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ConditionBackend

app_kit::workflow

Trait ConditionBackend 

Source 
pub trait ConditionBackend:
    Send
    + Sync
    + 'static {
    // Required methods
    fn declaration(&self) -> &ConditionDeclaration;
    fn evaluate(&self, state: &WorkflowState) -> Result<bool, AppError>;
}
Expand description

A caller-owned predicate evaluated against the full immutable workflow state.

App validates declared reads before evaluating the predicate, including reads within composed conditions that would otherwise short-circuit.

§Example

use app_kit::{AppError, workflow::{ConditionBackend, ConditionDeclaration, WorkflowState}};
struct Ready { declaration: ConditionDeclaration }
impl ConditionBackend for Ready {
    fn declaration(&self) -> &ConditionDeclaration { &self.declaration }
    fn evaluate(&self, state: &WorkflowState) -> Result<bool, AppError> {
        let count = state.values().get("count").and_then(serde_json::Value::as_i64)
            .ok_or_else(|| AppError::InvalidInput("count must be an integer".into()))?;
        Ok(count >= 3)
    }
}
let condition = Ready { declaration: ConditionDeclaration {
    key: "ready".into(), revision: "r1".into(), reads: vec!["count".into()],
} };
let state = WorkflowState::new(serde_json::from_str(r#"{"count":3}"#)?)?;
assert!(condition.evaluate(&state)?);

Required Methods§

Source

fn declaration(&self) -> &ConditionDeclaration

Returns the stable declaration for one logical predicate revision.

See the complete condition implementation.

Source

fn evaluate(&self, state: &WorkflowState) -> Result<bool, AppError>

Evaluates the predicate without advancing workflow state or action ordinals.

§Errors

Return an error when evaluation cannot produce a valid boolean. App validates declared reads before calling this method; caller failures stop that routing decision rather than being interpreted as false.

See the complete condition implementation.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§