Added string replacement function for future use

ziffers/common.py

@@ -1,9 +1,13 @@
 """ Common methods used in parsing """
+import re
+
+
 def flatten(arr: list) -> list:
     """Flattens array"""
     return (
         flatten(arr[0]) + (flatten(arr[1:]) if len(arr) > 1 else [])
-        if isinstance(arr, list) else [arr]
+        if isinstance(arr, list)
+        else [arr]
     )
 
 
@@ -17,4 +21,35 @@ def sum_dict(arr: list[dict]) -> dict:
             else:
                 result[key] = element[key]
     return result
-    
+
+
+def string_rewrite(axiom: str, rules: dict):
+    """String rewrite / Lindemeyer system for rule based text manipulation
+
+    Args:
+        axiom (str): Input string
+        rules (dict): String manipulation rules in dict:
+
+    Example:
+        rules = {
+            "1": "2",
+            "[2-9]": "45",
+            "4": lambda: str(randint(1, 7)),
+            "([1-9])(5)": lambda a, b: str(int(a)*int(b))
+        }
+
+        for i range(10):
+            print(string_rewrite("1", rules))
+    """
+
+    def _apply_rules(match):
+        for key, value in rules.items():
+            if re.match(key, match.group(0)):
+                if callable(value):
+                    yield value(
+                        *match.groups()
+                    ) if value.__code__.co_argcount > 0 else value()
+                yield value
+
+    pattern = re.compile("|".join(rules.keys()))
+    return pattern.sub(lambda m: next(_apply_rules(m)), axiom)