#!/usr/bin/env python3 """ Tiny Language Interpreter A complete interpreter implementation with lexer, parser, and evaluator. """ from enum import Enum, auto from dataclasses import dataclass from typing import Any, List, Dict, Optional, Callable import re # ============================================================================ # TOKENIZER/LEXER # ============================================================================ class TokenType(Enum): # Literals NUMBER = auto() STRING = auto() TRUE = auto() FALSE = auto() NULL = auto() # Identifiers and keywords IDENTIFIER = auto() IF = auto() ELSE = auto() WHILE = auto() FUNCTION = auto() RETURN = auto() LET = auto() # Operators PLUS = auto() MINUS = auto() STAR = auto() SLASH = auto() PERCENT = auto() # Comparison EQ = auto() # == NE = auto() # != LT = auto() # < GT = auto() # > LE = auto() # <= GE = auto() # >= # Logical AND = auto() OR = auto() NOT = auto() # Assignment ASSIGN = auto() # = # Delimiters LPAREN = auto() RPAREN = auto() LBRACE = auto() RBRACE = auto() COMMA = auto() SEMICOLON = auto() # Special EOF = auto() NEWLINE = auto() @dataclass class Token: type: TokenType value: Any line: int column: int class Lexer: def __init__(self, source: str): self.source = source self.pos = 0 self.line = 1 self.column = 1 self.tokens: List[Token] = [] self.keywords = { 'if': TokenType.IF, 'else': TokenType.ELSE, 'while': TokenType.WHILE, 'function': TokenType.FUNCTION, 'fn': TokenType.FUNCTION, 'return': TokenType.RETURN, 'true': TokenType.TRUE, 'false': TokenType.FALSE, 'null': TokenType.NULL, 'and': TokenType.AND, 'or': TokenType.OR, 'not': TokenType.NOT, 'let': TokenType.LET, } def current_char(self) -> Optional[str]: if self.pos >= len(self.source): return None return self.source[self.pos] def peek(self, offset: int = 1) -> Optional[str]: pos = self.pos + offset if pos >= len(self.source): return None return self.source[pos] def advance(self) -> Optional[str]: if self.pos >= len(self.source): return None char = self.source[self.pos] self.pos += 1 if char == '\n': self.line += 1 self.column = 1 else: self.column += 1 return char def skip_whitespace(self): while self.current_char() and self.current_char() in ' \t\r\n': self.advance() def skip_comment(self): # Handle both # and // comments while self.current_char() and self.current_char() != '\n': self.advance() def read_number(self) -> Token: start_line, start_col = self.line, self.column num_str = '' has_dot = False while self.current_char() and (self.current_char().isdigit() or self.current_char() == '.'): if self.current_char() == '.': if has_dot: break has_dot = True num_str += self.current_char() self.advance() value = float(num_str) if has_dot else int(num_str) return Token(TokenType.NUMBER, value, start_line, start_col) def read_string(self, quote: str) -> Token: start_line, start_col = self.line, self.column self.advance() # skip opening quote string_val = '' while self.current_char() and self.current_char() != quote: if self.current_char() == '\\': self.advance() next_char = self.current_char() if next_char == 'n': string_val += '\n' elif next_char == 't': string_val += '\t' elif next_char == '\\': string_val += '\\' elif next_char == quote: string_val += quote else: string_val += next_char self.advance() else: string_val += self.current_char() self.advance() if self.current_char() == quote: self.advance() # skip closing quote return Token(TokenType.STRING, string_val, start_line, start_col) def read_identifier(self) -> Token: start_line, start_col = self.line, self.column id_str = '' while self.current_char() and (self.current_char().isalnum() or self.current_char() == '_'): id_str += self.current_char() self.advance() token_type = self.keywords.get(id_str, TokenType.IDENTIFIER) value = id_str if token_type == TokenType.IDENTIFIER else None return Token(token_type, value, start_line, start_col) def tokenize(self) -> List[Token]: while self.pos < len(self.source): self.skip_whitespace() if self.current_char() is None: break # Comments: # or // if self.current_char() == '#': self.skip_comment() continue if self.current_char() == '/' and self.peek() == '/': self.skip_comment() continue start_line, start_col = self.line, self.column char = self.current_char() # Numbers if char.isdigit(): self.tokens.append(self.read_number()) continue # Strings if char in '"\'': self.tokens.append(self.read_string(char)) continue # Identifiers and keywords if char.isalpha() or char == '_': self.tokens.append(self.read_identifier()) continue # Two-character operators if char == '=' and self.peek() == '=': self.advance() self.advance() self.tokens.append(Token(TokenType.EQ, None, start_line, start_col)) continue if char == '!' and self.peek() == '=': self.advance() self.advance() self.tokens.append(Token(TokenType.NE, None, start_line, start_col)) continue if char == '<' and self.peek() == '=': self.advance() self.advance() self.tokens.append(Token(TokenType.LE, None, start_line, start_col)) continue if char == '>' and self.peek() == '=': self.advance() self.advance() self.tokens.append(Token(TokenType.GE, None, start_line, start_col)) continue # Single-character tokens single_char_tokens = { '+': TokenType.PLUS, '-': TokenType.MINUS, '*': TokenType.STAR, '/': TokenType.SLASH, '%': TokenType.PERCENT, '=': TokenType.ASSIGN, '<': TokenType.LT, '>': TokenType.GT, '(': TokenType.LPAREN, ')': TokenType.RPAREN, '{': TokenType.LBRACE, '}': TokenType.RBRACE, ',': TokenType.COMMA, ';': TokenType.SEMICOLON, } if char in single_char_tokens: self.advance() self.tokens.append(Token(single_char_tokens[char], None, start_line, start_col)) continue # Unknown character - skip it self.advance() self.tokens.append(Token(TokenType.EOF, None, self.line, self.column)) return self.tokens # ============================================================================ # ABSTRACT SYNTAX TREE (AST) # ============================================================================ @dataclass class ASTNode: pass @dataclass class NumberLiteral(ASTNode): value: float @dataclass class StringLiteral(ASTNode): value: str @dataclass class BooleanLiteral(ASTNode): value: bool @dataclass class NullLiteral(ASTNode): pass @dataclass class Identifier(ASTNode): name: str @dataclass class BinaryOp(ASTNode): left: ASTNode operator: TokenType right: ASTNode @dataclass class UnaryOp(ASTNode): operator: TokenType operand: ASTNode @dataclass class Assignment(ASTNode): name: str value: ASTNode @dataclass class LetDeclaration(ASTNode): name: str value: ASTNode @dataclass class IfStatement(ASTNode): condition: ASTNode then_block: List[ASTNode] else_block: Optional[List[ASTNode]] @dataclass class WhileStatement(ASTNode): condition: ASTNode body: List[ASTNode] @dataclass class FunctionDef(ASTNode): name: Optional[str] params: List[str] body: List[ASTNode] @dataclass class FunctionCall(ASTNode): function: ASTNode arguments: List[ASTNode] @dataclass class ReturnStatement(ASTNode): value: Optional[ASTNode] @dataclass class Program(ASTNode): statements: List[ASTNode] # ============================================================================ # PARSER # ============================================================================ class Parser: def __init__(self, tokens: List[Token]): self.tokens = tokens self.pos = 0 def current_token(self) -> Token: if self.pos >= len(self.tokens): return self.tokens[-1] # EOF return self.tokens[self.pos] def peek(self, offset: int = 1) -> Token: pos = self.pos + offset if pos >= len(self.tokens): return self.tokens[-1] # EOF return self.tokens[pos] def advance(self) -> Token: token = self.current_token() if self.pos < len(self.tokens) - 1: self.pos += 1 return token def expect(self, token_type: TokenType) -> Token: token = self.current_token() if token.type != token_type: raise SyntaxError(f"Expected {token_type}, got {token.type}") return self.advance() def parse(self) -> Program: statements = [] while self.current_token().type != TokenType.EOF: stmt = self.parse_statement() if stmt: statements.append(stmt) return Program(statements) def parse_statement(self) -> Optional[ASTNode]: token = self.current_token() # Skip semicolons if token.type == TokenType.SEMICOLON: self.advance() return None # Let declaration if token.type == TokenType.LET: return self.parse_let_declaration() # If statement if token.type == TokenType.IF: return self.parse_if_statement() # While statement if token.type == TokenType.WHILE: return self.parse_while_statement() # Function definition if token.type == TokenType.FUNCTION: return self.parse_function_def() # Return statement if token.type == TokenType.RETURN: self.advance() value = None if self.current_token().type not in [TokenType.SEMICOLON, TokenType.EOF, TokenType.RBRACE]: value = self.parse_expression() if self.current_token().type == TokenType.SEMICOLON: self.advance() return ReturnStatement(value) # Expression statement (including assignment) expr = self.parse_expression() if self.current_token().type == TokenType.SEMICOLON: self.advance() return