Regex lookahead / lookbehind questions

[Danp2]

I'll start off by stating that I am not a regex expert, so apologies if I'm looking at this incorrectly. There are several instances of regex used in this extension that I think need to be reviewed for correctness.

• I don't understand what purpose (?=\S) serves in these instances. Can anyone clarify this for me?
• Instead of a negative lookahead, shouldn't this be using a negative lookbehind for the comment detection?
  • IE (?<!;~\s) instead of (?!;~\s)
  • Removing the \s from the end also makes it function better IMO

Anyone have thoughts or comments on this topic? Below are the two lines of code --

AutoIt-VSCode/src/ai_commands.js

Line 915 in baac143

const findFunc = /(?=\S)(?!;~\s)Func\s+((\w+)\((.+)?\))/i;

and

AutoIt-VSCode/src/util.js

Line 258 in baac143

const includeFuncPattern = /(?=\S)(?!;~\s)Func\s+((\w+)\((.+)?\))/gi;

[Danp2]

[vanowm]

Hmmm that regex doesn't look right indeed.
It should be lookbehind, but only for ; character, no need match ~\s.
Also, it doesn't match functions with a space after its name.

There shouldn't be any non-whitespace characters in front of function, so this should be a better regex:

/^[\t ]*Func\s+(\w+)\s*\((.*)\)/im

[Danp2]

Hi @vanowm,

Thanks for taking a look at this. I will check out your PR in a bit.

Regards, Dan

[GrandStrateguerre]

hello,
Only detect the first function is it good ?

Best regards

[vanowm]

This depends on where this regex used in the code. Some places use g (global) flag:

AutoIt-VSCode/src/ai_completion.js

Line 110 in 32ca225

const functionPattern = /^[\t ]*Func\s+(\w+)\s*\(/gim;

other use this regex per individual line:

AutoIt-VSCode/src/ai_commands.js

Line 915 in 32ca225

const findFunc = /^[\t ]*Func\s+(\w+)\s*\((.*)\)/i;