fix(parser)!: remove annotation lexer and parser

core/ast/annotations.py

@@ -1,107 +0,0 @@
-from __future__ import annotations
-
-from abc import ABC, abstractmethod
-from dataclasses import dataclass
-from typing import Any, Generic, Optional, TypeVar
-
-from lexer.token import Token
-
-T = TypeVar("T")
-
-
-@dataclass(frozen=True)
-class Stmt(ABC):
-    @abstractmethod
-    def accept(self, visitor: Visitor[T]) -> T: ...
-
-    class Visitor(ABC, Generic[T]):
-        @abstractmethod
-        def visit_annotation_stmt(self, stmt: AnnotationStmt) -> T: ...
-
-
-@dataclass(frozen=True)
-class AnnotationStmt(Stmt):
-    name: Token
-    schema: Optional[SchemaExpr]
-
-    def accept(self, visitor: Stmt.Visitor[T]) -> T:
-        return visitor.visit_annotation_stmt(self)
-
-
-@dataclass(frozen=True)
-class Expr(ABC):
-    @abstractmethod
-    def accept(self, visitor: Visitor[T]) -> T: ...
-
-    class Visitor(ABC, Generic[T]):
-        @abstractmethod
-        def visit_wildcard_expr(self, expr: WildcardExpr) -> T: ...
-
-        @abstractmethod
-        def visit_literal_expr(self, expr: LiteralExpr) -> T: ...
-
-        @abstractmethod
-        def visit_type_expr(self, expr: TypeExpr) -> T: ...
-
-        @abstractmethod
-        def visit_constraint_expr(self, expr: ConstraintExpr) -> T: ...
-
-        @abstractmethod
-        def visit_schema_expr(self, expr: SchemaExpr) -> T: ...
-
-        @abstractmethod
-        def visit_schema_element_expr(self, expr: SchemaElementExpr) -> T: ...
-
-
-@dataclass(frozen=True)
-class WildcardExpr(Expr):
-    token: Token
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_wildcard_expr(self)
-
-
-@dataclass(frozen=True)
-class LiteralExpr(Expr):
-    value: Any
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_literal_expr(self)
-
-
-@dataclass(frozen=True)
-class TypeExpr(Expr):
-    name: Token
-    constraints: list[ConstraintExpr]
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_type_expr(self)
-
-
-@dataclass(frozen=True)
-class ConstraintExpr(Expr):
-    left: Expr
-    op: Token
-    right: Expr
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_constraint_expr(self)
-
-
-@dataclass(frozen=True)
-class SchemaExpr(Expr):
-    left: Token
-    elements: list[Expr]
-    right: Token
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_schema_expr(self)
-
-
-@dataclass(frozen=True)
-class SchemaElementExpr(Expr):
-    name: Optional[Token]
-    type: Optional[Expr]
-
-    def accept(self, visitor: Expr.Visitor[T]) -> T:
-        return visitor.visit_schema_element_expr(self)

core/ast/printer.py

@@ -1,11 +1,10 @@
 from __future__ import annotations
 
+import io
 from contextlib import contextmanager
 from enum import Enum, auto
-import io
 from typing import Generator, Generic, Optional, Protocol, TypeVar
 
-import core.ast.annotations as a
 import core.ast.midas as m
 
 
@@ -84,113 +83,6 @@ class AstPrinter(Generic[T]):
                 child.accept(self)
 
