From 79923754678a489b37095810e40569980237b80a Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Wed, 5 Mar 2025 22:58:39 +0100
Subject: [PATCH 01/10] use output_validator

---
 bin/export.py      | 10 ++++++++--
 bin/generate.py    |  5 +----
 bin/interactive.py |  2 +-
 bin/problem.py     | 26 ++++++++++----------------
 bin/run.py         | 22 +++++++++-------------
 bin/skel.py        |  2 +-
 bin/stats.py       |  2 +-
 bin/testcase.py    |  2 +-
 bin/upgrade.py     | 19 ++++++++++++++++++-
 bin/validate.py    |  5 ++---
 10 files changed, 52 insertions(+), 43 deletions(-)

diff --git a/bin/export.py b/bin/export.py
index 5b25b75a6..6abfacb77 100644
--- a/bin/export.py
+++ b/bin/export.py
@@ -121,7 +121,7 @@ def build_problem_zip(problem: Problem, output: Path):
         ]
 
     if problem.custom_output:
-        files.append(("output_validators/**/*", True))
+        files.append(("output_validator/**/*", True))
 
     if config.args.kattis:
         files.append(("input_validators/**/*", True))
@@ -224,7 +224,7 @@ def add_file(path, source):
     if problem.settings.constants:
         constants_supported = [
             "data/**/testdata.yaml",
-            "output_validators/**/*",
+            "output_validator/**/*",
             "input_validators/**/*",
             # "problem_statement/*", uses \constants
             # "submissions/*/**/*", removed support?
@@ -242,6 +242,12 @@ def add_file(path, source):
                     f.unlink()
                     f.write_text(text)
 
+    # TODO: Remove this if we know others use the output_validator dir
+    if (export_dir / "output_validator").exists():
+        (export_dir / "output_validator").rename(
+            export_dir / "output_validators" / "output_validator"
+        )
+
     # Build .ZIP file.
     message("writing zip file", "Zip", output, color_type=MessageType.LOG)
     try:
diff --git a/bin/generate.py b/bin/generate.py
index a472c1d69..42ffa1e03 100644
--- a/bin/generate.py
+++ b/bin/generate.py
@@ -729,10 +729,7 @@ def validate_ans(t, problem: Problem, testcase: Testcase, meta_yaml: dict, bar:
                     f".ans file is {size / 1024 / 1024:.3f}MiB, which is close to output limit (set limits.output to at least {(2 * size + 1024 * 1024 - 1) // 1024 // 1024}MiB in problem.yaml)"
                 )
 
-            answer_validator_hashes = {
-                **testcase.validator_hashes(validate.AnswerValidator, bar),
-                **testcase.validator_hashes(validate.OutputValidator, bar),
-            }
+            answer_validator_hashes = {**testcase.validator_hashes(validate.AnswerValidator, bar)}
             if all(h in meta_yaml["answer_validator_hashes"] for h in answer_validator_hashes):
                 return True
 
diff --git a/bin/interactive.py b/bin/interactive.py
index 83390c365..1180a1c2c 100644
--- a/bin/interactive.py
+++ b/bin/interactive.py
@@ -32,7 +32,7 @@ def run_interactive_testcase(
     bar: Optional[ProgressBar] = None,
 ):
     output_validators = run.problem.validators(validate.OutputValidator)
-    if len(output_validators) != 1:
+    if not output_validators:
         return None
     output_validator = output_validators[0]
 
diff --git a/bin/problem.py b/bin/problem.py
index de94046e2..203a80515 100644
--- a/bin/problem.py
+++ b/bin/problem.py
@@ -224,7 +224,7 @@ def __init__(
         self.interactive: bool = "interactive" in mode
         self.multi_pass: bool = "multi-pass" in mode
         self.custom_output: bool = (
-            self.interactive or self.multi_pass or (problem.path / "output_validators").exists()
+            self.interactive or self.multi_pass or (problem.path / "output_validator").is_dir()
         )
 
         self.name: dict[str, str] = parse_setting(yaml_data, "name", {"en": ""})
@@ -798,8 +798,6 @@ def validators(
                         warn("No input validators found.")
                     case validate.AnswerValidator, 0:
                         warn("No answer validators found")
-                    case validate.OutputValidator, l if l != 1:
-                        error(f"Found {len(validators)} output validators, expected exactly one.")
 
         build_ok = all(v.ok for v in validators)
 
@@ -815,15 +813,16 @@ def _validators(
             return problem._validators_cache[key]
 
         assert hasattr(cls, "source_dirs")
-        # TODO #424: We should not support multiple output validators inside output_validator/.
-        paths = [p for source_dir in cls.source_dirs for p in glob(problem.path / source_dir, "*")]
-
-        # Handle default output validation
         if cls == validate.OutputValidator:
-            if not paths:
-                if problem.custom_output:
-                    fatal("Problem validation type requires output_validators/")
+            assert len(cls.source_dirs) == 1
+            if problem.custom_output:
+                paths = [problem.path / cls.source_dirs[0]]
+            else:
                 paths = [config.TOOLS_ROOT / "support" / "default_output_validator.cpp"]
+        else:
+            paths = [
+                p for source_dir in cls.source_dirs for p in glob(problem.path / source_dir, "*")
+            ]
 
         # TODO: Instead of checking file contents, maybe specify this in generators.yaml?
         def has_constraints_checking(f):
@@ -875,13 +874,8 @@ def prepare_run(problem):
         if not testcases:
             return False
 
