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use std::{collections::BTreeMap, fmt::Debug};
use arc_bytes::serde::Bytes;
use serde::{Deserialize, Serialize};
use crate::{
document::{DocumentId, Header, OwnedDocument},
schema::view::{self, Key, SerializedView, View},
};
/// A document's entry in a View's mappings.
#[derive(PartialEq, Debug)]
pub struct Map<K: for<'a> Key<'a> = (), V = ()> {
/// The header of the document that emitted this entry.
pub source: Header,
/// The key used to index the View.
pub key: K,
/// An associated value stored in the view.
pub value: V,
}
impl<K: for<'a> Key<'a>, V> Map<K, V> {
/// Serializes this map.
pub(crate) fn serialized<View: SerializedView<Value = V>>(
&self,
) -> Result<Serialized, view::Error> {
Ok(Serialized {
source: self.source.clone(),
key: Bytes::from(
self.key
.as_ord_bytes()
.map_err(view::Error::key_serialization)?
.to_vec(),
),
value: Bytes::from(View::serialize(&self.value)?),
})
/// Creates a new Map entry for the document with id `source`.
pub fn new(source: Header, key: K, value: V) -> Self {
Self { source, key, value }
/// A collection of [`Map`]s.
#[derive(Debug, PartialEq)]
#[must_use]
pub enum Mappings<K: for<'a> Key<'a> = (), V = ()> {
/// Zero or one mappings.
Simple(Option<Map<K, V>>),
/// More than one mapping.
List(Vec<Map<K, V>>),
impl<K: for<'a> Key<'a>, V> Default for Mappings<K, V> {
fn default() -> Self {
Self::none()
impl<K: for<'a> Key<'a>, V> Mappings<K, V> {
/// Returns an empty collection of mappings.
pub fn none() -> Self {
Self::Simple(None)
/// Appends `mapping` to the end of this collection.
pub fn push(&mut self, mapping: Map<K, V>) {
match self {
Self::Simple(existing_mapping) => {
*self = if let Some(existing_mapping) = existing_mapping.take() {
Self::List(vec![existing_mapping, mapping])
} else {
Self::Simple(Some(mapping))
Self::List(vec) => vec.push(mapping),
/// Appends `mappings` to the end of this collection and returns self.
pub fn and(mut self, mappings: Self) -> Self {
self.extend(mappings);
self
impl<K: for<'a> Key<'a>, V> Extend<Map<K, V>> for Mappings<K, V> {
fn extend<T: IntoIterator<Item = Map<K, V>>>(&mut self, iter: T) {
let iter = iter.into_iter();
for map in iter {
self.push(map);
impl<K: for<'a> Key<'a>, V> FromIterator<Map<K, V>> for Mappings<K, V> {
fn from_iter<T: IntoIterator<Item = Map<K, V>>>(iter: T) -> Self {
let mut mappings = Self::none();
mappings.extend(iter);
mappings
impl<K: for<'a> Key<'a>, V> FromIterator<Self> for Mappings<K, V> {
fn from_iter<T: IntoIterator<Item = Self>>(iter: T) -> Self {
let mut iter = iter.into_iter();
if let Some(mut collected) = iter.next() {
for mappings in iter {
collected.extend(mappings);
collected
impl<K: for<'a> Key<'a>, V> IntoIterator for Mappings<K, V> {
type Item = Map<K, V>;
type IntoIter = MappingsIter<K, V>;
fn into_iter(self) -> Self::IntoIter {
Mappings::Simple(option) => MappingsIter::Inline(option),
Mappings::List(list) => MappingsIter::Vec(list.into_iter()),
/// An iterator over [`Mappings`].
pub enum MappingsIter<K: for<'a> Key<'a> = (), V = ()> {
/// An iterator over a [`Mappings::Simple`] value.
Inline(Option<Map<K, V>>),
/// An iterator over a [`Mappings::List`] value.
Vec(std::vec::IntoIter<Map<K, V>>),
impl<K: for<'a> Key<'a>, V> Iterator for MappingsIter<K, V> {
fn next(&mut self) -> Option<Self::Item> {
MappingsIter::Inline(opt) => opt.take(),
MappingsIter::Vec(iter) => iter.next(),
/// A collection of mappings and the associated documents.
