fix: diff performance (#48)

package.json

@@ -34,7 +34,7 @@
     "chalk": "^4.1.0",
     "cosmiconfig": "^7.0.1",
     "debug": "^4.3.2",
-    "diff": "^5.0.0",
+    "diff-match-patch": "^1.0.5",
     "fast-glob": "^3.2.7",
     "jsonc-eslint-parser": "^1.4.1",
     "pathe": "^0.2.0",
@@ -50,7 +50,7 @@
     "@secretlint/secretlint-rule-preset-recommend": "^3.3.0",
     "@types/chai": "^4.2.22",
     "@types/debug": "^4.1.7",
-    "@types/diff": "^5.0.1",
+    "@types/diff-match-patch": "^1.0.32",
     "@types/eslint": "^7.2.6",
     "@types/eslint-visitor-keys": "^1.0.0",
     "@types/glob": "^7.1.3",

src/utils.ts

@@ -1,6 +1,6 @@
 import createDebug from 'debug'
 import fg from 'fast-glob'
-import { diffChars as diff } from 'diff'
+import diff from 'diff-match-patch'
 import { parseJSON } from 'jsonc-eslint-parser'
 import { parseYAML } from 'yaml-eslint-parser'
 import { readFileSync } from 'fs'
@@ -145,9 +145,16 @@ export function escape(s: string): string {
   return s.replace(/[<>"&]/g, escapeChar)
 }
 
+const df = new diff.diff_match_patch()
+
 export function hasDiff(newContent: string, oldContent: string): boolean {
-  const contents = diff(oldContent, newContent)
-  return !!contents.find(content => content.added || content.removed)
+  const diffs = df.diff_main(oldContent, newContent, true)
+  if (diffs.length === 0) {
+    return false
+  }
+  return !!diffs.find(
+    d => d[0] === diff.DIFF_DELETE || d[0] === diff.DIFF_INSERT
+  )
 }
 
 export function buildSFCBlockTag(meta: {