Struct transform::inline_let::InlineLet

pub struct InlineLet {
    pub inline_mfp: bool,
    recursion_guard: RecursionGuard,
}

Install replace certain Get operators with their Let value.

Fields

inline_mfp: bool

If true, inline MFPs around a Get.

We want this value to be true for the InlineLet call that comes right before crate::join_implementation::JoinImplementation runs because crate::join_implementation::JoinImplementation cannot lift MFPs through a Let.

Generally, though, we prefer to be more conservative in our inlining in order to be able to better detect CSEs.

recursion_guard: RecursionGuard

A RecursionGuard to be used by the CheckedRecursion implementation.

Implementations

impl InlineLet

pub fn new(inline_mfp: bool) -> InlineLet

Construct a new InlineLet instance with the given inline_mfp where recursion_guard is initialized with RECURSION_LIMIT as limit.

impl InlineLet

pub fn action(
    &self,
    relation: &mut MirRelationExpr,
    lets: &mut Vec<(LocalId, MirRelationExpr)>
) -> Result<(), TransformError>

Install replace certain Get operators with their Let value.

IMPORTANT: This transform is used for cleaning up after RelationCSE, which adds Let operators pretty aggressively, leading to very deep dataflows. Nothing in this transform should lead to expensive recursive traversal of the subgraph, such as the one in MirRelationExpr::typ, since that may result in a stack overflow.

Trait Implementations

impl CheckedRecursion for InlineLet

fn recursion_guard(&self) -> &RecursionGuard

Extracts a reference to the recursion guard embedded within the type.

fn checked_recur<F, T, E>(&self, f: F) -> Result<T, E> where
    F: FnOnce(&Self) -> Result<T, E>,
    E: From<RecursionLimitError>, 

Checks whether it is safe to recur and calls f if so.

fn checked_recur_mut<F, T, E>(&mut self, f: F) -> Result<T, E> where
    F: FnOnce(&mut Self) -> Result<T, E>,
    E: From<RecursionLimitError>, 

Like CheckedRecursion::checked_recur, but operates on a mutable reference to Self.

impl Debug for InlineLet

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Transform for InlineLet

fn transform(
    &self,
    relation: &mut MirRelationExpr,
    _: TransformArgs<'_>
) -> Result<(), TransformError>

Transform a relation into a functionally equivalent relation.

fn debug(&self) -> String

A string describing the transform.