 
-class AnnotationAstPrinter(AstPrinter, a.Expr.Visitor[None], a.Stmt.Visitor[None]):
-    def visit_annotation_stmt(self, stmt: a.AnnotationStmt) -> None:
-        self._write_line("AnnotationStmt")
-        with self._child_level():
-            self._write_line(f'name: "{stmt.name.lexeme}"')
-            self._write_optional_child("schema", stmt.schema, last=True)
-
-    def visit_type_expr(self, expr: a.TypeExpr):
-        self._write_line("TypeExpr")
-        with self._child_level():
-            self._write_line(f'name: "{expr.name.lexeme}"')
-            self._write_line("constraints", last=True)
-            with self._child_level():
-                for i, constraint in enumerate(expr.constraints):
-                    self._idx = i
-                    if i == len(expr.constraints) - 1:
-                        self._mark_last()
-                    constraint.accept(self)
-
-    def visit_constraint_expr(self, expr: a.ConstraintExpr) -> None:
-        self._write_line("ConstraintExpr")
-        with self._child_level():
-            self._write_line("left")
-            with self._child_level():
-                self._mark_last()
-                expr.left.accept(self)
-
-            self._write_line(f"operator: {expr.op.lexeme}")
-
-            self._write_line("right", last=True)
-            with self._child_level():
-                self._mark_last()
-                expr.right.accept(self)
-
-    def visit_schema_expr(self, expr: a.SchemaExpr):
-        self._write_line("SchemaExpr")
-        with self._child_level():
-            for i, elmt in enumerate(expr.elements):
-                self._idx = i
-                if i == len(expr.elements) - 1:
-                    self._mark_last()
-                elmt.accept(self)
-
-    def visit_schema_element_expr(self, expr: a.SchemaElementExpr):
-        self._write_line("SchemaElementExpr")
-        with self._child_level():
-            name_text: str = "None" if expr.name is None else f'"{expr.name.lexeme}"'
-            self._write_line(f"name: {name_text}")
-            self._write_optional_child("type", expr.type, last=True)
-
-    def visit_wildcard_expr(self, expr: a.WildcardExpr) -> None:
-        self._write_line("WildcardExpr")
-
-    def visit_literal_expr(self, expr: a.LiteralExpr) -> None:
-        self._write_line("LiteralExpr")
-        with self._child_level():
-            self._write_line(f"value: {expr.value}", last=True)
-
-
-class AnnotationPrinter(a.Expr.Visitor[str], a.Stmt.Visitor[str]):
-    def print(self, expr: a.Expr | a.Stmt):
-        return expr.accept(self)
-
-    def visit_annotation_stmt(self, stmt: a.AnnotationStmt) -> str:
-        schema: str = ""
-        if stmt.schema is not None:
-            schema = stmt.schema.accept(self)
-        return f"{stmt.name.lexeme}{schema}"
-
-    def visit_type_expr(self, expr: a.TypeExpr) -> str:
-        parts: list[str] = [expr.name.lexeme]
-        for constraint in expr.constraints:
-            parts.append("(" + constraint.accept(self) + ")")
-        return " + ".join(parts)
-
-    def visit_constraint_expr(self, expr: a.ConstraintExpr) -> str:
-        parts: list[str] = [
-            expr.left.accept(self),
-            expr.op.lexeme,
-            expr.right.accept(self),
-        ]
-        return " ".join(parts)
-
-    def visit_schema_expr(self, expr: a.SchemaExpr) -> str:
-        res: str = expr.left.lexeme
-        res += ", ".join(elmt.accept(self) for elmt in expr.elements)
-        res += expr.right.lexeme
-        return res
-
-    def visit_schema_element_expr(self, expr: a.SchemaElementExpr) -> str:
-        parts: list[str] = []
-        if expr.name is not None:
-            parts.append(expr.name.lexeme)
-
-        if expr.type is None:
-            parts.append("_")
-        else:
-            parts.append(expr.type.accept(self))
-        return ": ".join(parts)
-
-    def visit_wildcard_expr(self, expr: a.WildcardExpr) -> str:
-        return "_"
-
-    def visit_literal_expr(self, expr: a.LiteralExpr) -> str:
-        return str(expr.value)
-
-
 class MidasAstPrinter(AstPrinter, m.Expr.Visitor[None], m.Stmt.Visitor[None]):
     def visit_type_stmt(self, stmt: m.TypeStmt):
         self._write_line("TypeStmt")
@@ -289,6 +181,7 @@ class MidasAstPrinter(AstPrinter, m.Expr.Visitor[None], m.Stmt.Visitor[None]):
         with self._child_level():
             self._write_line(f"value: {expr.value}", last=True)
 
