Expose configurable grouping token limit

sqlparse/__init__.py

@@ -16,10 +16,34 @@
 from sqlparse import tokens
 from sqlparse import filters
 from sqlparse import formatter
+from sqlparse.engine import grouping as _grouping
 
 
 __version__ = "0.5.6.dev0"
-__all__ = ["engine", "filters", "formatter", "sql", "tokens", "cli"]
+__all__ = [
+    "engine",
+    "filters",
+    "formatter",
+    "sql",
+    "tokens",
+    "cli",
+    "set_max_grouping_tokens",
+]
+
+
+def set_max_grouping_tokens(limit: Optional[int]) -> None:
+    """Set the maximum token count accepted by the grouping stage.
+
+    Pass ``None`` to disable the token-count limit. Positive integers set a
+    process-wide limit for subsequent parsing and formatting operations.
+    Disabling or increasing this limit is not recommended for SQL from
+    untrusted sources.
+    """
+    if limit is not None and (
+        isinstance(limit, bool) or not isinstance(limit, int) or limit < 1
+    ):
+        raise ValueError("Grouping token limit must be a positive integer or None")
+    _grouping.MAX_GROUPING_TOKENS = limit
 
 
 def parse(

tests/test_grouping_config.py

@@ -0,0 +1,36 @@
+import pytest
+
+import sqlparse
+from sqlparse.engine import grouping
+from sqlparse.exceptions import SQLParseError
+
+
+@pytest.fixture(autouse=True)
+def restore_grouping_token_limit():
+    original = grouping.MAX_GROUPING_TOKENS
+    try:
+        yield
+    finally:
+        grouping.MAX_GROUPING_TOKENS = original
+
+
+def test_set_max_grouping_tokens_changes_parser_limit():
+    sqlparse.set_max_grouping_tokens(1)
+
+    with pytest.raises(SQLParseError, match="Maximum number of tokens exceeded"):
+        sqlparse.parse("select value from example")
+
+
+def test_set_max_grouping_tokens_none_disables_limit():
+    sqlparse.set_max_grouping_tokens(None)
+
+    assert len(sqlparse.parse("select value from example")) == 1
+
+
+@pytest.mark.parametrize("limit", (0, -1, True, 1.5, "100"))
+def test_set_max_grouping_tokens_rejects_invalid_values(limit):
+    with pytest.raises(
+        ValueError,
+        match="Grouping token limit must be a positive integer or None",
+    ):
+        sqlparse.set_max_grouping_tokens(limit)

tests/test_grouping_config_format.py

@@ -0,0 +1,15 @@
+import pytest
+
+import sqlparse
+from sqlparse.engine import grouping
+from sqlparse.exceptions import SQLParseError
+
+
+def test_set_max_grouping_tokens_applies_to_formatting():
+    original = grouping.MAX_GROUPING_TOKENS
+    try:
+        sqlparse.set_max_grouping_tokens(1)
+        with pytest.raises(SQLParseError, match="Maximum number of tokens exceeded"):
+            sqlparse.format("select value from example", reindent=True)
+    finally:
+        grouping.MAX_GROUPING_TOKENS = original