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node_modules/tailwindcss/src/lib/cacheInvalidation.js

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+import crypto from 'crypto'
+import * as sharedState from './sharedState'
+
+/**
+ * Calculate the hash of a string.
+ *
+ * This doesn't need to be cryptographically secure or
+ * anything like that since it's used only to detect
+ * when the CSS changes to invalidate the context.
+ *
+ * This is wrapped in a try/catch because it's really dependent
+ * on how Node itself is build and the environment and OpenSSL
+ * version / build that is installed on the user's machine.
+ *
+ * Based on the environment this can just outright fail.
+ *
+ * See https://github.com/nodejs/node/issues/40455
+ *
+ * @param {string} str
+ */
+function getHash(str) {
+  try {
+    return crypto.createHash('md5').update(str, 'utf-8').digest('binary')
+  } catch (err) {
+    return ''
+  }
+}
+
+/**
+ * Determine if the CSS tree is different from the
+ * previous version for the given `sourcePath`.
+ *
+ * @param {string} sourcePath
+ * @param {import('postcss').Node} root
+ */
+export function hasContentChanged(sourcePath, root) {
+  let css = root.toString()
+
+  // We only care about files with @tailwind directives
+  // Other files use an existing context
+  if (!css.includes('@tailwind')) {
+    return false
+  }
+
+  let existingHash = sharedState.sourceHashMap.get(sourcePath)
+  let rootHash = getHash(css)
+  let didChange = existingHash !== rootHash
+
+  sharedState.sourceHashMap.set(sourcePath, rootHash)
+
+  return didChange
+}