+
 class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str]):
     def __init__(self, indent: int = 4):
         self.indent: int = indent
@@ -302,11 +195,8 @@ class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str]):
         return expr.accept(self)
 
     def visit_type_stmt(self, stmt: m.TypeStmt):
-        bases: list[str] = [
+        bases: list[str] = [b.accept(self) for b in stmt.bases]
-            b.accept(self)
+
-            for b in stmt.bases
-        ]
-        
         res: str = self.indented(f"type {stmt.name.lexeme}<{', '.join(bases)}>")
         if stmt.body is not None:
             res += " {\n"
@@ -348,8 +238,7 @@ class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str]):
 
     def visit_type_body_expr(self, expr: m.TypeBodyExpr):
         properties: list[str] = [
-            self.indented(prop.accept(self))
+            self.indented(prop.accept(self)) for prop in expr.properties
-            for prop in expr.properties
         ]
         return "\n".join(properties)
 
@@ -357,4 +246,4 @@ class MidasPrinter(m.Expr.Visitor[str], m.Stmt.Visitor[str]):
         return "_"
 
     def visit_literal_expr(self, expr: m.LiteralExpr):
-        return str(expr.value)
+        return str(expr.value)

lexer/annotations.py

@@ -1,102 +0,0 @@
-from lexer.base import Lexer
-from lexer.keyword import ANNOTATION_KEYWORDS
-from lexer.token import TokenType
-
-
-class AnnotationLexer(Lexer):
-    def scan_token(self) -> None:
-        char: str = self.advance()
-        match char:
-            case "(":
-                self.add_token(TokenType.LEFT_PAREN)
-            case ")":
-                self.add_token(TokenType.RIGHT_PAREN)
-            case "[":
-                self.add_token(TokenType.LEFT_BRACKET)
-            case "]":
-                self.add_token(TokenType.RIGHT_BRACKET)
-            case "<":
-                self.add_token(
-                    TokenType.LESS_EQUAL if self.match("=") else TokenType.LESS
-                )
-            case ">":
-                self.add_token(
-                    TokenType.GREATER_EQUAL if self.match("=") else TokenType.GREATER
-                )
-            case "=":
-                self.add_token(
-                    TokenType.EQUAL_EQUAL if self.match("=") else TokenType.EQUAL
-                )
-            case "!":
-                if self.match("="):
-                    self.add_token(TokenType.BANG_EQUAL)
-                else:
-                    self.error("Unexpected single bang. Did you mean '!=' ?")
-            case ":":
-                self.add_token(TokenType.COLON)
-            case ",":
-                self.add_token(TokenType.COMMA)
-            case "_":
-                self.add_token(TokenType.UNDERSCORE)
-            case "+":
-                self.add_token(TokenType.PLUS)
-            case "#":
-                self.scan_comment()
-            case "\n":
-                self.add_token(TokenType.NEWLINE)
-            case " " | "\r" | "\t":
-                # Consume all whitespace characters until EOL or EOF
-                while (
-                    self.peek().isspace()
-                    and self.peek() != "\n"
-                    and not self.is_at_end()
-                ):
-                    self.advance()
-                self.add_token(TokenType.WHITESPACE)
-            case _:
-                if char.isdigit():
-                    self.scan_number()
-                elif char.isalpha():
-                    self.scan_identifier()
-                else:
-                    self.error("Unexpected character")
-        return None
-
-    def scan_number(self):
-        """Scan the rest of number and add it as a token
-
-        This method handles both simple integers and floats. Scientific notation
-        and base prefixes (0x, 0b, 0o) are not supported
-        """
-        while self.peek().isdigit():
-            self.advance()
-
-        if self.peek() == "." and self.peek_next().isdigit():
-            self.advance()
-            while self.peek().isdigit():
-                self.advance()
-
-        value: float = float(self.source[self.start : self.idx])
-        self.add_token(TokenType.NUMBER, value)
-
-    def scan_identifier(self):
-        """Scan the rest of an identifier and add it as a token
-
-        An identifier starts with a letter, followed by any number of
-        alphanumerical characters or underscores
-        """
-        while self.peek().isalnum() or self.peek() == "_":
-            self.advance()
-        
-        lexeme: str = self.source[self.start : self.idx]
-        token_type: TokenType = ANNOTATION_KEYWORDS.get(lexeme, TokenType.IDENTIFIER)
-        self.add_token(token_type)
-
-    def scan_comment(self):
-        """Scan the rest of a comment and add it as a token
-
-        A comment starts with a `#` character and ends at the EOL/EOF
-        """
-        while self.peek() != "\n" and not self.is_at_end():
-            self.advance()
-        self.add_token(TokenType.COMMENT)

