By not doing excessive amounts of extra work, formatting can be sped up quite significantly (about 8x faster).
The main change comes from adding new, more efficient, primitive to query an object for the existence of an instance member.
The formatting system has been checking for if an object has properties other than some decorated properties added by PS remoting, and it doesn't this by retrieving all properties which results in heavy allocations and wasted cycles.
By adding `GetFirstOrDefault` to `PSObject` and similar primitives to the underlying Adapters, we are able to return early, without having to get all properties back.
When using a screen reader or just getting the output of a table with lots of rows, the header is no longer on the screen and the columns may no longer make sense without the context. This change adds a `-RepeatHeader` switch to `Format-Table` to enable re-outputting the header after every screen full (minus 1 row). Expectation is that the user is piping the output to a pager (e.g. less) which uses the bottom row for pager information. I followed the `AutoSize` parameter as the way to get the parameter from the cmdlet into the deep formatting object where it's needed.
Measure-Object should handle `ScriptBlock` properties. Fixed by renaming `MshExpression` to `PSPropertyExpression` and making it public. Then in `MeasureObjectCommand`, lifting it up to the parameter level. Previously the implementation exposed the Property as a string and
wrapped it internally as a `PSPropertyExpression`. Now the parameter type is `PSPropertyExpression` directly allowing for both wildcard strings and `ScriptBlock`.
`PSPropertyExpression` now lives in a public namespace where it can be used by cmdlet and script authors to easily add the same type of functionality to their commands. I also modified `PSPropertyExpression` to handle hashtables properly as objects so
@{prop = 3} | measure-object prop
and
@{prop = 3} | measure-object {$_.prop}
will work the same. (Previously the example using just the property name would fail.)
Based on standard practices, we need to have a copyright and license notice at the top of each source file. Removed existing copyrights and updated/added copyright notices for .h, .cpp, .cs, .ps1, and .psm1 files.
Updated module manifests for consistency to have Author = "PowerShell" and Company = "Microsoft Corporation". Removed multiple line breaks.
Separate PR coming to update contribution document for new source files: #6140
Manually reviewed each change.
Fix#6073
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