From 7c50da5385cb9e67e9be37544caa1649fd466dae Mon Sep 17 00:00:00 2001
From: Hannes Harnisch <hannes.harnisch@gmx.net>
Date: Thu, 19 Dec 2024 04:54:35 +0100
Subject: [PATCH] Allow getting size of dynamic format arg store (#4270)

---
 include/fmt/args.h |  3 +++
 test/args-test.cc  | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/fmt/args.h b/include/fmt/args.h
index 6ed30c0bd5c0..3ff47880748f 100644
--- a/include/fmt/args.h
+++ b/include/fmt/args.h
@@ -210,6 +210,9 @@ template <typename Context> class dynamic_format_arg_store {
     data_.reserve(new_cap);
     named_info_.reserve(new_cap_named);
   }
+
+  /// Returns the number of elements in the store.
+  size_t size() const noexcept { return data_.size(); }
 };
 
 FMT_END_NAMESPACE
diff --git a/test/args-test.cc b/test/args-test.cc
index f99ff74ed192..e3efa244bfb7 100644
--- a/test/args-test.cc
+++ b/test/args-test.cc
@@ -186,3 +186,17 @@ TEST(args_test, move_constructor) {
   store.reset();
   EXPECT_EQ(fmt::vformat("{} {} {a1}", moved_store), "42 foo foo");
 }
+
+TEST(args_test, size) {
+  fmt::dynamic_format_arg_store<fmt::format_context> store;
+  EXPECT_EQ(store.size(), 0);
+
+  store.push_back(42);
+  EXPECT_EQ(store.size(), 1);
+
+  store.push_back("Molybdenum");
+  EXPECT_EQ(store.size(), 2);
+
+  store.clear();
+  EXPECT_EQ(store.size(), 0);
+}