Parameters break syntax highlighting by capturing punctuation

[ct-martin]

Required information for this issue:

• Your VS Code Version: 1.96.2
• Your OS Version: Windows 11 23H2
• Is this extension running on VS Code Remote or https://vscode.dev: No

Steps to Reproduce:

1. Use the sample file below

Snippet of note:

  upstream big_server_com {
    server 127.0.0.3:8000 weight=5;
    server 127.0.0.3:8001 weight=5;
    server 192.168.0.1:8000;
    server 192.168.0.1:8001;
  }

VS Code doesn't properly highlight the line after a parameter is used:

I think what is happening is that on the final group of the regex on this line, the semicolon punctuation is being captured and then not being parsed as punctuation.

vscode-nginx-conf-hint/src/syntax/repository.ts

Line 46 in 5d5c43b

match: /(?:^|\s)(weight|max_conn|max_fails|fail_timeout|slow_start)(=)(\d[\d\.]*[bBkKmMgGtTsShHdD]?)(?:\s|;|$)/,

(Same line but in the XML)

vscode-nginx-conf-hint/src/syntax/nginx.tmLanguage

Line 3268 in 5d5c43b

<string>(?:^|\s)(weight|max_conn|max_fails|fail_timeout|slow_start)(=)(\d[\d\.]*[bBkKmMgGtTsShHdD]?)(?:\s|;|$)</string>

You can see it work correctly if you add a space before the semicolon like this:

    server 127.0.0.3:8001 weight=5 ; # <-- notice added space here
    server 192.168.0.1:8000;

This can be fixed by changing the final group from being a non-capturing group to a lookahead.

Current final group: (?:\s|;|$)

As a lookahead: (?=\s|;|$) (notice the = instead of :)

---

I can open a pull request for this if you'd like.

---

Full sample file

user       www www;  ## Default: nobody
worker_processes  5;  ## Default: 1
error_log  logs/error.log;
pid        logs/nginx.pid;
worker_rlimit_nofile 8192;

events {
  worker_connections  4096;  ## Default: 1024
}

http {
  include    conf/mime.types;
  include    /etc/nginx/proxy.conf;
  include    /etc/nginx/fastcgi.conf;
  index    index.html index.htm index.php;

  default_type application/octet-stream;
  log_format   main '$remote_addr - $remote_user [$time_local]  $status '
    '"$request" $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
  access_log   logs/access.log  main;
  sendfile     on;
  tcp_nopush   on;
  server_names_hash_bucket_size 128; # this seems to be required for some vhosts

  server { # php/fastcgi
    listen       80;
    server_name  domain1.com www.domain1.com;
    access_log   logs/domain1.access.log  main;
    root         html;

    location ~ \.php$ {
      fastcgi_pass   127.0.0.1:1025;
    }
  }

  server { # simple reverse-proxy
    listen       80;
    server_name  domain2.com www.domain2.com;
    access_log   logs/domain2.access.log  main;

    # serve static files
    location ~ ^/(images|javascript|js|css|flash|media|static)/  {
      root    /var/www/virtual/big.server.com/htdocs;
      expires 30d;
    }

    # pass requests for dynamic content to rails/turbogears/zope, et al
    location / {
      proxy_pass      http://127.0.0.1:8080;
    }
  }

  upstream big_server_com {
    server 127.0.0.3:8000 weight=5;
    server 127.0.0.3:8001 weight=5;
    server 192.168.0.1:8000;
    server 192.168.0.1:8001;
  }

  server { # simple load balancing
    listen          80;
    server_name     big.server.com;
    access_log      logs/big.server.access.log main;

    location / {
      proxy_pass      http://big_server_com;
    }
  }
}

# From https://www.nginx.com/resources/wiki/start/topics/examples/full/

[slevithan]

This can be fixed by changing the final group from being a capture group to a lookahead.

Current final group: (?:\s|;|$)

As a lookahead: (?=:\s|;|$) (notice the added =)

Your analysis seems good, but note that your lookahead version should be (?=\s|;|$) (without the : after (?=).

Another option is (?=[\s;]|$). Relying less on backtracking like this is often slightly better.

And a pedantic note: (?: is a non-capturing group, not a capturing group. If by "capture group" you were trying to distinguish both capturing and non-capturing groups from lookaround, there isn't a standard term but I might call them "consumptive groups", i.e. they add characters to the match.

[ct-martin]

Thanks for catching the typo, I edited the initial comment.

Re: the pedantic note, as far as I can tell they're just called "groups" (e.g. on MDN) but I agree that there could be better terms to describe how the different types of groups overlap with their effects.