refactor(webpack-cli): clarify myersX params and cover long-vs-short case

Address review feedback: rename the swapped myersX parameters to
longer/shorter so they match their internal usage, and add a regression
test for a long string against a much shorter one (40 vs 5).

https://claude.ai/code/session_013zogbY9uURTCwhdRrifVBt

Author: claude

packages/webpack-cli/src/levenshtein.ts

@@ -46,9 +46,9 @@ function myers32(a: string, b: string): number {
   return sc;
 }
 
-function myersX(b: string, a: string): number {
-  const n = a.length;
-  const m = b.length;
+function myersX(longer: string, shorter: string): number {
+  const n = shorter.length;
+  const m = longer.length;
   const mhc: number[] = [];
   const phc: number[] = [];
   const horizontalSize = Math.ceil(n / 32);
@@ -68,11 +68,11 @@ function myersX(b: string, a: string): number {
     const verticalLen = Math.min(32, m) + start;
 
     for (let k = start; k < verticalLen; k++) {
-      peq[b.charCodeAt(k)] |= 1 << k;
+      peq[longer.charCodeAt(k)] |= 1 << k;
     }
 
     for (let i = 0; i < n; i++) {
-      const eq = peq[a.charCodeAt(i)];
+      const eq = peq[shorter.charCodeAt(i)];
       const pb = (phc[(i / 32) | 0] >>> i) & 1;
       const mb = (mhc[(i / 32) | 0] >>> i) & 1;
       const xv = eq | mv;
@@ -95,7 +95,7 @@ function myersX(b: string, a: string): number {
     }
 
     for (let k = start; k < verticalLen; k++) {
-      peq[b.charCodeAt(k)] = 0;
+      peq[longer.charCodeAt(k)] = 0;
     }
   }
 
@@ -105,13 +105,13 @@ function myersX(b: string, a: string): number {
   const verticalLen = Math.min(32, m - start) + start;
 
   for (let k = start; k < verticalLen; k++) {
-    peq[b.charCodeAt(k)] |= 1 << k;
+    peq[longer.charCodeAt(k)] |= 1 << k;
   }
 
   let score = m;
 
   for (let i = 0; i < n; i++) {
-    const eq = peq[a.charCodeAt(i)];
+    const eq = peq[shorter.charCodeAt(i)];
     const pb = (phc[(i / 32) | 0] >>> i) & 1;
     const mb = (mhc[(i / 32) | 0] >>> i) & 1;
     const xv = eq | mv;
@@ -137,7 +137,7 @@ function myersX(b: string, a: string): number {
   }
 
   for (let k = start; k < verticalLen; k++) {
-    peq[b.charCodeAt(k)] = 0;
+    peq[longer.charCodeAt(k)] = 0;
   }
 
   return score;

test/api/levenshtein.test.js

@@ -33,4 +33,12 @@ describe("distance", () => {
     expect(distance(a, b)).toBe(1);
     expect(distance("a".repeat(40), "b".repeat(40))).toBe(40);
   });
+
+  it("should handle a long string against a much shorter one", () => {
+    const long = "abcdefghijklmnopqrstuvwxyz0123456789ABCD";
+
+    expect(long).toHaveLength(40);
+    expect(distance(long, "abcde")).toBe(35);
+    expect(distance("abcde", long)).toBe(35);
+  });
 });