From d8ab5bdc3e20759e5ba8a6844393757da3539372 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Wed, 22 Dec 2021 18:50:08 +0100
Subject: New buckets for 0.6.0: fix model and migration

---
 src/util/crdt/lww.rs     |  5 +----
 src/util/crdt/lww_map.rs |  9 +++++----
 src/util/crdt/map.rs     | 25 +++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 8 deletions(-)

(limited to 'src/util/crdt')

diff --git a/src/util/crdt/lww.rs b/src/util/crdt/lww.rs
index 99bd8e7c..adb07711 100644
--- a/src/util/crdt/lww.rs
+++ b/src/util/crdt/lww.rs
@@ -57,10 +57,7 @@ where
 		}
 	}
 
-	/// Build a new CRDT from a previous non-compatible one
-	///
-	/// Compared to new, the CRDT's timestamp is not set to now
-	/// but must be set to the previous, non-compatible, CRDT's timestamp.
+	/// Build a new LWW CRDT from its raw pieces: a timestamp and the value
 	pub fn raw(ts: u64, value: T) -> Self {
 		Self { ts, v: value }
 	}
diff --git a/src/util/crdt/lww_map.rs b/src/util/crdt/lww_map.rs
index 1746c3cc..c155c3a8 100644
--- a/src/util/crdt/lww_map.rs
+++ b/src/util/crdt/lww_map.rs
@@ -38,10 +38,11 @@ where
 		Self { vals: vec![] }
 	}
 
-	/// Used to migrate from a map defined in an incompatible format. This produces
-	/// a map that contains a single item with the specified timestamp (copied from
-	/// the incompatible format). Do this as many times as you have items to migrate,
-	/// and put them all together using the CRDT merge operator.
+	/// This produces a map that contains a single item with the specified timestamp.
+	///
+	/// Used to migrate from a map defined in an incompatible format. Do this as many
+	/// times as you have items to migrate, and put them all together using the
+	/// CRDT merge operator.
 	pub fn raw_item(k: K, ts: u64, v: V) -> Self {
 		Self {
 			vals: vec![(k, ts, v)],
diff --git a/src/util/crdt/map.rs b/src/util/crdt/map.rs
index ad9a6e55..f9ed19b6 100644
--- a/src/util/crdt/map.rs
+++ b/src/util/crdt/map.rs
@@ -1,3 +1,5 @@
+use std::iter::{FromIterator, IntoIterator};
+
 use serde::{Deserialize, Serialize};
 
 use crate::crdt::crdt::*;
@@ -98,3 +100,26 @@ where
 		Self::new()
 	}
 }
+
+/// A crdt map can be created from an iterator of key-value pairs.
+/// Note that all keys in the iterator must be distinct:
+/// this function will throw a panic if it is not the case.
+impl<K, V> FromIterator<(K, V)> for Map<K, V>
+where
+	K: Clone + Ord,
+	V: Clone + Crdt,
+{
+	fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
+		let mut vals: Vec<(K, V)> = iter.into_iter().collect();
+		vals.sort_by_cached_key(|tup| tup.0.clone());
+
+		// sanity check
+		for i in 1..vals.len() {
+			if vals[i - 1].0 == vals[i].0 {
+				panic!("Duplicate key in crdt::Map resulting from .from_iter() or .collect()");
+			}
+		}
+
+		Self { vals }
+	}
+}
-- 
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