expr def parse_let_declaration(self) -> LetDeclaration: self.expect(TokenType.LET) name = self.expect(TokenType.IDENTIFIER).value self.expect(TokenType.ASSIGN) value = self.parse_expression() if self.current_token().type == TokenType.SEMICOLON: self.advance() return LetDeclaration(name, value) def parse_if_statement(self) -> IfStatement: self.expect(TokenType.IF) # Parens are optional around condition has_paren = self.current_token().type == TokenType.LPAREN if has_paren: self.advance() condition = self.parse_expression() if has_paren: self.expect(TokenType.RPAREN) then_block = self.parse_block() else_block = None if self.current_token().type == TokenType.ELSE: self.advance() # Support "else if" chaining if self.current_token().type == TokenType.IF: else_block = [self.parse_if_statement()] else: else_block = self.parse_block() return IfStatement(condition, then_block, else_block) def parse_while_statement(self) -> WhileStatement: self.expect(TokenType.WHILE) # Parens are optional around condition has_paren = self.current_token().type == TokenType.LPAREN if has_paren: self.advance() condition = self.parse_expression() if has_paren: self.expect(TokenType.RPAREN) body = self.parse_block() return WhileStatement(condition, body) def parse_block(self) -> List[ASTNode]: if self.current_token().type == TokenType.LBRACE: self.advance() statements = [] while self.current_token().type != TokenType.RBRACE: if self.current_token().type == TokenType.EOF: raise SyntaxError("Unexpected EOF in block") stmt = self.parse_statement() if stmt: statements.append(stmt) self.expect(TokenType.RBRACE) return statements else: # Single statement stmt = self.parse_statement() return [stmt] if stmt else [] def parse_function_def(self) -> FunctionDef: self.expect(TokenType.FUNCTION) # Function name (optional for anonymous functions) name = None if self.current_token().type == TokenType.IDENTIFIER: name = self.current_token().value self.advance() self.expect(TokenType.LPAREN) # Parameters params = [] while self.current_token().type != TokenType.RPAREN: if self.current_token().type == TokenType.IDENTIFIER: params.append(self.current_token().value) self.advance() if self.current_token().type == TokenType.COMMA: self.advance() else: break self.expect(TokenType.RPAREN) # Body body = self.parse_block() return FunctionDef(name, params, body) def parse_expression(self) -> ASTNode: # Check for assignment: IDENTIFIER = expression if self.current_token().type == TokenType.IDENTIFIER and self.peek().type == TokenType.ASSIGN: name = self.current_token().value self.advance() self.advance() # skip = value = self.parse_expression() return Assignment(name, value) return self.parse_logical_or() def parse_logical_or(self) -> ASTNode: left = self.parse_logical_and() while self.current_token().type == TokenType.OR: op = self.current_token().type self.advance() right = self.parse_logical_and() left = BinaryOp(left, op, right) return left def parse_logical_and(self) -> ASTNode: left = self.parse_equality() while self.current_token().type == TokenType.AND: op = self.current_token().type self.advance() right = self.parse_equality() left = BinaryOp(left, op, right) return left def parse_equality(self) -> ASTNode: left = self.parse_comparison() while self.current_token().type in [TokenType.EQ, TokenType.NE]: op = self.current_token().type self.advance() right = self.parse_comparison() left = BinaryOp(left, op, right) return left def parse_comparison(self) -> ASTNode: left = self.parse_additive() while self.current_token().type in [TokenType.LT, TokenType.GT, TokenType.LE, TokenType.GE]: op = self.current_token().type self.advance() right = self.parse_additive() left = BinaryOp(left, op, right) return left def parse_additive(self) -> ASTNode: left = self.parse_multiplicative() while self.current_token().type in [TokenType.PLUS, TokenType.MINUS]: op = self.current_token().type self.advance() right = self.parse_multiplicative() left = BinaryOp(left, op, right) return left def parse_multiplicative(self) -> ASTNode: left = self.parse_unary() while self.current_token().type in [TokenType.STAR, TokenType.SLASH, TokenType.PERCENT]: op = self.current_token().type self.advance() right = self.parse_unary() left = BinaryOp(left, op, right) return left def parse_unary(self) -> ASTNode: if self.current_token().type in [TokenType.MINUS, TokenType.NOT]: op = self.current_token().type self.advance() operand = self.parse_unary() return UnaryOp(op, operand) return self.parse_postfix() def