Remove the older form of parse error handling.

Simplify parsing of $PS4 as well.

All unit tests and spec tests pass.

bin/oil.py

@@ -127,20 +127,7 @@ def InteractiveLoop(opts, ex, c_parser, arena):
         c_parser.Reset()
         c_parser.ResetInputObjects()
         continue
-      #log('parsed node: %s', node)
-
-      # Failed parse.
-      # TODO: Need an error for an empty command, which we ignore?  GetLine
-      # could do that in the first position?
-      # ParseSimpleCommand fails with '\n' token?
-      if not node:
-        e = c_parser.Error()
-        # NOTE: This is a bit verbose.
-        ui.PrintErrorStack(e, arena)
-
-        c_parser.Reset()
-        c_parser.ResetInputObjects()
-        continue
+      assert node is not None
 
       if ast_f:
         ast_lib.PrettyPrint(node)
@@ -333,13 +320,7 @@ def OshMain(argv0, argv, login_shell):
     except util.ParseError as e:
       ui.PrettyPrintError(e, arena, sys.stderr)
       return 2
-    else:
-      # TODO: Remove this older form of error handling.
-      if not node:
-        err = c_parser.Error()
-        assert err, err  # can't be empty
-        ui.PrintErrorStack(err, arena)
-        return 2  # parse error is code 2
+    assert node is not None
 
     do_exec = True
     if opts.fix:
@@ -506,13 +487,7 @@ def OshCommandMain(argv):
   except util.ParseError as e:
     ui.PrettyPrintError(e, arena, sys.stderr)
     return 2
-  else:
-    # TODO: Remove this older form of error handling.
-    if not node:
-      err = c_parser.Error()
-      assert err, err  # can't be empty
-      ui.PrintErrorStack(err, arena)
-      return 2  # parse error is code 2
+  assert node is not None
 
   f.close()
 

core/cmd_exec.py

@@ -218,19 +218,11 @@ def ParseTrapCode(self, code_str):
     self.arena.PushSource(source_name)
 
     try:
-      # TODO: Get rid of duplicate error handling:
-      err = None
       try:
         node = c_parser.ParseWholeFile()
       except util.ParseError as e:
-        err = e
-      else:
-        if not node:
-          err = c_parser.Error()
-
-      if err:
         util.error('Parse error in %r:', source_name)
-        ui.PrintErrorStack(err, self.arena, sys.stderr)
+        ui.PrettyPrintError(e, self.arena, sys.stderr)
         return None
 
     finally:
@@ -1482,21 +1474,9 @@ def _EvalPS4(self):
       # We have to parse this at runtime.  PS4 should usually remain constant.
       w_parser = parse_lib.MakeWordParserForPlugin(ps4, self.arena)
 
-      # NOTE: Reading PS4 is just like reading a here doc line.  "\n" is
-      # allowed too.  The OUTER mode would stop at spaces, and ReadWord
-      # doesn't allow lex_mode_e.DQ.
-      ok = True
-      ps4_word = ast.CompoundWord()
       try:
-        w_parser.ReadHereDocBody(ps4_word.parts)
+        ps4_word = w_parser.ReadPS()
       except util.ParseError as e:
-        ok = False
-      else:
-        # TODO: Get rid of duplicate forms of error handling.
-        if not ps4_word:
-          ok = False
-
-      if not ok:
         error_str = '<ERROR: cannot parse PS4>'
         t = ast.token(Id.Lit_Chars, error_str, const.NO_INTEGER)
         ps4_word = ast.CompoundWord([ast.LiteralPart(t)])

osh/word_parse.py

@@ -1160,3 +1160,12 @@ def ReadHereDocBody(self, parts):
     """
     self._ReadLikeDQ(None, parts)
     # Returns nothing
+
+  def ReadPS(self):
+    """For $PS1, $PS4, etc."""
+    # NOTE: Reading PS4 is just like reading a here doc line.  "\n" is allowed
+    # too.  The OUTER mode would stop at spaces, and ReadWord doesn't allow
+    # lex_mode_e.DQ.
+    w = ast.CompoundWord()
+    self._ReadLikeDQ(None, w.parts)
+    return w