OptimiserSettings: Add preset() and OptimisationPreset enum

libsolidity/interface/OptimiserSettings.h

@@ -23,12 +23,22 @@
 
 #pragma once
 
+#include <liblangutil/Exceptions.h>
+
 #include <cstddef>
 #include <string>
 
 namespace solidity::frontend
 {
 
+enum class OptimisationPreset
+{
+	None,
+	Minimal,
+	Standard,
+	Full,
+};
+
 struct OptimiserSettings
 {
 	static char constexpr DefaultYulOptimiserSteps[] =
@@ -84,6 +94,18 @@ struct OptimiserSettings
 		return standard();
 	}
 
+	static OptimiserSettings preset(OptimisationPreset _preset)
+	{
+		switch (_preset)
+		{
+			case OptimisationPreset::None: return none();
+			case OptimisationPreset::Minimal: return minimal();
+			case OptimisationPreset::Standard: return standard();
+			case OptimisationPreset::Full: return full();
+			default: solAssert(false, "");
+		}
+	}
+
 	bool operator==(OptimiserSettings const& _other) const
 	{
 		return