From d0e1e50135ec3118f3d4deb3a55f0e90e57abb2c Mon Sep 17 00:00:00 2001
From: DIGVIJAY <144053736+digvijay-y@users.noreply.github.com>
Date: Mon, 10 Aug 2026 17:01:51 +0000
Subject: [PATCH] Add get_by_comment method to NumberedObjectCollection and
 corresponding tests

- Implemented a method to yield objects matching a comment string or regex pattern.
- Added unit tests to validate functionality and error handling for the new method.
---
 montepy/numbered_object_collection.py | 39 +++++++++++++++++++++++++++
 tests/test_numbered_collection.py     | 15 +++++++++++
 2 files changed, 54 insertions(+)

diff --git a/montepy/numbered_object_collection.py b/montepy/numbered_object_collection.py
index 064742c3f..ab4dfb761 100644
--- a/montepy/numbered_object_collection.py
+++ b/montepy/numbered_object_collection.py
@@ -2,6 +2,7 @@
 from __future__ import annotations
 from abc import ABC
 import itertools as it
+import re
 import typing
 import weakref
 from numbers import Integral
@@ -262,6 +263,44 @@ def check_number(self, number):
                 f"Number {number} is already in use for the collection: {type(self).__name__} by {self[number]}"
             )
 
+    def get_by_comment(
+        self, searcher: str | re.Pattern
+    ) -> typing.Generator[Numbered_MCNP_Object, None, None]:
+        """Yield all objects whose comments match the given text or pattern.
+
+        The search is applied to each object's
+        :attr:`~montepy.mcnp_object.MCNP_Object.comments`, so both leading and
+        inline comments are considered.
+
+        Parameters
+        ----------
+        searcher : str or re.Pattern
+            A substring to search for, or a compiled regular expression.
+
+        Returns
+        -------
+        Generator[Numbered_MCNP_Object, None, None]
+            A generator of all matching objects.
+
+        Raises
+        ------
+        TypeError
+            if ``searcher`` is not a string or a regex compiled from a string.
+        """
+        if isinstance(searcher, re.Pattern):
+            if not isinstance(searcher.pattern, str):
+                raise TypeError(
+                    f"searcher must be a str, or a pattern compiled from a str. {searcher} given."
+                )
+        elif not isinstance(searcher, str):
+            raise TypeError(
+                f"searcher must be a str, or a pattern compiled from a str. {searcher} given."
+            )
+
+        for obj in self:
+            if obj.comments.search(searcher):
+                yield obj
+
     def _update_number(self, old_num, new_num, obj):
         """Updates the number associated with a specific object in the internal cache.
 
diff --git a/tests/test_numbered_collection.py b/tests/test_numbered_collection.py
index b4b67062b..b5106bebe 100644
--- a/tests/test_numbered_collection.py
+++ b/tests/test_numbered_collection.py
@@ -3,6 +3,7 @@
 from hypothesis import given, settings, strategies as st
 import copy
 import itertools as it
+import re
 
 import montepy
 import montepy.cells
@@ -102,6 +103,20 @@ def test_check_number(self, cp_simple_problem):
         with pytest.raises(ValueError):
             cp_simple_problem.materials.check_number(-1)
 
+    def test_get_by_comment(self):
+        problem = montepy.read_input(os.path.join("tests", "inputs", "pin_cell.imcnp"))
+
+        by_text = list(problem.cells.get_by_comment("uranium rod"))
+        assert by_text == [problem.cells[1]]
+
+        by_regex = list(problem.cells.get_by_comment(re.compile(r"URANIUM", re.I)))
+        assert by_regex == [problem.cells[1]]
+
+        assert list(problem.cells.get_by_comment("not present")) == []
+
+        with pytest.raises(TypeError):
+            list(problem.cells.get_by_comment(5))
+
     def test_update_number_not_in_cache(self):
         """Test that _update_number silently returns when object is not in cache."""
         cells = montepy.Cells()