it.unibo.jakta.agents.bdi.AgentLifecycle.kt Maven / Gradle / Ivy

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package it.unibo.jakta.agents.bdi

import it.unibo.jakta.agents.bdi.beliefs.BeliefBase
import it.unibo.jakta.agents.bdi.beliefs.Belief
import it.unibo.jakta.agents.bdi.beliefs.RetrieveResult
import it.unibo.jakta.agents.bdi.environment.Environment
import it.unibo.jakta.agents.bdi.events.Event
import it.unibo.jakta.agents.bdi.events.EventQueue
import it.unibo.jakta.agents.bdi.impl.AgentLifecycleImpl
import it.unibo.jakta.agents.bdi.intentions.Intention
import it.unibo.jakta.agents.bdi.intentions.IntentionPool
import it.unibo.jakta.agents.bdi.intentions.SchedulingResult
import it.unibo.jakta.agents.bdi.plans.Plan
import it.unibo.jakta.agents.bdi.plans.PlanLibrary
import it.unibo.jakta.agents.bdi.actions.effects.EnvironmentChange
import it.unibo.jakta.agents.bdi.context.AgentContext
import it.unibo.jakta.agents.bdi.executionstrategies.ExecutionResult
import it.unibo.jakta.agents.fsm.Activity

/** BDI Agent definition*/
interface AgentLifecycle {

    /**
     * STEP 1 of reasoning cycle: Belief Update Function.
     * This function defines how to merge new [perceptions] into the current [beliefBase]
     * @param perceptions: [BeliefBase] that collects all agent's perceptions of the environment
     * @param beliefBase: [BeliefBase] the current agent's [BeliefBase]
     * @return a [RetrieveResult] that contains the updated [BeliefBase] and the added [Belief]s
     */
    fun updateBelief(perceptions: BeliefBase, beliefBase: BeliefBase): RetrieveResult

    /**
     * STEP 5 of reasoning cycle: Selecting an Event.
     * This function select an event to be handled in a particular reasoning cycle.
     * The default implementation follows a FIFO policy for the [EventQueue].
     * @param events: [EventQueue] on which select the event
     * @return the selected [Event]
     */
    fun selectEvent(events: EventQueue): Event?

    /**
     * STEP 6 of reasoning cycle: Retrieving all Relevant Plans.
     * This function returns all plans from [PlanLibrary] that have a triggering event that can be unified
     * with the selected event.
     * @param event: the selected [Event]
     * @param planLibrary: the [PlanLibrary] of the Agent
     * @return the relevant [Plan]s
     */
    fun selectRelevantPlans(event: Event, planLibrary: PlanLibrary): PlanLibrary

    /**
     * STEP 7 of reasoning cycle: Determining the Applicable Plans.
     * This function defines if a plan is applicable based on the agent's Belief Base.
     * @param event: the selected [Event] that triggered the [Plan]
     * @param plan: the triggered [Plan]
     * @param beliefBase: the agent's [BeliefBase]
     * @return yes if it's applicable, false otherwise.
     */
    fun isPlanApplicable(event: Event, plan: Plan, beliefBase: BeliefBase): Boolean

    /**
     * Step 8 of reasoning cycle: Selecting one Applicable Plan.
     * Given all the applicable plans, this Selection Function returns the plan that the agent will commit to execute.
     * By default,
     * @param plans: applicable [Plan]s
     * @return the selected [Plan] to be executed
     */
    fun selectApplicablePlan(plans: Iterable): Plan?

    /**
     * Step 8 of reasoning cycle: Assign selected plan to an Intention.
     * If the event is external, then a new Intention is created. Otherwise, the selected plan is pushed on top of the
     * firing Intention.
     * @param event: the [Event] that triggered the [Plan]
     * @param plan: the selected [Plan]
     * @param intentions: the [IntentionPool] of the agent
     * @return the updated [Intention]
     */
    fun assignPlanToIntention(event: Event, plan: Plan, intentions: IntentionPool): Intention

    /**
     * Step 9 of reasoning cycle: Selecting an Intention for Further Execution.
     * Given all agent's intentions, this Selection Function selects the intention to be scheduled to execution
     * by the agent. By default, this function implements Round Robin scheduling.
     * @param intentions: the agent's [IntentionPool]
     * @return a [SchedulingResult] with the updated [IntentionPool] and the [Intention] to execute
     */
    fun scheduleIntention(intentions: IntentionPool): SchedulingResult

    /**
     * Step 10 of reasoning cycle: Executing One step of an Intention.
     * Depending on the formula on the top of the intention, the agent will execute the related action.
     * @param intention: [Intention] on which the agent is currently focused
     * @return the updated [Intention] after agent execution
     */
    fun runIntention(intention: Intention, context: AgentContext, environment: Environment): ExecutionResult

    /** Performs the whole procedure (10 steps) of the BDI Agent's Reasoning Cycle. */
    fun reason(
        environment: Environment,
        controller: Activity.Controller,
        debugEnabled: Boolean = false,
    ): Iterable

    companion object {
        fun of(agent: Agent): AgentLifecycle = AgentLifecycleImpl(agent)
    }
}