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Move static truthiness to new module
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103 changes: 103 additions & 0 deletions
103
crates/red_knot_python_semantic/src/types/static_truthiness.rs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,103 @@ | ||
| use crate::semantic_index::{ | ||
| ast_ids::HasScopedExpressionId, | ||
| branching_condition::BranchingCondition, | ||
| constraint::{Constraint, ConstraintNode, PatternConstraintKind}, | ||
| BranchingConditionsIterator, | ||
| }; | ||
| use crate::types::{infer_expression_types, Truthiness}; | ||
| use crate::Db; | ||
|
|
||
| /// The result of a static-truthiness analysis. | ||
| /// | ||
| /// Consider the following example: | ||
| /// ```py | ||
| /// a = 1 | ||
| /// if True: | ||
| /// b = 1 | ||
| /// if <bool>: | ||
| /// c = 1 | ||
| /// if False: | ||
| /// d = 1 | ||
| /// ``` | ||
| /// | ||
| /// Given an iterator over the branching conditions for each of these bindings, we would get: | ||
| /// ``` | ||
| /// - a: {any_always_false: false, all_always_true: true, at_least_one_condition: false} | ||
| /// - b: {any_always_false: false, all_always_true: true, at_least_one_condition: true} | ||
| /// - c: {any_always_false: false, all_always_true: false, at_least_one_condition: true} | ||
| /// - d: {any_always_false: true, all_always_true: false, at_least_one_condition: true} | ||
| /// ``` | ||
| pub(crate) struct StaticTruthiness { | ||
| /// Is any of the branching conditions always false? (false if there are no conditions) | ||
| pub(crate) any_always_false: bool, | ||
| /// Are all of the branching conditions always true? (true if there are no conditions) | ||
| pub(crate) all_always_true: bool, | ||
| /// Is there at least one branching condition? | ||
| pub(crate) at_least_one_condition: bool, | ||
| } | ||
|
|
||
| impl StaticTruthiness { | ||
| /// Analyze the (statically known) truthiness for a list of branching conditions. | ||
| pub(crate) fn analyze<'db>( | ||
| db: &'db dyn Db, | ||
| branching_conditions: BranchingConditionsIterator<'_, 'db>, | ||
| ) -> Self { | ||
| let mut result = Self { | ||
| any_always_false: false, | ||
| all_always_true: true, | ||
| at_least_one_condition: false, | ||
| }; | ||
|
|
||
| for condition in branching_conditions { | ||
| let truthiness = match condition { | ||
| BranchingCondition::ConditionalOn(Constraint { | ||
| node: ConstraintNode::Expression(test_expr), | ||
| is_positive, | ||
| }) => { | ||
| let inference = infer_expression_types(db, test_expr); | ||
| let scope = test_expr.scope(db); | ||
| let ty = inference | ||
| .expression_ty(test_expr.node_ref(db).scoped_expression_id(db, scope)); | ||
|
|
||
| ty.bool(db).negate_if(!is_positive) | ||
| } | ||
| BranchingCondition::ConditionalOn(Constraint { | ||
| node: ConstraintNode::Pattern(inner), | ||
| .. | ||
| }) => match inner.kind(db) { | ||
| PatternConstraintKind::Value(value) => { | ||
| let subject_expression = inner.subject(db); | ||
| let inference = infer_expression_types(db, *subject_expression); | ||
| let scope = subject_expression.scope(db); | ||
| let subject_ty = inference.expression_ty( | ||
| subject_expression | ||
| .node_ref(db) | ||
| .scoped_expression_id(db, scope), | ||
| ); | ||
|
|
||
| let inference = infer_expression_types(db, *value); | ||
| let scope = value.scope(db); | ||
| let value_ty = inference | ||
| .expression_ty(value.node_ref(db).scoped_expression_id(db, scope)); | ||
|
|
||
| if subject_ty.is_single_valued(db) { | ||
| Truthiness::from_bool(subject_ty.is_equivalent_to(db, value_ty)) | ||
| } else { | ||
| Truthiness::Ambiguous | ||
| } | ||
| } | ||
| PatternConstraintKind::Singleton(_) | PatternConstraintKind::Unsupported => { | ||
| Truthiness::Ambiguous | ||
| } | ||
| }, | ||
| BranchingCondition::Ambiguous => Truthiness::Ambiguous, | ||
| }; | ||
|
|
||
| result.any_always_false |= truthiness.is_always_false(); | ||
| result.all_always_true &= truthiness.is_always_true(); | ||
| result.at_least_one_condition = true; | ||
| } | ||
|
|
||
| result | ||
| } | ||
| } |