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cpython/Python/ast.c

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/*
* This file includes functions to transform a concrete syntax tree (CST) to
* an abstract syntax tree (AST). The main function is PyAST_FromNode().
*
*/
#include "Python.h"
#include "Python-ast.h"
#include "ast.h"
#include "token.h"
#include "pythonrun.h"
#include <assert.h>
#include <stdbool.h>
#define MAXLEVEL 200 /* Max parentheses level */
static int validate_stmts(asdl_seq *);
static int validate_exprs(asdl_seq *, expr_context_ty, int);
static int validate_nonempty_seq(asdl_seq *, const char *, const char *);
static int validate_stmt(stmt_ty);
static int validate_expr(expr_ty, expr_context_ty);
static int
validate_name(PyObject *name)
{
assert(PyUnicode_Check(name));
static const char * const forbidden[] = {
"None",
"True",
"False",
NULL
};
for (int i = 0; forbidden[i] != NULL; i++) {
if (_PyUnicode_EqualToASCIIString(name, forbidden[i])) {
PyErr_Format(PyExc_ValueError, "Name node can't be used with '%s' constant", forbidden[i]);
return 0;
}
}
return 1;
}
static int
validate_comprehension(asdl_seq *gens)
{
Py_ssize_t i;
if (!asdl_seq_LEN(gens)) {
PyErr_SetString(PyExc_ValueError, "comprehension with no generators");
return 0;
}
for (i = 0; i < asdl_seq_LEN(gens); i++) {
comprehension_ty comp = asdl_seq_GET(gens, i);
if (!validate_expr(comp->target, Store) ||
!validate_expr(comp->iter, Load) ||
!validate_exprs(comp->ifs, Load, 0))
return 0;
}
return 1;
}
static int
validate_keywords(asdl_seq *keywords)
{
Py_ssize_t i;
for (i = 0; i < asdl_seq_LEN(keywords); i++)
if (!validate_expr(((keyword_ty)asdl_seq_GET(keywords, i))->value, Load))
return 0;
return 1;
}
static int
validate_args(asdl_seq *args)
{
Py_ssize_t i;
for (i = 0; i < asdl_seq_LEN(args); i++) {
arg_ty arg = asdl_seq_GET(args, i);
if (arg->annotation && !validate_expr(arg->annotation, Load))
return 0;
}
return 1;
}
static const char *
expr_context_name(expr_context_ty ctx)
{
switch (ctx) {
case Load:
return "Load";
case Store:
return "Store";
case Del:
return "Del";
default:
Py_UNREACHABLE();
}
}
static int
validate_arguments(arguments_ty args)
{
if (!validate_args(args->posonlyargs) || !validate_args(args->args)) {
return 0;
}
if (args->vararg && args->vararg->annotation
&& !validate_expr(args->vararg->annotation, Load)) {
return 0;
}
if (!validate_args(args->kwonlyargs))
return 0;
if (args->kwarg && args->kwarg->annotation
&& !validate_expr(args->kwarg->annotation, Load)) {
return 0;
}
if (asdl_seq_LEN(args->defaults) > asdl_seq_LEN(args->posonlyargs) + asdl_seq_LEN(args->args)) {
PyErr_SetString(PyExc_ValueError, "more positional defaults than args on arguments");
return 0;
}
if (asdl_seq_LEN(args->kw_defaults) != asdl_seq_LEN(args->kwonlyargs)) {
PyErr_SetString(PyExc_ValueError, "length of kwonlyargs is not the same as "
"kw_defaults on arguments");
return 0;
}
return validate_exprs(args->defaults, Load, 0) && validate_exprs(args->kw_defaults, Load, 1);
}
static int
validate_constant(PyObject *value)
{
if (value == Py_None || value == Py_Ellipsis)
return 1;
if (PyLong_CheckExact(value)
|| PyFloat_CheckExact(value)
|| PyComplex_CheckExact(value)
|| PyBool_Check(value)
|| PyUnicode_CheckExact(value)
|| PyBytes_CheckExact(value))
return 1;
if (PyTuple_CheckExact(value) || PyFrozenSet_CheckExact(value)) {
PyObject *it;
it = PyObject_GetIter(value);
if (it == NULL)
return 0;
while (1) {
PyObject *item = PyIter_Next(it);
if (item == NULL) {
if (PyErr_Occurred()) {
Py_DECREF(it);
return 0;
}
break;
}
if (!validate_constant(item)) {
Py_DECREF(it);
Py_DECREF(item);
return 0;
}
Py_DECREF(item);
}
Py_DECREF(it);
return 1;
}
if (!PyErr_Occurred()) {
PyErr_Format(PyExc_TypeError,
"got an invalid type in Constant: %s",
_PyType_Name(Py_TYPE(value)));
}
return 0;
}
static int
validate_expr(expr_ty exp, expr_context_ty ctx)
