Add upb_StringView_Compare function.

PiperOrigin-RevId: 703267593

upb/base/BUILD

@@ -39,6 +39,16 @@ cc_library(
     deps = ["//upb:port"],
 )
 
+cc_test(
+    name = "string_view_test",
+    srcs = ["string_view_test.cc"],
+    deps = [
+        ":base",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 filegroup(
     name = "source_files",
     srcs = glob(

upb/base/string_view.h

@@ -45,6 +45,16 @@ UPB_INLINE bool upb_StringView_IsEqual(upb_StringView a, upb_StringView b) {
   return (a.size == b.size) && (!a.size || !memcmp(a.data, b.data, a.size));
 }
 
+// Compares StringViews following strcmp rules.
+// Please note this comparison is neither unicode nor locale aware.
+UPB_INLINE int upb_StringView_Compare(upb_StringView a, upb_StringView b) {
+  int result = memcmp(a.data, b.data, UPB_MIN(a.size, b.size));
+  if (result == 0) {
+    return a.size - b.size;
+  }
+  return result;
+}
+
 // LINT.ThenChange(
 //  GoogleInternalName1,
 //  //depot/google3/third_party/upb/bits/golang/accessor.go:map_go_string,

upb/base/string_view_test.cc

@@ -0,0 +1,69 @@
+#include "upb/base/string_view.h"
+
+#include <string>
+
+#include <gtest/gtest.h>
+
+namespace {
+
+TEST(upb_StringView, Compare_Eq) {
+  std::string s1("12345");
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_EQ(upb_StringView_Compare(h1, h2), 0);
+}
+
+TEST(upb_StringView, Compare_Eq_Shorter) {
+  std::string s1("1234");  // s1 is shorter.
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_LT(upb_StringView_Compare(h1, h2), 0);
+}
+
+TEST(upb_StringView, Compare_Eq_Longer) {
+  std::string s1("123456");  // s1 is longer.
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_GT(upb_StringView_Compare(h1, h2), 0);
+}
+
+TEST(upb_StringView, Compare_Less) {
+  std::string s1("12245");  // 2 < 3
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_LT(upb_StringView_Compare(h1, h2), 0);
+}
+
+TEST(upb_StringView, Compare_Greater) {
+  std::string s1("12445");  // 4 > 3
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_GT(upb_StringView_Compare(h1, h2), 0);
+}
+
+TEST(upb_StringView, Compare_Greater_Shorter) {
+  std::string s1("1244");  // s1 is shorter but 4 > 3.
+  std::string s2("12345");
+
+  upb_StringView h1 = upb_StringView_FromDataAndSize(s1.data(), s1.size());
+  upb_StringView h2 = upb_StringView_FromDataAndSize(s2.data(), s2.size());
+
+  ASSERT_GT(upb_StringView_Compare(h1, h2), 0);
+}
+
+}  // namespace