Enum Expr

pub enum Expr {
    Alias(Alias),
    Column(Column),
    ScalarVariable(DataType, Vec<String>),
    Literal(ScalarValue),
    BinaryExpr(BinaryExpr),
    Like(Like),
    SimilarTo(Like),
    Not(Box<Expr>),
    IsNotNull(Box<Expr>),
    IsNull(Box<Expr>),
    IsTrue(Box<Expr>),
    IsFalse(Box<Expr>),
    IsUnknown(Box<Expr>),
    IsNotTrue(Box<Expr>),
    IsNotFalse(Box<Expr>),
    IsNotUnknown(Box<Expr>),
    Negative(Box<Expr>),
    Between(Between),
    Case(Case),
    Cast(Cast),
    TryCast(TryCast),
    ScalarFunction(ScalarFunction),
    AggregateFunction(AggregateFunction),
    WindowFunction(WindowFunction),
    InList(InList),
    Exists(Exists),
    InSubquery(InSubquery),
    ScalarSubquery(Subquery),
    Wildcard {
        qualifier: Option<TableReference>,
        options: WildcardOptions,
    },
    GroupingSet(GroupingSet),
    Placeholder(Placeholder),
    OuterReferenceColumn(DataType, Column),
    Unnest(Unnest),
}

Represents logical expressions such as A + 1, or CAST(c1 AS int).

For example the expression A + 1 will be represented as

  BinaryExpr {
    left: Expr::Column("A"),
    op: Operator::Plus,
    right: Expr::Literal(ScalarValue::Int32(Some(1)))
 }

Creating Expressions

Exprs can be created directly, but it is often easier and less verbose to use the fluent APIs in crate::expr_fn such as col and lit, or methods such as Expr::alias, Expr::cast_to, and Expr::Like).

See also ExprFunctionExt for creating aggregate and window functions.

Schema Access

See ExprSchemable::get_type to access the DataType and nullability of an Expr.

Visiting and Rewriting Exprs

The Expr struct implements the TreeNode trait for walking and rewriting expressions. For example TreeNode::apply recursively visits an Expr and TreeNode::transform can be used to rewrite an expression. See the examples below and TreeNode for more information.

Examples

Column references and literals

Expr::Column refer to the values of columns and are often created with the col function. For example to create an expression c1 referring to column named “c1”:

let expr = col("c1");
assert_eq!(expr, Expr::Column(Column::from_name("c1")));

Expr::Literal refer to literal, or constant, values. These are created with the lit function. For example to create an expression 42:

// All literals are strongly typed in DataFusion. To make an `i64` 42:
let expr = lit(42i64);
assert_eq!(expr, Expr::Literal(ScalarValue::Int64(Some(42))));
// To make a (typed) NULL:
let expr = Expr::Literal(ScalarValue::Int64(None));
// to make an (untyped) NULL (the optimizer will coerce this to the correct type):
let expr = lit(ScalarValue::Null);

Binary Expressions

Exprs implement traits that allow easy to understand construction of more complex expressions. For example, to create c1 + c2 to add columns “c1” and “c2” together

// Use the `+` operator to add two columns together
let expr = col("c1") + col("c2");
assert!(matches!(expr, Expr::BinaryExpr { ..} ));
if let Expr::BinaryExpr(binary_expr) = expr {
  assert_eq!(*binary_expr.left, col("c1"));
  assert_eq!(*binary_expr.right, col("c2"));
  assert_eq!(binary_expr.op, Operator::Plus);
}

The expression c1 = 42 to compares the value in column “c1” to the literal value 42:

let expr = col("c1").eq(lit(42_i32));
assert!(matches!(expr, Expr::BinaryExpr { .. } ));
if let Expr::BinaryExpr(binary_expr) = expr {
  assert_eq!(*binary_expr.left, col("c1"));
  let scalar = ScalarValue::Int32(Some(42));
  assert_eq!(*binary_expr.right, Expr::Literal(scalar));
  assert_eq!(binary_expr.op, Operator::Eq);
}

Here is how to implement the equivalent of SELECT * to select all Expr::Column from a DFSchema’s columns:

