feat: per-term anonymization output via term=>replacement

A term entered as "Anonymous=>ABC" now scrubs "Anonymous" to "ABC"
instead of "XXXX-N". Lets users keep anonymized identifiers valid in
source code (no hyphen) and align tokens between paper text and repo.
Indexing for default-mask terms is unchanged: a list of
"Alpha=>AAA", "Beta" still produces XXXX-2 for Beta.

Fixes #285.

src/core/anonymize-utils.ts

@@ -4,7 +4,11 @@ import { StringDecoder } from "string_decoder";
 import { isText } from "istextorbinary";
 
 import config from "../config";
-import { termVariants, withWordBoundaries } from "./term-matching";
+import {
+  parseTermSpec,
+  termVariants,
+  withWordBoundaries,
+} from "./term-matching";
 
 const urlRegex =
   /<?\b((https?|ftp|file):\/\/)[-A-Za-z0-9+&@#/%?=~_|!:,.;]+[-A-Za-z0-9+&@#/%=~_|]\b\/?>?/g;
@@ -189,11 +193,19 @@ export class ContentAnonimizer {
   private replaceTerms(content: string): string {
     const terms = this.opt.terms || [];
     for (let i = 0; i < terms.length; i++) {
-      let term = terms[i];
-      if (term.trim() == "") {
+      const spec = terms[i];
+      if (spec.trim() == "") {
         continue;
       }
-      const mask = config.ANONYMIZATION_MASK + "-" + (i + 1);
+      // #285 — entries of the form "term=>replacement" override the default
+      // XXXX-N mask so users can scrub with their preferred token (e.g.
+      // "ABC", "XYZ"), keeping anonymized identifiers valid in source code.
+      const parsed = parseTermSpec(spec);
+      let term = parsed.term;
+      const mask =
+        parsed.replacement !== null
+          ? parsed.replacement
+          : config.ANONYMIZATION_MASK + "-" + (i + 1);
       try {
         new RegExp(term, "gi");
       } catch {
@@ -239,20 +251,23 @@ export class ContentAnonimizer {
 
 export function anonymizePath(path: string, terms: string[]) {
   for (let i = 0; i < terms.length; i++) {
-    let term = terms[i];
-    if (term.trim() == "") {
+    const spec = terms[i];
+    if (spec.trim() == "") {
       continue;
     }
+    const parsed = parseTermSpec(spec);
+    let term = parsed.term;
+    const mask =
+      parsed.replacement !== null
+        ? parsed.replacement
+        : config.ANONYMIZATION_MASK + "-" + (i + 1);
     try {
       new RegExp(term, "gi");
     } catch {
       // escape regex characters
       term = term.replace(/[-[\]{}()*+?.,\\^$|#]/g, "\\$&");
     }
-    path = path.replace(
-      new RegExp(term, "gi"),
-      config.ANONYMIZATION_MASK + "-" + (i + 1)
-    );
+    path = path.replace(new RegExp(term, "gi"), mask);
   }
   return path;
 }

src/core/term-matching.ts

@@ -102,3 +102,27 @@ export function termVariants(escapedTerm: string): {
     { pattern: diacriticInsensitive(stripped), sniff: stripped, unicode: true },
   ];
 }
+
+// A term can override the default `XXXX-N` mask via the syntax
+//     <term>=><replacement>
+// e.g. "Anonymous=>ABC" replaces "Anonymous" with "ABC". Whitespace around
+// `=>` is allowed. The replacement is inserted verbatim, so users can pick
+// strings without the hyphen that breaks identifiers.
+//
+// If the entry is just `=>` with no LHS, or has no separator, the original
+// term is returned and the caller falls back to the default mask.
+export function parseTermSpec(spec: string): {
+  term: string;
+  replacement: string | null;
+} {
+  const idx = spec.indexOf("=>");
+  if (idx < 0) {
+    return { term: spec, replacement: null };
+  }
+  const term = spec.slice(0, idx).replace(/\s+$/, "");
+  const replacement = spec.slice(idx + 2).replace(/^\s+/, "");
+  if (!term) {
+    return { term: spec, replacement: null };
+  }
+  return { term, replacement };
+}