squash! Make UUID validation RegEx a static class member

LibrePCB · Jan 23, 2020 · 1eb7dce · 1eb7dce
1 parent 2df00b0
commit 1eb7dce
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Showing 2 changed files with 46 additions and 17 deletions.
diff --git a/libs/librepcb/common/uuid.cpp b/libs/librepcb/common/uuid.cpp
@@ -30,29 +30,63 @@
  ******************************************************************************/
 namespace librepcb {
 
-/*******************************************************************************
- *  Static Members
- ******************************************************************************/
-
-// Initialize validation regex
-const QRegularExpression Uuid::mValidationRe(
-    "\\A[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\\z");
-
 /*******************************************************************************
  *  Static Methods
  ******************************************************************************/
 
+inline bool isLowerHex(const QChar chr) noexcept {
+  return (chr >= QChar('0') && chr <= QChar('9')) || (chr >= QChar('a') && chr <= QChar('f'));
+}
+
 bool Uuid::isValid(const QString& str) noexcept {
-  // check format of string (only accept EXACT matches!)
-  QRegularExpressionMatch match = mValidationRe.match(
-      str, 0, QRegularExpression::PartialPreferCompleteMatch);
-  if (!match.hasMatch()) return false;
+  // Note: This used to be done using a RegEx, but when profiling and
+  // optimizing the library rescan code we found that a manually unrolled
+  // comparison loop performs much better than the previous RegEx.
+  // See https://github.com/LibrePCB/LibrePCB/pull/651 for more details.
+  if (str.length() != 36) return false;
+  if (!isLowerHex(str[0])) return false;
+  if (!isLowerHex(str[1])) return false;
+  if (!isLowerHex(str[2])) return false;
+  if (!isLowerHex(str[3])) return false;
+  if (!isLowerHex(str[4])) return false;
+  if (!isLowerHex(str[5])) return false;
+  if (!isLowerHex(str[6])) return false;
+  if (!isLowerHex(str[7])) return false;
+  if (str[8] != QChar('-')) return false;
+  if (!isLowerHex(str[9])) return false;
+  if (!isLowerHex(str[10])) return false;
+  if (!isLowerHex(str[11])) return false;
+  if (!isLowerHex(str[12])) return false;
+  if (str[13] != QChar('-')) return false;
+  if (!isLowerHex(str[14])) return false;
+  if (!isLowerHex(str[15])) return false;
+  if (!isLowerHex(str[16])) return false;
+  if (!isLowerHex(str[17])) return false;
+  if (str[18] != QChar('-')) return false;
+  if (!isLowerHex(str[19])) return false;
+  if (!isLowerHex(str[20])) return false;
+  if (!isLowerHex(str[21])) return false;
+  if (!isLowerHex(str[22])) return false;
+  if (str[23] != QChar('-')) return false;
+  if (!isLowerHex(str[24])) return false;
+  if (!isLowerHex(str[25])) return false;
+  if (!isLowerHex(str[26])) return false;
+  if (!isLowerHex(str[27])) return false;
+  if (!isLowerHex(str[28])) return false;
+  if (!isLowerHex(str[29])) return false;
+  if (!isLowerHex(str[30])) return false;
+  if (!isLowerHex(str[31])) return false;
+  if (!isLowerHex(str[32])) return false;
+  if (!isLowerHex(str[33])) return false;
+  if (!isLowerHex(str[34])) return false;
+  if (!isLowerHex(str[35])) return false;
 
   // check type of uuid
   QUuid quuid(str);
   if (quuid.isNull()) return false;
   if (quuid.variant() != QUuid::DCE) return false;
   if (quuid.version() != QUuid::Random) return false;
+
   return true;
 }
 

diff --git a/libs/librepcb/common/uuid.h b/libs/librepcb/common/uuid.h
@@ -158,11 +158,6 @@ class Uuid final {
 
 private:          // Data
   QString mUuid;  ///< Guaranteed to always contain a valid UUID
-
-  /**
-   * @brief mRe Regular expression for validating UUIDs.
-   */
-  static const QRegularExpression mValidationRe;
 };
 
 /*******************************************************************************