From bf428df4e25760b23bf12d356439966ca59de685 Mon Sep 17 00:00:00 2001
From: Mitchell Donaldson <mitchell.m.donaldson@gmail.com>
Date: Tue, 3 Nov 2020 08:28:43 +1100
Subject: [PATCH] Add hasPrevious method to Path (#3963)

* Add hasPrevious method to Path API.

Co-authored-by: Mitchell Donaldson <mitch@nod.money>
---
 packages/slate/src/interfaces/path.ts                     | 8 ++++++++
 packages/slate/test/interfaces/Path/hasPrevious/root.tsx  | 7 +++++++
 .../slate/test/interfaces/Path/hasPrevious/success.tsx    | 7 +++++++
 3 files changed, 22 insertions(+)
 create mode 100644 packages/slate/test/interfaces/Path/hasPrevious/root.tsx
 create mode 100644 packages/slate/test/interfaces/Path/hasPrevious/success.tsx

diff --git a/packages/slate/src/interfaces/path.ts b/packages/slate/src/interfaces/path.ts
index fb256082b..94120b216 100755
--- a/packages/slate/src/interfaces/path.ts
+++ b/packages/slate/src/interfaces/path.ts
@@ -118,6 +118,14 @@ export const Path = {
     )
   },
 
+  /**
+   * Check if the path of previous sibling node exists
+   */
+
+  hasPrevious(path: Path): boolean {
+    return path[path.length - 1] > 0
+  },
+
   /**
    * Check if a path is after another.
    */
diff --git a/packages/slate/test/interfaces/Path/hasPrevious/root.tsx b/packages/slate/test/interfaces/Path/hasPrevious/root.tsx
new file mode 100644
index 000000000..827d102e8
--- /dev/null
+++ b/packages/slate/test/interfaces/Path/hasPrevious/root.tsx
@@ -0,0 +1,7 @@
+import { Path } from 'slate'
+
+export const input = [0, 0]
+export const test = path => {
+  return Path.hasPrevious(path)
+}
+export const output = false
diff --git a/packages/slate/test/interfaces/Path/hasPrevious/success.tsx b/packages/slate/test/interfaces/Path/hasPrevious/success.tsx
new file mode 100644
index 000000000..76e772bd4
--- /dev/null
+++ b/packages/slate/test/interfaces/Path/hasPrevious/success.tsx
@@ -0,0 +1,7 @@
+import { Path } from 'slate'
+
+export const input = [0, 1]
+export const test = path => {
+  return Path.hasPrevious(path)
+}
+export const output = true