// Create a schema c1(int, c2 float)
let arrow_schema = Schema::new(vec![
   Field::new("c1", DataType::Int32, false),
   Field::new("c2", DataType::Float64, false),
]);
// DFSchema is a an Arrow schema with optional relation name
let df_schema = DFSchema::try_from_qualified_schema("t1", &arrow_schema)
  .unwrap();

// Form Vec<Expr> with an expression for each column in the schema
let exprs: Vec<_> = df_schema.iter()
  .map(Expr::from)
  .collect();

assert_eq!(exprs, vec![
  Expr::from(Column::from_qualified_name("t1.c1")),
  Expr::from(Column::from_qualified_name("t1.c2")),
]);

Visiting and Rewriting Exprs

Here is an example that finds all literals in an Expr tree:

use datafusion_common::ScalarValue;
use datafusion_common::tree_node::{TreeNode, TreeNodeRecursion};
// Expression a = 5 AND b = 6
let expr = col("a").eq(lit(5)) & col("b").eq(lit(6));
// find all literals in a HashMap
let mut scalars = HashSet::new();
// apply recursively visits all nodes in the expression tree
expr.apply(|e| {
   if let Expr::Literal(scalar) = e {
      scalars.insert(scalar);
   }
   // The return value controls whether to continue visiting the tree
   Ok(TreeNodeRecursion::Continue)
}).unwrap();;
// All subtrees have been visited and literals found
assert_eq!(scalars.len(), 2);
assert!(scalars.contains(&ScalarValue::Int32(Some(5))));
assert!(scalars.contains(&ScalarValue::Int32(Some(6))));

Rewrite an expression, replacing references to column “a” in an to the literal 42:

// expression a = 5 AND b = 6
let expr = col("a").eq(lit(5)).and(col("b").eq(lit(6)));
// rewrite all references to column "a" to the literal 42
let rewritten = expr.transform(|e| {
 if let Expr::Column(c) = &e {
   if &c.name == "a" {
     // return Transformed::yes to indicate the node was changed
     return Ok(Transformed::yes(lit(42)))
   }
 }
 // return Transformed::no to indicate the node was not changed
 Ok(Transformed::no(e))
}).unwrap();
// The expression has been rewritten
assert!(rewritten.transformed);
// to 42 = 5 AND b = 6
assert_eq!(rewritten.data, lit(42).eq(lit(5)).and(col("b").eq(lit(6))));

Variants

Alias(Alias)

An expression with a specific name.

Column(Column)

A named reference to a qualified field in a schema.

ScalarVariable(DataType, Vec<String>)

A named reference to a variable in a registry.

Literal(ScalarValue)

A constant value.

BinaryExpr(BinaryExpr)

A binary expression such as “age > 21”

Like(Like)

LIKE expression

SimilarTo(Like)

LIKE expression that uses regular expressions

Not(Box<Expr>)

Negation of an expression. The expression’s type must be a boolean to make sense.

IsNotNull(Box<Expr>)

True if argument is not NULL, false otherwise. This expression itself is never NULL.

IsNull(Box<Expr>)

True if argument is NULL, false otherwise. This expression itself is never NULL.

IsTrue(Box<Expr>)

True if argument is true, false otherwise. This expression itself is never NULL.

IsFalse(Box<Expr>)

True if argument is false, false otherwise. This expression itself is never NULL.

IsUnknown(Box<Expr>)

True if argument is NULL, false otherwise. This expression itself is never NULL.

IsNotTrue(Box<Expr>)

True if argument is FALSE or NULL, false otherwise. This expression itself is never NULL.

IsNotFalse(Box<Expr>)

True if argument is TRUE OR NULL, false otherwise. This expression itself is never NULL.

IsNotUnknown(Box<Expr>)

True if argument is TRUE or FALSE, false otherwise. This expression itself is never NULL.

Negative(Box<Expr>)

arithmetic negation of an expression, the operand must be of a signed numeric data type

Between(Between)

Whether an expression is between a given range.

Case(Case)

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

Cast(Cast)

Casts the expression to a given type and will return a runtime error if the expression cannot be cast. This expression is guaranteed to have a fixed type.