-        if problem.interactive or problem.multi_pass:
-            validators = problem.validators(validate.OutputValidator)
-            if not validators:
-                return False
-
         # Pre build the output validator to prevent nested ProgressBars.
-        if problem.validators(validate.OutputValidator) is False:
+        if not problem.validators(validate.OutputValidator):
             return False
 
         submissions = problem.submissions()
diff --git a/bin/run.py b/bin/run.py
index 87d29b88d..308b6d670 100644
--- a/bin/run.py
+++ b/bin/run.py
@@ -217,12 +217,12 @@ def _prepare_nextpass(self, nextpass):
 
     def _validate_output(self, bar):
         output_validators = self.problem.validators(validate.OutputValidator)
-        if len(output_validators) != 1:
+        if not output_validators:
             return None
-        validator = output_validators[0]
-
-        return validator.run(
-            self.testcase, self, args=self.testcase.testdata_yaml_validator_args(validator, bar)
+        return output_validators[0].run(
+            self.testcase,
+            self,
+            args=self.testcase.testdata_yaml_validator_args(output_validators[0], bar),
         )
 
 
@@ -522,10 +522,8 @@ def test(self):
 
         testcases = self.problem.testcases(needans=False)
 
-        if self.problem.interactive:
-            output_validators = self.problem.validators(validate.OutputValidator)
-            if output_validators is False:
-                return
+        if not self.problem.validators(validate.OutputValidator):
+            return
 
         for testcase in testcases:
             header = ProgressBar.action("Running " + str(self.name), testcase.name)
@@ -589,10 +587,8 @@ def test(self):
 
     # Run the submission using stdin as input.
     def test_interactive(self):
-        if self.problem.interactive:
-            output_validators = self.problem.validators(validate.OutputValidator)
-            if output_validators is False:
-                return
+        if not self.problem.validators(validate.OutputValidator):
+            return
 
         bar = ProgressBar("Running " + str(self.name), max_len=1, count=1)
         bar.start()
diff --git a/bin/skel.py b/bin/skel.py
index 20feaab90..59de1ce74 100644
--- a/bin/skel.py
+++ b/bin/skel.py
@@ -242,7 +242,7 @@ def new_problem():
         variables,
         exist_ok=True,
         preserve_symlinks=preserve_symlinks,
-        skip=[skeldir / "output_validators"] if not custom_output else None,
+        skip=[skeldir / "output_validator"] if not custom_output else None,
     )
 
     # Warn about missing problem statement skeletons for non-en languages
diff --git a/bin/stats.py b/bin/stats.py
index 69eb8a638..e2f4d96f5 100644
--- a/bin/stats.py
+++ b/bin/stats.py
@@ -52,7 +52,7 @@ def problem_stats(problems):
         ("sol", "problem_statement/solution*.tex", 1),
         ("  val: I", ["input_validators/*", "input_format_validators/*"]),
         ("A", ["answer_validators/*"]),
-        ("O", ["output_validators/*"]),
+        ("O", ["output_validator/"]),
         (
             "  sample",
             [lambda s: {x.stem for x in s if x.parts[2] == "sample"}],
diff --git a/bin/testcase.py b/bin/testcase.py
index d4bdb6255..d580bfe76 100644
--- a/bin/testcase.py
+++ b/bin/testcase.py
@@ -150,7 +150,7 @@ def validator_hashes(self, cls: type["validate.AnyValidator"], bar):
         indicating which validators will be run for this testcase.
         """
         assert cls in [validate.InputValidator, validate.AnswerValidator, validate.OutputValidator]
-        validators = self.problem.validators(cls) or []
+        validators = self.problem.validators(cls)
 
         d = dict()
 
diff --git a/bin/upgrade.py b/bin/upgrade.py
index 15c3b72ba..6798544f8 100644
--- a/bin/upgrade.py
+++ b/bin/upgrade.py
@@ -188,6 +188,23 @@ def upgrade_statement(problem_path: Path, bar: ProgressBar) -> None:
             shutil.move(f, dest)
 
 
+def upgrade_output_validators(problem_path: Path, bar: ProgressBar) -> None:
+    if (problem_path / "output_validators").is_dir():
+        if (problem_path / "output_validator").exists():
+            bar.error(
+                "can't rename 'output_validators/', 'output_validator/' already exists", resume=True
+            )
+            return
+        content = [*(problem_path / "output_validators").iterdir()]
+        if len(content) == 1 and content[0].is_dir():
+            bar.log(f"renaming 'output_validators/{content[0].name}' to 'output_validator/'")
+            content[0].rename(problem_path / "output_validator")
+            (problem_path / "output_validators").rmdir()
+        else:
+            bar.log("renaming 'output_validators/' to 'output_validator/'")
+            (problem_path / "output_validators").rename(problem_path / "output_validator")
+
+
 def upgrade_problem_yaml(problem_path: Path, bar: ProgressBar) -> None:
     assert (problem_path / "problem.yaml").exists()
     data = cast(CommentedMap, read_yaml(problem_path / "problem.yaml"))
@@ -364,7 +381,7 @@ def _upgrade(problem_path: Path, bar: ProgressBar) -> None:
     upgrade_testdata_yaml(problem_path, bar)
     upgrade_generators_yaml(problem_path, bar)
     # upgrade_statement(problem_path, bar) TODO: activate this when we support the new statement dirs
-    # TODO: output_validators -> output_validator
+    upgrade_output_validators(problem_path, bar)
     upgrade_problem_yaml(problem_path, bar)
 
     bar.done()
diff --git a/bin/validate.py b/bin/validate.py
index 527fc5ad6..1b4094925 100644
--- a/bin/validate.py
+++ b/bin/validate.py
@@ -333,12 +333,11 @@ class OutputValidator(Validator):
     """
 
     def __init__(self, problem, path, **kwargs):
-        super().__init__(problem, path, "output_validators", **kwargs)
+        super().__init__(problem, path, "output_validator", **kwargs)
 
     validator_type = "output"
 
