# purity URL: /kida/api/analysis/purity/ Section: analysis Description: Purity analysis for template introspection. Determines if expressions and blocks are pure (deterministic). Pure blocks produce the same output for the same inputs. --- > For a complete page index, fetch /kida/llms.txt. Open LLM text (/kida/api/analysis/purity/index.txt) Share with AI Ask Claude (https://claude.ai/new?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fpurity%2Findex.txt) Ask ChatGPT (https://chatgpt.com/?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fpurity%2Findex.txt) Ask Gemini (https://gemini.google.com/app?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fpurity%2Findex.txt) Ask Copilot (https://copilot.microsoft.com/?q=Please%20help%20me%20understand%20this%20documentation%3A%20%2Fkida%2Fapi%2Fanalysis%2Fpurity%2Findex.txt) Module # `analysis.purity` Purity analysis for template introspection. Determines if expressions and blocks are pure (deterministic). Pure blocks produce the same output for the same inputs. 1Class1Function ## Classes `PurityAnalyzer` 47 ▼ Determine if an expression or block is pure (deterministic). Pure expressions produce the same out… Determine if an expression or block is pure (deterministic). Pure expressions produce the same output for the same inputs. This is used to determine cache safety. Conservative: defaults to "unknown" when uncertain. Purity Rules: - Constants, variables, attribute access: pure - Binary/unary operations, comparisons: pure - Known pure filters (upper, lower, sort, etc.): pure - Known impure filters (random, shuffle): impure - Unknown filters/functions: unknown #### Methods `analyze` 1 `PurityLevel` ▼ Analyze a node and return its purity level. `def analyze(self, node: Node) -> PurityLevel` ##### Parameters Name Type Description `node` `—` AST node to analyze. ##### Returns `PurityLevel` "pure", "impure", or "unknown" Internal Methods 46 ▼ `__init__` 3 ▼ Initialize analyzer with optional extensions. `def __init__(self, extra_pure_functions: frozenset[str] | None = None, extra_impure_filters: frozenset[str] | None = None, template_resolver: Callable[[str], Any] | None = None) -> None` ##### Parameters Name Type Description `extra_pure_functions` `—` Additional functions to treat as pure. Default:`None` `extra_impure_filters` `—` Additional filters to treat as impure. Default:`None` `template_resolver` `—` Optional callback(name: str) -> Template | None to resolve included templates. If None, includes return "unknown". Default:`None` `_visit` 1 `PurityLevel` ▼ Visit a node and determine purity. `def _visit(self, node: Node | None) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_children` 1 `PurityLevel` ▼ Visit children and combine purity. `def _visit_children(self, node: Node) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_const` 1 `PurityLevel` ▼ Constants are pure. `def _visit_const(self, node: Const) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_name` 1 `PurityLevel` ▼ Variable access is pure (reading doesn't mutate). `def _visit_name(self, node: Name) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_getattr` 1 `PurityLevel` ▼ Attribute access is pure. `def _visit_getattr(self, node: Getattr) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_optionalgetattr` 1 `PurityLevel` ▼ Optional attribute access is pure. `def _visit_optionalgetattr(self, node: OptionalGetattr) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_getitem` 1 `PurityLevel` ▼ Subscript access is pure. `def _visit_getitem(self, node: Getitem) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_optionalgetitem` 1 `PurityLevel` ▼ Optional subscript access is pure. `def _visit_optionalgetitem(self, node: OptionalGetitem) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_binop` 1 `PurityLevel` ▼ Binary operations are pure. `def _visit_binop(self, node: BinOp) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_unaryop` 1 `PurityLevel` ▼ Unary operations are pure. `def _visit_unaryop(self, node: UnaryOp) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_compare` 1 `PurityLevel` ▼ Comparisons are pure. `def _visit_compare(self, node: Compare) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_boolop` 1 `PurityLevel` ▼ Boolean operations are pure. `def _visit_boolop(self, node: BoolOp) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_condexpr` 1 `PurityLevel` ▼ Conditional expressions are pure if all parts are pure. `def _visit_condexpr(self, node: CondExpr) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_nullcoalesce` 1 `PurityLevel` ▼ Null coalescing is pure. `def _visit_nullcoalesce(self, node: NullCoalesce) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_concat` 1 `PurityLevel` ▼ String concatenation is pure. `def _visit_concat(self, node: Concat) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_range` 1 `PurityLevel` ▼ Range literals are pure. `def _visit_range(self, node: Range) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_slice` 1 `PurityLevel` ▼ Slice expressions are pure. `def _visit_slice(self, node: Slice) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_list` 1 `PurityLevel` ▼ List literals are