Struct datafusion_physical_expr::expressions::CaseExpr

pub struct CaseExpr { /* private fields */ }

The CASE expression is similar to a series of nested if/else and there are two forms that can be used. The first form consists of a series of boolean “when” expressions with corresponding “then” expressions, and an optional “else” expression.

CASE WHEN condition THEN result [WHEN …] [ELSE result] END

The second form uses a base expression and then a series of “when” clauses that match on a literal value.

CASE expression WHEN value THEN result [WHEN …] [ELSE result] END

Implementations

impl CaseExpr

pub fn try_new(
    expr: Option<Arc<dyn PhysicalExpr>>,
    when_then_expr: Vec<(Arc<dyn PhysicalExpr>, Arc<dyn PhysicalExpr>)>,
    else_expr: Option<Arc<dyn PhysicalExpr>>
) -> Result<Self>

Create a new CASE WHEN expression

pub fn expr(&self) -> &Option<Arc<dyn PhysicalExpr>>

Optional base expression that can be compared to literal values in the “when” expressions

pub fn when_then_expr(
    &self
) -> &[(Arc<dyn PhysicalExpr>, Arc<dyn PhysicalExpr>)]

One or more when/then expressions

pub fn else_expr(&self) -> Option<&Arc<dyn PhysicalExpr>>

Optional “else” expression

Trait Implementations

impl Debug for CaseExpr

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

Formats the value using the given formatter.

impl Display for CaseExpr

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

Formats the value using the given formatter.

impl PhysicalExpr for CaseExpr

fn as_any(&self) -> &dyn Any

Return a reference to Any that can be used for down-casting

fn data_type(&self, input_schema: &Schema) -> Result<DataType>

Get the data type of this expression, given the schema of the input

fn nullable(&self, input_schema: &Schema) -> Result<bool>

Determine whether this expression is nullable, given the schema of the input

fn evaluate(&self, batch: &RecordBatch) -> Result<ColumnarValue>

Evaluate an expression against a RecordBatch

fn evaluate_selection(
    &self,
    batch: &RecordBatch,
    selection: &BooleanArray
) -> Result<ColumnarValue>

Evaluate an expression against a RecordBatch after first applying a validity array