From 18be33a18c5021dbe1630234d391d3200dc3c758 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Wed, 30 Dec 2020 18:12:43 +0300
Subject: [PATCH] Add td::unique helper method.

---
 tdutils/td/utils/misc.h | 20 ++++++++++++++++++++
 tdutils/test/misc.cpp   | 20 ++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/tdutils/td/utils/misc.h b/tdutils/td/utils/misc.h
index 323d33626..0e3e64946 100644
--- a/tdutils/td/utils/misc.h
+++ b/tdutils/td/utils/misc.h
@@ -124,6 +124,26 @@ bool remove(V &v, const T &value) {
   return true;
 }
 
+template <class V>
+void unique(V &v) {
+  if (v.empty()) {
+    return;
+  }
+
+  std::sort(v.begin(), v.end());  // caller will need to #include <algorithm>
+
+  size_t j = 1;
+  for (size_t i = 1; i < v.size(); i++) {
+    if (v[i] != v[i - 1]) {
+      if (i != j) {
+        v[j] = std::move(v[i]);
+      }
+      j++;
+    }
+  }
+  v.resize(j);
+}
+
 template <class V, class T>
 bool contains(const V &v, const T &value) {
   for (auto &x : v) {
diff --git a/tdutils/test/misc.cpp b/tdutils/test/misc.cpp
index 8f5e7a385..afdf3e3ab 100644
--- a/tdutils/test/misc.cpp
+++ b/tdutils/test/misc.cpp
@@ -38,6 +38,7 @@
 #include "td/utils/unicode.h"
 #include "td/utils/utf8.h"
 
+#include <algorithm>
 #include <atomic>
 #include <clocale>
 #include <limits>
@@ -346,6 +347,25 @@ TEST(Misc, remove) {
   test_remove(v, 1, v);
 }
 
+static void test_unique(td::vector<int> v, td::vector<int> expected) {
+  td::unique(v);
+  ASSERT_EQ(expected, v);
+}
+
+TEST(Misc, unique) {
+  test_unique({1, 2, 3, 4, 5, 6}, {1, 2, 3, 4, 5, 6});
+  test_unique({5, 2, 1, 6, 3, 4}, {1, 2, 3, 4, 5, 6});
+  test_unique({}, {});
+  test_unique({0}, {0});
+  test_unique({0, 0}, {0});
+  test_unique({0, 1}, {0, 1});
+  test_unique({1, 0}, {0, 1});
+  test_unique({1, 1}, {1});
+  test_unique({3, 3, 3, 3, 3, 2, 2, 2, 1, 1, 0}, {0, 1, 2, 3});
+  test_unique({3, 3, 3, 3, 3}, {3});
+  test_unique({3, 3, -1, 3, 3}, {-1, 3});
+}
+
 TEST(Misc, contains) {
   td::vector<int> v{1, 3, 5, 7, 4, 2};
   for (int i = -10; i < 20; i++) {