Count number of comments over multiple files, including multi-line comments - powershell

Question

I'm trying to write a script that counts all comments in multiple files, including both single line (//) and multi-line (/* */) comments and prints out the total. So, the following file would return 4
// Foo
var text = "hello world";
/*
Bar
*/
alert(text);
There's a requirement to include specific file types and exclude certain file types and folders, which I already have working in my code.
My current code is:
( gci -include *.cs,*.aspx,*.js,*.css,*.master,*.html -exclude *.designer.cs,jquery* -recurse `
| ? { $_.FullName -inotmatch '\\obj' } `
| ? { $_.FullName -inotmatch '\\packages' } `
| ? { $_.FullName -inotmatch '\\release' } `
| ? { $_.FullName -inotmatch '\\debug' } `
| ? { $_.FullName -inotmatch '\\plugin-.*' } `
| select-string "^\s*//" `
).Count
How do I change this to get multi-line comments as well?
UPDATE: My final solution (slightly more robust than what I was asking for) is as follows:
$CodeFiles = Get-ChildItem -include *.cs,*.aspx,*.js,*.css,*.master,*.html -exclude *.designer.cs,jquery* -recurse |
Where-Object { $_.FullName -notmatch '\\(obj|packages|release|debug|plugin-.*)\\' }
$TotalFiles = $CodeFiles.Count
$IndividualResults = #()
$CommentLines = ($CodeFiles | ForEach-Object{
#Get the comments via regex
$Comments = ([regex]::matches(
[IO.File]::ReadAllText($_.FullName),
'(?sm)^[ \t]*(//[^\n]*|/[*].*?[*]/)'
).Value -split '\r?\n') | Where-Object { $_.length -gt 0 }
#Get the total lines
$Total = ($_ | select-string .).Count
#Add to the results table
$IndividualResults += #{
File = $_.FullName | Resolve-Path -Relative;
Comments = $Comments.Count;
Code = ($Total - $Comments.Count)
Total = $Total
}
Write-Output $Comments
}).Count
$TotalLines = ($CodeFiles | select-string .).Count
$TotalResults = New-Object PSObject -Property #{
Files = $TotalFiles
Code = $TotalLines - $CommentLines
Comments = $CommentLines
Total = $TotalLines
}
Write-Output (Get-Location)
Write-Output $IndividualResults | % { new-object PSObject -Property $_} | Format-Table File,Code,Comments,Total
Write-Output $TotalResults | Format-Table Files,Code,Comments,Total

Answer 1

To be clear: Using string matching / regular expressions is not a fully robust way to detect comments in JavaScript / C# code, because there can be false positives (e.g., var s = "/* hi */";); for robust parsing you'd need a language parser.
If that is not a concern, and it is sufficient to detect comments (that start) on their own line, optionally preceded by whitespace, here's a concise solution (PSv3+):
(Get-ChildItem -include *.cs,*.aspx,*.js,*.css,*.master,*.html -exclude *.designer.cs,jquery* -recurse |
Where-Object { $_.FullName -notmatch '\\(obj|packages|release|debug|plugin-.*)' } |
ForEach-Object {
[regex]::matches(
[IO.File]::ReadAllText($_.FullName),
'(?sm)^[ \t]*(//[^\n]*|/[*].*?[*]/)'
).Value -split '\r?\n'
}
).Count
With the sample input, the ForEach-Object command yields 4.
Remove the ^[ \t]* part to match comments starting anywhere on a line.
The solution reads each input file as a single string with [IO.File]::ReadAllText() and then uses the [regex]::Matches() method to extract all (potentially line-spanning) comments.
Note: You could use Get-Content -Raw instead to read the file as a single string, but that is much slower, especially when processing multiple files.
The regex uses in-line options s and m ((?sm)) to respectively make . match newlines too and to make anchors ^ and $ match line-individually.
^[ \t]* matches any mix of spaces and tabs, if any, at the start of a line.
//[^\n]*$ matches a string that starts with // through the end of the line.
/[*].*?[*]/ matches a block comment across multiple lines; note the lazy quantifier, *?, which ensures that very next instance of the closing */ delimiter is matched.
The matched comments (.Value) are then split into individual lines (-split '\r?\n'), which are output.
The resulting lines across all files are then counted (.Count)
As for what you tried:
The fundamental problem with your approach is that Select-String with file-info object input (such as provided by Get-ChildItem) invariably processes the input files line by line.
While this could be remedied by calling Select-String inside a ForEach-Object script block in which you pass each file's content as a single string to Select-String, direct use of the underlying regex .NET types, as shown above, is more efficient.

Answer 2

An IMO better approach is to count net code lines by removing single/multi line comments.
For a start a script that handles single files and returns for your above sample.cs the result 5
((Get-Content sample.cs -raw) -replace "(?sm)^\s*\/\/.*?$" `
-replace "(?sm)\/\*.*?\*\/.*`n" | Measure-Object -Line).Lines
EDIT: without removing empty lines, build the difference from total lines
## Q:\Test\2018\10\31\SO_53092258.ps1
$Data = Get-ChildItem *.cs | ForEach-Object {
$Content = Get-Content $_.FullName -Raw
$TotalLines = (Measure-Object -Input $Content -Line).Lines
$CodeLines = ($Content -replace "(?sm)^\s*\/\/.*?$" `
-replace "(?sm)\/\*.*?\*\/.*`n" | Measure-Object -Line).Lines
$Comments = $TotalLines - $CodeLines
[PSCustomObject]#{
File = $_.FullName
Lines = $TotalLines
Comments= $Comments
}
}
$Data
"="*40
"TotalLines={0} TotalCommentLines={1}" -f (
$Data | Measure-Object -Property Lines,Comments -Sum).Sum
Sample output:
> Q:\Test\2018\10\31\SO_53092258.ps1
File Lines Comments
---- ----- --------
Q:\Test\2018\10\31\example.cs 10 5
Q:\Test\2018\10\31\sample.cs 9 4
============================================
TotalLines=19 TotalCommentLines=9