From dc2f7a9a0c4dc6c193ec817ea0d294254ffb30b0 Mon Sep 17 00:00:00 2001
From: Edward Chen <18449977+edgchen1@users.noreply.github.com>
Date: Thu, 30 Jan 2025 13:55:54 -0800
Subject: [PATCH] Add overload of `TryParseStringWithClassicLocale()` that uses
 `std::from_chars()` (#23541)

Add overload of `TryParseStringWithClassicLocale()` that uses `std::from_chars()` for certain types.

Reduce binary size. It recently increased after PR #23526.
---
 .../onnxruntime/core/common/parse_string.h    | 40 ++++++++++++++++---
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/include/onnxruntime/core/common/parse_string.h b/include/onnxruntime/core/common/parse_string.h
index 941e3f3377..6345b2a554 100644
--- a/include/onnxruntime/core/common/parse_string.h
+++ b/include/onnxruntime/core/common/parse_string.h
@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <charconv>
 #include <locale>
 #include <sstream>
 #include <string_view>
@@ -12,18 +13,45 @@
 
 namespace onnxruntime {
 
+namespace detail {
+
+// Whether we will use std::from_chars() to parse to `T`.
+#if defined(_LIBCPP_VERSION)
+// Note: Currently (e.g., in LLVM 19), libc++'s std::from_chars() doesn't support floating point types yet.
+template <typename T>
+constexpr bool ParseWithFromChars = !std::is_same_v<bool, T> && std::is_integral_v<T>;
+#else
+template <typename T>
+constexpr bool ParseWithFromChars = !std::is_same_v<bool, T> && (std::is_integral_v<T> || std::is_floating_point_v<T>);
+#endif
+
+}  // namespace detail
+
 /**
  * Tries to parse a value from an entire string.
+ * If successful, sets `value` and returns true. Otherwise, does not modify `value` and returns false.
  */
 template <typename T>
-bool TryParseStringWithClassicLocale(std::string_view str, T& value) {
-  if constexpr (std::is_integral<T>::value && std::is_unsigned<T>::value) {
-    // if T is unsigned integral type, reject negative values which will wrap
-    if (!str.empty() && str[0] == '-') {
-      return false;
-    }
+std::enable_if_t<detail::ParseWithFromChars<T>, bool>
+TryParseStringWithClassicLocale(std::string_view str, T& value) {
+  T parsed_value{};
+  const auto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(), parsed_value);
+
+  if (ec != std::errc{}) {
+    return false;
   }
 
+  if (ptr != str.data() + str.size()) {
+    return false;
+  }
+
+  value = parsed_value;
+  return true;
+}
+
+template <typename T>
+std::enable_if_t<!detail::ParseWithFromChars<T>, bool>
+TryParseStringWithClassicLocale(std::string_view str, T& value) {
   // don't allow leading whitespace
   if (!str.empty() && std::isspace(str[0], std::locale::classic())) {
     return false;