Version's compatibility with Slic3r extended with pre-release

compatibility check:
A release Slic3r is not compatible with alpha and beta configs,
a beta Slic3r is not compatible with alpha configs, but is compatible
with beta configs etc.

xs/src/slic3r/Config/Version.cpp

@@ -15,11 +15,131 @@ namespace Config {
 
 static boost::optional<Semver> s_current_slic3r_semver = Semver::parse(SLIC3R_VERSION);
 
+// Optimized lexicographic compare of two pre-release versions, ignoring the numeric suffix.
+static int compare_prerelease(const char *p1, const char *p2)
+{
+	for (;;) {
+		char c1 = *p1 ++;
+		char c2 = *p2 ++;
+		bool a1 = std::isalpha(c1) && c1 != 0;
+		bool a2 = std::isalpha(c2) && c2 != 0;
+		if (a1) {
+			if (a2) {
+				if (c1 != c2)
+					return (c1 < c2) ? -1 : 1;
+			} else
+				return 1;
+		} else {
+			if (a2)
+				return -1;
+			else
+				return 0;
+		}
+	}
+	// This shall never happen.
+	return 0;
+}
+
+bool Version::is_slic3r_supported(const Semver &slic3r_version) const
+{ 
+	if (! slic3r_version.in_range(min_slic3r_version, max_slic3r_version))
+		return false;
+	// Now verify, whether the configuration pre-release status is compatible with the Slic3r's pre-release status.
+	// Alpha Slic3r will happily load any configuration, while beta Slic3r will ignore alpha configurations etc.
+	const char *prerelease_slic3r = slic3r_version.prerelease();
+	const char *prerelease_config = this->config_version.prerelease();
+	if (prerelease_config == nullptr)
+		// Released config is always supported.
+		return true;
+	else if (prerelease_slic3r == nullptr)
+		// Released slic3r only supports released configs.
+		return false;
+	// Compare the pre-release status of Slic3r against the config.
+	// If the prerelease status of slic3r is lexicographically lower or equal 
+	// to the prerelease status of the config, accept it.
+	return compare_prerelease(prerelease_slic3r, prerelease_config) != 1;
+}
+
 bool Version::is_current_slic3r_supported() const
 {
 	return this->is_slic3r_supported(*s_current_slic3r_semver);
 }
 
+#if 0
+//TODO: This test should be moved to a unit test, once we have C++ unit tests in place.
+static int version_test()
+{
+	Version v;
+	v.config_version 	 = *Semver::parse("1.1.2");
+	v.min_slic3r_version = *Semver::parse("1.38.0");
+	v.max_slic3r_version = Semver::inf();
+	assert(v.is_slic3r_supported(*Semver::parse("1.38.0")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.38.0-alpha")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.37.0-alpha")));
+	// Test the prerelease status.
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	v.config_version 	 = *Semver::parse("1.1.2-alpha");
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	v.config_version 	 = *Semver::parse("1.1.2-alpha1");
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	v.config_version 	 = *Semver::parse("1.1.2-beta");
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-rc")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	v.config_version 	 = *Semver::parse("1.1.2-rc");
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-rc")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	v.config_version 	 = *Semver::parse("1.1.2-rc2");
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-alpha1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-beta1")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-rc")));
+	assert(v.is_slic3r_supported(*Semver::parse("1.39.0-rc2")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.39.0")));
+	// Test the upper boundary.
+	v.config_version 	 = *Semver::parse("1.1.2");
+	v.max_slic3r_version = *Semver::parse("1.39.3-beta1");
+	assert(v.is_slic3r_supported(*Semver::parse("1.38.0")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.38.0-alpha")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.38.0-alpha1")));
+	assert(! v.is_slic3r_supported(*Semver::parse("1.37.0-alpha")));
+	return 0;
+}
+static int version_test_run = version_test();
+#endif
+
 inline char* left_trim(char *c)
 {
 	for (; *c == ' ' || *c == '\t'; ++ c);

xs/src/slic3r/Config/Version.hpp

@@ -27,7 +27,7 @@ struct Version
 	// Single comment line.
 	std::string comment;
 
-	bool 		is_slic3r_supported(const Semver &slicer_version) const { return slicer_version.in_range(min_slic3r_version, max_slic3r_version); }
+	bool 		is_slic3r_supported(const Semver &slicer_version) const;
 	bool 		is_current_slic3r_supported() const;
 };
 

xs/src/slic3r/Utils/Semver.hpp

@@ -77,6 +77,13 @@ public:
 
 	~Semver() { ::semver_free(&ver); }
 
+	// const accessors
+	int 		major() 	 const { return ver.major; }
+	int 		minor() 	 const { return ver.minor; }
+	int 		patch() 	 const { return ver.patch; }
+	const char*	prerelease() const { return ver.prerelease; }
+	const char*	metadata() 	 const { return ver.metadata; }
+
 	// Comparison
 	bool operator<(const Semver &b)  const { return ::semver_compare(ver, b.ver) == -1; }
 	bool operator<=(const Semver &b) const { return ::semver_compare(ver, b.ver) <= 0; }