From 353eeb16e99044dd8b3e875b5f861067f60a3f87 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 12 Dec 2016 22:08:13 +0000
Subject: Load stylesheets as needed and reload them on change

---
 icespider/xslt/Jamfile.jam              |  2 ++
 icespider/xslt/xsltStreamSerializer.cpp | 19 +++++++++++++++----
 icespider/xslt/xsltStreamSerializer.h   |  6 +++++-
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/icespider/xslt/Jamfile.jam b/icespider/xslt/Jamfile.jam
index 1bf62a8..97408be 100644
--- a/icespider/xslt/Jamfile.jam
+++ b/icespider/xslt/Jamfile.jam
@@ -1,6 +1,7 @@
 lib adhocutil : : : : <include>/usr/include/adhocutil ;
 lib slicer-xml : : : : <include>/usr/include/slicer ;
 lib boost_system ;
+lib boost_filesystem ;
 lib IceUtil ;
 lib xslt ;
 lib exslt ;
@@ -11,6 +12,7 @@ lib icespider-xslt :
 	<library>adhocutil
 	<library>slicer-xml
 	<library>boost_system
+	<library>boost_filesystem
 	<library>IceUtil
 	<library>xslt
 	<library>exslt
diff --git a/icespider/xslt/xsltStreamSerializer.cpp b/icespider/xslt/xsltStreamSerializer.cpp
index 3e27fc3..d89adcd 100644
--- a/icespider/xslt/xsltStreamSerializer.cpp
+++ b/icespider/xslt/xsltStreamSerializer.cpp
@@ -2,6 +2,7 @@
 #include <libxslt/xsltInternals.h>
 #include <libxml/HTMLtree.h>
 #include <factory.impl.h>
+#include <boost/filesystem/convenience.hpp>
 
 namespace IceSpider {
 	static int xmlstrmclosecallback(void * context)
@@ -17,11 +18,10 @@ namespace IceSpider {
 	}
 
 	XsltStreamSerializer::IceSpiderFactory::IceSpiderFactory(const char * path) :
-		stylesheet(xsltParseStylesheetFile(BAD_CAST path))
+		stylesheetPath(path),
+		stylesheetWriteTime(0),
+		stylesheet(nullptr)
 	{
-		if (!stylesheet) {
-			throw xmlpp::exception("Failed to load stylesheet");
-		}
 	}
 
 	XsltStreamSerializer::IceSpiderFactory::~IceSpiderFactory()
@@ -32,6 +32,17 @@ namespace IceSpider {
 	XsltStreamSerializer *
 	XsltStreamSerializer::IceSpiderFactory::create(std::ostream & strm) const
 	{
+		auto newMtime = boost::filesystem::last_write_time(stylesheetPath);
+		if (newMtime != stylesheetWriteTime) {
+			if (stylesheet) {
+				xsltFreeStylesheet(stylesheet);
+			}
+			stylesheet = xsltParseStylesheetFile(BAD_CAST stylesheetPath.c_str());
+			if (!stylesheet) {
+				throw xmlpp::exception("Failed to load stylesheet");
+			}
+			stylesheetWriteTime = newMtime;
+		}
 		return new XsltStreamSerializer(strm, stylesheet);
 	}
 
diff --git a/icespider/xslt/xsltStreamSerializer.h b/icespider/xslt/xsltStreamSerializer.h
index b9b9372..b061012 100644
--- a/icespider/xslt/xsltStreamSerializer.h
+++ b/icespider/xslt/xsltStreamSerializer.h
@@ -4,6 +4,7 @@
 #include <slicer/xml/serializer.h>
 #include <visibility.h>
 #include <libxslt/transform.h>
+#include <boost/filesystem/path.hpp>
 
 namespace IceSpider {
 	class DLL_PUBLIC XsltStreamSerializer : public Slicer::XmlDocumentSerializer {
@@ -15,7 +16,10 @@ namespace IceSpider {
 
 					XsltStreamSerializer * create(std::ostream &) const override;
 
-					xsltStylesheet * stylesheet;
+				private:
+					const boost::filesystem::path stylesheetPath;
+					mutable std::time_t stylesheetWriteTime;
+					mutable xsltStylesheet * stylesheet;
 			};
 
 			XsltStreamSerializer(std::ostream &, xsltStylesheet *);
-- 
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