Optimize conversion of MouseAction enum from/to string, remove allocations

[h3xds1nz]

Description

Parsing optimization for MouseAction and its conversion from/to string. Allocation-free.

• Removes trimming on string, now trims on the span, resulting in no allocations.
• Removes conversion ToUpperInvariant and uses StringComparison.OrdinalIgnoreCase instead.
• This will allow for string interning between Convert/ConvertFrom and other literals, saving static memory.
• The JITTed codegen takes up less memory as we removed few things.
• Adds/completes code documentation for the whole class.

Last value in the enumeration

Method	source	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size	Allocated
Original	MiddleDoubleClick	19.632 ns	0.2160 ns	0.2020 ns	0.0033	1,270 B	56 B
PR__EDIT	MiddleDoubleClick	2.776 ns	0.0166 ns	0.0155 ns	-	988 B	-

Last value in the enumeration with space (trimmed)

Method	source	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size	Allocated
Original	MiddleDoubleClick\x20	28.230 ns	0.5535 ns	0.5177 ns	0.0067	2,176 B	112 B
PR__EDIT	MiddleDoubleClick\x20	5.659 ns	0.0315 ns	0.0280 ns	-	1,448 B	-

Customer Impact

Increased performance, zero allocations, less static memory.

Regression

No.

Testing

Local build, CI, assert test:

//Special case
string emptyToNone = string.Empty;
MouseAction constantName = MouseAction.None;

MouseAction lowerCase = (MouseAction)ConvertFrom(null, null, emptyToNone.ToLowerInvariant());
MouseAction upperCase = (MouseAction)ConvertFrom(null, null, emptyToNone.ToUpperInvariant());
MouseAction normalColor = (MouseAction)ConvertFrom(null, null, emptyToNone);

Assert.AreEqual<MouseAction>(constantName, lowerCase);
Assert.AreEqual<MouseAction>(constantName, upperCase);
Assert.AreEqual<MouseAction>(constantName, normalColor);

foreach (string action in Enum.GetNames<MouseAction>())
{
     constantName = Enum.Parse<MouseAction>(action);

     lowerCase = (MouseAction)ConvertFrom(null, null, action.ToLowerInvariant());
     upperCase = (MouseAction)ConvertFrom(null, null, action.ToUpperInvariant());
     normalColor = (MouseAction)ConvertFrom(null, null, action);

    Assert.AreEqual<MouseAction>(constantName, lowerCase);
    Assert.AreEqual<MouseAction>(constantName, upperCase);
    Assert.AreEqual<MouseAction>(constantName, normalColor);

    //Back to the original values
    string result = (string)ConvertTo(null, null, constantName, typeof(string));
    result = result == string.Empty ? "None" : result; //Special case
    Assert.AreEqual(action, result);
}

Risk

Low.

Microsoft Reviewers: Open in CodeFlow

[harshit7962]

@h3xds1nz Thank you for contributing.

[h3xds1nz]

@harshit7962 Happy to see this one get in, thank you :)