#[derive(Debug)]
pub struct MappedDocuments<D, V: View> {
/// The collection of mappings.
pub mappings: Vec<Map<V::Key, V::Value>>,
/// All associated documents by ID.
///
/// Documents can appear in a mapping query multiple times. As a result, they are stored separately to avoid duplication.
pub documents: BTreeMap<DocumentId, D>,
impl<D, V: View> MappedDocuments<D, V> {
/// The number of mappings contained in this collection.
pub fn len(&self) -> usize {
self.mappings.len()
/// Returns true if there are no mappings in this collection.
pub fn is_empty(&self) -> bool {
self.len() == 0
/// Returns the mapped document at`index`, or `None` if `index >=
/// self.len()`.
pub fn get(&self, index: usize) -> Option<MappedDocument<'_, D, V::Key, V::Value>> {
if index < self.len() {
let mapping = &self.mappings[index];
let document = self
.documents
.get(&mapping.source.id)
.expect("missing mapped document");
Some(MappedDocument {
key: &mapping.key,
value: &mapping.value,
document,
None
/// An iterator of mapped documents.
pub struct MappedDocumentsIter<'a, D, V: View> {
docs: &'a MappedDocuments<D, V>,
index: usize,
impl<'a, D, V: View> IntoIterator for &'a MappedDocuments<D, V> {
type Item = MappedDocument<'a, D, V::Key, V::Value>;
type IntoIter = MappedDocumentsIter<'a, D, V>;
MappedDocumentsIter {
docs: self,
index: 0,
impl<'a, D, V: View> Iterator for MappedDocumentsIter<'a, D, V> {
let doc = self.docs.get(self.index);
self.index = self.index.saturating_add(1);
doc
/// A mapped document returned from a view query.
pub struct MappedDocument<'a, D, K, V> {
/// The key that this document mapped to.
pub key: &'a K,
/// The associated value of this key.
pub value: &'a V,
/// The source document of this mapping.
pub document: &'a D,
/// Represents a document's entry in a View's mappings, serialized and ready to store.
#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct Serialized {
/// The key used to index the View.Operation
pub key: Bytes,
/// An associated value stored in the view.Operation
pub value: Bytes,
impl Serialized {
/// Deserializes this map.
pub fn deserialized<View: SerializedView>(
) -> Result<Map<View::Key, View::Value>, view::Error> {
Ok(Map::new(
self.source.clone(),
<View::Key as Key>::from_ord_bytes(&self.key)
.map_err(view::Error::key_serialization)?,
View::deserialize(&self.value)?,
))
/// A serialized [`MappedDocument`](MappedDocument).
#[derive(Clone, Serialize, Deserialize, Debug)]
pub struct MappedSerializedDocuments {
/// The serialized mapped value.
pub mappings: Vec<Serialized>,
/// The source document.
pub documents: BTreeMap<DocumentId, OwnedDocument>,
impl MappedSerializedDocuments {
/// Deserialize into a [`MappedDocument`](MappedDocument).
self,
) -> Result<MappedDocuments<OwnedDocument, View>, crate::Error> {
let mappings = self
.mappings
.iter()
.map(Serialized::deserialized::<View>)
.collect::<Result<Vec<_>, _>>()?;
Ok(MappedDocuments {
mappings,
documents: self.documents,
/// A key value pair
#[derive(Clone, PartialEq, Debug)]
pub struct MappedValue<K: for<'a> Key<'a>, V> {
/// The key responsible for generating the value
/// The value generated by the `View`
impl<K: for<'a> Key<'a>, V> MappedValue<K, V> {
/// Returns a new instance with the key/value pair.
pub fn new(key: K, value: V) -> Self {
Self { key, value }
/// A mapped value in a [`View`].
#[allow(type_alias_bounds)] // False positive, required for associated types
pub type ViewMappedValue<V: View> = MappedValue<V::Key, V::Value>;
/// A serialized [`MappedValue`].
pub struct MappedSerializedValue {
/// The serialized key.
/// The serialized value.