2:
              self.AddErrorContext('_ReadArrayLiteralPart failed')
              return False
            assert part2 is not None
            word.parts.append(part2)

      elif self.token_kind == Kind.VSub:
@@ -970,15 +965,13 @@ def _ReadCompoundWord(self, eof_type=Id.Undefined_Tok,

      elif self.token_kind == Kind.ExtGlob:
        part = self._ReadExtGlobPart()
        if not part:
          return None
        assert part is not None
        word.parts.append(part)

      elif self.token_kind == Kind.Left:
        #print('_ReadLeftParts')
        part = self._ReadLeftParts()
        if not part:
          return None
        assert part is not None
        word.parts.append(part)

      # NOT done yet, will advance below
@@ -1051,8 +1044,6 @@ def _ReadArithWord(self):

    elif self.token_kind in (Kind.Lit, Kind.Left):
      w = self._ReadCompoundWord(lex_mode=lex_mode_e.ARITH)
      if not w:
        return None, True
      return w, False

    elif self.token_kind == Kind.VSub:
@@ -1125,10 +1116,7 @@ def _ReadWord(self, lex_mode):

      else:
        w = self._ReadCompoundWord(lex_mode=lex_mode)
        if not w:
          self.AddErrorContext(
              'Error reading command word', token=self.cur_token)
          return None, False
        assert w is not None
        return w, False

    else:

test/parse-errors.sh

@@ -93,6 +93,7 @@ array-literal() {
  _error-case 'a=(1 & 2)'
  _error-case 'a= (1 2)'
  _error-case 'a=(1 2'
  _error-case 'a=(1 ${2@} )'  # error in word inside array literal
}

arith-context() {