From 73f829d3051f5c6c02ce629991f1757d1586bf74 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 25 Nov 2013 17:21:46 +0200
Subject: [PATCH] Refactor version number extraction and checks

---
 source/extension.cpp | 48 ++++++++++++++++++++++++++++++--------------
 source/extension.h   |  6 ++++++
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/source/extension.cpp b/source/extension.cpp
index 56f96d4e..41b06b21 100644
--- a/source/extension.cpp
+++ b/source/extension.cpp
@@ -14,6 +14,31 @@ using namespace std;
 namespace Msp {
 namespace GL {
 
+Version::Version()
+{
+	major = 0;
+	minor = 0;
+}
+
+Version::Version(unsigned short a, unsigned short i)
+{
+	major = a;
+	minor = i;
+}
+
+Version::Version(const string &s)
+{
+	vector<string> parts = split(s, '.');
+	major = lexical_cast<unsigned>(parts[0]);
+	minor = lexical_cast<unsigned>(parts[1]);
+}
+
+bool Version::operator>=(const Version &other) const
+{
+	return major>other.major || (major==other.major && minor>=other.minor);
+}
+
+
 Extension::Extension(const char *n, InitFunc f):
 	name(n),
 	init_func(f),
@@ -66,28 +91,21 @@ bool is_supported(const string &ext)
 	return extensions.count(ext);
 }
 
-const Version &get_gl_version()
+inline Version _get_gl_version()
 {
-	static Version version;
-	static bool init_done = false;
-
-	if(!init_done)
-	{
-		string gl_ver = reinterpret_cast<const char *>(glGetString(GL_VERSION));
-		vector<string> parts = split(gl_ver.substr(0, gl_ver.find(' ')), '.');
-		version.major = lexical_cast<unsigned>(parts[0]);
-		version.minor = lexical_cast<unsigned>(parts[1]);
-
-		init_done = true;
-	}
+	string gl_ver = reinterpret_cast<const char *>(glGetString(GL_VERSION));
+	return Version(gl_ver.substr(0, gl_ver.find(' ')));
+}
 
+const Version &get_gl_version()
+{
+	static Version version = _get_gl_version();
 	return version;
 }
 
 bool is_version_at_least(unsigned a, unsigned b)
 {
-	const Version &ver = get_gl_version();
-	return (ver.major>a || (ver.major==a && ver.minor>=b));
+	return get_gl_version()>=Version(a, b);
 }
 
 ExtFunc *get_proc_address(const string &name)
diff --git a/source/extension.h b/source/extension.h
index e6c2aca0..df6bd78d 100644
--- a/source/extension.h
+++ b/source/extension.h
@@ -10,6 +10,12 @@ struct Version
 {
 	unsigned short major;
 	unsigned short minor;
+
+	Version();
+	Version(unsigned short, unsigned short);
+	Version(const std::string &);
+
+	bool operator>=(const Version &) const;
 };
 
 
-- 
2.45.2