pure if all items are pure. `def _visit_list(self, node: List) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_listcomp` 1 `PurityLevel` ▼ List comprehensions are pure if iter, elt, and ifs are all pure. `def _visit_listcomp(self, node: ListComp) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_tuple` 1 `PurityLevel` ▼ Tuple literals are pure if all items are pure. `def _visit_tuple(self, node: Tuple) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_dict` 1 `PurityLevel` ▼ Dict literals are pure if all keys and values are pure. `def _visit_dict(self, node: Dict) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_filter` 1 `PurityLevel` ▼ Filter purity depends on the filter. `def _visit_filter(self, node: Filter) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_pipeline` 1 `PurityLevel` ▼ Pipeline purity depends on all filters in the chain. `def _visit_pipeline(self, node: Pipeline) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_funccall` 1 `PurityLevel` ▼ Function call purity depends on the function. `def _visit_funccall(self, node: FuncCall) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_test` 1 `PurityLevel` ▼ Tests are pure (they're just predicates). `def _visit_test(self, node: Test) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_for` 1 `PurityLevel` ▼ For loops are pure if body is pure. `def _visit_for(self, node: For) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_if` 1 `PurityLevel` ▼ Conditionals are pure if all branches are pure. `def _visit_if(self, node: If) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_match` 1 `PurityLevel` ▼ Match statements are pure if all branches are pure. `def _visit_match(self, node: Match) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_output` 1 `PurityLevel` ▼ Output is pure if expression is pure. `def _visit_output(self, node: Output) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_data` 1 `PurityLevel` ▼ Static data is pure. `def _visit_data(self, node: Data) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_cache` 1 `PurityLevel` ▼ Cache blocks: the body is evaluated, but result is cached. The block itself is… `def _visit_cache(self, node: Cache) -> PurityLevel` Cache blocks: the body is evaluated, but result is cached. The block itself is pure if the body is pure. ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_block` 1 `PurityLevel` ▼ Block is pure if body is pure. `def _visit_block(self, node: Block) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_with` 1 `PurityLevel` ▼ With blocks are pure if bindings and body are pure. `def _visit_with(self, node: With) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_withconditional` 1 `PurityLevel` ▼ Conditional with is pure if expr and body are pure. `def _visit_withconditional(self, node: WithConditional) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_set` 1 `PurityLevel` ▼ Set is pure if value is pure. `def _visit_set(self, node: Set) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_let` 1 `PurityLevel` ▼ Let is pure if value is pure. `def _visit_let(self, node: Let) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_capture` 1 `PurityLevel` ▼ Capture is pure if body is pure. `def _visit_capture(self, node: Capture) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_include` 1 `PurityLevel` ▼ Include purity depends on included template. If template_resolver is provided … `def _visit_include(self, node: Include) -> PurityLevel` Include purity depends on included template. If template_resolver is provided and template name is a constant, resolves and analyzes the included template. Otherwise returns "unknown". ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_extends` 1 `PurityLevel` ▼ Extends is unknown (depends on parent template). `def _visit_extends(self, node: Extends) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_def` 1 `PurityLevel` ▼ Function definition is pure if body is pure. `def _visit_def(self, node: Def) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_macro` 1 `PurityLevel` ▼ Macro definition (same as def). `def _visit_macro(self, node: Def) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_inlinedfilter` 1 `PurityLevel` ▼ Inlined filter is pure (only pure filters are inlined). `def _visit_inlinedfilter(self, node: InlinedFilter) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_marksafe` 1 `PurityLevel` ▼ Mark safe is pure. `def _visit_marksafe(self, node: MarkSafe) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_await` 1 `PurityLevel` ▼ Await is unknown (async operations may have side effects). `def _visit_await(self, node: Await) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` `_visit_trans` 1 `PurityLevel` ▼ Trans blocks are impure — gettext/ngettext depend on locale state. `def _visit_trans(self, node: Trans) -> PurityLevel` ##### Parameters Name Type Description `node` `—` ##### Returns `PurityLevel` ## Functions `_combine_purity` 2 `PurityLevel` ▼ Combine two purity levels (take worst case). `def _combine_purity(a: PurityLevel, b: PurityLevel) -> PurityLevel` ##### Parameters Name Type Description `a` `PurityLevel` `b` `PurityLevel` ##### Returns `PurityLevel`