From 56fef50c0a7c0e3a604b8a9b68017ed265b9fa88 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 5 Aug 2023 15:23:10 +0100
Subject: Use faster std::from_chars over boost::lexical_cast for XML numeric
 parse

---
 slicer/xml/serializer.cpp    | 31 +++++++++++++++++++++++++------
 slicer/xml/testSpecifics.cpp |  6 +++---
 slicer/xml/xmlExceptions.ice |  4 ++++
 3 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/slicer/xml/serializer.cpp b/slicer/xml/serializer.cpp
index 27bf10b..56cdbaa 100644
--- a/slicer/xml/serializer.cpp
+++ b/slicer/xml/serializer.cpp
@@ -1,5 +1,6 @@
 #include "serializer.h"
 #include <boost/lexical_cast.hpp>
+#include <charconv>
 #include <compileTimeFormatter.h>
 #include <functional>
 #pragma GCC diagnostic push
@@ -73,37 +74,37 @@ namespace Slicer {
 		void
 		set(Ice::Byte & v) const override
 		{
-			v = boost::numeric_cast<Ice::Byte>(boost::lexical_cast<int>(value));
+			from_chars(v);
 		}
 
 		void
 		set(Ice::Short & v) const override
 		{
-			v = boost::lexical_cast<Ice::Short>(value);
+			from_chars(v);
 		}
 
 		void
 		set(Ice::Int & v) const override
 		{
-			v = boost::lexical_cast<Ice::Int>(value);
+			from_chars(v);
 		}
 
 		void
 		set(Ice::Long & v) const override
 		{
-			v = boost::lexical_cast<Ice::Long>(value);
+			from_chars(v);
 		}
 
 		void
 		set(Ice::Float & v) const override
 		{
-			v = boost::lexical_cast<Ice::Float>(value);
+			from_chars(v);
 		}
 
 		void
 		set(Ice::Double & v) const override
 		{
-			v = boost::lexical_cast<Ice::Double>(value);
+			from_chars(v);
 		}
 
 		void
@@ -113,6 +114,16 @@ namespace Slicer {
 		}
 
 	private:
+		template<typename T>
+		void
+		from_chars(T & v) const
+		{
+			std::string_view raw {value.raw()};
+			if (std::from_chars(raw.begin(), raw.end(), v).ec != std::errc {}) {
+				throw BadNumericValue(value);
+			}
+		}
+
 		const Glib::ustring value;
 	};
 
@@ -489,4 +500,12 @@ namespace Slicer {
 	{
 		BadBooleanValueMsg::write(s, text);
 	}
+
+	AdHocFormatter(BadNumericValueMsg, "Bad numeric value [%?]");
+
+	void
+	BadNumericValue::ice_print(std::ostream & s) const
+	{
+		BadNumericValueMsg::write(s, text);
+	}
 }
diff --git a/slicer/xml/testSpecifics.cpp b/slicer/xml/testSpecifics.cpp
index ec9fe11..24edf78 100644
--- a/slicer/xml/testSpecifics.cpp
+++ b/slicer/xml/testSpecifics.cpp
@@ -54,11 +54,11 @@ BOOST_AUTO_TEST_CASE(int_values)
 	doc.parse_memory("<Int>-4</Int>");
 	BOOST_REQUIRE_EQUAL(-4, BoostThrowWrapperHelper<Ice::Int>(doc.get_document()));
 	doc.parse_memory("<Int> </Int>");
-	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), std::bad_cast);
+	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), Slicer::BadNumericValue);
 	doc.parse_memory("<Int>notanint</Int>");
-	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), std::bad_cast);
+	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), Slicer::BadNumericValue);
 	doc.parse_memory("<Int></Int>");
-	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), std::bad_cast);
+	BOOST_REQUIRE_THROW(BoostThrowWrapperHelper<Ice::Int>(doc.get_document()), Slicer::BadNumericValue);
 }
 
 BOOST_AUTO_TEST_CASE(factories)
diff --git a/slicer/xml/xmlExceptions.ice b/slicer/xml/xmlExceptions.ice
index 390f458..26d8aa2 100644
--- a/slicer/xml/xmlExceptions.ice
+++ b/slicer/xml/xmlExceptions.ice
@@ -8,6 +8,10 @@ module Slicer {
 	exception BadBooleanValue extends DeserializerError {
 		string text;
 	};
+	["cpp:ice_print"]
+	exception BadNumericValue extends DeserializerError {
+		string text;
+	};
 };
 
 #endif
-- 
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