Files
midas/midas/generator/generator.py

342 lines
11 KiB
Python

import ast
import shutil
from dataclasses import dataclass, field
from pathlib import Path
from typing import Optional
import midas.ast.python as p
from midas.ast.location import Location
from midas.checker.types import (
AliasType,
AppliedType,
BaseType,
ComplexType,
ExtensionType,
Function,
GenericType,
OverloadedFunction,
TopType,
Type,
TypeVar,
UnitType,
)
from midas.utils import TypedAST
@dataclass
class Scope:
pre_assertions: list[ast.stmt] = field(default_factory=list)
aliases: list[str] = field(default_factory=list)
class Generator(p.Stmt.Visitor[ast.stmt], p.Expr.Visitor[ast.expr]):
def __init__(self, workdir: Path) -> None:
self.workdir: Path = workdir.resolve()
self.build_dir: Path = self.workdir / "build" / "midas"
if self.build_dir.exists():
shutil.rmtree(self.build_dir)
self.build_dir.mkdir(parents=True, exist_ok=True)
self.rel_src_path: Path = Path()
self._typed_ast: TypedAST = TypedAST(
stmts=[],
judgements=[],
)
self._alias_count: int = 0
self._scopes: list[Scope] = []
def generate_ast(self, typed_ast: TypedAST, src_path: Path) -> ast.AST:
self.rel_src_path = src_path.relative_to(self.workdir)
self._typed_ast = typed_ast
body: list[ast.stmt] = self._visit_body(typed_ast.stmts)
module = ast.Module(body=body, type_ignores=[])
module = ast.fix_missing_locations(module)
return module
def generate(
self, typed_ast: TypedAST, src_path: Path, out_path: Optional[Path] = None
) -> Path:
module: ast.AST = self.generate_ast(typed_ast, src_path)
compiled: str = ast.unparse(module)
if out_path is None:
out_path = (self.build_dir / self.rel_src_path).resolve()
try:
_ = out_path.relative_to(self.build_dir)
except ValueError:
raise ValueError(
f"Directory traversal, {self.rel_src_path} points outside of parent directory"
)
out_path.parent.mkdir(parents=True, exist_ok=True)
out_path.write_text(compiled)
return out_path
def visit_binary_expr(self, expr: p.BinaryExpr) -> ast.expr:
return ast.BinOp(
left=expr.left.accept(self),
op=expr.operator,
right=expr.right.accept(self),
)
def visit_compare_expr(self, expr: p.CompareExpr) -> ast.expr:
return ast.Compare(
left=expr.left.accept(self),
ops=[expr.operator],
comparators=[expr.right.accept(self)],
)
def visit_unary_expr(self, expr: p.UnaryExpr) -> ast.expr:
return ast.UnaryOp(
op=expr.operator,
operand=expr.right.accept(self),
)
def visit_call_expr(self, expr: p.CallExpr) -> ast.expr:
return ast.Call(
func=expr.callee.accept(self),
args=[arg.accept(self) for arg in expr.arguments],
keywords=[
ast.keyword(arg=name, value=arg.accept(self))
for name, arg in expr.keywords.items()
],
)
def visit_get_expr(self, expr: p.GetExpr) -> ast.expr:
return ast.Attribute(
value=expr.object.accept(self),
attr=expr.name,
)
def visit_literal_expr(self, expr: p.LiteralExpr) -> ast.expr:
return ast.Constant(value=expr.value)
def visit_variable_expr(self, expr: p.VariableExpr) -> ast.expr:
return ast.Name(id=expr.name)
def visit_logical_expr(self, expr: p.LogicalExpr) -> ast.expr:
return ast.BoolOp(
op=expr.operator,
values=[expr.left.accept(self), expr.right.accept(self)],
)
def visit_cast_expr(self, expr: p.CastExpr) -> ast.expr:
expr2: ast.expr = expr.expr.accept(self)
alias: ast.expr = self._make_alias(expr2)
type: Type = self._get_expr_type(expr)
self._make_cast_asserts(expr.location, alias, type)
return alias
def visit_ternary_expr(self, expr: p.TernaryExpr) -> ast.expr:
return ast.IfExp(
test=expr.test.accept(self),
body=expr.if_true.accept(self),
orelse=expr.if_false.accept(self),
)
def visit_list_expr(self, expr: p.ListExpr) -> ast.expr:
return ast.List(
elts=[item.accept(self) for item in expr.items],
)
def visit_dict_expr(self, expr: p.DictExpr) -> ast.expr:
return ast.Dict(
keys=[key.accept(self) if key is not None else None for key in expr.keys],
values=[value.accept(self) for value in expr.values],
)
def visit_subscript_expr(self, expr: p.SubscriptExpr) -> ast.expr:
return ast.Subscript(
value=expr.object.accept(self),
slice=expr.index.accept(self),
)
def visit_slice_expr(self, expr: p.SliceExpr) -> ast.expr:
return ast.Slice(
lower=expr.lower.accept(self) if expr.lower is not None else None,
upper=expr.upper.accept(self) if expr.upper is not None else None,
step=expr.step.accept(self) if expr.step is not None else None,
)
def visit_raw_expr(self, expr: p.RawExpr) -> ast.expr:
return expr.expr
def visit_expression_stmt(self, stmt: p.ExpressionStmt) -> ast.stmt:
return ast.Expr(
value=stmt.expr.accept(self),
)
def visit_function(self, stmt: p.Function) -> ast.stmt:
return ast.FunctionDef(
name=stmt.name,
args=ast.arguments(
posonlyargs=[ast.arg(arg=arg.name) for arg in stmt.posonlyargs],
vararg=None,
args=[ast.arg(arg=arg.name) for arg in stmt.args],
kwonlyargs=[ast.arg(arg=arg.name) for arg in stmt.kwonlyargs],
kwarg=None,
defaults=[
arg.default.accept(self)
for arg in stmt.posonlyargs + stmt.args
if arg.default is not None
],
kw_defaults=[
arg.default.accept(self) if arg.default is not None else None
for arg in stmt.kwonlyargs
],
),
body=self._visit_body(stmt.body),
decorator_list=[],
)
def visit_type_assign(self, stmt: p.TypeAssign) -> ast.stmt:
