✨ Support backreferences on regex substitution

Reference #361

Author: richardfrost

src/script/lib/filter.ts

@@ -141,6 +141,16 @@ export default class Filter {
             if (this.checkWhitelist(match, string, matchStartIndex, word)) { return match; } // Check for whitelisted match
             if (statsType) { this.foundMatch(word, statsType); }
 
+            // Support backreferences for REGEX match method (only checks for 1 capture group)
+            if (word.matchMethod == Constants.MATCH_METHODS.REGEX && captureGroups.length && word.sub.includes('\\1')) {
+              let sub = word.sub;
+              captureGroups.forEach((captureGroup, i) => { sub = sub.replace(`\\${i + 1}`, captureGroup); });
+              if (sub !== word.sub) {
+                // Only return if something was substituted
+                return sub;
+              }
+            }
+
             // Filter
             let sub = word.sub || this.cfg.defaultSubstitution;
 

test/lib/filter.spec.js

@@ -386,6 +386,16 @@ describe('Filter', () => {
           filter.init();
           expect(filter.replaceText('Have you ever been cut by a Cat?')).to.equal('Have you ever been bit by a Bit?');
         });
+
+        it('Should support backreferences in replace', () => {
+          const filter = new Filter;
+          filter.cfg = new Config({ words: Object.assign({}, testWords), filterMethod: Constants.FILTER_METHODS.SUBSTITUTE });
+          filter.cfg.words['pee([ed]{0,2}[ ]?\\w*?) off'] = { matchMethod: Constants.MATCH_METHODS.REGEX, repeat: Constants.FALSE, sub: 'tick\\1 off' };
+          filter.cfg.words['scare([ ]?\\w*) off'] = { matchMethod: Constants.MATCH_METHODS.REGEX, repeat: Constants.FALSE, sub: 'spook\\1 off' };
+          filter.init();
+          expect(filter.replaceText('Try not to pee John off.')).to.equal('Try not to tick John off.');
+          expect(filter.replaceText('Try not to scare John off.')).to.equal('Try not to spook John off.');
+        });
       });
 
       describe('whitelist', () => {