tramli 3.1.0

Constrained flow engine — state machines that prevent invalid transitions at build time
Documentation 
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use std::time::Instant;

use crate::context::FlowContext;
use crate::definition::FlowDefinition;
use crate::types::FlowState;

pub struct FlowInstance<S: FlowState> {
    pub id: String,
    pub session_id: String,
    pub definition: std::sync::Arc<FlowDefinition<S>>,
    pub context: FlowContext,
    current_state: S,
    guard_failure_count: usize,
    version: u32,
    pub created_at: Instant,
    pub expires_at: Instant,
    exit_state: Option<String>,
}

impl<S: FlowState> FlowInstance<S> {
    pub fn new(
        id: String, session_id: String,
        definition: std::sync::Arc<FlowDefinition<S>>,
        context: FlowContext, current_state: S, expires_at: Instant,
    ) -> Self {
        Self {
            id, session_id, definition, context, current_state,
            guard_failure_count: 0, version: 0,
            created_at: Instant::now(), expires_at,
            exit_state: None,
        }
    }

    /// Restore from persisted state.
    pub fn restore(
        id: String, session_id: String,
        definition: std::sync::Arc<FlowDefinition<S>>,
        context: FlowContext, current_state: S,
        created_at: Instant, expires_at: Instant,
        guard_failure_count: usize, version: u32,
        exit_state: Option<String>,
    ) -> Self {
        Self {
            id, session_id, definition, context, current_state,
            guard_failure_count, version, created_at, expires_at, exit_state,
        }
    }

    pub fn current_state(&self) -> S { self.current_state }
    pub fn guard_failure_count(&self) -> usize { self.guard_failure_count }
    pub fn version(&self) -> u32 { self.version }
    pub fn exit_state(&self) -> Option<&str> { self.exit_state.as_deref() }
    pub fn is_completed(&self) -> bool { self.exit_state.is_some() }

    /// State path from root. E.g. ["PAYMENT", "CONFIRM"].
    pub fn state_path(&self) -> Vec<String> {
        vec![format!("{:?}", self.current_state)]
    }

    /// State path as slash-separated string.
    pub fn state_path_string(&self) -> String {
        self.state_path().join("/")
    }

    /// Update the version in-place. For FlowStore optimistic locking after save.
    pub fn set_version_public(&mut self, new_version: u32) {
        self.version = new_version;
    }

    pub(crate) fn transition_to(&mut self, state: S) { self.current_state = state; }
    pub(crate) fn increment_guard_failure(&mut self) { self.guard_failure_count += 1; }
    pub(crate) fn complete(&mut self, exit_state: impl Into<String>) { self.exit_state = Some(exit_state.into()); }
}