use std::collections::BTreeMap; use serde::{Deserialize, Serialize}; use crate::FieldId; #[derive(Debug, Clone, Serialize, Deserialize)] pub struct FieldsIdsMap { names_ids: BTreeMap, ids_names: BTreeMap, next_id: Option, } impl FieldsIdsMap { pub fn new() -> FieldsIdsMap { FieldsIdsMap { names_ids: BTreeMap::new(), ids_names: BTreeMap::new(), next_id: Some(0) } } /// Returns the number of fields ids in the map. pub fn len(&self) -> usize { self.names_ids.len() } /// Returns `true` if the map is empty. pub fn is_empty(&self) -> bool { self.names_ids.is_empty() } /// Returns the field id related to a field name, it will create a new field id if the /// name is not already known. Returns `None` if the maximum field id as been reached. pub fn insert(&mut self, name: &str) -> Option { match self.names_ids.get(name) { Some(id) => Some(*id), None => { let id = self.next_id?; self.next_id = id.checked_add(1); self.names_ids.insert(name.to_owned(), id); self.ids_names.insert(id, name.to_owned()); Some(id) } } } /// Get the id of a field based on its name. pub fn id(&self, name: &str) -> Option { self.names_ids.get(name).copied() } /// Get the name of a field based on its id. pub fn name(&self, id: FieldId) -> Option<&str> { self.ids_names.get(&id).map(String::as_str) } /// Remove a field name and id based on its name. pub fn remove(&mut self, name: &str) -> Option { match self.names_ids.remove(name) { Some(id) => self.ids_names.remove_entry(&id).map(|(id, _)| id), None => None, } } /// Iterate over the ids and names in the ids order. pub fn iter(&self) -> impl Iterator { self.ids_names.iter().map(|(id, name)| (*id, name.as_str())) } /// Iterate over the ids in the order of the ids. pub fn ids(&'_ self) -> impl Iterator + '_ { self.ids_names.keys().copied() } /// Iterate over the names in the order of the ids. pub fn names(&self) -> impl Iterator { self.ids_names.values().map(AsRef::as_ref) } } impl Default for FieldsIdsMap { fn default() -> FieldsIdsMap { FieldsIdsMap::new() } } #[cfg(test)] mod tests { use super::*; #[test] fn fields_ids_map() { let mut map = FieldsIdsMap::new(); assert_eq!(map.insert("id"), Some(0)); assert_eq!(map.insert("title"), Some(1)); assert_eq!(map.insert("description"), Some(2)); assert_eq!(map.insert("id"), Some(0)); assert_eq!(map.insert("title"), Some(1)); assert_eq!(map.insert("description"), Some(2)); assert_eq!(map.id("id"), Some(0)); assert_eq!(map.id("title"), Some(1)); assert_eq!(map.id("description"), Some(2)); assert_eq!(map.id("date"), None); assert_eq!(map.len(), 3); assert_eq!(map.name(0), Some("id")); assert_eq!(map.name(1), Some("title")); assert_eq!(map.name(2), Some("description")); assert_eq!(map.name(4), None); assert_eq!(map.remove("title"), Some(1)); assert_eq!(map.id("title"), None); assert_eq!(map.insert("title"), Some(3)); assert_eq!(map.len(), 3); let mut iter = map.iter(); assert_eq!(iter.next(), Some((0, "id"))); assert_eq!(iter.next(), Some((2, "description"))); assert_eq!(iter.next(), Some((3, "title"))); assert_eq!(iter.next(), None); } }