-    # TODO #424: We should not support multiple output validators inside output_validator/.
-    source_dirs = ["output_validator", "output_validators"]
+    source_dirs = ["output_validator"]
 
     def run(
         self,

From 0e07aae0c3150e40d752713401d63a5bc8b80b27 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Wed, 5 Mar 2025 22:59:19 +0100
Subject: [PATCH 02/10] upgraded tests

---
 .../boolfind_run => output_validator}/build            |  0
 .../boolfind_run => output_validator}/run              |  0
 .../runjury_boolfind.c                                 |  0
 .../output_validator/output_validator.cpp              |  0
 .../output_validator/validation.h                      |  0
 .../validate.cc                                        |  0
 .../validate.h                                         |  0
 .../guess_validator => output_validator}/validate.cc   |  0
 .../guess_validator => output_validator}/validate.h    |  0
 .../guess_validator => output_validator}/validate.cc   |  0
 .../guess_validator => output_validator}/validate.h    |  0
 .../interctive_multipass_validator.py                  |  0
 .../multipass_validator.py                             |  0
 .../{output_validators => output_validator}/.gitkeep   |  0
 test/test_default_output_validator.py                  | 10 +++++-----
 15 files changed, 5 insertions(+), 5 deletions(-)
 rename test/problems/boolfind/{output_validators/boolfind_run => output_validator}/build (100%)
 rename test/problems/boolfind/{output_validators/boolfind_run => output_validator}/run (100%)
 rename test/problems/boolfind/{output_validators/boolfind_run => output_validator}/runjury_boolfind.c (100%)
 rename test/problems/constants/{output_validators => }/output_validator/output_validator.cpp (100%)
 rename test/problems/constants/{output_validators => }/output_validator/validation.h (100%)
 rename test/problems/different/{output_validators/different_validator => output_validator}/validate.cc (100%)
 rename test/problems/different/{output_validators/different_validator => output_validator}/validate.h (100%)
 rename test/problems/guess/{output_validators/guess_validator => output_validator}/validate.cc (100%)
 rename test/problems/guess/{output_validators/guess_validator => output_validator}/validate.h (100%)
 rename test/problems/guessnoeofcheck/{output_validators/guess_validator => output_validator}/validate.cc (100%)
 rename test/problems/guessnoeofcheck/{output_validators/guess_validator => output_validator}/validate.h (100%)
 rename test/problems/interactivemultipass/{output_validators/interactive_multipass_validator => output_validator}/interctive_multipass_validator.py (100%)
 rename test/problems/multipass/{output_validators/multipass_validator => output_validator}/multipass_validator.py (100%)
 rename test/problems/testproblemconfig/{output_validators => output_validator}/.gitkeep (100%)

diff --git a/test/problems/boolfind/output_validators/boolfind_run/build b/test/problems/boolfind/output_validator/build
similarity index 100%
rename from test/problems/boolfind/output_validators/boolfind_run/build
rename to test/problems/boolfind/output_validator/build
diff --git a/test/problems/boolfind/output_validators/boolfind_run/run b/test/problems/boolfind/output_validator/run
similarity index 100%
rename from test/problems/boolfind/output_validators/boolfind_run/run
rename to test/problems/boolfind/output_validator/run
diff --git a/test/problems/boolfind/output_validators/boolfind_run/runjury_boolfind.c b/test/problems/boolfind/output_validator/runjury_boolfind.c
similarity index 100%
rename from test/problems/boolfind/output_validators/boolfind_run/runjury_boolfind.c
rename to test/problems/boolfind/output_validator/runjury_boolfind.c
diff --git a/test/problems/constants/output_validators/output_validator/output_validator.cpp b/test/problems/constants/output_validator/output_validator.cpp
similarity index 100%
rename from test/problems/constants/output_validators/output_validator/output_validator.cpp
rename to test/problems/constants/output_validator/output_validator.cpp
diff --git a/test/problems/constants/output_validators/output_validator/validation.h b/test/problems/constants/output_validator/validation.h
similarity index 100%
rename from test/problems/constants/output_validators/output_validator/validation.h
rename to test/problems/constants/output_validator/validation.h
diff --git a/test/problems/different/output_validators/different_validator/validate.cc b/test/problems/different/output_validator/validate.cc
similarity index 100%
rename from test/problems/different/output_validators/different_validator/validate.cc
rename to test/problems/different/output_validator/validate.cc
diff --git a/test/problems/different/output_validators/different_validator/validate.h b/test/problems/different/output_validator/validate.h
similarity index 100%
rename from test/problems/different/output_validators/different_validator/validate.h
rename to test/problems/different/output_validator/validate.h
diff --git a/test/problems/guess/output_validators/guess_validator/validate.cc b/test/problems/guess/output_validator/validate.cc
similarity index 100%
rename from test/problems/guess/output_validators/guess_validator/validate.cc
rename to test/problems/guess/output_validator/validate.cc
diff --git a/test/problems/guess/output_validators/guess_validator/validate.h b/test/problems/guess/output_validator/validate.h
similarity index 100%
rename from test/problems/guess/output_validators/guess_validator/validate.h
rename to test/problems/guess/output_validator/validate.h
diff --git a/test/problems/guessnoeofcheck/output_validators/guess_validator/validate.cc b/test/problems/guessnoeofcheck/output_validator/validate.cc
similarity index 100%
rename from test/problems/guessnoeofcheck/output_validators/guess_validator/validate.cc
rename to test/problems/guessnoeofcheck/output_validator/validate.cc
diff --git a/test/problems/guessnoeofcheck/output_validators/guess_validator/validate.h b/test/problems/guessnoeofcheck/output_validator/validate.h
similarity index 100%
rename from test/problems/guessnoeofcheck/output_validators/guess_validator/validate.h
rename to test/problems/guessnoeofcheck/output_validator/validate.h
diff --git a/test/problems/interactivemultipass/output_validators/interactive_multipass_validator/interctive_multipass_validator.py b/test/problems/interactivemultipass/output_validator/interctive_multipass_validator.py
similarity index 100%
rename from test/problems/interactivemultipass/output_validators/interactive_multipass_validator/interctive_multipass_validator.py
rename to test/problems/interactivemultipass/output_validator/interctive_multipass_validator.py
diff --git a/test/problems/multipass/output_validators/multipass_validator/multipass_validator.py b/test/problems/multipass/output_validator/multipass_validator.py
similarity index 100%
rename from test/problems/multipass/output_validators/multipass_validator/multipass_validator.py
rename to test/problems/multipass/output_validator/multipass_validator.py
diff --git a/test/problems/testproblemconfig/output_validators/.gitkeep b/test/problems/testproblemconfig/output_validator/.gitkeep
similarity index 100%
rename from test/problems/testproblemconfig/output_validators/.gitkeep
rename to test/problems/testproblemconfig/output_validator/.gitkeep
diff --git a/test/test_default_output_validator.py b/test/test_default_output_validator.py
index 9c7286726..220b12d9f 100644
--- a/test/test_default_output_validator.py
+++ b/test/test_default_output_validator.py
@@ -13,7 +13,7 @@
 