TryCast(TryCast)

Casts the expression to a given type and will return a null value if the expression cannot be cast. This expression is guaranteed to have a fixed type.

ScalarFunction(ScalarFunction)

Represents the call of a scalar function with a set of arguments.

AggregateFunction(AggregateFunction)

Calls an aggregate function with arguments, and optional ORDER BY, FILTER, DISTINCT and NULL TREATMENT.

See also ExprFunctionExt to set these fields.

WindowFunction(WindowFunction)

Represents the call of a window function with arguments.

InList(InList)

Returns whether the list contains the expr value.

Exists(Exists)

EXISTS subquery

InSubquery(InSubquery)

IN subquery

ScalarSubquery(Subquery)

Scalar subquery

Wildcard

Represents a reference to all available fields in a specific schema, with an optional (schema) qualifier.

This expr has to be resolved to a list of columns before translating logical plan into physical plan.

Fields

qualifier: Option<TableReference>

options: WildcardOptions

GroupingSet(GroupingSet)

List of grouping set expressions. Only valid in the context of an aggregate GROUP BY expression list

Placeholder(Placeholder)

A place holder for parameters in a prepared statement (e.g. $foo or $1)

OuterReferenceColumn(DataType, Column)

A place holder which hold a reference to a qualified field in the outer query, used for correlated sub queries.

Unnest(Unnest)

Unnest expression

Implementations

impl Expr

pub fn display_name(&self) -> Result<String, DataFusionError>

👎Deprecated since 40.0.0: use schema_name instead

pub fn schema_name(&self) -> impl Display

The name of the column (field) that this Expr will produce.

For example, for a projection (e.g. SELECT <expr>) the resulting arrow Schema will have a field with this name.

Note that the resulting string is subtlety different from the Display representation for certain Expr. Some differences:

1. Expr::Alias, which shows only the alias itself
2. Expr::Cast / Expr::TryCast, which only displays the expression

Example

let expr = col("foo").eq(lit(42));
assert_eq!("foo = Int32(42)", expr.schema_name().to_string());

let expr = col("foo").alias("bar").eq(lit(11));
assert_eq!("bar = Int32(11)", expr.schema_name().to_string());

pub fn qualified_name(&self) -> (Option<TableReference>, String)

Returns the qualifier and the schema name of this expression.

Used when the expression forms the output field of a certain plan. The result is the field’s qualifier and field name in the plan’s output schema. We can use this qualified name to reference the field.

pub fn canonical_name(&self) -> String

👎Deprecated: use format! instead

Returns a full and complete string representation of this expression.

pub fn variant_name(&self) -> &str

Return String representation of the variant represented by self Useful for non-rust based bindings

pub fn eq(self, other: Expr) -> Expr

Return self == other

pub fn not_eq(self, other: Expr) -> Expr

Return self != other

pub fn gt(self, other: Expr) -> Expr

Return self > other

pub fn gt_eq(self, other: Expr) -> Expr

Return self >= other

pub fn lt(self, other: Expr) -> Expr

Return self < other

pub fn lt_eq(self, other: Expr) -> Expr

Return self <= other

pub fn and(self, other: Expr) -> Expr

Return self && other

pub fn or(self, other: Expr) -> Expr

Return self || other

pub fn like(self, other: Expr) -> Expr

Return self LIKE other

pub fn not_like(self, other: Expr) -> Expr

Return self NOT LIKE other

pub fn ilike(self, other: Expr) -> Expr

Return self ILIKE other

pub fn not_ilike(self, other: Expr) -> Expr

Return self NOT ILIKE other

pub fn name_for_alias(&self) -> Result<String, DataFusionError>

Return the name to use for the specific Expr

pub fn alias_if_changed( self, original_name: String, ) -> Result<Expr, DataFusionError>

Ensure expr has the name as original_name by adding an alias if necessary.

pub fn alias(self, name: impl Into<String>) -> Expr

Return self AS name alias expression

pub fn alias_qualified( self, relation: Option<impl Into<TableReference>>, name: impl Into<String>, ) -> Expr

Return self AS name alias expression with a specific qualifier

pub fn unalias(self) -> Expr

Remove an alias from an expression if one exists.

