What I'm looking for
I would like to match hash comments excluding inline comments in PowerShell . I can match them using #(?<!<#)(?![<>])(.*)$ (see regex101). However I would want to achieve this by not using lookbehind. Is there any way I can get the same (or closest) behavior to the regex with lookbehind?
A regex only solution would be nice but I would also appreciate solutions JavaScript only solutions.
What I tried
My best was try #(?!.*>)(.*)$ (see regex101), but I'm unhappy that it misses anything that has> after #.
I also tried writing JavaScript only parsing but it got very complex (more than 30 lines) and was very slow.
Why I need it
I use this to inline PowerShell used in an open-source project (GitHub code). However, the project is online and runs on browser (website) and unfortunately I realized that it does not work in Safari as Safari does not yet support lookbehind (caniuse.com).
Syntax: Hash comment vs inline comment
Rule: Match all hash comments but exclude inline comments
Hash comments in PowerShell, just like in bash and other languages starts from hash (#) and continues until the end of the line.
Write-Host "Hello world" # Here is a hash comment
Inline comments in PowerShell is between <# and #>
Write-Host <# Here is an inline comment #> "Hello world"
CodePudding user response：
With regular expressions, that represent plain text patterns, you can not just match pieces of texts, you can also capture parts of the matches. Once you capture a substring, you can apply any logic you want after that, be it replacing or keeping parts of the string.
To replace the comments, you can use
text = text.replace(/(<#.*?#>)|#.*/g, (m, g) => g ? g : "REPLACED")
To remove the comments, you can use
text = text.replace(/(<#.*?#>)|#.*/g, "$1")
In both cases, the pattern is (<#.*?#>)|#.*:
(<#.*?#>)- Group 1: a<#text, then any zero or more chars other than line break chars, as few as possible, and then#>text|- or#.*-#char and the rest of the line.
In the first case, (m, g) => g ? g : "REPLACED" replacement keeps group 1 value if Group 1 matched (m stands for the whole match and g stands for the Group 1 value). In the second case, the Group 1 value is put back if it was matched with the help of the $1 backreference. It represents an empty string if Group 1 did not match.
CodePudding user response：
You could match the following regular expression.
^(?:<#.*?#>|[^#])*(#.*)?
The capture group, if not empty, contains the comment to be removed.
Hover the cursor over each element of the expression at the link to obtain a description of its function.