Enum sql::query_model::model::scalar::BoxScalarExpr

pub(crate) enum BoxScalarExpr {
    ColumnReference(ColumnReference),
    BaseColumn(BaseColumn),
    Literal(Row, ColumnType),
    CallNullary(NullaryFunc),
    CallUnary {
        func: UnaryFunc,
        expr: Box<BoxScalarExpr>,
    },
    CallBinary {
        func: BinaryFunc,
        expr1: Box<BoxScalarExpr>,
        expr2: Box<BoxScalarExpr>,
    },
    CallVariadic {
        func: VariadicFunc,
        exprs: Vec<BoxScalarExpr>,
    },
    If {
        cond: Box<BoxScalarExpr>,
        then: Box<BoxScalarExpr>,
        els: Box<BoxScalarExpr>,
    },
    Aggregate {
        func: AggregateFunc,
        expr: Box<BoxScalarExpr>,
        distinct: bool,
    },
}

Representation for scalar expressions within a query graph model.

Similar to HirScalarExpr but:

• subqueries are represented as column references to the subquery quantifiers within the same box the expression belongs to,
• aggregate expressions are considered scalar expressions here even though they are only valid in the context of a Grouping box,
• column references are represented by a pair (quantifier ID, column position),
• BaseColumn is used to represent leaf columns, only allowed in the projection of BaseTables and TableFunctions.

Scalar expressions only make sense within the context of a super::graph::QueryBox, and hence, their name.

Variants

ColumnReference(ColumnReference)

Tuple Fields

0: ColumnReference

A reference to a column from a quantifier that either lives in the same box as the expression or is a sibling quantifier of an ascendent box of the box that contains the expression.

BaseColumn(BaseColumn)

Tuple Fields

0: BaseColumn

A leaf column. Only allowed as standalone expressions in the projection of BaseTable and TableFunction boxes.

Literal(Row, ColumnType)

Tuple Fields

0: Row

1: ColumnType

A literal value. (A single datum stored as a row, because we can’t own a Datum)

CallNullary(NullaryFunc)

Tuple Fields

0: NullaryFunc

CallUnary

Fields

func: UnaryFunc

expr: Box<BoxScalarExpr>

CallBinary

Fields

func: BinaryFunc

expr1: Box<BoxScalarExpr>

expr2: Box<BoxScalarExpr>

CallVariadic

Fields

func: VariadicFunc

exprs: Vec<BoxScalarExpr>

If

Fields

cond: Box<BoxScalarExpr>

then: Box<BoxScalarExpr>

els: Box<BoxScalarExpr>

Aggregate

Fields

func: AggregateFunc

Names the aggregation function.

expr: Box<BoxScalarExpr>

An expression which extracts from each row the input to func.

distinct: bool

Should the aggregation be applied only to distinct results in each group.

Implementations

impl BoxScalarExpr

pub fn visit_children<'a, F>(&'a self, f: F) where
    F: FnMut(&'a Self), 

pub fn try_visit_pre_post<F1, F2>(&self, pre: &mut F1, post: &mut F2) where
    F1: FnMut(&Self) -> Option<Vec<&Self>>,
    F2: FnMut(&Self), 

A generalization of visit. The function pre runs on a BoxScalarExpr before it runs on any of the child BoxScalarExprs. The function post runs on child BoxScalarExprs first before the parent. Optionally, pre can return which child BoxScalarExprs, if any, should be visited (default is to visit all children).

pub fn visit_mut_children<'a, F>(&'a mut self, f: F) where
    F: FnMut(&'a mut Self), 

pub fn visit_mut_post<F>(&mut self, f: &mut F) where
    F: FnMut(&mut Self), 

pub fn collect_column_references_from_context(
    &self,
    context: &BTreeSet<QuantifierId>,
    column_refs: &mut HashSet<ColumnReference>
)

Trait Implementations

impl Clone for BoxScalarExpr

fn clone(&self) -> BoxScalarExpr

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BoxScalarExpr

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

Formats the value using the given formatter.

impl Display for BoxScalarExpr

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

Formats the value using the given formatter.

impl PartialEq<BoxScalarExpr> for BoxScalarExpr

fn eq(&self, other: &BoxScalarExpr) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &BoxScalarExpr) -> bool

This method tests for !=.

impl StructuralPartialEq for BoxScalarExpr