{
int check_ctx = 1;
expr_context_ty actual_ctx;
/* First check expression context. */
switch (exp->kind) {
case Attribute_kind:
actual_ctx = exp->v.Attribute.ctx;
break;
case Subscript_kind:
actual_ctx = exp->v.Subscript.ctx;
break;
case Starred_kind:
actual_ctx = exp->v.Starred.ctx;
break;
case Name_kind:
if (!validate_name(exp->v.Name.id)) {
return 0;
}
actual_ctx = exp->v.Name.ctx;
break;
case List_kind:
actual_ctx = exp->v.List.ctx;
break;
case Tuple_kind:
actual_ctx = exp->v.Tuple.ctx;
break;
default:
if (ctx != Load) {
PyErr_Format(PyExc_ValueError, "expression which can't be "
"assigned to in %s context", expr_context_name(ctx));
return 0;
}
check_ctx = 0;
/* set actual_ctx to prevent gcc warning */
actual_ctx = 0;
}
if (check_ctx && actual_ctx != ctx) {
PyErr_Format(PyExc_ValueError, "expression must have %s context but has %s instead",
expr_context_name(ctx), expr_context_name(actual_ctx));
return 0;
}
/* Now validate expression. */
switch (exp->kind) {
case BoolOp_kind:
if (asdl_seq_LEN(exp->v.BoolOp.values) < 2) {
PyErr_SetString(PyExc_ValueError, "BoolOp with less than 2 values");
return 0;
}
return validate_exprs(exp->v.BoolOp.values, Load, 0);
case BinOp_kind:
return validate_expr(exp->v.BinOp.left, Load) &&
validate_expr(exp->v.BinOp.right, Load);
case UnaryOp_kind:
return validate_expr(exp->v.UnaryOp.operand, Load);
case Lambda_kind:
return validate_arguments(exp->v.Lambda.args) &&
validate_expr(exp->v.Lambda.body, Load);
case IfExp_kind:
return validate_expr(exp->v.IfExp.test, Load) &&
validate_expr(exp->v.IfExp.body, Load) &&
validate_expr(exp->v.IfExp.orelse, Load);
case Dict_kind:
if (asdl_seq_LEN(exp->v.Dict.keys) != asdl_seq_LEN(exp->v.Dict.values)) {
PyErr_SetString(PyExc_ValueError,
"Dict doesn't have the same number of keys as values");
return 0;
}
/* null_ok=1 for keys expressions to allow dict unpacking to work in
dict literals, i.e. ``{**{a:b}}`` */
return validate_exprs(exp->v.Dict.keys, Load, /*null_ok=*/ 1) &&
validate_exprs(exp->v.Dict.values, Load, /*null_ok=*/ 0);
case Set_kind:
return validate_exprs(exp->v.Set.elts, Load, 0);
#define COMP(NAME) \
case NAME ## _kind: \
return validate_comprehension(exp->v.NAME.generators) && \
validate_expr(exp->v.NAME.elt, Load);
COMP(ListComp)
COMP(SetComp)
COMP(GeneratorExp)
#undef COMP
case DictComp_kind:
return validate_comprehension(exp->v.DictComp.generators) &&
validate_expr(exp->v.DictComp.key, Load) &&
validate_expr(exp->v.DictComp.value, Load);
case Yield_kind:
return !exp->v.Yield.value || validate_expr(exp->v.Yield.value, Load);
case YieldFrom_kind:
return validate_expr(exp->v.YieldFrom.value, Load);
case Await_kind:
return validate_expr(exp->v.Await.value, Load);
case Compare_kind:
if (!asdl_seq_LEN(exp->v.Compare.comparators)) {
PyErr_SetString(PyExc_ValueError, "Compare with no comparators");
return 0;
}
if (asdl_seq_LEN(exp->v.Compare.comparators) !=
asdl_seq_LEN(exp->v.Compare.ops)) {
PyErr_SetString(PyExc_ValueError, "Compare has a different number "
"of comparators and operands");
return 0;
}
return validate_exprs(exp->v.Compare.comparators, Load, 0) &&
validate_expr(exp->v.Compare.left, Load);
case Call_kind:
return validate_expr(exp->v.Call.func, Load) &&
validate_exprs(exp->v.Call.args, Load, 0) &&
validate_keywords(exp->v.Call.keywords);
case Constant_kind:
if (!validate_constant(exp->v.Constant.value)) {
return 0;
}
return 1;
case JoinedStr_kind:
return validate_exprs(exp->v.JoinedStr.values, Load, 0);
case FormattedValue_kind:
if (validate_expr(exp->v.FormattedValue.value, Load) == 0)
return 0;
if (exp->v.FormattedValue.format_spec)
return validate_expr(exp->v.FormattedValue.format_spec, Load);
return 1;
case Attribute_kind:
return validate_expr(exp->v.Attribute.value, Load);
case Subscript_kind:
return validate_expr(exp->v.Subscript.slice, Load) &&
validate_expr(exp->v.Subscript.value, Load);
