You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: logic.rs
    path of file: ./repos/grafbase/engine/crates/engine-v2/src/plan/planning
    
    the code of the file until where you have to start completion: use schema::{FieldId, FieldSet, ResolverWalker};

use crate::plan::PlanId;

/// Defines whether a field can be provided or not for a given resolver. Initially all fields with
/// no resolver or a compatible one (same subgraph t
    
    pub(super) fn child(&self, field_id: FieldId) -> Self {
        match self {
            PlanningLogic::CompatibleResolver {
                resolver,
                providable,
                plan_id,
            } => {
                let providable = FieldSet::merge_opt(
                    providable.get(field_id).map(|s| &s.subselection),
                    resolver.walk(field_id).provides_for(resolver).as_deref(),
                );
                if resolver.can_provide(field_id) {
                    PlanningLogic::CompatibleResolver {
                        plan_id: *plan_id,
                        resolver: *resolver,
                        providable,
                    }
                } else {
                    PlanningLogic::OnlyProvidable {
                        plan_id: *plan_id,
                        resolver: *resolver,
                        providable,
                    }
                }
            }
            PlanningLogic::OnlyProvidable {
                resolver,
                providable,
                plan_id,
            } => PlanningLogic::OnlyProvidable {
                plan_id: *plan_id,
                resolver: *resolver,
                providable: providable
                    .get(field_id)
                    .map(|s| &s.subselection)
                    .cloned()
                    .unwrap_or_default(),
            },
        }
    }