From 1ae9bf2a489f1b00d1632f2867921d295cda0ec7 Mon Sep 17 00:00:00 2001
From: Zixuan Chen <remch183@outlook.com>
Date: Wed, 23 Nov 2022 16:26:38 +0800
Subject: [PATCH] feat: init delta

---
 crates/loro-core/src/delta.rs     | 82 +++++++++++++++++++++++++++++++
 crates/loro-core/src/event.rs     | 47 ++++++++++++++++++
 crates/loro-core/src/lib.rs       |  3 ++
 crates/loro-core/src/log_store.rs |  2 +-
 crates/loro-core/src/version.rs   |  2 +
 crates/rle/src/rle_vec.rs         |  2 +-
 6 files changed, 136 insertions(+), 2 deletions(-)
 create mode 100644 crates/loro-core/src/delta.rs
 create mode 100644 crates/loro-core/src/event.rs

diff --git a/crates/loro-core/src/delta.rs b/crates/loro-core/src/delta.rs
new file mode 100644
index 00000000..3cdf3101
--- /dev/null
+++ b/crates/loro-core/src/delta.rs
@@ -0,0 +1,82 @@
+use enum_as_inner::EnumAsInner;
+use rle::{HasLength, Mergable, RleVec};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Delta<Value, Meta = ()> {
+    vec: RleVec<[DeltaItem<Value, Meta>; 1]>,
+}
+
+#[derive(Debug, EnumAsInner, PartialEq, Eq, Clone)]
+pub enum DeltaItem<Value, Meta> {
+    Retain { len: usize, meta: Meta },
+    Insert { value: Value, meta: Meta },
+    Delete(usize),
+}
+
+impl<Value: HasLength, Meta> HasLength for DeltaItem<Value, Meta> {
+    fn content_len(&self) -> usize {
+        match self {
+            DeltaItem::Retain { len, meta: _ } => *len,
+            DeltaItem::Insert { value, meta: _ } => value.atom_len(),
+            DeltaItem::Delete(len) => *len,
+        }
+    }
+}
+
+impl<Value, Meta> Mergable for DeltaItem<Value, Meta> {}
+
+impl<Value: HasLength, Meta> Delta<Value, Meta> {
+    pub fn new() -> Self {
+        Self { vec: RleVec::new() }
+    }
+
+    pub fn retain_with_meta(&mut self, len: usize, meta: Meta) {
+        self.vec.push(DeltaItem::Retain { len, meta });
+    }
+
+    pub fn insert_with_meta(&mut self, value: Value, meta: Meta) {
+        self.vec.push(DeltaItem::Insert { value, meta });
+    }
+
+    pub fn delete(&mut self, len: usize) {
+        self.vec.push(DeltaItem::Delete(len));
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &DeltaItem<Value, Meta>> {
+        self.vec.iter()
+    }
+
+    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut DeltaItem<Value, Meta>> {
+        self.vec.iter_mut()
+    }
+
+    pub fn len(&self) -> usize {
+        self.vec.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+}
+
+impl<Value: HasLength, Meta> Default for Delta<Value, Meta> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<Value: HasLength, Meta: Default> Delta<Value, Meta> {
+    pub fn retain(&mut self, len: usize) {
+        self.vec.push(DeltaItem::Retain {
+            len,
+            meta: Default::default(),
+        });
+    }
+
+    pub fn insert(&mut self, value: Value) {
+        self.vec.push(DeltaItem::Insert {
+            value,
+            meta: Default::default(),
+        });
+    }
+}
diff --git a/crates/loro-core/src/event.rs b/crates/loro-core/src/event.rs
new file mode 100644
index 00000000..7302cdc1
--- /dev/null
+++ b/crates/loro-core/src/event.rs
@@ -0,0 +1,47 @@
+use fxhash::{FxHashMap, FxHashSet};
+
+use crate::{
+    container::ContainerID, delta::Delta, id::ContainerIdx, version::Frontiers, InternalString,
+    LoroValue,
+};
+
+pub(crate) struct RawEvent {
+    container_idx: ContainerIdx,
+    old_version: Frontiers,
+    new_version: Frontiers,
+    diff: Diff,
+}
+
+pub struct Event {
+    pub old_version: Frontiers,
+    pub new_version: Frontiers,
+    pub current_target: ContainerID,
+    pub target: ContainerID,
+    /// the relative path from current_target to target
+    pub relative_path: Path,
+    pub diff: Vec<Diff>,
+}
+
+pub type Path = Vec<Index>;
+
+pub enum Index {
+    Key(InternalString),
+    Index(usize),
+}
+
+pub enum Diff {
+    List(Delta<Vec<LoroValue>>),
+    Text(Delta<String>),
+    Map(MapDiff),
+}
+
+pub struct ValuePair {
+    pub old: LoroValue,
+    pub new: LoroValue,
+}
+
+pub struct MapDiff {
+    pub added: FxHashMap<InternalString, LoroValue>,
+    pub updated: FxHashMap<InternalString, ValuePair>,
+    pub deleted: FxHashSet<InternalString>,
+}
diff --git a/crates/loro-core/src/lib.rs b/crates/loro-core/src/lib.rs
index 0a51629a..0c20dca6 100644
--- a/crates/loro-core/src/lib.rs
+++ b/crates/loro-core/src/lib.rs
@@ -24,6 +24,8 @@ mod span;
 #[cfg(test)]
 pub mod tests;
 
+pub mod delta;
+pub mod event;
 mod value;
 
 pub use error::LoroError;
@@ -32,6 +34,7 @@ pub(crate) use change::{Lamport, Timestamp};
 pub(crate) use id::{ClientID, ID};
 pub(crate) use op::{ContentType, InsertContentTrait, Op};
 
+// TODO: rename as Key?
 pub(crate) type InternalString = DefaultAtom;
 pub(crate) use container::Container;
 
diff --git a/crates/loro-core/src/log_store.rs b/crates/loro-core/src/log_store.rs
index 520d703c..ff59044e 100644
--- a/crates/loro-core/src/log_store.rs
+++ b/crates/loro-core/src/log_store.rs
@@ -20,7 +20,7 @@ use crate::{
     configure::Configure,
     container::{
         registry::{ContainerInstance, ContainerRegistry},
-        Container, ContainerID,
+        ContainerID,
     },
     dag::Dag,
     debug_log,
diff --git a/crates/loro-core/src/version.rs b/crates/loro-core/src/version.rs
index fc7395a5..0baa4a6c 100644
--- a/crates/loro-core/src/version.rs
+++ b/crates/loro-core/src/version.rs
@@ -30,6 +30,8 @@ use crate::{
 #[derive(Debug, Clone)]
 pub struct VersionVector(FxHashMap<ClientID, Counter>);
 
+pub struct Frontiers(SmallVec<[ID; 1]>);
+
 impl PartialEq for VersionVector {
     fn eq(&self, other: &Self) -> bool {
         self.iter()
diff --git a/crates/rle/src/rle_vec.rs b/crates/rle/src/rle_vec.rs
index 6a6cf168..22f53670 100644
--- a/crates/rle/src/rle_vec.rs
+++ b/crates/rle/src/rle_vec.rs
@@ -223,7 +223,7 @@ impl<A: Array> Index<usize> for RleVecWithLen<A> {
 
 impl<A: Array> PartialEq for RleVec<A>
 where
-    A::Item: Eq + PartialEq,
+    A::Item: PartialEq,
 {
     fn eq(&self, other: &Self) -> bool {
         self.vec == other.vec