 RUN_DIR = Path.cwd().resolve()
 # Note: the python version isn't tested by default, because it's quite slow.
-DEFAULT_OUTPUT_VALIDATORS = ["default_output_validator.cpp"]
+DEFAULT_OUTPUT_VALIDATOR = ["default_output_validator.cpp"]
 
 config.args.verbose = 2
 config.args.error = True
@@ -42,7 +42,7 @@ def read_tests():
     return tests
 
 
-@pytest.fixture(scope="class", params=DEFAULT_OUTPUT_VALIDATORS)
+@pytest.fixture(scope="class", params=DEFAULT_OUTPUT_VALIDATOR)
 def validator(request):
     problem_dir = RUN_DIR / "test/problems/identity"
     os.chdir(problem_dir)
@@ -65,9 +65,9 @@ class MockRun:
 
 
 @pytest.mark.usefixtures("validator")
-class TestDefaultOutputValidators:
+class TestDefaultOutputValidator:
     @pytest.mark.parametrize("testdata", read_tests())
-    def test_default_output_validators(self, validator, testdata):
+    def test_default_output_validator(self, validator, testdata):
         problem, validator = validator
         flags, ans, out, exp = testdata
         flags = flags.split()
@@ -87,7 +87,7 @@ def test_default_output_validators(self, validator, testdata):
         r.out_path = out_path
         r.feedbackdir = problem.tmpdir / "data"
 
-        # TODO: the validators should probably be able to figure the flags out from the Problem config
+        # TODO: the validator should probably be able to figure the flags out from the Problem config
         result = validator.run(t, r, args=flags)
 
         if result.status != exp:

From 4a85c453a7cc4ae9776af6ab9ef3d47a28d31d64 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Wed, 5 Mar 2025 22:59:33 +0100
Subject: [PATCH 03/10] updated skel

---
 .../output_validator/output_validator.cpp                        | 0
 skel/problem/output_validator/validation.h                       | 1 +
 skel/problem/output_validators/output_validator/validation.h     | 1 -
 3 files changed, 1 insertion(+), 1 deletion(-)
 rename skel/problem/{output_validators => }/output_validator/output_validator.cpp (100%)
 create mode 120000 skel/problem/output_validator/validation.h
 delete mode 120000 skel/problem/output_validators/output_validator/validation.h

diff --git a/skel/problem/output_validators/output_validator/output_validator.cpp b/skel/problem/output_validator/output_validator.cpp
similarity index 100%
rename from skel/problem/output_validators/output_validator/output_validator.cpp
rename to skel/problem/output_validator/output_validator.cpp
diff --git a/skel/problem/output_validator/validation.h b/skel/problem/output_validator/validation.h
new file mode 120000
index 000000000..8394e5a44
--- /dev/null
+++ b/skel/problem/output_validator/validation.h
@@ -0,0 +1 @@
+../../../headers/validation.h
\ No newline at end of file
diff --git a/skel/problem/output_validators/output_validator/validation.h b/skel/problem/output_validators/output_validator/validation.h
deleted file mode 120000
index 9a928c978..000000000
--- a/skel/problem/output_validators/output_validator/validation.h
+++ /dev/null
@@ -1 +0,0 @@
-../../../../headers/validation.h
\ No newline at end of file

From 6cb4db5b67b6e2184bffe3249079f1b9bd73c136 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Wed, 5 Mar 2025 23:22:52 +0100
Subject: [PATCH 04/10] fix symlink

