Struct FunctionExpr 

pub struct FunctionExpr { /* private fields */ }

Expression that evaluates a scalar function and compares the result

This expression wraps a scalar function call with its arguments, evaluates the function for each row, and compares the result to a target value using a comparison operator.

Example

For UPPER(name) = 'ALICE':

• function: UPPER
• arguments: [ColumnArg(“name”)]
• operator: Eq
• compare_value: Text(“ALICE”)

Implementations

impl FunctionExpr

pub fn new( function: Arc<dyn ScalarFunction>, arguments: Vec<FunctionArg>, operator: Operator, compare_value: Value, ) -> Self

Create a new function expression

Arguments

• function - The scalar function to call
• arguments - Arguments to pass to the function
• operator - Comparison operator
• compare_value - Value to compare the function result against

pub fn eq( function: Arc<dyn ScalarFunction>, arguments: Vec<FunctionArg>, compare_value: Value, ) -> Self

Create a function expression for equality comparison

pub fn boolean( function: Arc<dyn ScalarFunction>, arguments: Vec<FunctionArg>, ) -> Self

Create a function expression that evaluates to boolean (no comparison)

This is for functions that return boolean directly, like custom predicates

pub fn function_name(&self) -> &str

Get the function name

pub fn get_arguments(&self) -> &[FunctionArg]

Get the arguments

pub fn get_operator(&self) -> Operator

Get the operator

pub fn get_compare_value(&self) -> &Value

Get the compare value

Trait Implementations

impl Debug for FunctionExpr

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

Formats the value using the given formatter.

impl Expression for FunctionExpr

fn evaluate(&self, row: &Row) -> Result<bool>

Evaluate the expression against a row

fn evaluate_fast(&self, row: &Row) -> bool

Fast evaluation without detailed error handling

fn with_aliases( &self, aliases: &FxHashMap<String, String>, ) -> Box<dyn Expression>

Create a copy of this expression with column aliases resolved

fn prepare_for_schema(&mut self, schema: &Schema)

Prepare the expression for a specific schema

fn is_prepared(&self) -> bool

Check if this expression has been prepared for a schema

fn can_use_index(&self) -> bool

Check if this expression can potentially use an index

fn clone_box(&self) -> Box<dyn Expression>

Clone the expression into a boxed trait object

fn as_any(&self) -> &dyn Any

Get a reference to the expression as Any for downcasting

fn get_column_name(&self) -> Option<&str>

Get the column name this expression operates on (if single column)

fn get_comparison_info(&self) -> Option<(&str, Operator, &Value)>

Extract equality comparison info for index lookups

fn get_and_operands(&self) -> Option<&[Box<dyn Expression>]>

Get child expressions if this is an AND expression

fn get_or_operands(&self) -> Option<&[Box<dyn Expression>]>

Get child expressions if this is an OR expression

fn get_like_prefix_info(&self) -> Option<(&str, String, bool)>

Get LIKE prefix info for index range scanning

fn collect_comparisons(&self) -> Vec<(&str, Operator, &Value)>

Collect all simple comparisons from this expression tree

fn is_unknown_due_to_null(&self, _row: &Row) -> bool

Check if the expression result would be UNKNOWN (NULL) for this row