If the expression is not an alias, the expression is returned unchanged. This method does not remove aliases from nested expressions.

Example

// `foo as "bar"` is unaliased to `foo`
let expr = col("foo").alias("bar");
assert_eq!(expr.unalias(), col("foo"));

// `foo as "bar" + baz` is not unaliased
let expr = col("foo").alias("bar") + col("baz");
assert_eq!(expr.clone().unalias(), expr);

// `foo as "bar" as "baz" is unalaised to foo as "bar"
let expr = col("foo").alias("bar").alias("baz");
assert_eq!(expr.unalias(), col("foo").alias("bar"));

pub fn unalias_nested(self) -> Transformed<Expr>

Recursively removed potentially multiple aliases from an expression.

This method removes nested aliases and returns Transformed to signal if the expression was changed.

Example

// `foo as "bar"` is unaliased to `foo`
let expr = col("foo").alias("bar");
assert_eq!(expr.unalias_nested().data, col("foo"));

// `foo as "bar" + baz` is  unaliased
let expr = col("foo").alias("bar") + col("baz");
assert_eq!(expr.clone().unalias_nested().data, col("foo") + col("baz"));

// `foo as "bar" as "baz" is unalaised to foo
let expr = col("foo").alias("bar").alias("baz");
assert_eq!(expr.unalias_nested().data, col("foo"));

pub fn in_list(self, list: Vec<Expr>, negated: bool) -> Expr

Return self IN <list> if negated is false, otherwise return self NOT IN <list>.a

pub fn is_null(self) -> Expr

Return `IsNull(Box(self))

pub fn is_not_null(self) -> Expr

Return `IsNotNull(Box(self))

pub fn sort(self, asc: bool, nulls_first: bool) -> Sort

Create a sort configuration from an existing expression.

let sort_expr = col("foo").sort(true, true); // SORT ASC NULLS_FIRST

pub fn is_true(self) -> Expr

Return IsTrue(Box(self))

pub fn is_not_true(self) -> Expr

Return IsNotTrue(Box(self))

pub fn is_false(self) -> Expr

Return IsFalse(Box(self))

pub fn is_not_false(self) -> Expr

Return IsNotFalse(Box(self))

pub fn is_unknown(self) -> Expr

Return IsUnknown(Box(self))

pub fn is_not_unknown(self) -> Expr

Return IsNotUnknown(Box(self))

pub fn between(self, low: Expr, high: Expr) -> Expr

return self BETWEEN low AND high

pub fn not_between(self, low: Expr, high: Expr) -> Expr

return self NOT BETWEEN low AND high

pub fn try_into_col(&self) -> Result<Column, DataFusionError>

👎Deprecated since 39.0.0: use try_as_col instead

pub fn try_as_col(&self) -> Option<&Column>

Return a reference to the inner Column if any

returns None if the expression is not a Column

Note: None may be returned for expressions that are not Column but are convertible to Column such as Cast expressions.

Example

use datafusion_expr::{col, Expr};
let expr = col("foo");
assert_eq!(expr.try_as_col(), Some(&Column::from("foo")));

let expr = col("foo").alias("bar");
assert_eq!(expr.try_as_col(), None);

pub fn get_as_join_column(&self) -> Option<&Column>

Returns the inner Column if any. This is a specialized version of Self::try_as_col that take Cast expressions into account when the expression is as on condition for joins.

Called this method when you are sure that the expression is a Column or a Cast expression that wraps a Column.

pub fn to_columns(&self) -> Result<HashSet<Column>, DataFusionError>

👎Deprecated since 40.0.0: use Expr::column_refs instead

Return all referenced columns of this expression.

pub fn column_refs(&self) -> HashSet<&Column>

Return all references to columns in this expression.

Example

// For an expression `a + (b * a)`
let expr = col("a") + (col("b") * col("a"));
let refs = expr.column_refs();
// refs contains "a" and "b"
assert_eq!(refs.len(), 2);
assert!(refs.contains(&Column::new_unqualified("a")));
assert!(refs.contains(&Column::new_unqualified("b")));

pub fn add_column_refs<'a>(&'a self, set: &mut HashSet<&'a Column>)

Adds references to all columns in this expression to the set

See Self::column_refs for details

pub fn column_refs_counts(&self) -> HashMap<&Column, usize>

Return all references to columns and their occurrence counts in the expression.

