How to process autocalc values in a sheet worker (no sendChat)

Sorry, I feel like I have missed something obvious but I can't seem to figure this out. Working on updates to my Runequest6/Mythras sheet and I want to give users the ability to change the values used for Attribute table lookups.  A number of example gifts from the rulebook change the attributes that may be used.  For example you normally add STR and SIZ and lookup the result a table to find your Damage Modifier.  Through a cult gift however this could change to STR+SIZ+POW.   My plan was to simply provide a field which defaults to @{str}+@{siz} and allow the user to edit it as needed.  This is fine for most attributes because I can simply include that formula in a larger one to get the table result but the damage mod table has no formula driving the results.  Problem is I use getAttrs and the value I get is a string = "@{str}+@{siz}" and not the resulting value.  This is expected but I can't find a way to evaluate it into an integer. In the API you would use sendChat but it seems this is not available in the sheet workers.  

var autocalc = '@{str}+@{siz}-floor(@{example|max}/2)', regexp = /@\{(.+?(?:\|max)?)\}/g, matches = [], tmp; while ((tmp = regexp.exec(autocalc)) !== null) { matches.push(tmp[1].replace(/\|max$/, '_max')); } // matches == ['str', 'siz', 'example_max'] This would let you produce the array you need for the first parameter to getAttrs, to ensure you have all of the attributes being referenced. var autocalc = '@{str}+@{siz}-floor(@{example|max}/2', regexp = /@\{(.+?(?:\|max)?)\}/g, reformatted = autocalc.replace(regexp, ($0, $1) => `${values[$1.replace(/\|max$/, '_max')]}`), evalStr = reformatted.replace(/(abs|ceil|floor|round)\((.+?)\)/g, 'Math.$1($2)'), calculatedValue = eval(evalStr); // reformatted == '5+2-floor(7/2)', assuming values.str == 5, values.siz == 2, and values.example_max == 7 // evalStr == '5+2-Math.floor(7/2)' // calculatedValue == 4 I'm assuming here that eval is available to sheet workers, and that may be an incorrect assumption. If eval isn't available, you'd have to include a complicated parser in your sheet worker. So, putting it together: on(..., function(e) { getAttrs(['my_autocalc_value'], function(v) { var regexp = /@\{(.+?(?:\|max)?)\}/g, matches = [], tmp; while ((tmp = regexp.exec(v.my_autocalc_value)) !== null) { matches.push(tmp[1].replace(/\|max$/, '_max')); } getAttrs(matches, function(values) { var reformatted = v.my_autocalc_value.replace(regexp, ($0, $1) => `${values[$1.replace(/\|max$/, '_max')]}`), evalStr = reformatted.replace(/(abs|ceil|floor|round)\((.+?)\)/g, 'Math.$1($2)'), calculatedValue = eval(evalStr); setAttrs({ my_autocalc_calculation: calculatedValue }); }); }); }); If the attributes being used themselves contain references to other attributes, you would have to apply this process recursively, which could get tricky since getAttrs is asynchronous.

Thanks for the help.  I was afraid I would need to essentially parse the string manually.  To simplify matters I'll probably just convert most stuff to sheet worker calcs to avoid recursion and include a checkbox for the gift and have the sheet worker include @{pow} in the total table lookup value if it is checked.  Making it entirely customized was probably overkill anyway.