Struct ProjectionExpr 

pub struct ProjectionExpr {
    pub expr: Arc<dyn PhysicalExpr>,
    pub alias: String,
}

An expression used by projection operations.

The expression is evaluated and the result is stored in a column with the name specified by alias.

For example, the SQL expression a + b AS sum_ab would be represented as a ProjectionExpr where expr is the expression a + b and alias is the string sum_ab.

See ProjectionExprs for a collection of projection expressions.

Fields

expr: Arc<dyn PhysicalExpr>

The expression that will be evaluated.

alias: String

The name of the output column for use an output schema.

Implementations

impl ProjectionExpr

pub fn new( expr: Arc<dyn PhysicalExpr>, alias: impl Into<String>, ) -> ProjectionExpr

Create a new projection expression

pub fn new_from_expression( expr: Arc<dyn PhysicalExpr>, schema: &Schema, ) -> Result<ProjectionExpr, DataFusionError>

Create a new projection expression from an expression and a schema using the expression’s output field name as alias.

Trait Implementations

impl AsPhysicalExprRef for ProjectionExpr

Allows a ProjectionExpr to be treated as a reference to its Arc<dyn PhysicalExpr>.

fn as_physical_expr_ref(&self) -> &Arc<dyn PhysicalExpr>

Returns the referenced physical expression.

impl AsRef<Arc<dyn PhysicalExpr>> for ProjectionExpr

Enables ProjectionExpr to be treated as a reference to its wrapped Arc<dyn PhysicalExpr> using AsRef::as_ref.

fn as_ref(&self) -> &Arc<dyn PhysicalExpr>

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for ProjectionExpr

fn clone(&self) -> ProjectionExpr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProjectionExpr

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

Formats the value using the given formatter.

impl Display for ProjectionExpr

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

Formats the value using the given formatter.

impl Eq for ProjectionExpr

impl From<&(Arc<dyn PhysicalExpr>, String)> for ProjectionExpr

fn from(value: &(Arc<dyn PhysicalExpr>, String)) -> ProjectionExpr

Converts to this type from the input type.

impl From<(Arc<dyn PhysicalExpr>, String)> for ProjectionExpr

fn from(value: (Arc<dyn PhysicalExpr>, String)) -> ProjectionExpr

Converts to this type from the input type.

impl FromIterator<ProjectionExpr> for ProjectionExprs

fn from_iter<T>(exprs: T) -> ProjectionExprs

where T: IntoIterator<Item = ProjectionExpr>,

Creates a value from an iterator.

impl PartialEq for ProjectionExpr

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

Equality operator ==.

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

Inequality operator !=.