---
 test/problems/constants/output_validator/validation.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/problems/constants/output_validator/validation.h b/test/problems/constants/output_validator/validation.h
index 2b74c5d6a..9a928c978 120000
--- a/test/problems/constants/output_validator/validation.h
+++ b/test/problems/constants/output_validator/validation.h
@@ -1 +1 @@
-../../../../../headers/validation.h
\ No newline at end of file
+../../../../headers/validation.h
\ No newline at end of file

From 97a1a34d2abd755fedeb3c3ec38449d563a9ed96 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Wed, 5 Mar 2025 23:30:59 +0100
Subject: [PATCH 05/10] create output_validators dir

---
 bin/export.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/bin/export.py b/bin/export.py
index 6abfacb77..74d547dc9 100644
--- a/bin/export.py
+++ b/bin/export.py
@@ -244,6 +244,7 @@ def add_file(path, source):
 
     # TODO: Remove this if we know others use the output_validator dir
     if (export_dir / "output_validator").exists():
+        (export_dir / "output_validators").mkdir(parents=True)
         (export_dir / "output_validator").rename(
             export_dir / "output_validators" / "output_validator"
         )

From fb56fdef1e602b1039c339754e885e29efc05de6 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Sat, 8 Mar 2025 14:46:16 +0100
Subject: [PATCH 06/10] changed class constants

---
 bin/problem.py  |  5 ++---
 bin/validate.py | 12 ++++++------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/bin/problem.py b/bin/problem.py
index a5fa48f3e..b2019a9f9 100644
--- a/bin/problem.py
+++ b/bin/problem.py
@@ -815,14 +815,13 @@ def _validators(
         if key in problem._validators_cache:
             return problem._validators_cache[key]
 
-        assert hasattr(cls, "source_dirs")
         if cls == validate.OutputValidator:
-            assert len(cls.source_dirs) == 1
             if problem.custom_output:
-                paths = [problem.path / cls.source_dirs[0]]
+                paths = [problem.path / validate.OutputValidator.source_dirs]
             else:
                 paths = [config.TOOLS_ROOT / "support" / "default_output_validator.cpp"]
         else:
+            assert hasattr(cls, "source_dirs")
             paths = [
                 p for source_dir in cls.source_dirs for p in glob(problem.path / source_dir, "*")
             ]
diff --git a/bin/validate.py b/bin/validate.py
index 1b4094925..375252ed6 100644
--- a/bin/validate.py
+++ b/bin/validate.py
@@ -224,9 +224,9 @@ class InputValidator(Validator):
     def __init__(self, problem, path, **kwargs):
         super().__init__(problem, path, "input_validators", **kwargs)
 
-    validator_type = "input"
+    validator_type: Final[str] = "input"
 
-    source_dirs = ["input_validators", "input_format_validators"]
+    source_dir: Final[list[str]] = ["input_validators", "input_format_validators"]
 
     def run(
         self,
@@ -284,9 +284,9 @@ class AnswerValidator(Validator):
     def __init__(self, problem, path, **kwargs):
         super().__init__(problem, path, "answer_validators", **kwargs)
 
-    validator_type = "answer"
+    validator_type: Final[str] = "answer"
 
-    source_dirs = ["answer_validators", "answer_format_validators"]
+    source_dirs: Final[list[str]] = ["answer_validators", "answer_format_validators"]
 
     def run(
         self,
@@ -335,9 +335,9 @@ class OutputValidator(Validator):
     def __init__(self, problem, path, **kwargs):
         super().__init__(problem, path, "output_validator", **kwargs)
 
-    validator_type = "output"
+    validator_type: Final[str] = "output"
 
-    source_dirs = ["output_validator"]
+    source_dirs: Final[str] = "output_validator"
 
     def run(
         self,

From b4b6d38ba1426a1cab4ea15bc724266ecbcd8fd5 Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Sat, 8 Mar 2025 14:57:46 +0100
Subject: [PATCH 07/10] fix source_dir(s)

---
 bin/problem.py  | 2 +-
 bin/validate.py | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/bin/problem.py b/bin/problem.py
index b2019a9f9..9820dcfb0 100644
--- a/bin/problem.py
+++ b/bin/problem.py
@@ -817,7 +817,7 @@ def _validators(
 
         if cls == validate.OutputValidator:
             if problem.custom_output:
-                paths = [problem.path / validate.OutputValidator.source_dirs]
+                paths = [problem.path / validate.OutputValidator.source_dir]
             else:
                 paths = [config.TOOLS_ROOT / "support" / "default_output_validator.cpp"]
         else:
diff --git a/bin/validate.py b/bin/validate.py
index 375252ed6..3c8d4867d 100644
--- a/bin/validate.py
+++ b/bin/validate.py
@@ -226,7 +226,7 @@ def __init__(self, problem, path, **kwargs):
 
     validator_type: Final[str] = "input"
 
-    source_dir: Final[list[str]] = ["input_validators", "input_format_validators"]
+    source_dirs: Final[list[str]] = ["input_validators", "input_format_validators"]
 
     def run(
         self,
@@ -337,7 +337,7 @@ def __init__(self, problem, path, **kwargs):
 
     validator_type: Final[str] = "output"
 
-    source_dirs: Final[str] = "output_validator"
+    source_dir: Final[str] = "output_validator"
 
     def run(
         self,

From 1b77bcbf747a108131e973240d37e80f42b3386a Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Sat, 8 Mar 2025 17:59:09 +0100
Subject: [PATCH 08/10] copy symlinks

