word_parse.py: Simplify arithmetic parsing.

Remove an unneeded helper method and the do_next= keyword arg.

osh/arith_parse_test.py

@@ -19,12 +19,16 @@
from core import util

from osh import parse_lib
from osh.meta import types
#from osh import arith_parse

lex_mode_e = types.lex_mode_e


def ParseAndEval(code_str):
  arena = test_lib.MakeArena('<arith_parse_test.py>')
  w_parser, _ = parse_lib.MakeParserForCompletion(code_str, arena)
  w_parser._Next(lex_mode_e.ARITH)  # Calling private method
  anode = w_parser._ReadArithExpr()  # need the right lex state?
  print('node:', anode)

osh/word_parse.py

@@ -144,19 +144,14 @@ def _ReadVarOpArg(self, arg_lex_mode, eof_type=Id.Undefined_Tok,
      w.parts.append(ast.EmptyPart())
    return w

  def _ReadSliceArg(self):
    """Read an arithmetic expression for either part of ${a : i+1 : i+2}."""
    anode = self._ReadArithExpr(do_next=False)
    return anode

  def _ReadSliceVarOp(self):
    """ VarOf ':' ArithExpr (':' ArithExpr )? """
    self._Next(lex_mode_e.ARITH)
    self._Peek()
    if self.token_type == Id.Arith_Colon:  # A pun for Id.VOp2_Colon
      begin = None  # no beginning specified
    else:
      begin = self._ReadSliceArg()
      begin = self._ReadArithExpr()
      if not begin: return None
      #print('BEGIN', begin)
      #print('BVS2', self.cur_token)
@@ -167,7 +162,7 @@ def _ReadSliceVarOp(self):
    # Id.Arith_Colon is a pun for Id.VOp2_Colon
    elif self.token_type == Id.Arith_Colon:
      self._Next(lex_mode_e.ARITH)
      length = self._ReadSliceArg()
      length = self._ReadArithExpr()
      if not length: return None

      #print('after colon', self.cur_token)
@@ -258,6 +253,7 @@ def _ReadSubscript(self):
      self._Next(lex_mode_e.ARITH)  # skip past @
      self._Peek()
    else:
      self._Next(lex_mode_e.ARITH)  # skip past [
      anode = self._ReadArithExpr()
      op = ast.ArrayIndex(anode)

@@ -709,7 +705,7 @@ def _ReadCommandSubPart(self, token_type):
    cs_part.spids.append(right_spid)
    return cs_part

  def _ReadArithExpr(self, do_next=True):
  def _ReadArithExpr(self):
    """Read and parse an arithmetic expression in various contexts.

    $(( 1+2 ))
@@ -729,8 +725,6 @@ def _ReadArithExpr(self, do_next=True):

    See the assertion in ArithParser.Parse() -- unexpected extra input.
    """
    if do_next:
      self._Next(lex_mode_e.ARITH)
    # calls self.ReadWord(lex_mode_e.ARITH)
    a_parser = tdop.TdopParser(arith_parse.SPEC, self)
    anode = a_parser.Parse()
@@ -755,6 +749,7 @@ def _ReadArithSubPart(self):
    # $((echo * foo))  # looks like multiplication
    # $((echo / foo))  # looks like division

    self._Next(lex_mode_e.ARITH)
    anode = self._ReadArithExpr()
    if self.token_type != Id.Arith_RParen:
      p_die('Expected first ) to end arith sub, got %r', self.cur_token.val,
@@ -780,6 +775,7 @@ def _ReadArithSub2Part(self):
    """Non-standard arith sub $[a + 1]."""
    left_span_id = self.cur_token.span_id

    self._Next(lex_mode_e.ARITH)
    anode = self._ReadArithExpr()
    if self.token_type != Id.Arith_RBracket:
      p_die('Expected ], got %r', self.cur_token.val, token=self.cur_token)
@@ -802,6 +798,7 @@ def ReadDParen(self):
    # Then you can get rid of this.
    self.lexer.PushHint(Id.Op_RParen, Id.Op_DRightParen)

    self._Next(lex_mode_e.ARITH)
    anode = self._ReadArithExpr()
    assert anode is not None

@@ -836,21 +833,21 @@ def ReadForExpression(self):
    if self.token_type == Id.Arith_Semi:  # for (( ; i < 10; i++ ))
      init_node = None
    else:
      init_node = self._ReadArithExpr(do_next=False)
      init_node = self._ReadArithExpr()
    self._NextNonSpace()

    self._Peek()
    if self.token_type == Id.Arith_Semi:  # for (( ; ; i++ ))
      cond_node = None
    else:
      cond_node = self._ReadArithExpr(do_next=False)
      cond_node = self._ReadArithExpr()
    self._NextNonSpace()

    self._Peek()
    if self.token_type == Id.Arith_RParen:  # for (( ; ; ))
      update_node = None
    else:
      update_node = self._ReadArithExpr(do_next=False)
      update_node = self._ReadArithExpr()
    self._NextNonSpace()

    self._Peek()
@@ -1032,7 +1029,7 @@ def _ReadArithWord(self):
      return w, False

    else:
      assert False, ("Unexpected token parsing arith sub: %s", self.cur_token)
      assert False, ("Unexpected token parsing arith sub: %s" % self.cur_token)

    raise AssertionError("Shouldn't get here")