From 7dcad74d144879f4cce790067de1c164df9bd697 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 29 Jul 2023 20:21:00 +0100
Subject: Simplified convert interface

Removes need to scope temps, boost lexical_cast catch/throw, two functions
---
 icespider/core/util.h                 | 70 +++++++++++++----------------------
 icespider/core/xwwwFormUrlEncoded.cpp |  2 +-
 2 files changed, 27 insertions(+), 45 deletions(-)

diff --git a/icespider/core/util.h b/icespider/core/util.h
index d31c7da..f4868c3 100644
--- a/icespider/core/util.h
+++ b/icespider/core/util.h
@@ -121,61 +121,43 @@ private:
 namespace IceSpider {
 	[[noreturn]] DLL_PUBLIC void conversion_failure();
 
-	static_assert(std::is_constructible_v<std::string, std::string_view>);
-	static_assert(std::is_convertible_v<std::string_view, std::string_view>);
-
-	template<typename T>
-	inline T
-	from_chars(const std::string_view v, T && out)
-	{
-		if (std::from_chars(v.begin(), v.end(), out).ec != std::errc {}) {
-			conversion_failure();
-		}
-		return out;
-	}
-
-	template<typename T>
-	inline T
-	lexical_cast(const std::string_view v)
-	{
-		try {
-			return boost::lexical_cast<T>(v);
-		}
-		catch (const boost::bad_lexical_cast & e) {
-			conversion_failure();
+	static_assert(std::is_assignable_v<std::string, std::string_view>);
+	static_assert(std::is_assignable_v<std::string_view, std::string_view>);
+
+	namespace {
+		template<typename T>
+		inline T
+		from_chars(const std::string_view v, T && out)
+		{
+			if (std::from_chars(v.begin(), v.end(), out).ec != std::errc {}) {
+				conversion_failure();
+			}
+			return out;
 		}
-	}
 
-	template<typename T>
-	inline void
-	convert(const std::string_view v, T & out)
-	{
-		if constexpr (std::is_assignable_v<std::string_view, T>) {
-			out = v;
-		}
-		if constexpr (requires { std::from_chars(v.begin(), v.end(), out); }) {
-			from_chars(v, out);
-		}
-		else {
-			out = lexical_cast<T>(v);
+		template<typename T>
+		inline T
+		lexical_cast(const std::string_view v, T && out)
+		{
+			if (!boost::conversion::try_lexical_convert(v, out)) {
+				conversion_failure();
+			}
+			return out;
 		}
 	}
 
 	template<typename T>
 	inline T
-	convert(const std::string_view v)
+	convert(const std::string_view v, T && out = {})
 	{
-		if constexpr (std::is_convertible_v<std::string_view, T>) {
-			return v;
-		}
-		else if constexpr (std::is_constructible_v<T, std::string_view>) {
-			return T {v};
+		if constexpr (std::is_assignable_v<T, std::string_view>) {
+			return (out = v);
 		}
-		else if constexpr (requires(T out) { std::from_chars(v.begin(), v.end(), out); }) {
-			return from_chars<T>(v, {});
+		else if constexpr (requires { std::from_chars(v.begin(), v.end(), out); }) {
+			return from_chars(v, out);
 		}
 		else {
-			return lexical_cast<T>(v);
+			return lexical_cast(v, out);
 		}
 	}
 
diff --git a/icespider/core/xwwwFormUrlEncoded.cpp b/icespider/core/xwwwFormUrlEncoded.cpp
index 639b07a..d5b8388 100644
--- a/icespider/core/xwwwFormUrlEncoded.cpp
+++ b/icespider/core/xwwwFormUrlEncoded.cpp
@@ -181,7 +181,7 @@ namespace IceSpider {
 	/* NOLINTNEXTLINE(bugprone-macro-parentheses) */ \
 	void set(T & t) const override \
 	{ \
-		convert<T>(s, t); \
+		convert(s, t); \
 	}
 
 		SET(Ice::Byte);
-- 
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