Overload base::GUID comparison operators

operator<() needs to be overloaded so base::GUID can be used in set
containers.

Per the style guide, overload all other comparison operators.

Bug: 1026195
Change-Id: I9c36f0aee13b34c3bbdfdc3581a84a9c23485e21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533649
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827413}

base/guid.cc

@@ -153,6 +153,22 @@ bool GUID::operator!=(const GUID& other) const {
   return !(*this == other);
 }
 
+bool GUID::operator<(const GUID& other) const {
+  return AsLowercaseString() < other.AsLowercaseString();
+}
+
+bool GUID::operator<=(const GUID& other) const {
+  return *this < other || *this == other;
+}
+
+bool GUID::operator>(const GUID& other) const {
+  return !(*this <= other);
+}
+
+bool GUID::operator>=(const GUID& other) const {
+  return !(*this < other);
+}
+
 std::ostream& operator<<(std::ostream& out, const GUID& guid) {
   return out << guid.AsLowercaseString();
 }

base/guid.h

@@ -72,6 +72,10 @@ class BASE_EXPORT GUID {
   // Invalid GUIDs are equal.
   bool operator==(const GUID& other) const;
   bool operator!=(const GUID& other) const;
+  bool operator<(const GUID& other) const;
+  bool operator<=(const GUID& other) const;
+  bool operator>(const GUID& other) const;
+  bool operator>=(const GUID& other) const;
 
  private:
   // TODO(crbug.com/1026195): Consider using a different internal type.

base/guid_unittest.cc

@@ -7,6 +7,7 @@
 #include <stdint.h>
 
 #include <limits>
+#include <set>
 #include <unordered_set>
 
 #include "base/strings/string_util.h"
@@ -164,4 +165,67 @@ TEST(GUIDTest, UnorderedSet) {
   EXPECT_EQ(2u, guid_set.size());
 }
 
+TEST(GUIDTest, Set) {
+  std::set<GUID> guid_set;
+
+  static constexpr char kGUID1[] = "01234567-89ab-cdef-0123-456789abcdef";
+  const GUID guid1 = GUID::ParseLowercase(kGUID1);
+  ASSERT_TRUE(guid1.is_valid());
+  guid_set.insert(guid1);
+
+  static constexpr char kGUID2[] = "deadbeef-dead-beef-dead-beefdeadbeef";
+  const GUID guid2 = GUID::ParseLowercase(kGUID2);
+  ASSERT_TRUE(guid2.is_valid());
+  guid_set.insert(guid2);
+
+  // Test that the order of the GUIDs was preserved.
+  auto it = guid_set.begin();
+  EXPECT_EQ(guid1, *it);
+  ++it;
+  EXPECT_EQ(guid2, *it);
+  ++it;
+  EXPECT_EQ(guid_set.end(), it);
+}
+
+TEST(GUIDTest, Compare) {
+  static constexpr char kGUID[] = "21abd97f-73e8-4b88-9389-a9fee6abda5e";
+  static constexpr char kGUIDLess[] = "1e0dcaca-9e7c-4f4b-bcc6-e4c02b0c99df";
+  static constexpr char kGUIDGreater[] = "6eeb1bc8-186b-433c-9d6a-a827bc96b2d4";
+
+  const GUID guid = GUID::ParseLowercase(kGUID);
+  const GUID guid_eq = GUID::ParseLowercase(kGUID);
+  const GUID guid_lt = GUID::ParseLowercase(kGUIDLess);
+  const GUID guid_gt = GUID::ParseLowercase(kGUIDGreater);
+  const GUID guid_invalid = GUID();
+
+  EXPECT_TRUE(guid_eq == guid);
+  EXPECT_FALSE(guid_eq != guid);
+  EXPECT_FALSE(guid_eq < guid);
+  EXPECT_TRUE(guid_eq <= guid);
+  EXPECT_FALSE(guid_eq > guid);
+  EXPECT_TRUE(guid_eq >= guid);
+
+  EXPECT_FALSE(guid_lt == guid);
+  EXPECT_TRUE(guid_lt != guid);
+  EXPECT_TRUE(guid_lt < guid);
+  EXPECT_TRUE(guid_lt <= guid);
+  EXPECT_FALSE(guid_lt > guid);
+  EXPECT_FALSE(guid_lt >= guid);
+
+  EXPECT_FALSE(guid_gt == guid);
+  EXPECT_TRUE(guid_gt != guid);
+  EXPECT_FALSE(guid_gt < guid);
+  EXPECT_FALSE(guid_gt <= guid);
+  EXPECT_TRUE(guid_gt > guid);
+  EXPECT_TRUE(guid_gt >= guid);
+
+  // Invalid GUIDs are the "least".
+  EXPECT_FALSE(guid_invalid == guid);
+  EXPECT_TRUE(guid_invalid != guid);
+  EXPECT_TRUE(guid_invalid < guid);
+  EXPECT_TRUE(guid_invalid <= guid);
+  EXPECT_FALSE(guid_invalid > guid);
+  EXPECT_FALSE(guid_invalid >= guid);
+}
+
 }  // namespace base