expression-parsing: add notation_warnings and NotationWarning

expression_parsing/CHANGELOG.md

@@ -42,6 +42,7 @@ The first public release. Further tidy-up after the 0.2.0 extraction: previewing
 ### Added
 
 - `SympyParsingConfig.replace` also takes `extra_unsplittable_symbols` and `extra_symbol_assumptions`, alongside parameter changes (`config.replace(simplify=False, extra_unsplittable_symbols=(...))`); they needed `dataclasses.replace` before.
+- `notation_warnings(response, strict_syntax)` returns the `NotationWarning`s for a response: `EXPONENT` (`^`) and `FACTORIAL` (`!`) under strict syntax, and `TRIPLE_FACTORIAL` (`!!!`) always. `NotationWarning` is a `StrEnum` whose values are compareExpressions' feedback tags (`NOTATION_WARNING_EXPONENT`, ...), so a tag lookup keeps working. Wording the warnings is still up to the caller. It was `notation_warnings` in compareExpressions' `evaluation.py`, and behaves the same: the checks are substring tests, so under strict syntax `!=` also warns `FACTORIAL`, and `!!!` warns both `FACTORIAL` and `TRIPLE_FACTORIAL`.
 - DEBUG logging through module loggers (`lambdafeedback.expression_parsing.*`), with a `NullHandler` on the package logger; nothing is logged at INFO or above. See the repository README. Preprocessing, parsing and `parse_latex` log each step's result.
 
 ### Security

expression_parsing/src/lambdafeedback/expression_parsing/__init__.py

@@ -31,6 +31,7 @@
     UnknownConventionError,
 )
 from .latex import MAX_LATEX_NESTING, extract_latex, latex_symbols, parse_latex, sanitise_latex, sympy_to_latex
+from .notation import NotationWarning, notation_warnings
 from .numbers import (
     compute_relative_tolerance_from_significant_decimals,
     generate_arbitrary_number_pattern_matcher,
@@ -82,6 +83,7 @@
     "FunctionName",
     "InvalidParameterError",
     "LatexParseError",
+    "NotationWarning",
     "SymbolAssumptionError",
     "SymbolSpec",
     "SympyParsingConfig",
@@ -103,6 +105,7 @@
     "is_number",
     "latex_symbols",
     "normalise_unicode_operators",
+    "notation_warnings",
     "parse_expression",
     "parse_expressions",
     "parse_latex",

expression_parsing/src/lambdafeedback/expression_parsing/notation.py

@@ -0,0 +1,37 @@
+"""Notation in a response that is likely to be misread, such as ``^`` for a power under strict syntax.
+
+Only the detection lives here: wording the warnings for a learner is up to
+the caller, keyed by :class:`NotationWarning`.
+"""
+
+from __future__ import annotations
+
+from enum import StrEnum
+
+
+class NotationWarning(StrEnum):
+    """A notation warning; the values are compareExpressions' feedback tags."""
+
+    EXPONENT = "NOTATION_WARNING_EXPONENT"
+    """``^`` under strict syntax, which doesn't read it as a power."""
+    FACTORIAL = "NOTATION_WARNING_FACTORIAL"
+    """``!`` under strict syntax, which doesn't read it as a factorial."""
+    TRIPLE_FACTORIAL = "NOTATION_WARNING_TRIPLE_FACTORIAL"
+    """``!!!``, which is never supported."""
+
+
+def notation_warnings(response: str, strict_syntax: bool) -> list[NotationWarning]:
+    """The notation warnings for ``response``, in the order of :class:`NotationWarning`.
+
+    The checks look for the characters anywhere in ``response``, so under
+    strict syntax ``!`` also warns for ``!=`` and ``!!!`` (which gets both
+    factorial warnings).
+    """
+    warnings = []
+    if strict_syntax and "^" in response:
+        warnings.append(NotationWarning.EXPONENT)
+    if strict_syntax and "!" in response:
+        warnings.append(NotationWarning.FACTORIAL)
+    if "!!!" in response:
+        warnings.append(NotationWarning.TRIPLE_FACTORIAL)
+    return warnings

expression_parsing/tests/test_api.py

@@ -8,6 +8,7 @@
     ExpressionParsingError,
     InvalidParameterError,
     LatexParseError,
+    NotationWarning,
     SymbolAssumptionError,
     SymbolSpec,
     SympyParsingConfig,
@@ -17,6 +18,7 @@
     is_complex_number_on_cartesian_form,
     is_complex_number_on_exponential_form,
     is_number,
+    notation_warnings,
     parse_expression,
     parse_expressions,
     parse_latex,
@@ -185,3 +187,29 @@ def test_number_forms():
     assert is_complex_number_on_cartesian_form("1+2*I")
     assert is_complex_number_on_exponential_form("2*exp(3*I)")
     assert not is_number("x")
+
+
+class TestNotationWarnings:
+    @pytest.mark.parametrize(
+        "response, strict, expected",
+        [
+            ("x**2", True, []),
+            ("x^2", True, [NotationWarning.EXPONENT]),
+            ("x^2", False, []),
+            ("n!", True, [NotationWarning.FACTORIAL]),
+            ("n!", False, []),
+            ("x != y", True, [NotationWarning.FACTORIAL]),
+            ("n!!!", False, [NotationWarning.TRIPLE_FACTORIAL]),
+            ("n!!!", True, [NotationWarning.FACTORIAL, NotationWarning.TRIPLE_FACTORIAL]),
+            ("x^n!", True, [NotationWarning.EXPONENT, NotationWarning.FACTORIAL]),
+        ],
+    )
+    def test_warnings(self, response, strict, expected):
+        assert notation_warnings(response, strict) == expected
+
+    def test_values_are_the_compare_expressions_tags(self):
+        assert [str(warning) for warning in NotationWarning] == [
+            "NOTATION_WARNING_EXPONENT",
+            "NOTATION_WARNING_FACTORIAL",
+            "NOTATION_WARNING_TRIPLE_FACTORIAL",
+        ]