lexer/keyword.py

@@ -1,12 +1,6 @@
 from lexer.token import TokenType
 
-ANNOTATION_KEYWORDS: dict[str, TokenType] = {
+KEYWORDS: dict[str, TokenType] = {
-    "True": TokenType.TRUE,
-    "False": TokenType.FALSE,
-    "None": TokenType.NONE,
-}
-
-MIDAS_KEYWORDS: dict[str, TokenType] = {
     "type": TokenType.TYPE,
     "op": TokenType.OP,
     "constraint": TokenType.CONSTRAINT,

lexer/midas.py

@@ -1,5 +1,5 @@
 from lexer.base import Lexer
-from lexer.keyword import MIDAS_KEYWORDS
+from lexer.keyword import KEYWORDS
 from lexer.token import TokenType
 
 
@@ -102,7 +102,7 @@ class MidasLexer(Lexer):
             self.advance()
 
         lexeme: str = self.source[self.start : self.idx]
-        token_type: TokenType = MIDAS_KEYWORDS.get(lexeme, TokenType.IDENTIFIER)
+        token_type: TokenType = KEYWORDS.get(lexeme, TokenType.IDENTIFIER)
         self.add_token(token_type)
 
     def scan_comment(self):

parser/annotations.py

@@ -1,152 +0,0 @@
-from typing import Optional
-
-from core.ast.annotations import (
-    AnnotationStmt,
-    ConstraintExpr,
-    Expr,
-    LiteralExpr,
-    SchemaElementExpr,
-    SchemaExpr,
-    Stmt,
-    TypeExpr,
-    WildcardExpr,
-)
-from lexer.token import Token, TokenType
-from parser.base import Parser
-from parser.errors import ParsingError
-
-
-class AnnotationParser(Parser):
-    """A simple parser for custom type annotations"""
-
-    SYNC_BOUNDARY: set[TokenType] = set()
-
-    def parse(self) -> Optional[Stmt]:
-        stmt: Optional[Stmt] = None
-        try:
-            stmt = self.annotation()
-        except ParsingError:
-            self.synchronize()
-        if not self.is_at_end():
-            self.error(self.peek(), "Extra tokens")
-        return stmt
-
-    def synchronize(self):
-        """Skip tokens until a synchronization boundary is found
-
-        This method allows gracefully recovering from a parse error
-        to a safe place and continue parsing
-        """
-        self.advance()
-        while not self.is_at_end():
-            if self.peek().type in self.SYNC_BOUNDARY:
-                return
-            self.advance()
-
-    def annotation(self) -> AnnotationStmt:
-        """Parse an annotation
-
-        An annotation is written as `Type` or `Type[Schema]`
-
-        Returns:
-            AnnotationStmt: the parsed annotation statement
-        """
-
-        name: Token = self.consume(TokenType.IDENTIFIER, "Expected type identifier")
-        schema: Optional[SchemaExpr] = None
-        if self.match(TokenType.LEFT_BRACKET):
-            schema = self.schema()
-        return AnnotationStmt(name=name, schema=schema)
-
-    def type_expr(self) -> TypeExpr:
-        """Parse a type expression
-
-        Returns:
-            TypeExpr: the parsed type expression
-        """
-        name: Token = self.consume(TokenType.IDENTIFIER, "Expected type name")
-        constraints: list[ConstraintExpr] = []
-
-        while not self.is_at_end() and self.match(TokenType.PLUS):
-            self.consume(TokenType.LEFT_PAREN, "Expected '(' before type constraint")
