Optimize parsing/conversion of TextDecorations from string, reduce allocations

[h3xds1nz]

Description

Optimize parsing of TextDecorations from string into TextDecorationCollection, reduces allocations in all steps and improves performance, also reduces the memory footprint + readibility of the entire class by a large amount.

• Removes static array TextDecorationNames, that also removes the strings allocations on its own (not used anywhere else).
• Removes static array PredefinedTextDecorations, which was redundant from the start.
• And removes another 120 lines trying to avoid allocations in NetFX by using few newer BCL features.
• The static collections are frozen after creation, so are its items, so we can just grab it via indexer.

ConvertFromString benchmarks

Method	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size [B]	Allocated [B]
Original	252.0 ns	1.16 ns	1.08 ns	0.0234	1,243 B	392 B
PR__EDIT	119.0 ns	0.41 ns	0.38 ns	0.0091	3,335 B	152 B

ConvertFromString("  Strikethrough   ,Underline, Baseline        , Overline             ");

Method	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size [B]	Allocated [B]
Original	56.77 ns	0.544 ns	0.509 ns	0.0091	1,141 B	152 B
PR__EDIT	36.73 ns	0.414 ns	0.388 ns	0.0067	2,659 B	112 B

ConvertFromString("Strikethrough");

Method	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size [B]	Allocated [B]
Original	20.19 ns	0.318 ns	0.298 ns	0.0048	1,119 B	80 B
PR__EDIT	15.81 ns	0.265 ns	0.247 ns	0.0048	1,730 B	80 B

ConvertFromString("None");

Customer Impact

Improved performance, decreased allocations.

Regression

No.

Testing

Local build, CI, extensive assert testing:

private static void CheckEqual(TextDecorationCollection collection1, TextDecorationCollection collection2, int expectedCount)
{
    //Check count
    Assert.AreEqual(expectedCount, collection1.Count);
    Assert.AreEqual(collection1.Count, collection2.Count);

    for (int i = 0; i < collection1.Count; i++)
    {
        Assert.AreEqual(collection1[i], collection2[i]);
    }
}

// Valid cases
// "None" returns no items
CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString(string.Empty),
              TextDecorationCollectionConverter.ConvertFromString(string.Empty), 0);
CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("          "),
              TextDecorationCollectionConverter.ConvertFromString("          "), 0);
CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("None"),
              TextDecorationCollectionConverter.ConvertFromString("None"), 0);
CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("    None    "),
              TextDecorationCollectionConverter.ConvertFromString("    None    "), 0);

CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("Strikethrough"),
              TextDecorationCollectionConverter.ConvertFromString("Strikethrough"), 1);

CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("Strikethrough       "),
              TextDecorationCollectionConverter.ConvertFromString("Strikethrough       "), 1);

CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("Underline, Baseline "),
              TextDecorationCollectionConverter.ConvertFromString("Underline, Baseline "), 2);

CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("  Strikethrough   ,Underline, Baseline "),
              TextDecorationCollectionConverter.ConvertFromString("  Strikethrough   ,Underline, Baseline "), 3);

CheckEqual(TextDecorationCollectionConverterNEW.ConvertFromString("  Strikethrough   ,Underline, Baseline        , Overline             "),
              TextDecorationCollectionConverter.ConvertFromString("  Strikethrough   ,Underline, Baseline        , Overline             "), 4);

// Special case

Assert.AreEqual(TextDecorationCollectionConverterNEW.ConvertFromString(null), TextDecorationCollectionConverter.ConvertFromString(null));

// Exception cases
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString(",  Strikethrough   ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString("  Strikethrough  , Strikethrough, ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString("None,  Strikethrough   ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString("None,  Strikethrough   ,Underline, Baseline, Overline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString(" Strikethrough   ,Underline, Baseline, Overline, x "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString(" Strikethrough   ,Underline, Baseline, Overline, "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString(" Underline, Underline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverterNEW.ConvertFromString(" Noneee "));

Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString(",  Strikethrough   ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString("  Strikethrough  , Strikethrough, ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString("None,  Strikethrough   ,Underline, Baseline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString("None,  Strikethrough   ,Underline, Baseline, Overline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString(" Strikethrough   ,Underline, Baseline, Overline, x "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString(" Strikethrough   ,Underline, Baseline, Overline, "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString(" Underline, Underline "));
Assert.ThrowsException<ArgumentException>(() => TextDecorationCollectionConverter.ConvertFromString(" Noneee "));

Risk

Should be safe, I believe I've tested thoroughly all cases and we shall have no surprises.

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 97.43590% with 1 line in your changes missing coverage. Please review.

Project coverage is 11.21368%. Comparing base (6514196) to head (7b630e3).
Report is 122 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main       #9778         +/-   ##
===================================================
- Coverage   11.22814%   11.21368%   -0.01446%     
===================================================
  Files           3352        3352                 
  Lines         668000      667934         -66     
  Branches       74980       74971          -9     
===================================================
- Hits           75004       74900        -104     
- Misses        591745      591871        +126     
+ Partials        1251        1163         -88     

Flag	Coverage Δ
Debug	11.21368% <97.43590%> (-0.01446%)	⬇️

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[h3xds1nz]

@dipeshmsft Any news on this one? We've merged the tests several weeks ago already for this one.

[dipeshmsft]

Thanks @h3xds1nz for this contribution.

[h3xds1nz]

@dipeshmsft Great, happy to see it in :)