Spaces around equals in gerber pad shape variable definition formula

[adneedle]

When Mentor Xpedition creates shape definitions in gerber files, it seems to add spaces around equal signs in the variable definition formulas. For example:

%AMVB_Custom_Oblong*
21,1,$2-$3,$3,0,0,$1*
$2 = $2/2*
$3 = $3/2*
$6 = $2-$3*
1,1,$3X2,$4X$6,$5X$6*
$6 = 0-$6*
1,1,$3X2,$4X$6,$5X$6*
%

This causes the regular expression in _parse-macro-block.js, var RE_VAR_DEF = /^(\$[\d+])=(.+)/, to fail to match. The pad variable definitions are then out of sync for the file and it tries to use undefined variables.

I am not sure if the spaces around the equal signs comply with the gerber spec, but I ended up locally changing the regex to var RE_VAR_DEF = /^(\$[\d+])\s?=\s?(.+)/ to make it work in my situation.

[mcous]

Very interesting. This is 100% not compliant with the Gerber File Format specification

3.3 Character Set
...
Space characters can only be used inside strings (see 3.6.5).

If possible, I would definitely raise a bug report with Mentor for this.

From a tracespace perspective, yeah I think allowing the equal sign regex to have some optional spaces makes sense for leniency, if that leniency is common in other Gerber viewing tools. The risk in leniency is that it may give someone a false sense of security that their invalid Gerber file will be understood by a fab. I would also probably limit the regex to just literal space characters rather than \s, but I'd accept a PR for this functionality.

[adneedle]

Thanks. It does not surprise me very much that the Xpedition gerber output is buggy. I am not sure if we have seen a fab issue before, but that may be because we almost always use ODB++ now for the fab data.