Implemented find_first() function

find_first()

Author: springcomp

jmespath/functions.py

@@ -308,6 +308,17 @@ def _func_keys(self, arg):
         # should we also return the indices of a list?
         return list(arg.keys())
 
+    @signature(
+        {'type': 'string'},
+        {'type': 'string'},
+        {'type': 'number', 'optional': True},
+        {'type': 'number', 'optional': True})
+    def _func_find_first(self, text, search, start = 0, end = -1):
+        if end == -1:
+            end = len(text)
+        pos = text.find(search, start, end)
+        return pos if pos != -1 else None
+
     @signature(
         {'type': 'string'},
         {'type': 'number'},