@@ -0,0 +1,160 @@
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/#use-with-ide
+.pdm.toml
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/

@@ -0,0 +1,50 @@
+from typing import Any
+
+from structs import Program, ASTNodeTypes, BinaryExpression, TokenTypes, AST, UnaryExpression
+
+
+class Interpreter:
+    _ast: Program
+
+    def __init__(self, ast):
+        self._ast = ast
+
+    def run(self):
+        for expr in self._ast.body:
+            print(self._run_expr(expr))
+
+    def _run_expr(self, expr: AST):
+        match expr.type:
+            case ASTNodeTypes.Literal:
+                return expr.value
+            case ASTNodeTypes.BinaryExpression:
+                return self._run_binary(expr)
+            case ASTNodeTypes.UnaryExpression:
+                return self._run_unary(expr)
+            case other:
+                raise Exception('Unknown type of expression.')
+
+    def _run_binary(self, expr: BinaryExpression) -> Any:
+        left = self._run_expr(expr.left)
+        right = self._run_expr(expr.right)
+        match expr.operator.type:
+            case TokenTypes.PLUS:
+                return left + right
+            case TokenTypes.MINUS:
+                return left - right
+            case TokenTypes.MULT:
+                return left * right
+            case TokenTypes.DIV:
+                return left / right
+            case other:
+                raise Exception('Operator not supported')
+
+    def _run_unary(self, expr: UnaryExpression) -> Any:
+        value = self._run_expr(expr.value)
+        match expr.operator.type:
+            case TokenTypes.PLUS:
+                return value
+            case TokenTypes.MINUS:
+                return -value
+            case other:
+                raise Exception('Operator not supported')

@@ -0,0 +1,69 @@
+from typing import List
+
+from structs import TokenTypes, Token
+
+
+KEYS_TO_TOKENS = {
+    '+': TokenTypes.PLUS,
+    '-': TokenTypes.MINUS,
+    '*': TokenTypes.MULT,
+    '/': TokenTypes.DIV,
+    '(': TokenTypes.OPEN_PAREN,
+    ')': TokenTypes.CLOSE_PAREN
+}
+
+
+class Lexer:
+    _offset: int = 0
+    _string: str
+    _line: int = 1
+
+    @property
+    def _current(self):
+        return self._string[self._offset]
+
+    @property
+    def _previous(self):
+        return self._string[self._offset - 1]
+
+    def __init__(self, string: str):
+        self._string = string
+
+    def _lex_number(self) -> Token:
+        number_str = ''
+        did_dot_appear = False
+
+        while self._current.isdigit() or self._current == '.':
+            if self._current == '.':
+                did_dot_appear = True
+            number_str += self._current
+            self._offset += 1
+
+        if did_dot_appear:
+            return Token(TokenTypes.FLOAT, float(number_str), self._line)
+        else:
+            return Token(TokenTypes.INT, int(number_str), self._line)
+
+    def next(self) -> Token:
+        if self._offset >= len(self._string):
+            return Token(TokenTypes.EOF, None, self._line)
+
+        if self._current == '\n':
+            self._line += 1
+            self._offset += 1
+            return self.next()
+        elif self._current.isspace():
+            self._offset += 1
+            return self.next()
+        elif self._current.isdigit() or self._current == '.':
+            return self._lex_number()
+        elif self._current in KEYS_TO_TOKENS:
+            self._offset += 1
+            return Token(KEYS_TO_TOKENS[self._previous], self._previous, self._line)
+        raise Exception(f'Invalid token "{self._current}".')
+
+    def lex(self) -> List[Token]:
+        tokens = []
+        while (token := self.next()).type != TokenTypes.EOF:
+            tokens.append(token)
+        return tokens

@@ -0,0 +1,28 @@
+import sys
+
+from intepreter import Interpreter
+from lexer import Lexer
+from parser import Parser
+
+
+def main():
+    print('->', end=' ')
+    sys.stdout.flush()
+    for line in sys.stdin:
+        lexer = Lexer(line)
+        tokens = lexer.lex()
+        # for token in tokens:
+        #     print(token)
+
+        parser = Parser(tokens)
+        ast = parser.parse()
+        # print(ast)
+
+        interpreter = Interpreter(ast)
+        interpreter.run()
+        print('->', end=' ')
+        sys.stdout.flush()
+
+
+if __name__ == '__main__':
+    main()