-            constraints.append(self.constraint_expr())
-            self.consume(TokenType.RIGHT_PAREN, "Expected ')' after type constraint")
-
-        return TypeExpr(name=name, constraints=constraints)
-
-    def constraint_expr(self) -> ConstraintExpr:
-        """Parse a type constraint
-
-        Returns:
-            ConstraintExpr: the parsed type constraint expression
-        """
-        
-        left: Expr = self.constraint_value()
-        op: Token = self.constraint_operator()
-        right: Expr = self.constraint_value()
-        return ConstraintExpr(left=left, op=op, right=right)
-
-    def constraint_value(self) -> Expr:
-        if self.match(TokenType.UNDERSCORE):
-            return WildcardExpr(self.previous())
-        return self.literal()
-
-    def literal(self) -> LiteralExpr:
-        if self.match(TokenType.FALSE):
-            return LiteralExpr(False)
-        if self.match(TokenType.TRUE):
-            return LiteralExpr(True)
-        if self.match(TokenType.NONE):
-            return LiteralExpr(None)
-        
-        if self.match(TokenType.NUMBER):
-            return LiteralExpr(self.previous().value)
-        
-        raise self.error(self.peek(), "Expected literal")
-
-    def constraint_operator(self) -> Token:
-        if self.match(TokenType.LESS, TokenType.LESS_EQUAL, TokenType.GREATER, TokenType.GREATER_EQUAL, TokenType.EQUAL_EQUAL, TokenType.BANG_EQUAL):
-            return self.previous()
-        raise self.error(self.peek(), "Expected constraint operator")
-
-    def schema(self) -> SchemaExpr:
-        """Parse a schema definition
-
-        A comma separated list of schema elements
-
-        Returns:
-            SchemaExpr: the parsed schema expression
-        """
-        left: Token = self.previous()
-        elements: list[Expr] = []
-        while not self.check(TokenType.RIGHT_BRACKET) and not self.is_at_end():
-            elements.append(self.schema_element())
-            if not self.check(TokenType.RIGHT_BRACKET):
-                self.consume(TokenType.COMMA, "Expected ',' between schema elements")
-
-        right: Token = self.consume(TokenType.RIGHT_BRACKET, "Unclosed schema")
-        return SchemaExpr(left=left, elements=elements, right=right)
-
-    def schema_element(self) -> SchemaElementExpr:
-        """Parse a schema element
-
-        An anonymous element (`_`), a type, an untyped named column (`name: _`),
-        or a named column (`name: Type`)
-
-        Returns:
-            SchemaElementExpr: the parsed schema element expression
-        """
-        if self.match(TokenType.UNDERSCORE):
-            return SchemaElementExpr(name=None, type=None)
-
-        if not self.check(TokenType.IDENTIFIER):
-            raise self.error(self.peek(), "Expected schema element")
-
-        name: Optional[Token] = None
-        type: Optional[TypeExpr] = None
-        if self.check_next(TokenType.COLON):
-            name = self.advance()
-            self.advance()
-        if not self.match(TokenType.UNDERSCORE):
-            type = self.type_expr()
-        return SchemaElementExpr(name=name, type=type)

