From 673c62414f4b4a5260507de954b8fc2853c6e4ee Mon Sep 17 00:00:00 2001
From: Rangi <sylvie.oukaour+rangi42@gmail.com>
Date: Wed, 27 May 2026 21:11:39 -0400
Subject: [PATCH] Use `std::string_view` keys for `UpperMap`

This avoids constructing temporary `std::string` objects on lookup
---
 include/helpers.hpp |  4 ++++
 include/util.hpp    | 12 +++++++-----
 src/link/main.cpp   | 20 +++++++++++++-------
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/include/helpers.hpp b/include/helpers.hpp
index c6180a00..8e7ff439 100644
--- a/include/helpers.hpp
+++ b/include/helpers.hpp
@@ -101,6 +101,10 @@ static inline int clz(unsigned int x) {
 #define RANGE(s)  std::begin(s), std::end(s)
 #define RRANGE(s) std::rbegin(s), std::rend(s)
 
+// Macros to print-format a `std::string_view` (like <inttype.h> macros)
+#define PRI_SV         ".*s"
+#define PRI_SV_ARG(sv) static_cast<int>((sv).length()), (sv).data()
+
 // MSVC does not inline `strlen()` or `.length()` of a constant string
 template<int SizeOfString>
     requires(SizeOfString > 0)
diff --git a/include/util.hpp b/include/util.hpp
index 4b06531f..f03bcbe5 100644
--- a/include/util.hpp
+++ b/include/util.hpp
@@ -8,7 +8,7 @@
 #include <optional>
 #include <stddef.h>
 #include <stdint.h>
-#include <string>
+#include <string_view>
 #include <unordered_map>
 
 #include "helpers.hpp"
@@ -76,23 +76,25 @@ std::optional<uint64_t> parseWholeNumber(char const *str, NumberBase base = BASE
 char const *printChar(int c);
 
 struct Uppercase {
+	using is_transparent = void;
+
 	// FNV-1a hash of an uppercased string
-	constexpr size_t operator()(std::string const &str) const {
+	constexpr size_t operator()(std::string_view str) const {
 		return std::accumulate(RANGE(str), size_t(0x811C9DC5), [](size_t hash, char c) {
 			return (hash ^ toUpper(c)) * 16777619;
 		});
 	}
 
 	// Compare two strings without case-sensitivity (by converting to uppercase)
-	constexpr bool operator()(std::string const &str1, std::string const &str2) const {
+	constexpr bool operator()(std::string_view str1, std::string_view str2) const {
 		return std::equal(RANGE(str1), RANGE(str2), [](char c1, char c2) {
 			return toUpper(c1) == toUpper(c2);
 		});
 	}
 };
 
-// An unordered map from case-insensitive `std::string` keys to `ItemT` items
+// An unordered map from case-insensitive `std::string_view` keys to `ItemT` items
 template<typename ItemT>
-using UpperMap = std::unordered_map<std::string, ItemT, Uppercase, Uppercase>;
+using UpperMap = std::unordered_map<std::string_view, ItemT, Uppercase, Uppercase>;
 
 #endif // RGBDS_UTIL_HPP
diff --git a/src/link/main.cpp b/src/link/main.cpp
index 3c19279f..f03232c5 100644
--- a/src/link/main.cpp
+++ b/src/link/main.cpp
@@ -176,6 +176,7 @@ static void parseScrambleSpec(char *spec) {
 			fatal("Unknown region name \"%s\" in spec for option '-S'", regionName);
 		}
 
+		uint16_t *scrambleLimit = search->second.first;
 		uint16_t limit = search->second.second;
 		if (regionSize) {
 			char const *ptr = regionSize + skipBlankSpace(regionSize);
@@ -183,24 +184,29 @@ static void parseScrambleSpec(char *spec) {
 				fatal("Invalid region size limit \"%s\" for option '-S'", regionSize);
 			} else if (*value > limit) {
 				fatal(
-				    "%s region size for option '-S' must be between 0 and %" PRIu16,
-				    search->first.c_str(),
+				    "%" PRI_SV " region size for option '-S' must be between 0 and %" PRIu16,
+				    PRI_SV_ARG(search->first),
 				    limit
 				);
 			} else {
 				limit = *value;
 			}
-		} else if (search->second.first != &options.scrambleWRAMX) {
+		} else if (scrambleLimit != &options.scrambleWRAMX) {
 			// Only WRAMX limit can be implied, since ROMX and SRAM size may vary.
-			fatal("Missing %s region size limit for option '-S'", search->first.c_str());
+			fatal(
+			    "Missing %" PRI_SV " region size limit for option '-S'", PRI_SV_ARG(search->first)
+			);
 		}
 
-		if (*search->second.first != limit && *search->second.first != 0) {
-			warnx("Overriding %s region size limit for option '-S'", search->first.c_str());
+		if (*scrambleLimit != limit && *search->second.first != 0) {
+			warnx(
+			    "Overriding %" PRI_SV " region size limit for option '-S'",
+			    PRI_SV_ARG(search->first)
+			);
 		}
 
 		// Update the scrambling region size limit.
-		*search->second.first = limit;
+		*scrambleLimit = limit;
 	}
 }