Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[1.0.0] - 2026-03-29

Added

• Semantic equality comparison: All expression types now implement __eq__ and __hash__ for structural equality. Comparison is order-insensitive for commutative compound expressions (AllExpr, AnyExpr, In). Enables expressions to be used in sets and as dict keys, and fixes Field.__eq__ so it returns a bool instead of an Eq node when compared to another expression object.

Changed

• Optimizer — NOT of comparison folded to its complement (runs before De Morgan's law):
• NOT(f == v) → f != v
• NOT(f != v) → f == v
• NOT(f < v) → f >= v
• NOT(f <= v) → f > v
• NOT(f > v) → f <= v
• NOT(f >= v) → f < v
• NOT(f.is_null()) → f.is_not_null()
• NOT(f.is_not_null()) → f.is_null()

Fixed

• Optimizer recursion: The optimizer now recurses into sub-expressions created by each rule before moving on.

[0.8.0] - 2026-03-26

Changed

• Aggregation COUNT field handling: Constructing an Aggregation with AggregationFunction.COUNT and a non-None field no longer raises ValueError. The field is now silently ignored and set to None.

[0.7.0] - 2026-03-25

Added

• Field pruning and projection (therismos.prune_fields): Remove or project field-based constraints from an expression tree in a polarity-aware manner. See Field Pruning.

[0.6.0] - 2026-03-21

Added

• Expression Templates: Parameterized, persistable filter expressions with named placeholders and a transform pipeline DSL. See Templates.

• Between expression: A new first-class expression for half-open range checks (lower <= field < upper). Constructed via Field.between(lower, upper).

[0.5.0] - 2026-02-25

Added

• Polars backend (therismos[polars]): PolarsExprVisitor, PolarsSortSpecVisitor, PolarsGroupSpecVisitor.
• Pandas backend (therismos[pandas]): PandasExprVisitor, PandasSortSpecVisitor, PandasGroupSpecVisitor.

[0.4.1] - 2026-01-27

Changed

• Internal Refactoring: Generic OptimizationRecord[T], shared keep_last_occurrence() utility, Serializer.GRAMMAR class constant. No public API changes.

[0.4.0] - 2026-01-20

Added

• Expression Class Hierarchy: New abstract base classes: AtomicExpr, CompositeExpr, DecoratorExpr, FieldBasedExpr, SingleValuedFieldExpr, MultiValuedFieldExpr, ComparisonExpr.
• Multi-Valued Field Evaluation: unwind_data utility and "any"/"none" semantics for list fields.
• Construction-Time Validation: SingleValuedFieldExpr subclasses raise TypeError for list/tuple/set values.

Changed

• BREAKING: Serializer parameter renamed field_types → implicit_field_types.
• BREAKING: Serializer method renamed register_type() → register_custom_type().
• BREAKING: Expr.evaluate() input must now be wrapped with unwind_data.
• BREAKING: Expr.evaluate() renamed from the previous Expr.run_eval() — avoids false positives from static analyzers that flag unsafe dynamic evaluation.

[0.3.0] - 2025-11-23

Added

• Sorting Module: SortOrder, SortCriterion, SortSpec, optimizer, visitors, MongoDB converter, serializer.
• Grouping and Aggregation Module: AggregationFunction, Aggregation, GroupSpec, optimizer, visitors, MongoDB converter, serializer.

[0.2.0] - 2025-11-23

Added

• Expression Serialization: Grammar-based Serializer for compact string representations. See Serialization.

[0.1.0] - 2025-11-22

Added

• Core expression AST with Eq, Ne, Lt, Le, Gt, Ge, Regex, In, IsNull.
• Compound expressions: AllExpr, AnyExpr, NotExpr.
• Optimizer with contradiction/tautology detection, De Morgan's law, and more.
• Visitor pattern with built-in StringVisitor, DictVisitor, CountVisitor, FieldGathererVisitor.
• MongoDB backend converter (MongoVisitor).