tests/lexer/test_annotation_lexer.py

@@ -1,129 +0,0 @@
-from typing import Any
-
-import pytest
-
-from lexer.annotations import AnnotationLexer
-from lexer.token import Token, TokenType
-
-
-def scan(source: str) -> list[Token]:
-    return AnnotationLexer(source).process()
-
-
-def assert_n_tokens(tokens: list[Token], n: int):
-    assert len(tokens) == n + 1
-    assert tokens[-1].type == TokenType.EOF
-
-
-@pytest.mark.parametrize(
-    "src,expected",
-    [
-        ("(", TokenType.LEFT_PAREN),
-        (")", TokenType.RIGHT_PAREN),
-        ("[", TokenType.LEFT_BRACKET),
-        ("]", TokenType.RIGHT_BRACKET),
-        (":", TokenType.COLON),
-        (",", TokenType.COMMA),
-        ("_", TokenType.UNDERSCORE),
-    ],
-)
-def test_punctuation(src: str, expected: TokenType):
-    tokens: list[Token] = scan(src)
-    assert_n_tokens(tokens, 1)
-    assert tokens[0].type == expected
-
-
-@pytest.mark.parametrize(
-    "src,expected",
-    [
-        ("+", TokenType.PLUS),
-        (">", TokenType.GREATER),
-        (">=", TokenType.GREATER_EQUAL),
-        ("<", TokenType.LESS),
-        ("<=", TokenType.LESS_EQUAL),
-        ("=", TokenType.EQUAL),
-        ("==", TokenType.EQUAL_EQUAL),
-        ("!=", TokenType.BANG_EQUAL),
-    ],
-)
-def test_operators(src: str, expected: TokenType):
-    tokens: list[Token] = scan(src)
-    assert_n_tokens(tokens, 1)
-    assert tokens[0].type == expected
-
-
-@pytest.mark.parametrize(
-    "src,expected",
-    [
-        ("a", TokenType.IDENTIFIER),
-        ("foo", TokenType.IDENTIFIER),
-        ("foo1", TokenType.IDENTIFIER),
-        ("foo_", TokenType.IDENTIFIER),
-        ("foo_bar1_baz2", TokenType.IDENTIFIER),
-        ("FOO_BAR1_BAZ2", TokenType.IDENTIFIER),
-        ("True", TokenType.TRUE),
-        ("False", TokenType.FALSE),
-        ("None", TokenType.NONE),
-    ],
-)
-def test_identifiers_keywords(src: str, expected: TokenType):
-    tokens: list[Token] = scan(src)
-    assert_n_tokens(tokens, 1)
-    assert tokens[0].type == expected
-
-
-@pytest.mark.parametrize(
-    "src,expected",
-    [
-        ("#", TokenType.COMMENT),
-        ("# This is a comment", TokenType.COMMENT),
-        (" ", TokenType.WHITESPACE),
-        ("\t", TokenType.WHITESPACE),
-        ("\r", TokenType.WHITESPACE),
-        ("  \t  \t", TokenType.WHITESPACE),
-        ("\n", TokenType.NEWLINE),
-    ],
-)
-def test_misc(src: str, expected: TokenType):
-    tokens: list[Token] = scan(src)
-    assert_n_tokens(tokens, 1)
-    assert tokens[0].type == expected
-
-
-@pytest.mark.parametrize(
-    "src,expected_type,expected_value",
-    [
-        ("0", TokenType.NUMBER, 0),
-        ("0.0", TokenType.NUMBER, 0),
-        ("1234.56", TokenType.NUMBER, 1234.56),
-    ],
-)
-def test_literals(src: str, expected_type: TokenType, expected_value: Any):
-    tokens: list[Token] = scan(src)
-    assert_n_tokens(tokens, 1)
-    assert tokens[0].type == expected_type
-    assert tokens[0].value == expected_value
-
-
-def test_single_bang_error():
-    with pytest.raises(SyntaxError):
-        scan("!")
-
-
-@pytest.mark.parametrize(
-    "src",
-    [
-        "-",
-        "*",
-        "/",
-        "{",
-        "}",
-        "@",
-        '"',
-        "'",
-        ".",
-    ],
-)
-def test_unexpected_character(src: str):
-    with pytest.raises(SyntaxError):
-        scan(src)

