From 98756f559191256497319c4a9bf017a5f51007b4 Mon Sep 17 00:00:00 2001
From: Flamme Shadow <FlammeShadow@outlook.com>
Date: Tue, 17 Dec 2024 22:15:21 +0800
Subject: [PATCH] impl Eq/Compare for ArrayView

---
 array/view_test.mbt   | 18 ++++++++++++++++++
 builtin/arrayview.mbt | 34 ++++++++++++++++++++++++++++++++++
 builtin/builtin.mbti  |  2 ++
 3 files changed, 54 insertions(+)

diff --git a/array/view_test.mbt b/array/view_test.mbt
index e71ecabf3..d5715c756 100644
--- a/array/view_test.mbt
+++ b/array/view_test.mbt
@@ -57,3 +57,21 @@ test "contains" {
   assert_true!(v.contains(4))
   assert_false!(v.contains(6))
 }
+
+test "op_equal" {
+  let v1 = [1, 2, 3][:]
+  let v2 = [1, 2, 3][:]
+  assert_true!(v1 == v2)
+  let v3 = [1, 2, 4, 6, 10][1:3]
+  let v4 = [0, 1, 2, 4, 6, 10, 12][2:4]
+  assert_true!(v3 == v4)
+  assert_false!(v1 == v3)
+}
+
+test "compare" {
+  assert_eq!([1, 2, 4][:].compare([1, 2, 3][:]), 1)
+  assert_eq!([-1, 2, 4][:].compare([1, 2, 4][:]), -1)
+  assert_eq!([1, 2, 3][:].compare([1, 2, 3][:]), 0)
+  assert_eq!([1, 2, 0][:].compare([1, 2][:]), 1)
+  assert_eq!([1, 2][:].compare([1, 2, 0][:]), -1)
+}
diff --git a/builtin/arrayview.mbt b/builtin/arrayview.mbt
index 1da101357..a4df2409b 100644
--- a/builtin/arrayview.mbt
+++ b/builtin/arrayview.mbt
@@ -260,3 +260,37 @@ pub fn filter[T](self : ArrayView[T], f : (T) -> Bool) -> Array[T] {
   }
   arr
 }
+
+///|
+pub impl[T : Eq] Eq for ArrayView[T] with op_equal(self, other) -> Bool {
+  if self.length() != other.length() {
+    return false
+  }
+  for i in 0..<self.length() {
+    if not(self[i] == other[i]) {
+      return false
+    }
+  } else {
+    true
+  }
+}
+
+///|
+pub impl[T : Compare] Compare for ArrayView[T] with compare(self, other) -> Int {
+  let len_self = self.length()
+  let len_other = other.length()
+  if len_self < len_other {
+    -1
+  } else if len_self > len_other {
+    1
+  } else {
+    for i in 0..<len_self {
+      let cmp = self[i].compare(other[i])
+      if cmp != 0 {
+        break cmp
+      }
+    } else {
+      0
+    }
+  }
+}
diff --git a/builtin/builtin.mbti b/builtin/builtin.mbti
index a70c66a7f..58befb92a 100644
--- a/builtin/builtin.mbti
+++ b/builtin/builtin.mbti
@@ -141,6 +141,8 @@ impl ArrayView {
   to_json[X : ToJson](Self[X]) -> Json
   to_string[X : Show](Self[X]) -> String
 }
+impl[T : Compare] Compare for ArrayView[T]
+impl[T : Eq] Eq for ArrayView[T]
 impl[X : Show] Show for ArrayView[X]
 
 type BigInt