Example

// For an expression `a + (b * a)`
let expr = col("a") + (col("b") * col("a"));
let mut refs = expr.column_refs_counts();
// refs contains "a" and "b"
assert_eq!(refs.len(), 2);
assert_eq!(*refs.get(&Column::new_unqualified("a")).unwrap(), 2);
assert_eq!(*refs.get(&Column::new_unqualified("b")).unwrap(), 1);

pub fn add_column_ref_counts<'a>(&'a self, map: &mut HashMap<&'a Column, usize>)

Adds references to all columns and their occurrence counts in the expression to the map.

See Self::column_refs_counts for details

pub fn any_column_refs(&self) -> bool

Returns true if there are any column references in this Expr

pub fn contains_outer(&self) -> bool

Return true when the expression contains out reference(correlated) expressions.

pub fn is_volatile_node(&self) -> bool

Returns true if the expression node is volatile, i.e. whether it can return different results when evaluated multiple times with the same input. Note: unlike Self::is_volatile, this function does not consider inputs:

• rand() returns true,
• a + rand() returns false

pub fn is_volatile(&self) -> Result<bool, DataFusionError>

Returns true if the expression is volatile, i.e. whether it can return different results when evaluated multiple times with the same input.

pub fn infer_placeholder_types( self, schema: &DFSchema, ) -> Result<Expr, DataFusionError>

Recursively find all Expr::Placeholder expressions, and to infer their DataType from the context of their use.

For example, gicen an expression like <int32> = $0 will infer $0 to have type int32.

pub fn short_circuits(&self) -> bool

Returns true if some of this exprs subexpressions may not be evaluated and thus any side effects (like divide by zero) may not be encountered

pub fn hash_node<H>(&self, hasher: &mut H)

where H: Hasher,

Hashes the direct content of an Expr without recursing into its children.

This method is useful to incrementally compute hashes, such as in CommonSubexprEliminate which builds a deep hash of a node and its descendants during the bottom-up phase of the first traversal and so avoid computing the hash of the node and then the hash of its descendants separately.

If a node doesn’t have any children then this method is similar to .hash(), but not necessarily returns the same value.

As it is pretty easy to forget changing this method when Expr changes the implementation doesn’t use wildcard patterns (.., _) to catch changes compile time.

Trait Implementations

impl Add for Expr

Support <expr> + <expr> fluent style

type Output = Expr

The resulting type after applying the + operator.

fn add(self, rhs: Expr) -> Expr

Performs the + operation.

impl BitAnd for Expr

Support <expr> & <expr> fluent style

type Output = Expr

The resulting type after applying the & operator.

fn bitand(self, rhs: Expr) -> Expr

Performs the & operation.

impl BitOr for Expr

Support <expr> | <expr> fluent style

type Output = Expr

The resulting type after applying the | operator.

fn bitor(self, rhs: Expr) -> Expr

Performs the | operation.

impl BitXor for Expr

Support <expr> ^ <expr> fluent style

type Output = Expr

The resulting type after applying the ^ operator.

fn bitxor(self, rhs: Expr) -> Expr

Performs the ^ operation.

impl Clone for Expr

fn clone(&self) -> Expr

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Expr

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

Formats the value using the given formatter.

impl Default for Expr

fn default() -> Expr

Returns the “default value” for a type.

impl Display for Expr

Format expressions for display as part of a logical plan. In many cases, this will produce similar output to Expr.name() except that column names will be prefixed with ‘#’.