tests/parser/test_annotation_parser.py

@@ -1,130 +0,0 @@
-from typing import Optional
-
-import pytest
-
-from core.ast.annotations import (
-    AnnotationStmt,
-    ConstraintExpr,
-    Expr,
-    LiteralExpr,
-    SchemaElementExpr,
-    SchemaExpr,
-    Stmt,
-    TypeExpr,
-    WildcardExpr,
-)
-from lexer.annotations import AnnotationLexer
-from lexer.position import Position
-from lexer.token import Token
-from parser.annotations import AnnotationParser
-
-
-class AstSerializer(Stmt.Visitor[str], Expr.Visitor[str]):
-    def serialize(self, stmt: Stmt):
-        return stmt.accept(self)
-
-    def visit_annotation_stmt(self, stmt: AnnotationStmt) -> str:
-        schema: str = ""
-        if stmt.schema is not None:
-            schema = " " + stmt.schema.accept(self)
-        return f"(annotation {stmt.name.lexeme}{schema})"
-
-    def visit_schema_expr(self, expr: SchemaExpr) -> str:
-        elements: list[str] = [elmt.accept(self) for elmt in expr.elements]
-        return f"(schema {' '.join(elements)})"
-
-    def visit_schema_element_expr(self, expr: SchemaElementExpr) -> str:
-        name: str = expr.name.lexeme if expr.name is not None else "_"
-        type: str = expr.type.accept(self) if expr.type is not None else "_"
-        return f"({name} {type})"
-
-    def visit_type_expr(self, expr: TypeExpr) -> str:
-        res: str = f"({expr.name.lexeme}"
-        for constraint in expr.constraints:
-            res += " " + constraint.accept(self)
-        res += ")"
-        return res
-
-    def visit_constraint_expr(self, expr: ConstraintExpr) -> str:
-        return f"(constraint {expr.left.accept(self)} {expr.op.lexeme} {expr.right.accept(self)})"
-
-    def visit_wildcard_expr(self, expr: WildcardExpr) -> str:
-        return "(_)"
-
-    def visit_literal_expr(self, expr: LiteralExpr) -> str:
-        return f"({expr.value})"
-
-
-def parse(source: str) -> Optional[Stmt]:
-    tokens: list[Token] = AnnotationLexer(source).process()
-    return AnnotationParser(tokens).parse()
-
-
-def must_parse(source: str) -> Stmt:
-    stmt: Optional[Stmt] = parse(source)
-    assert stmt is not None
-    return stmt
-
-
-def ast_str(source: str) -> str:
-    stmt: Stmt = must_parse(source)
-    return AstSerializer().serialize(stmt)
-
-
-@pytest.mark.parametrize(
-    "src,expected",
-    [
-        ("Type", "(annotation Type)"),
-        ("Type[]", "(annotation Type (schema ))"),
-        (
-            """
-            Frame[
-                verified: bool,
-                birth_year: int,
-                height: float + ( _ > 0 ) + ( _ < 250 ),
-                name: str,
-                date: datetime,
-                float,  # unnamed
-                unknown: _,  # untyped
-                _  # unnamed and untyped
-            ]
-            """,
-            "(annotation Frame (schema (verified (bool)) (birth_year (int)) (height (float (constraint (_) > (0.0)) (constraint (_) < (250.0)))) (name (str)) (date (datetime)) (_ (float)) (unknown _) (_ _)))",
-        ),
-    ],
-)
-def test_expressions(src: str, expected: str):
-    assert ast_str(src) == expected
-
-
-@pytest.mark.parametrize(
-    "src,pos,should_fail",
-    [
-        ("", (1, 1), True),
-        ("42", (1, 1), True),
-        ("True", (1, 1), True),
-        ("Type[", (1, 6), True),
-        ("Type[] Type2", (1, 8), False),
-        ("Type[bool:]", (1, 11), True),
-        ("Type[3]", (1, 6), True),
-        ("Type[bool float]", (1, 11), True),
-        ("Type[bool (_ < 2)]", (1, 11), True),
-        ("Type[bool + _ < 2)]", (1, 13), True),
-        ("Type[bool + (_ < 2]", (1, 19), True),
-        ("Type[bool + (< 2)]", (1, 14), True),
-        ("Type[bool + (_ + 2)]", (1, 16), True),
-        ("Type[bool + (Foo + Bar)]", (1, 14), True),
-        # ("Type[bool,]", (1, 11), True),  # trailing comma is accepted, TODO: update parser or EBNF
-        ("Type[bool, Type[]]", (1, 16), True),
-        ("Type[foo: 3]", (1, 11), True),
-    ],
-)
-def test_parsing_error(src: str, pos: tuple[int, int], should_fail: bool):
-    tokens: list[Token] = AnnotationLexer(src).process()
-    parser: AnnotationParser = AnnotationParser(tokens)
-    stmt: Optional[Stmt] = parser.parse()
-    if should_fail:
-        assert stmt is None
-    assert len(parser.errors) != 0
-    error_pos: Position = parser.errors[0].token.position
-    assert (error_pos.line, error_pos.column) == pos