diff --git a/src/ytdl_sub/script/__init__.py b/src/ytdl_sub/script/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/src/ytdl_sub/script/functions.py b/src/ytdl_sub/script/functions.py
new file mode 100644
index 00000000..c4095fba
--- /dev/null
+++ b/src/ytdl_sub/script/functions.py
@@ -0,0 +1,31 @@
+
+
+class Functions:
+
+    @staticmethod
+    def lower(string: str) -> str:
+        """
+        Returns
+        -------
+        Lower-cased string
+        """
+        return string.lower()
+
+    @staticmethod
+    def upper(string: str) -> str:
+        """
+        Returns
+        -------
+        Upper-cased string
+        """
+        return string.upper()
+
+    @staticmethod
+    def capitalize(string: str) -> str:
+        """
+        Returns
+        -------
+        Capitalized string
+        """
+        return string.capitalize()
+    
\ No newline at end of file
diff --git a/src/ytdl_sub/script/parser.py b/src/ytdl_sub/script/parser.py
new file mode 100644
index 00000000..c61dce0a
--- /dev/null
+++ b/src/ytdl_sub/script/parser.py
@@ -0,0 +1,75 @@
+from dataclasses import dataclass
+from queue import LifoQueue
+from typing import Optional, List
+
+from ytdl_sub.validators.string_formatter_validators import is_valid_source_variable_name
+
+@dataclass
+class Variable:
+    name: str
+
+@dataclass
+class Function:
+    name: str
+    args: List[str]
+
+
+class Parser:
+
+    def __init__(self, text: str):
+        self._text = text
+        self._pos = 0
+        self._stack: LifoQueue[Variable | Function] = LifoQueue()
+
+    def read(self) -> Optional[str]:
+        try:
+            ch = self._text[self._pos]
+        except IndexError:
+            return None
+
+        self._pos += 1
+        return ch
+
+    def parse_variable(self) -> Variable:
+        var_name = ""
+        while ch := self.read():
+            if ch == "}":
+                break
+            var_name += ch
+
+        _ = is_valid_source_variable_name(var_name, raise_exception=True)
+        return Variable(var_name)
+
+    def parse_function(self) -> Function:
+        parenthesis_counter = 0
+        func_name = ""
+        func_args = ""
+
+        while ch := self.read():
+            if ch not in ['(', ')']:
+                if parenthesis_counter > 0:
+                    func_args += ch
+                else:
+                    func_name += ch
+            elif ch == '(':
+                parenthesis_counter += 1
+            elif ch == ')':
+                parenthesis_counter -= 1
+                if parenthesis_counter == 0:
+                    break
+
+
+
+
+
+
+
+    def parse(self):
+        while True:
+            ch = self.read()
+            if ch == '{':
+                self.parse_variable()
+            if ch == '%':
+                self.parse_function()
+
+