Struct VariableBindings

pub struct VariableBindings<'f> { /* private fields */ }

Runtime variable bindings.

VariableBindings manages variable bindings during CEL expression evaluation. It maps variable names to concrete values or value providers.

Unlike compile-time VariableRegistry, VariableBindings provides actual variable values at runtime and supports two types of bindings:

• Value bindings: Directly stored variable values
• Provider bindings: Function-computed variable values through lazy evaluation

Lifetime Parameters

• 'f: Lifetime of function providers, allowing closures valid within specific scopes

Examples

use cel_cxx::VariableBindings;

let mut bindings = VariableBindings::new();

// Bind static values
bindings.bind("name", "Alice")?;
bindings.bind("age", 30i64)?;

// Bind dynamic value providers
bindings.bind_provider("current_time", || {
    std::time::SystemTime::now()
})?;

assert_eq!(bindings.len(), 3);

Implementations

impl<'f> VariableBindings<'f>

pub fn new() -> Self

Creates a new empty variable bindings.

impl<'f> VariableBindings<'f>

pub fn bind<T>( &mut self, name: impl Into<String>, value: T, ) -> Result<&mut Self, Error>

where T: IntoValue + TypedValue,

Binds a variable value.

Binds a variable name to a concrete value. The value must implement IntoValue and TypedValue traits.

Type Parameters

• T: Value type, must implement IntoValue + TypedValue

Parameters

• name: Variable name
• value: Variable value

Returns

Returns &mut Self to support method chaining

Examples

use cel_cxx::VariableBindings;

let mut bindings = VariableBindings::new();
bindings
    .bind("user_id", 123i64)?
    .bind("is_admin", true)?
    .bind("username", "alice")?;

pub fn bind_provider<F, Fm>( &mut self, name: impl Into<String>, provider: F, ) -> Result<&mut Self, Error>

where F: IntoFunction<'f, Fm>, Fm: FnMarker,

Binds a variable to a value provider.

Binds a variable name to a provider function that computes the value dynamically. This enables lazy evaluation and allows variables to have values computed at runtime.

Type Parameters

• F: Provider function type, must implement IntoFunction
• Fm: Function marker type (sync/async)

Parameters

• name: Variable name
• provider: Provider function that computes the variable value

Returns

Returns &mut Self to support method chaining

Examples

use cel_cxx::VariableBindings;

let mut bindings = VariableBindings::new();
bindings.bind_provider("current_time", || -> i64 {
    std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap()
        .as_secs() as i64
})?;

pub fn find(&self, name: &str) -> Option<&VariableBinding<'f>>

Finds a variable binding by name.

Parameters

• name: Variable name

Returns

Returns Some(&VariableBinding) if found, None otherwise

pub fn find_mut(&mut self, name: &str) -> Option<&mut VariableBinding<'f>>

Finds a mutable variable binding by name.

Parameters

• name: Variable name

Returns

Returns Some(&mut VariableBinding) if found, None otherwise

pub fn entries(&self) -> impl Iterator<Item = (&str, &VariableBinding<'f>)>

Returns an iterator over all variable bindings.

The iterator yields (name, binding) pairs for all bound variables.

Returns

Iterator yielding (&str, &VariableBinding) pairs

pub fn entries_mut( &mut self, ) -> impl Iterator<Item = (&str, &mut VariableBinding<'f>)>

Returns a mutable iterator over all variable bindings.

The iterator yields (name, binding) pairs and allows modifying the bindings.

Returns

Iterator yielding (&str, &mut VariableBinding) pairs

pub fn remove(&mut self, name: &str) -> Result<(), Error>

Removes a variable binding by name.

Parameters

• name: Variable name to remove

Returns

Returns Ok(()) if successfully removed, or an error if the variable doesn’t exist

pub fn clear(&mut self)

Clears all variable bindings.

pub fn len(&self) -> usize

Returns the number of variable bindings.

Returns

Number of bound variables

pub fn is_empty(&self) -> bool

Returns whether the bindings are empty.

Returns

true if no variables are bound, false otherwise

Trait Implementations

impl<'f> Debug for VariableBindings<'f>

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

Formats the value using the given formatter.

impl<'f> Default for VariableBindings<'f>

fn default() -> VariableBindings<'f>

Returns the “default value” for a type.