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

Formats the value using the given formatter.

impl Div for Expr

Support <expr> / <expr> fluent style

type Output = Expr

The resulting type after applying the / operator.

fn div(self, rhs: Expr) -> Expr

Performs the / operation.

impl ExprFunctionExt for Expr

fn order_by(self, order_by: Vec<Sort>) -> ExprFuncBuilder

Add ORDER BY <order_by>

fn filter(self, filter: Expr) -> ExprFuncBuilder

Add FILTER <filter>

fn distinct(self) -> ExprFuncBuilder

Add DISTINCT

fn null_treatment( self, null_treatment: impl Into<Option<NullTreatment>>, ) -> ExprFuncBuilder

Add RESPECT NULLS or IGNORE NULLS

fn partition_by(self, partition_by: Vec<Expr>) -> ExprFuncBuilder

Add PARTITION BY

fn window_frame(self, window_frame: WindowFrame) -> ExprFuncBuilder

Add appropriate window frame conditions

impl ExprSchemable for Expr

fn get_type(&self, schema: &dyn ExprSchema) -> Result<DataType, DataFusionError>

Returns the arrow::datatypes::DataType of the expression based on ExprSchema

Note: DFSchema implements ExprSchema.

Examples

Get the type of an expression that adds 2 columns. Adding an Int32 and Float32 results in Float32 type

fn main() {
  let expr = col("c1") + col("c2");
  let schema = DFSchema::from_unqualified_fields(
    vec![
      Field::new("c1", DataType::Int32, true),
      Field::new("c2", DataType::Float32, true),
      ].into(),
      HashMap::new(),
  ).unwrap();
  assert_eq!("Float32", format!("{}", expr.get_type(&schema).unwrap()));
}

Errors

This function errors when it is not possible to compute its arrow::datatypes::DataType. This happens when e.g. the expression refers to a column that does not exist in the schema, or when the expression is incorrectly typed (e.g. [utf8] + [bool]).

fn nullable( &self, input_schema: &dyn ExprSchema, ) -> Result<bool, DataFusionError>

Returns the nullability of the expression based on ExprSchema.

Note: DFSchema implements ExprSchema.

Errors

This function errors when it is not possible to compute its nullability. This happens when the expression refers to a column that does not exist in the schema.

fn data_type_and_nullable( &self, schema: &dyn ExprSchema, ) -> Result<(DataType, bool), DataFusionError>

Returns the datatype and nullability of the expression based on ExprSchema.

Note: DFSchema implements ExprSchema.

Errors

This function errors when it is not possible to compute its datatype or nullability.

fn to_field( &self, input_schema: &dyn ExprSchema, ) -> Result<(Option<TableReference>, Arc<Field>), DataFusionError>

Returns a arrow::datatypes::Field compatible with this expression.

So for example, a projected expression col(c1) + col(c2) is placed in an output field named col(“c1 + c2”)

fn cast_to( self, cast_to_type: &DataType, schema: &dyn ExprSchema, ) -> Result<Expr, DataFusionError>

Wraps this expression in a cast to a target arrow::datatypes::DataType.

Errors

This function errors when it is impossible to cast the expression to the target arrow::datatypes::DataType.

fn metadata( &self, schema: &dyn ExprSchema, ) -> Result<HashMap<String, String>, DataFusionError>

given a schema, return the expr’s optional metadata

impl FieldAccessor for Expr

fn field(self, name: impl Literal) -> Expr

impl<'a> From<(Option<&'a TableReference>, &'a Arc<Field>)> for Expr

Create an Expr from an optional qualifier and a FieldRef. This is useful for creating Expr from a DFSchema.

See example on Expr

fn from(value: (Option<&'a TableReference>, &'a Arc<Field>)) -> Expr

Converts to this type from the input type.

impl From<Column> for Expr

Create an Expr from a Column

fn from(value: Column) -> Expr

Converts to this type from the input type.

impl Hash for Expr

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl IndexAccessor for Expr

fn index(self, key: Expr) -> Expr

impl Mul for Expr

Support <expr> * <expr> fluent style

type Output = Expr

The resulting type after applying the * operator.

fn mul(self, rhs: Expr) -> Expr

Performs the * operation.

impl Neg for Expr

Support - <expr> fluent style

type Output = Expr

The resulting type after applying the - operator.

fn neg(self) -> <Expr as Neg>::Output

Performs the unary - operation.

impl Not for Expr

Support NOT <expr> fluent style

type Output = Expr

The resulting type after applying the ! operator.

