Revert results names for packaging compatibility (#110)

CHANGES

@@ -4,6 +4,9 @@ Change Log
 
 Version 3.0.6 -
 ---------------
+- Refactored warning suppression code to preserve internal results names,
+  which, while undocumented, had been adopted by some projects.
+
 - Fix bug when `delimited_list` was called with a str literal instead of a
   parse expression.
 

pyparsing/core.py

@@ -468,6 +468,11 @@ def __init__(self, savelist: bool = False):
         # avoid redundant calls to preParse
         self.callPreparse = True
         self.callDuringTry = False
+        self.suppress_warnings_ = []
+
+    def suppress_warning(self, warning_type: Diagnostics):
+        self.suppress_warnings_.append(warning_type)
+        return self
 
     def copy(self) -> "ParserElement":
         """
@@ -3679,12 +3684,17 @@ def copy(self):
         return ret
 
     def _setResultsName(self, name, listAllMatches=False):
-        if __diag__.warn_ungrouped_named_tokens_in_collection:
+        if (
+            __diag__.warn_ungrouped_named_tokens_in_collection
+            and Diagnostics.warn_ungrouped_named_tokens_in_collection
+            not in self.suppress_warnings_
+        ):
             for e in self.exprs:
                 if (
                     isinstance(e, ParserElement)
                     and e.resultsName
-                    and not e.resultsName.startswith("_NOWARN")
+                    and Diagnostics.warn_ungrouped_named_tokens_in_collection
+                    not in e.suppress_warnings_
                 ):
                     warnings.warn(
                         "{}: setting results name {!r} on {} expression "
@@ -3982,7 +3992,8 @@ def _setResultsName(self, name, listAllMatches=False):
                 warnings.warn(
                     "{}: setting results name {!r} on {} expression "
                     "will return a list of all parsed tokens in an And alternative, "
-                    "in prior versions only the first token was returned".format(
+                    "in prior versions only the first token was returned; enclose"
+                    "contained argument in Group".format(
                         "warn_multiple_tokens_in_named_alternation",
                         name,
                         type(self).__name__,
@@ -4080,8 +4091,9 @@ def _setResultsName(self, name, listAllMatches=False):
             if any(isinstance(e, And) for e in self.exprs):
                 warnings.warn(
                     "{}: setting results name {!r} on {} expression "
-                    "may only return a single token for an And alternative, "
-                    "in future will return the full list of tokens".format(
+                    "will return a list of all parsed tokens in an And alternative, "
+                    "in prior versions only the first token was returned; enclose"
+                    "contained argument in Group".format(
                         "warn_multiple_tokens_in_named_alternation",
                         name,
                         type(self).__name__,
@@ -4724,12 +4736,17 @@ def parseImpl(self, instring, loc, doActions=True):
         return loc, tokens
 
     def _setResultsName(self, name, listAllMatches=False):
-        if __diag__.warn_ungrouped_named_tokens_in_collection:
+        if (
+            __diag__.warn_ungrouped_named_tokens_in_collection
+            and Diagnostics.warn_ungrouped_named_tokens_in_collection
+            not in self.suppress_warnings_
+        ):
             for e in [self.expr] + self.expr.recurse():
                 if (
                     isinstance(e, ParserElement)
                     and e.resultsName
-                    and not e.resultsName.startswith("_NOWARN")
+                    and Diagnostics.warn_ungrouped_named_tokens_in_collection
+                    not in e.suppress_warnings_
                 ):
                     warnings.warn(
                         "{}: setting results name {!r} on {} expression "

pyparsing/helpers.py

@@ -390,23 +390,17 @@ def original_text_for(
     locMarker = Empty().set_parse_action(lambda s, loc, t: loc)
     endlocMarker = locMarker.copy()
     endlocMarker.callPreparse = False
-    # prefix these transient names with _NOWARN to suppress ungrouped name warnings
-    matchExpr = (
-        locMarker("_NOWARN_original_start")
-        + expr
-        + endlocMarker("_NOWARN_original_end")
-    )
+    matchExpr = locMarker("_original_start") + expr + endlocMarker("_original_end")
     if asString:
-        extractText = lambda s, l, t: s[
-            t._NOWARN_original_start : t._NOWARN_original_end
-        ]
+        extractText = lambda s, l, t: s[t._original_start : t._original_end]
     else:
 
         def extractText(s, l, t):
-            t[:] = [s[t.pop("_NOWARN_original_start") : t.pop("_NOWARN_original_end")]]
+            t[:] = [s[t.pop("_original_start") : t.pop("_original_end")]]
 
     matchExpr.set_parse_action(extractText)
     matchExpr.ignoreExprs = expr.ignoreExprs
+    matchExpr.suppress_warning(Diagnostics.warn_ungrouped_named_tokens_in_collection)
     return matchExpr
 
 

tests/test_unit.py

@@ -113,15 +113,18 @@ def assertRaises(self, expected_exception_type: Any, msg: Any = None):
         return ar
 
     @contextlib.contextmanager
-    def assertDoesNotWarn(self, msg: str = None):
+    def assertDoesNotWarn(self, warning_type: type = UserWarning, msg: str = None):
         if msg is None:
             msg = "unexpected warning raised"
         with warnings.catch_warnings(record=True) as w:
             warnings.simplefilter("error")
             try:
                 yield
             except Exception as e:
-                self.fail("{}: {}".format(msg, e))
+                if isinstance(e, warning_type):
+                    self.fail("{}: {}".format(msg, e))
+                else:
+                    raise
 
 
 class Test01_PyparsingTestInit(TestCase):
@@ -169,6 +172,23 @@ def runTest(self):
         self.assertTrue(all_success, "failed warnings enable test")
 
 
+class Test01b_PyparsingUnitTestUtilitiesTests(TestCase):
+    def runTest(self):
+        with ppt.reset_pyparsing_context():
+            pp.enable_diag(pp.Diagnostics.warn_on_parse_using_empty_Forward)
+
+            # test assertDoesNotWarn raises an AssertionError
+            with self.assertRaises(AssertionError):
+                with self.assertDoesNotWarn(
+                    msg="failed to warn when naming an empty Forward expression",
+                ):
+                    base = pp.Forward()
+                    try:
+                        print(base.parseString("x"))
+                    except ParseException as pe:
+                        pass
+
+
 class Test02_WithoutPackrat(ppt.TestParseResultsAsserts, TestCase):
     suite_context = None
     save_suite_context = None

tox.ini

@@ -16,7 +16,5 @@ deps=
 commands=
     python -c "import shutil,os,stat;os.path.exists('packaging') and shutil.rmtree('packaging', onerror=lambda fn, path, _:os.chmod(path,stat.S_IWRITE) or fn(path))"
     git clone --depth 1 https://github.com/pypa/packaging.git
-    # patch packaging parser pre 21.2 release
-    python -c "from pathlib import Path;p=Path('packaging/packaging/requirements.py');p.write_text(p.read_text().replace('MARKER_EXPR.setParseAction','MARKER_EXPR.addParseAction').replace('s[t._original_start : t._original_end]','t.marker'))"
     python -m pytest packaging/tests
     python -c "import shutil,os,stat;shutil.rmtree('packaging', onerror=lambda fn, path, _:os.chmod(path,stat.S_IWRITE) or fn(path))"