def test_string():
program = ast.Program(statements=[
ast.LetStatement(token=tokens.Token(typ=tokens.LET, literal="let"),
name=ast.Identifier(token=tokens.Token(
typ=tokens.IDENT, literal="my_var"),
value="my_var"),
value=ast.Identifier(token=tokens.Token(
typ=tokens.IDENT, literal="another_var"),
value="another_var"))
])
expected = "let my_var = another_var;"
assert str(
program
) == expected, f"str(program) wrong. got '{str(program)}'' but expected '{expected}'"
def parse_for_expression(self) -> ast.Expression:
cur_token = self.cur_token
if not self.expect_peek(tokens.LPAREN):
return None
self.next_token()
ident = ast.Identifier(token=self.cur_token,
value=self.cur_token.literal)
if not self.expect_peek(tokens.IN):
return None
self.next_token()
iterator = self.parse_expression(LOWEST)
if not self.expect_peek(tokens.RPAREN):
return None
if not self.expect_peek(tokens.LBRACE):
return None
body = self.parse_block_statement()
return ast.ForExpression(token=cur_token,
iterator=iterator,
element=ident,
body=body)
def parse_function_parameters(self):
identifiers = []
if self.peek_token_is(TokenType.RParen):
self.next_token()
return identifiers
self.next_token()
ident = ast.Identifier(self.cur_token, self.cur_token.literal)
identifiers.append(ident)
while self.peek_token_is(TokenType.Comma):
self.next_token()
self.next_token()
ident = ast.Identifier(self.cur_token, self.cur_token.literal)
identifiers.append(ident)
if not self.expect_peek(TokenType.RParen):
return None
return identifiers
def parse_function_parameters(self) -> List[ast.Identifier]:
identifiers: List[ast.Identifier] = []
if self.peek_token_is(tokens.RPAREN):
self.next_token()
return identifiers
self.next_token()
ident: ast.Identifier = ast.Identifier(token=self.cur_token,
value=self.cur_token.literal)
identifiers.append(ident)
while self.peek_token_is(tokens.COMMA):
self.next_token()
self.next_token()
ident = ast.Identifier(token=self.cur_token,
value=self.cur_token.literal)
identifiers.append(ident)
if not self.expect_peek(tokens.RPAREN):
return None
return identifiers
def parse_let_statement(self):
tok = self.cur_token
if not self.expect_peek(TokenType.Ident):
return None
name = ast.Identifier(self.cur_token, self.cur_token.literal)
if not self.expect_peek(TokenType.Assign):
return None
self.next_token()
value = self.parse_expression(Precedence.LOWEST)
if self.peek_token_is(TokenType.Semicolon):
self.next_token()
return ast.LetStatement(tok, name, value)
def parse_let_statement(self):
statement = ast.LetStatement(token=self.cur_token)
if not self.expect_peek(tokens.IDENT):
return None
statement.name = ast.Identifier(token=self.cur_token,
value=self.cur_token.literal)
if not self.expect_peek(tokens.ASSIGN):
return None
self.next_token()
statement.value = self.parse_expression(LOWEST)
if self.peek_token_is(tokens.SEMICOLON):
self.next_token()
return statement
def parse_identifier(self) -> ast.Expression:
return ast.Identifier(token=self.cur_token,
value=self.cur_token.literal)
def parse_identifier(self):
return ast.Identifier(self.cur_token, self.cur_token.literal)