parse_postfix(self) -> ASTNode: expr = self.parse_primary() # Function call while self.current_token().type == TokenType.LPAREN: self.advance() arguments = [] while self.current_token().type != TokenType.RPAREN: arguments.append(self.parse_expression()) if self.current_token().type == TokenType.COMMA: self.advance() elif self.current_token().type != TokenType.RPAREN: break self.expect(TokenType.RPAREN) expr = FunctionCall(expr, arguments) return expr def parse_primary(self) -> ASTNode: token = self.current_token() # Number if token.type == TokenType.NUMBER: self.advance() return NumberLiteral(token.value) # String if token.type == TokenType.STRING: self.advance() return StringLiteral(token.value) # Boolean if token.type == TokenType.TRUE: self.advance() return BooleanLiteral(True) if token.type == TokenType.FALSE: self.advance() return BooleanLiteral(False) # Null if token.type == TokenType.NULL: self.advance() return NullLiteral() # Identifier if token.type == TokenType.IDENTIFIER: self.advance() return Identifier(token.value) # Parenthesized expression if token.type == TokenType.LPAREN: self.advance() expr = self.parse_expression() self.expect(TokenType.RPAREN) return expr # Anonymous function if token.type == TokenType.FUNCTION: return self.parse_function_def() raise SyntaxError(f"Unexpected token: {token.type}") # ============================================================================ # ENVIRONMENT (SCOPE CHAIN) # ============================================================================ class Environment: def __init__(self, parent: Optional['Environment'] = None): self.parent = parent self.bindings: Dict[str, Any] = {} def define(self, name: str, value: Any): self.bindings[name] = value def get(self, name: str) -> Any: if name in self.bindings: return self.bindings[name] if self.parent: return self.parent.get(name) raise NameError(f"Undefined variable: {name}") def set(self, name: str, value: Any): if name in self.bindings: self.bindings[name] = value elif self.parent: self.parent.set(name, value) else: # Allow creating new variables at top level self.bindings[name] = value # ============================================================================ # EVALUATOR # ============================================================================ class ReturnValue(Exception): """Exception used to implement return statements""" def __init__(self, value: Any): self.value = value @dataclass class Function: """Runtime representation of a function""" name: Optional[str] params: List[str] body: List[ASTNode] closure: Environment # Captured environment class Evaluator: def __init__(self): self.global_env = Environment() self.setup_builtins() def setup_builtins(self): """Setup built-in functions""" def builtin_print(*args): print(*args) return None def builtin_len(obj): if isinstance(obj, str): return len(obj) raise TypeError(f"len() not supported for {type(obj)}") def builtin_type(obj): if obj is None: return "null" elif isinstance(obj, bool): return "boolean" elif isinstance(obj, int): return "integer" elif isinstance(obj, float): return "float" elif isinstance(obj, str): return "string" elif isinstance(obj, Function): return "function" else: return "unknown" self.global_env.define('print', builtin_print) self.global_env.define('len', builtin_len) self.global_env.define('type', builtin_type) def eval(self, node: ASTNode, env: Environment) -> Any: # Literals if isinstance(node, NumberLiteral): return node.value if isinstance(node, StringLiteral): return node.value if isinstance(node, BooleanLiteral): return node.value if isinstance(node, NullLiteral): return None # Identifier if isinstance(node, Identifier): return env.get(node.name) # Binary operations if isinstance(node, BinaryOp): left = self.eval(node.left, env) right = self.eval(node.right, env) if node.operator == TokenType.PLUS: return left + right elif node.operator == TokenType.MINUS: return left - right elif node.operator == TokenType.STAR: return left * right elif node.operator == TokenType.SLASH: if right == 0: raise ZeroDivisionError("Division by zero") return left / right elif node.operator == TokenType.PERCENT: if right == 0: raise ZeroDivisionError("Modulo by zero") return left % right elif node.operator == TokenType.EQ: return left == right elif node.operator == TokenType.NE: return left != right elif node.operator == TokenType.LT: return left < right elif node.operator == TokenType.GT: return left > right elif node.operator == TokenType.LE: return left <= right elif node.operator == TokenType.GE: return left >= right elif node.operator == TokenType.AND: return left and right elif node.operator == TokenType.OR: return left or right # Unary operations if isinstance(node, UnaryOp): operand = self.eval(node.operand, env) if node.operator == TokenType.MINUS: return -operand elif node.operator == TokenType.NOT: return not operand # Let declaration - defines in current scope if isinstance(node, LetDeclaration): value = self.eval(node.value, env) env.define(node.name, value) return value # Assignment - updates existing variable in scope chain if isinstance(node, Assignment): value = self.eval(node.value, env) env.set(node.name, value) return value # If statement if isinstance(node, IfStatement): condition = self.eval(node.condition, env) if condition: return self.eval_block(node.then_block, env) elif node.else_block: return self.eval_block(node.else_block, env) return None # While statement if isinstance(node, WhileStatement): result = None while self.eval(node.condition, env): result = self.eval_block(node.body, env) return result # Function definition if isinstance(node, FunctionDef): func = Function(node.name, node.params, node.body, env) if node.name: env.define(node.name, func) return func # Function call if isinstance(node, FunctionCall): func = self.eval(node.function, env) args = [self.eval(arg, env) for arg in node.arguments] # Built-in function (Python callable) if callable(func) and not isinstance(func, Function): return func(*args) # User-defined function if isinstance(func, Function): if len(args) != len(func.params): raise TypeError(f"Function expects {len(func.params)} arguments, got {len(args)}") # Create new environment for function execution with closure as parent func_env = Environment(func.closure) # Bind parameters for param, arg in zip(func.params, args): func_env.define(param, arg) # Execute function body try: self.eval_block(func.body, func_env) return None # No explicit return except ReturnValue as ret: return ret.value raise TypeError(f"Cannot call non-function value") # Return statement if isinstance(node, ReturnStatement): value = None if node.value is None else self.eval(node.value, env) raise ReturnValue(value) # Program if isinstance(node, Program): return self.eval_block(node.statements, env) raise RuntimeError(f"Unknown node type: {type(node)}") def eval_block(self, statements: List[ASTNode], env: Environment) -> Any: result = None for stmt in statements: result = self.eval(stmt, env) return result def run(self, source: str) -> Any: lexer = Lexer(source) tokens = lexer.tokenize() parser = Parser(tokens) ast = parser.parse() return self.eval(ast, self.global_env) # ============================================================================ # MAIN / TESTING # ============================================================================ def main(): """Run test programs from the battle prompt""" interpreter = Evaluator() # Test 1: Fibonacci with recursion print("=" * 60) print("Test 1: Fibonacci Recursion") print("=" * 60) test1 = """ // Test 1: Fibonacci with recursion fn fib(n) { if n <= 1 { return n } return fib(n - 1) + fib(n - 2) } print(fib(10)) """ interpreter.run(test1) print() # Test 2: Closure - counter factory print("=" * 60) print("Test 2: Closure Counter Factory") print("=" * 60) test2 = """ // Test 2: Closure - counter factory fn make_counter() { let count = 0 fn increment() { count = count + 1 return count } return increment } let counter = make_counter() print(counter()) print(counter()) print(counter()) """ interpreter.run(test2) print() # Test 3: Higher-order functions print("=" * 60) print("Test 3: Higher-Order Functions") print("=" * 60) test3 = """ // Test 3: Higher-order functions fn apply_twice(f, x) { return f(f(x)) } fn double(x) { return x * 2 } print(apply_twice(double, 3)) """ interpreter.run(test3) print() # Test 4: String operations print("=" * 60) print("Test 4: String Operations") print("=" * 60) test4 = """ // Test 4: String operations let greeting = "Hello" + " " + "World" print(greeting) print(len(greeting)) """ interpreter.run(test4) print() # Test 5: Complex control flow print("=" * 60) print("Test 5: Complex Control Flow") print("=" * 60) test5 = """ // Test 5: Complex control flow let sum = 0 let i = 1 while i <= 100 { if i % 3 == 0 and i % 5 == 0 { sum = sum + i } i = i + 1 } print(sum) """ interpreter.run(test5) print() if __name__ == '__main__': main()

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