fn not(self) -> <Expr as Not>::Output

Performs the unary ! operation.

impl PartialEq for Expr

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Expr

fn partial_cmp(&self, other: &Expr) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Rem for Expr

Support <expr> % <expr> fluent style

type Output = Expr

The resulting type after applying the % operator.

fn rem(self, rhs: Expr) -> Expr

Performs the % operation.

impl Shl for Expr

Support <expr> << <expr> fluent style

type Output = Expr

The resulting type after applying the << operator.

fn shl(self, rhs: Expr) -> <Expr as Shl>::Output

Performs the << operation.

impl Shr for Expr

Support <expr> >> <expr> fluent style

type Output = Expr

The resulting type after applying the >> operator.

fn shr(self, rhs: Expr) -> <Expr as Shr>::Output

Performs the >> operation.

impl SliceAccessor for Expr

fn range(self, start: Expr, stop: Expr) -> Expr

impl Sub for Expr

Support <expr> - <expr> fluent style

type Output = Expr

The resulting type after applying the - operator.

fn sub(self, rhs: Expr) -> Expr

Performs the - operation.

impl TreeNode for Expr

fn apply_children<'n, F>( &'n self, f: F, ) -> Result<TreeNodeRecursion, DataFusionError>

where F: FnMut(&'n Expr) -> Result<TreeNodeRecursion, DataFusionError>,

Low-level API used to implement other APIs.

fn map_children<F>(self, f: F) -> Result<Transformed<Expr>, DataFusionError>

where F: FnMut(Expr) -> Result<Transformed<Expr>, DataFusionError>,

Low-level API used to implement other APIs.

fn visit<'n, V>( &'n self, visitor: &mut V, ) -> Result<TreeNodeRecursion, DataFusionError>

where V: TreeNodeVisitor<'n, Node = Self>,

Visit the tree node with a TreeNodeVisitor, performing a depth-first walk of the node and its children.

fn rewrite<R>( self, rewriter: &mut R, ) -> Result<Transformed<Self>, DataFusionError>

where R: TreeNodeRewriter<Node = Self>,

Rewrite the tree node with a TreeNodeRewriter, performing a depth-first walk of the node and its children.

fn apply<'n, F>(&'n self, f: F) -> Result<TreeNodeRecursion, DataFusionError>

where F: FnMut(&'n Self) -> Result<TreeNodeRecursion, DataFusionError>,

Applies f to the node then each of its children, recursively (a top-down, pre-order traversal).

fn transform<F>(self, f: F) -> Result<Transformed<Self>, DataFusionError>

where F: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

Recursively rewrite the node’s children and then the node using f (a bottom-up post-order traversal).

fn transform_down<F>(self, f: F) -> Result<Transformed<Self>, DataFusionError>

where F: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

Recursively rewrite the tree using f in a top-down (pre-order) fashion.

fn transform_down_mut<F>( self, f: &mut F, ) -> Result<Transformed<Self>, DataFusionError>

where F: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

👎Deprecated since 38.0.0: Use transform_down instead

Same as Self::transform_down but with a mutable closure.

fn transform_up<F>(self, f: F) -> Result<Transformed<Self>, DataFusionError>

where F: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

Recursively rewrite the node using f in a bottom-up (post-order) fashion.

fn transform_up_mut<F>( self, f: &mut F, ) -> Result<Transformed<Self>, DataFusionError>

where F: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

👎Deprecated since 38.0.0: Use transform_up instead

Same as Self::transform_up but with a mutable closure.

fn transform_down_up<FD, FU>( self, f_down: FD, f_up: FU, ) -> Result<Transformed<Self>, DataFusionError>

where FD: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>, FU: FnMut(Self) -> Result<Transformed<Self>, DataFusionError>,

Transforms the node using f_down while traversing the tree top-down (pre-order), and using f_up while traversing the tree bottom-up (post-order).

fn exists<F>(&self, f: F) -> Result<bool, DataFusionError>

where F: FnMut(&Self) -> Result<bool, DataFusionError>,

Returns true if f returns true for any node in the tree.

impl Eq for Expr

impl StructuralPartialEq for Expr