---
 bin/upgrade.py | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/bin/upgrade.py b/bin/upgrade.py
index 547a06a9e..45485f0f5 100644
--- a/bin/upgrade.py
+++ b/bin/upgrade.py
@@ -198,8 +198,29 @@ def upgrade_output_validators(problem_path: Path, bar: ProgressBar) -> None:
         content = [*(problem_path / "output_validators").iterdir()]
         if len(content) == 1 and content[0].is_dir():
             bar.log(f"renaming 'output_validators/{content[0].name}' to 'output_validator/'")
-            content[0].rename(problem_path / "output_validator")
-            (problem_path / "output_validators").rmdir()
+
+            def move(src: str, dst: str) -> None:
+                if Path(src).is_symlink():
+                    src_dst = Path(src).resolve()
+                    if src_dst.is_relative_to(content[0]):  # local symlink
+                        Path(src).rename(dst)
+                    else:  # link outside output_validators/
+                        dst_pos = Path(dst).resolve()
+                        common = [
+                            a
+                            for a, b in zip(reversed(src_dst.parents), reversed(dst_pos.parents))
+                            if a == b
+                        ][-1]
+                        link = Path(
+                            "../" * (len(dst_pos.parents) - len(common.parts))
+                        ) / src_dst.relative_to(common)
+                        Path(dst).symlink_to(link)
+                        Path(src).unlink()
+                else:
+                    Path(src).rename(dst)
+
+            shutil.copytree(content[0], problem_path / "output_validator", copy_function=move)
+            shutil.rmtree(problem_path / "output_validators")
         else:
             bar.log("renaming 'output_validators/' to 'output_validator/'")
             (problem_path / "output_validators").rename(problem_path / "output_validator")

From e8399c0ef21550b66cfa61e5e2319f69b97629bd Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Sat, 8 Mar 2025 23:37:40 +0100
Subject: [PATCH 09/10] export legacy

---
 bin/export.py  | 91 +++++++++++++++++++++++++++++++++++---------------
 bin/upgrade.py | 69 +++++++++-----------------------------
 bin/util.py    | 37 ++++++++++++++++++++
 3 files changed, 117 insertions(+), 80 deletions(-)

diff --git a/bin/export.py b/bin/export.py
index 1e577bc13..86d81a647 100644
--- a/bin/export.py
+++ b/bin/export.py
@@ -92,6 +92,10 @@ def build_samples_zip(problems, output, statement_language):
 def build_problem_zip(problem: Problem, output: Path):
     """Make DOMjudge/Kattis ZIP file for specified problem."""
 
+    if not has_ryaml:
+        error("zip needs the ruamel.yaml python3 library. Install python[3]-ruamel.yaml.")
+        return
+
     # Add problem PDF for only one language to the zip file (note that Kattis export does not include PDF)
     statement_language = None if config.args.kattis else force_single_language([problem])
 
@@ -170,33 +174,64 @@ def add_file(path, source):
                             out = f2.relative_to(problem.path)
                             add_file(out, f2)
 
-    # DOMjudge does not support 'type' in problem.yaml nor 'output_validator_args' in testdata.yaml yet.
-    # TODO: Remove this once it does.
-    if not config.args.kattis:
-        yaml_path = export_dir / "problem.yaml"
-        yaml_data = [yaml_path.read_text(), "\nvalidation:"]
-        if problem.custom_output:
-            yaml_data.append(" custom")
-            if problem.interactive:
-                yaml_data.append(" interactive")
-            if problem.multi_pass:
-                yaml_data.append(" multi-pass")
-        else:
-            yaml_data.append(" default")
-        yaml_data.append("\n")
-
-        validator_flags = " ".join(
-            problem.get_testdata_yaml(
-                problem.path / "data",
-                "output_validator_args",
-                PrintBar("Getting validator_flags for legacy DOMjudge export"),
-            )
+    # DOMjudge and Kattis do not support draft yet.
+    # TODO: Remove they do.
+    from ruamel.yaml.comments import CommentedMap
+
+    yaml_path = export_dir / "problem.yaml"
+    yaml_data = read_yaml(yaml_path)
+    # drop format version -> legacy
+    if "problem_format_version" in yaml_data:
+        ryaml_filter(yaml_data, "problem_format_version")
+    # type -> validation
+    if "type" in yaml_data:
+        ryaml_filter(yaml_data, "type")
+    validation = []
+    if problem.custom_output:
+        validation.append("custom")
+        if problem.interactive:
+            validation.append("interactive")
+        if problem.multi_pass:
+            validation.append("multi-pass")
+    else:
+        validation.append("default")
+    yaml_data["validation"] = " ".join(validation)
+    # credits -> author
+    if "credits" in yaml_data:
+        ryaml_filter(yaml_data, "credits")
+        if problem.settings.credits.authors:
+            yaml_data["author"] = ", ".join(p.name for p in problem.settings.credits.authors)
+    # change source:
+    if problem.settings.source:
+        if len(problem.settings.source) > 1:
+            util.warn(f"Found multiple sources, using '{problem.settings.source[0].name}'.")
+        yaml_data["source"] = problem.settings.source[0].name
+        yaml_data["source_url"] = problem.settings.source[0].url
+    # limits.time_multipliers -> time_multiplier / time_safety_margin
+    if "limits" not in yaml_data or not yaml_data["limits"]:
+        yaml_data["limits"] = CommentedMap()
+    limits = yaml_data["limits"]
+    if "time_multipliers" in limits:
+        ryaml_filter(limits, "time_multipliers")
+    limits["time_multiplier"] = problem.limits.ac_to_time_limit
+    limits["time_safety_margin"] = problem.limits.time_limit_to_tle
+    # drop explicit timelimit for kattis:
+    if "time_limit" in limits:
+        # keep this for kattis even when "time_limit" is supported
+        ryaml_filter(limits, "time_limit")
+    # validator_flags
+    validator_flags = " ".join(
+        problem.get_testdata_yaml(
+            problem.path / "data",
+            "output_validator_args",
+            PrintBar("Getting validator_flags for legacy export"),
         )
-        if validator_flags:
-            yaml_data.append(f"validator_flags: {validator_flags}\n")
-
-        yaml_path.unlink()
-        yaml_path.write_text("".join(yaml_data))
+    )
+    if validator_flags:
+        yaml_data["validator_flags"] = validator_flags
+    # write legacy style yaml
+    yaml_path.unlink()
+    write_yaml(yaml_data, yaml_path)
 