# TODO: is that ok?
return ast.Pass()
def visit_assign_stmt(self, stmt: p.AssignStmt) -> ast.stmt:
return ast.Assign(
targets=[target.accept(self) for target in stmt.targets],
value=stmt.value.accept(self),
)
def visit_return_stmt(self, stmt: p.ReturnStmt) -> ast.stmt:
return ast.Return(
value=stmt.value.accept(self) if stmt.value is not None else None,
)
def visit_if_stmt(self, stmt: p.IfStmt) -> ast.stmt:
return ast.If(
test=stmt.test.accept(self),
body=self._visit_body(stmt.body),
orelse=self._visit_body(stmt.orelse),
)
def visit_pass(self, stmt: p.Pass) -> ast.stmt:
return ast.Pass()
def visit_for_stmt(self, stmt: p.ForStmt) -> ast.stmt:
return ast.For(
target=stmt.target.accept(self),
iter=stmt.iterator.accept(self),
body=self._visit_body(stmt.body),
orelse=[],
)
def visit_raw_stmt(self, stmt: p.RawStmt) -> ast.stmt:
return stmt.stmt
def _visit_body(self, stmts: list[p.Stmt]) -> list[ast.stmt]:
generated: list[ast.stmt] = []
for stmt in stmts:
scope = Scope()
self._scopes.append(scope)
stmt2 = stmt.accept(self)
generated.extend(scope.pre_assertions)
generated.append(stmt2)
if len(scope.aliases) != 0:
generated.append(
ast.Delete(targets=[ast.Name(id=alias) for alias in scope.aliases])
)
self._scopes.pop()
# Remove redundant pass statements
if len(generated) > 1:
generated = [stmt for stmt in generated if not isinstance(stmt, ast.Pass)]
return generated
def _make_alias(self, expr: ast.expr) -> ast.expr:
name: str = f"__midas_alias_{self._alias_count}__"
alias = ast.Name(id=name)
self._alias_count += 1
self._scopes[-1].aliases.append(name)
self._scopes[-1].pre_assertions.append(
ast.Assign(
targets=[alias],
value=expr,
)
)
return alias
def _add_assert(self, expr: ast.expr, message: str | ast.expr):
if isinstance(message, str):
message = ast.Constant(value=message)
self._scopes[-1].pre_assertions.append(
ast.Assert(
test=expr,
msg=message,
)
)
def _get_expr_type(self, query: p.Expr) -> Type:
for expr, type in self._typed_ast.judgements:
if expr == query:
return type
raise RuntimeError(f"Cannot get type judgement for {query}")
def _make_cast_asserts(self, src_location: Location, expr: ast.expr, type: Type):
match type:
case BaseType(name=name):
self._add_assert(
ast.Call(
func=ast.Name(id="isinstance"),
args=[expr, ast.Name(id=name)],
keywords=[],
),
self._make_cast_assert_message(src_location, expr, type),
)
case AliasType(type=base):
self._make_cast_asserts(src_location, expr, base)
case UnitType():
self._add_assert(
ast.Compare(
left=expr,
ops=[ast.Is()],
comparators=[
ast.Constant(value=None),
],
),
self._make_cast_assert_message(src_location, expr, type),
)
case AppliedType():
self._make_cast_asserts(src_location, expr, type.body)
case (
TopType()
| Function()
| OverloadedFunction()
| ComplexType()
| ExtensionType()
| GenericType()
):
raise NotImplementedError(f"Can't make assertion for type {type}")
case TypeVar():
raise RuntimeError("Unexpected TypeVar")
def _make_cast_assert_message(
self, location: Location, expr: ast.expr, type: Type
) -> ast.expr:
loc_str: str = f"{self.rel_src_path}:L{location.lineno}:{location.col_offset+1}"
# f"file.py:L1:1: CastError: Cannot cast {type(expr).__name__} to Type"
return ast.JoinedStr(
values=[
ast.Constant(f"{loc_str}: CastError: Cannot cast "),
ast.FormattedValue(
value=ast.Attribute(
value=ast.Call(
func=ast.Name(id="type"),
args=[expr],
keywords=[],
),
attr="__name__",
),
conversion=-1,
),
ast.Constant(f" to {type}"),
]
)