Powershell regex- how to avoid commented blocks

Question

I have several regular expression blocks that parse a c++ file for certain info. I'm trying to change my regex so that it avoids the commented blocks. The code that still captures the commented block is:

Function Get-CaseContents{
  [cmdletbinding()]
  Param ( [string]$parsedCaseMethod, [string]$basePathFull)
  Process
  {
      # split into separate "case" blocks.
      # (the funky "(?=...)" preserves the delimiter)
      $blocks = $parsedCaseMethod -split "(?=case (.*):)";

      $pattern = `
      "_stprintf[\s\S]*?_T\D*" +
      "(?<sdkErr>[x\d]+)" +
      "\D[\s\S]*?" +
      "\((?<sdkDesc>(.+?)`")\)" +
      "[\s\S]*?" +
      "(outError\s*=\s*(?<sdkOutErr>[a-zA-Z_0-9]*))" +
      "[\s\S]*?" +
      "(?<sdkSeverity>outSeverity\s*=\s[a-zA-Z_]*)";

      # note - skip first block as it's the preamble before the first "if"
      $result = $blocks `
      | select-object -skip 1 `
      | select-string -pattern $pattern `
      | foreach-object {
          $match = $_.Matches[0];
          $tmp_removeParen = $match.Groups['sdkDesc'] -replace '\(|\)|%s|\"',"."
          [PSCustomObject] [ordered] @{
              "sdkErr"      = $($match.Groups['sdkErr'])
              "sdkDesc"     = $($tmp_removeParen)
              "sdkOutErr"   = $($match.Groups['sdkOutErr'])
              "sdkSeverity" = ($match.Groups['sdkSeverity'] -split '_')[-1]
          }
      };
      return $result 



     
  }#End of Process
}#End of Function

That gets all of the targeted contents plus the commented blocks, which I want to avoid. The c++ code that is being parsed looks like this:

        case kRESULT_STATUS_SHORTAGE:  
            _stprintf(outDevStr, _T("2000 - (Shortage issue) - %s(Shortage)"), errorStr);
            outError = HOP_SHORTAGE;
            outSeverity = CCC_INFORMATION;
            break;


// New Error codes(really old errors broken out with unique error codes) - not all have this line
        //case kRESULT_STATUS_User_CoverOpenErr:    //comment here  
        //  _stprintf( outDevStr, _T("2900 - (Cover Open) - %s(Upper cover open.)"), errorStr);
        //  outError    = HOP_COVER_OPEN;
        //  outSeverity = CCC_INFORMATION;
        //  break;

I tried changing the first part with the split to this, but it makes it return no results. I feel like if I just figure out how to not include a case block that is commented on the case line, it will fix everything.

$blocks = $parsedCaseMethod -split "(?=^[\s]+case (.*):)"; #didn't work - nothing in $result

Any help would be appreciated. Thanks! :)

This is with Powershell 5.1 and VS Code.

I thought this looked familiar. For this slightly changed problem statement I still maintain that running things through a C++ preprocessor to strip the comments would be an effective solution -- certainly more reliable than regexes. If an actual C++ preprocessor is just too much effort to install, a little comment stripping routine before we try to parse things with regexes would probably be simpler than integrating it into the existing regexes. — Jeroen Mostert
– Jeroen Mostert, Commented Mar 23, 2022 at 14:59
@JeroenMostert - thanks for the idea but I still need to keep with my current design. This is about the 6th device I'm getting to this point where I parse the data out of the cpp file, which is why the info being parsed is different than the link you showed. The idea to preprocess/remove the commented out lines was a good idea, but I knew if I could just figure out how to change my $blocks line to exclude the ones that didn't have only spaces before the case part, it would fix it, so I'm going with what mkelement0 answered below. — Michele
– Michele, Commented Mar 23, 2022 at 15:20

mklement0 · Accepted Answer · 2022-03-23 15:24:13Z

1

The simplest approach is probably to eliminate all comment lines in a first step, before splitting:

$blocks = $parsedCaseMethod -replace '(?m)^\s*//.*' -split '(?=case (.*):)'

Note:

To keep the regex simple, the above effectively replaces the comment lines with empty lines (it does, however, remove empty and all-whitespace lines preceding a comment line). If you want to avoid that, use -replace '(?m)^\s*//.*(?:\r?\n)?'
- For an explanation of the regex and the ability to experiment with it, see this regex101.com page.
The assumption is that your C++ code doesn't contain multi-line comments (/* ... */), and no //-prefixed lines inside C++ 11 raw string literals.

edited Mar 23, 2022 at 15:24

answered Mar 23, 2022 at 14:58

mklement0

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1 Comment

mklement0 Over a year ago

@Michele, (?m) is the inline form of the Multiline regex option, which makes ^ and $ match on the start and end of individual lines - please see the regex101.com link I've just added to the answer.

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