@@ -0,0 +1,71 @@
+from typing import List
+
+from structs import (Token, AST, Program, ExpressionStatement, UnaryExpression, BinaryExpression, Literal, ASTNodeTypes,
+                     TokenTypes)
+
+
+class Parser:
+    _tokens: List[Token]
+    _index: int = 0
+
+    @property
+    def _current(self) -> Token:
+        return self._tokens[self._index]
+
+    @property
+    def _previous(self) -> Token:
+        return self._tokens[self._index - 1]
+
+    def __init__(self, tokens: List[Token]):
+        self._tokens = tokens
+
+    def parse(self):
+        ast: Program = Program(ASTNodeTypes.Program, [])
+
+        while self._index < len(self._tokens):
+            ast.body.append(self._plus_minus())
+
+        return ast
+
+    def _match(self, *args: TokenTypes):
+        if value := (self._index < len(self._tokens) and self._current.type in args):
+            self._index += 1
+        return value
+
+    def _plus_minus(self) -> Literal:
+        expr = self._mult_div()
+
+        while self._match(TokenTypes.PLUS, TokenTypes.MINUS):
+            operator = self._previous
+            right = self._plus_minus()
+            expr = BinaryExpression(expr, right, operator)
+
+        return expr
+
+    def _mult_div(self) -> Literal:
+        expr = self._unary()
+
+        while self._match(TokenTypes.MULT, TokenTypes.DIV):
+            operator = self._previous
+            right = self._mult_div()
+            expr = BinaryExpression(expr, right, operator)
+
+        return expr
+
+    def _unary(self) -> Literal:
+        while self._match(TokenTypes.PLUS, TokenTypes.MINUS):
+            operator = self._previous
+            value = self._unary()
+            return UnaryExpression(operator, value)
+
+        return self._literal()
+
+    def _literal(self) -> Literal:
+        if self._match(TokenTypes.INT, TokenTypes.FLOAT):
+            return Literal(self._previous.value)
+
+        if self._match(TokenTypes.OPEN_PAREN):
+            expr = self._plus_minus()
+            if not self._match(TokenTypes.CLOSE_PAREN):
+                raise Exception(f'Expected for close parentheses ")" at line {self._previous.line}.')
+            return expr

@@ -0,0 +1,77 @@
+from dataclasses import dataclass
+from typing import Any, List
+from enum import auto, IntEnum
+
+
+class TokenTypes(IntEnum):
+    INT = auto()
+    FLOAT = auto()
+    PLUS = auto()
+    MINUS = auto()
+    MULT = auto()
+    DIV = auto()
+    OPEN_PAREN = auto()
+    CLOSE_PAREN = auto()
+    EOF = auto()
+
+
+@dataclass()
+class Token:
+    type: TokenTypes
+    value: Any
+    line: int
+
+
+class ASTNodeTypes(IntEnum):
+    Program = auto()
+    ExpressionStatement = auto()
+    BinaryExpression = auto()
+    UnaryExpression = auto()
+    Literal = auto()
+
+
+@dataclass()
+class AST:
+    type: ASTNodeTypes
+
+
+@dataclass()
+class Program(AST):
+    body: List[AST]
+
+
+@dataclass()
+class ExpressionStatement(AST):
+    expression: AST
+
+
+@dataclass()
+class Literal(AST):
+    value: Any
+
+    def __init__(self, value: Any):
+        self.type = ASTNodeTypes.Literal
+        self.value = value
+
+
+@dataclass()
+class BinaryExpression(AST):
+    left: Literal
+    right: Literal
+    operator: Token
+
+    def __init__(self, left: Literal, right: Literal, operator: Token):
+        self.type = ASTNodeTypes.BinaryExpression
+        self.left = left
+        self.right = right
+        self.operator = operator
+
+
+@dataclass()
+class UnaryExpression(Literal):
+    operator: Token
+
+    def __init__(self, operator: Token, value: Any):
+        self.type = ASTNodeTypes.UnaryExpression
+        self.operator = operator
+        self.value = value