     # DOMjudge does not support 'limits.time_limit' in problem.yaml yet.
     # TODO: Remove this once it does.
@@ -293,6 +328,10 @@ def add_file(path, source):
 # solutions*.{lang}.pdf
 # Output is <outfile>
 def build_contest_zip(problems, zipfiles, outfile, statement_language):
+    if not has_ryaml:
+        error("zip needs the ruamel.yaml python3 library. Install python[3]-ruamel.yaml.")
+        return
+
     print(f"writing ZIP file {outfile}", file=sys.stderr)
 
     if not config.args.kattis:  # Kattis does not use problems.yaml.
diff --git a/bin/upgrade.py b/bin/upgrade.py
index 45485f0f5..ee959e7bc 100644
--- a/bin/upgrade.py
+++ b/bin/upgrade.py
@@ -10,45 +10,6 @@
     from ruamel.yaml.comments import CommentedMap, CommentedSeq
 
 
-# This tries to preserve the correct comments.
-def _filter(data: Any, remove: str) -> Any:
-    assert isinstance(data, CommentedMap)
-
-    remove_index = list(data.keys()).index(remove)
-    if remove_index == 0:
-        return data.pop(remove)
-
-    curr = data
-    prev_key = list(data.keys())[remove_index - 1]
-    while isinstance(curr[prev_key], list | dict):
-        # Try to remove the comment from the last element in the preceding list/dict
-        curr = curr[prev_key]
-        if isinstance(curr, list):
-            prev_key = len(curr) - 1
-        else:
-            prev_key = list(curr.keys())[-1]
-
-    if remove in data.ca.items:
-        # Move the comment that belongs to the removed key (which comes _after_ the removed key)
-        # to the preceding key
-        curr.ca.items[prev_key] = data.ca.items.pop(remove)
-    elif prev_key in data.ca.items:
-        # If the removed key does not have a comment,
-        # the comment after the previous key should be removed
-        curr.ca.items.pop(prev_key)
-
-    return data.pop(remove)
-
-
-# Insert a new key before an old key, then remove the old key.
-# If new_value is not given, the default is to simply rename the old key to the new key.
-def _replace(data: Any, old_key: str, new_key: str, new_value: Any = None) -> None:
-    if new_value is None:
-        new_value = data[old_key]
-    data.insert(list(data.keys()).index(old_key), new_key, new_value)
-    _filter(data, old_key)
-
-
 def upgrade_data(problem_path: Path, bar: ProgressBar) -> None:
     rename = [
         ("data/invalid_inputs", "data/invalid_input"),
@@ -85,7 +46,7 @@ def upgrade_testdata_yaml(problem_path: Path, bar: ProgressBar) -> None:
                         resume=True,
                     )
                     continue
-                _replace(data, old, new)
+                ryaml_replace(data, old, new)
 
         write_yaml(data, f)
 
@@ -115,7 +76,7 @@ def upgrade_generators_yaml(problem_path: Path, bar: ProgressBar) -> None:
                 )
                 continue
             bar.log(f"renaming 'data.{old_name}' to 'data.{new_name}' in generators.yaml")
-            _replace(data, old_name, new_name)
+            ryaml_replace(data, old_name, new_name)
             changed = True
 
     def upgrade_generated_testdata_yaml(data: dict[str, Any], path: str) -> bool:
@@ -138,7 +99,7 @@ def upgrade_generated_testdata_yaml(data: dict[str, Any], path: str) -> bool:
                         )
                         continue
                     bar.log(f"change '{old}' to '{new}' in generators.yaml{print_path}")
-                    _replace(testdata, old, new)
+                    ryaml_replace(testdata, old, new)
                     changed = True
         if "data" in data and data["data"]:
             children = data["data"] if isinstance(data["data"], list) else [data["data"]]
@@ -256,7 +217,7 @@ def upgrade_problem_yaml(problem_path: Path, bar: ProgressBar) -> None:
             # "type" comes before "name" in the spec
             pos = list(data.keys()).index("name") if "name" in data else 0
             data.insert(pos, "type", type if len(type) > 1 else type[0])
-            _filter(data, "validation")
+            ryaml_filter(data, "validation")
 
     if "author" in data:
         if "credits" in data:
@@ -269,23 +230,23 @@ def upgrade_problem_yaml(problem_path: Path, bar: ProgressBar) -> None:
                 name.strip() for name in data["author"].replace("and", ",").split(",")
             )
             credits = CommentedMap({"authors": authors if len(authors) > 1 else authors[0]})
-            _replace(data, "author", "credits", credits)
+            ryaml_replace(data, "author", "credits", credits)
 
