1 files changed, 13 insertions, 0 deletions
diff --git a/src/functions.hpp b/src/functions.hpp
index 123f4ab..89e3b01 100644
--- a/src/functions.hpp
+++ b/src/functions.hpp
@@ -6,6 +6,7 @@
 #define T_FUNCTIONS_HPP
 
 #include "sha256/picosha2.h"
+#include <string>
 
 std::string &ltrim(std::string &str, const std::string &chars = "\t\n\v\f\r ") {
   str.erase(0, str.find_first_not_of(chars));
@@ -28,4 +29,16 @@ std::string sha256_hash(std::string text) {
   std::string hex_str = picosha2::bytes_to_hex_string(hash.begin(), hash.end());
   return hex_str;
 }
+
+std::string prefix(std::string hash,
+                   std::unordered_map<std::string, std::string> tasks) {
+  std::string prefix;
+  for (size_t i = 1; i <= hash.length(); i++) {
+    prefix = hash.substr(0, i);
+    if (tasks.find(prefix) == tasks.end())
+      return prefix;
+  }
+  return hash;
+}
+
 #endif // T_FUNCTIONS_HPP