     if "source_url" in data:
         if "source" not in data:
-            _replace(data, "source_url", "source")
+            ryaml_replace(data, "source_url", "source")
         elif data["source"]:
             bar.log("change 'source_url' to 'source.url' in problem.yaml")
             old_pos = list(data.keys()).index("source")
-            old_source = _filter(data, "source")
-            old_source_url = _filter(data, "source_url")
+            old_source = ryaml_filter(data, "source")
+            old_source_url = ryaml_filter(data, "source_url")
             data.insert(
                 old_pos, "source", CommentedMap({"name": old_source, "url": old_source_url})
             )
         else:
             bar.log("remove empty 'source(_url)' in problem.yaml")
-            _filter(data, "source")
-            _filter(data, "source_url")
+            ryaml_filter(data, "source")
+            ryaml_filter(data, "source_url")
 
     if "limits" in data:
         limits = data["limits"]
@@ -304,19 +265,19 @@ def upgrade_problem_yaml(problem_path: Path, bar: ProgressBar) -> None:
                 if "time_multiplier" in limits:
                     if limits["time_multiplier"] != 2:  # Skip if it's equal to the new default
                         time_multipliers["ac_to_time_limit"] = limits["time_multiplier"]
-                    _filter(limits, "time_multiplier")
+                    ryaml_filter(limits, "time_multiplier")
 
                 if "time_safety_margin" in limits:
                     if limits["time_safety_margin"] != 1.5:  # Skip if it's equal to the new default
                         time_multipliers["time_limit_to_tle"] = limits["time_safety_margin"]
-                    _filter(limits, "time_safety_margin")
+                    ryaml_filter(limits, "time_safety_margin")
 
                 if time_multipliers:
                     limits["time_multipliers"] = time_multipliers
                 # If both time multipliers are default, remove the comments (this only works if
                 # there are no other limits configured, but that's the most common case anyway)
                 if not limits:
-                    _filter(data, "limits")
+                    ryaml_filter(data, "limits")
 
     def add_args(new_data: dict[str, Any]) -> bool:
         if "output_validator_args" in new_data:
@@ -327,7 +288,7 @@ def add_args(new_data: dict[str, Any]) -> bool:
             return False
         bar.log("change 'validator_flags' to 'output_validator_args' in testdata.yaml")
         new_data["output_validator_args"] = data["validator_flags"]
-        _filter(data, "validator_flags")
+        ryaml_filter(data, "validator_flags")
         return True
 
     if "validator_flags" in data:
@@ -359,7 +320,7 @@ def add_args(new_data: dict[str, Any]) -> bool:
                 if add_args(testdata_data):
                     write_yaml(testdata_data, testdata_path)
         else:
-            _filter(data, "validator_flags")
+            ryaml_filter(data, "validator_flags")
 
     timelimit_path = problem_path / ".timelimit"
     if timelimit_path.is_file():
diff --git a/bin/util.py b/bin/util.py
index 0ff476f2b..b4b570ddf 100644
--- a/bin/util.py
+++ b/bin/util.py
@@ -713,6 +713,43 @@ def ryaml_get_or_add(
         assert isinstance(value, t)
         return value  # type: ignore
 
+    # This tries to preserve the correct comments.
+    def ryaml_filter(data: Any, remove: str) -> Any:
+        assert isinstance(data, ruamel.yaml.comments.CommentedMap)
+        remove_index = list(data.keys()).index(remove)
+        if remove_index == 0:
+            return data.pop(remove)
+
+        curr = data
+        prev_key = list(data.keys())[remove_index - 1]
+        while isinstance(curr[prev_key], list | dict):
+            # Try to remove the comment from the last element in the preceding list/dict
+            curr = curr[prev_key]
+            if isinstance(curr, list):
+                prev_key = len(curr) - 1
+            else:
+                prev_key = list(curr.keys())[-1]
+
+        if remove in data.ca.items:
+            # Move the comment that belongs to the removed key (which comes _after_ the removed key)
+            # to the preceding key
+            curr.ca.items[prev_key] = data.ca.items.pop(remove)
+        elif prev_key in data.ca.items:
+            # If the removed key does not have a comment,
+            # the comment after the previous key should be removed
+            curr.ca.items.pop(prev_key)
+
+        return data.pop(remove)
+
+    # Insert a new key before an old key, then remove the old key.
+    # If new_value is not given, the default is to simply rename the old key to the new key.
+    def ryaml_replace(data: Any, old_key: str, new_key: str, new_value: Any = None) -> None:
+        assert isinstance(data, ruamel.yaml.comments.CommentedMap)
+        if new_value is None:
+            new_value = data[old_key]
+        data.insert(list(data.keys()).index(old_key), new_key, new_value)
+        ryaml_filter(data, old_key)
+
 
 # Only allow one thread to write at the same time. Else, e.g., generating test cases in parallel goes wrong.
 write_yaml_lock = threading.Lock()

From 18417fea1e4692345afdef514e3c442fa9456413 Mon Sep 17 00:00:00 2001
From: Maarten Sijm <9739541+mpsijm@users.noreply.github.com>
Date: Sun, 9 Mar 2025 14:09:00 +0100
Subject: [PATCH 10/10] [export] Fix typo in comment

---
 bin/export.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/bin/export.py b/bin/export.py
index 86d81a647..f5d5e6028 100644
--- a/bin/export.py
+++ b/bin/export.py
@@ -174,8 +174,8 @@ def add_file(path, source):
                             out = f2.relative_to(problem.path)
                             add_file(out, f2)
 
-    # DOMjudge and Kattis do not support draft yet.
-    # TODO: Remove they do.
+    # DOMjudge and Kattis do not support 2023-07-draft yet.
+    # TODO: Remove once they do.
     from ruamel.yaml.comments import CommentedMap
 
     yaml_path = export_dir / "problem.yaml"