case Starred_kind:
return validate_expr(exp->v.Starred.value, ctx);
case Slice_kind:
return (!exp->v.Slice.lower || validate_expr(exp->v.Slice.lower, Load)) &&
(!exp->v.Slice.upper || validate_expr(exp->v.Slice.upper, Load)) &&
(!exp->v.Slice.step || validate_expr(exp->v.Slice.step, Load));
case List_kind:
return validate_exprs(exp->v.List.elts, ctx, 0);
case Tuple_kind:
return validate_exprs(exp->v.Tuple.elts, ctx, 0);
case NamedExpr_kind:
return validate_expr(exp->v.NamedExpr.value, Load);
/* This last case doesn't have any checking. */
case Name_kind:
return 1;
}
PyErr_SetString(PyExc_SystemError, "unexpected expression");
return 0;
}
static int
validate_nonempty_seq(asdl_seq *seq, const char *what, const char *owner)
{
if (asdl_seq_LEN(seq))
return 1;
PyErr_Format(PyExc_ValueError, "empty %s on %s", what, owner);
return 0;
}
static int
validate_assignlist(asdl_seq *targets, expr_context_ty ctx)
{
return validate_nonempty_seq(targets, "targets", ctx == Del ? "Delete" : "Assign") &&
validate_exprs(targets, ctx, 0);
}
static int
validate_body(asdl_seq *body, const char *owner)
{
return validate_nonempty_seq(body, "body", owner) && validate_stmts(body);
}
static int
validate_stmt(stmt_ty stmt)
{
Py_ssize_t i;
switch (stmt->kind) {
case FunctionDef_kind:
return validate_body(stmt->v.FunctionDef.body, "FunctionDef") &&
validate_arguments(stmt->v.FunctionDef.args) &&
validate_exprs(stmt->v.FunctionDef.decorator_list, Load, 0) &&
(!stmt->v.FunctionDef.returns ||
validate_expr(stmt->v.FunctionDef.returns, Load));
case ClassDef_kind:
return validate_body(stmt->v.ClassDef.body, "ClassDef") &&
validate_exprs(stmt->v.ClassDef.bases, Load, 0) &&
validate_keywords(stmt->v.ClassDef.keywords) &&
validate_exprs(stmt->v.ClassDef.decorator_list, Load, 0);
case Return_kind:
return !stmt->v.Return.value || validate_expr(stmt->v.Return.value, Load);
case Delete_kind:
return validate_assignlist(stmt->v.Delete.targets, Del);
case Assign_kind:
return validate_assignlist(stmt->v.Assign.targets, Store) &&
validate_expr(stmt->v.Assign.value, Load);
case AugAssign_kind:
return validate_expr(stmt->v.AugAssign.target, Store) &&
validate_expr(stmt->v.AugAssign.value, Load);
case AnnAssign_kind:
if (stmt->v.AnnAssign.target->kind != Name_kind &&
stmt->v.AnnAssign.simple) {
PyErr_SetString(PyExc_TypeError,
"AnnAssign with simple non-Name target");
return 0;
}
return validate_expr(stmt->v.AnnAssign.target, Store) &&
(!stmt->v.AnnAssign.value ||
validate_expr(stmt->v.AnnAssign.value, Load)) &&
validate_expr(stmt->v.AnnAssign.annotation, Load);
case For_kind:
return validate_expr(stmt->v.For.target, Store) &&
validate_expr(stmt->v.For.iter, Load) &&
validate_body(stmt->v.For.body, "For") &&
validate_stmts(stmt->v.For.orelse);
case AsyncFor_kind:
return validate_expr(stmt->v.AsyncFor.target, Store) &&
validate_expr(stmt->v.AsyncFor.iter, Load) &&
validate_body(stmt->v.AsyncFor.body, "AsyncFor") &&
validate_stmts(stmt->v.AsyncFor.orelse);
case While_kind:
return validate_expr(stmt->v.While.test, Load) &&
validate_body(stmt->v.While.body, "While") &&
validate_stmts(stmt->v.While.orelse);
case If_kind:
return validate_expr(stmt->v.If.test, Load) &&
validate_body(stmt->v.If.body, "If") &&
validate_stmts(stmt->v.If.orelse);
case With_kind:
if (!validate_nonempty_seq(stmt->v.With.items, "items", "With"))
return 0;
for (i = 0; i < asdl_seq_LEN(stmt->v.With.items); i++) {
withitem_ty item = asdl_seq_GET(stmt->v.With.items, i);
if (!validate_expr(item->context_expr, Load) ||
(item->optional_vars && !validate_expr(item->optional_vars, Store)))
return 0;
}
return validate_body(stmt->v.With.body, "With");
case AsyncWith_kind:
if (!validate_nonempty_seq(stmt->v.AsyncWith.items, "items", "AsyncWith"))
return 0;
for (i = 0; i < asdl_seq_LEN(stmt->v.AsyncWith.items); i++) {
withitem_ty item = asdl_seq_GET(stmt->v.AsyncWith.items, i);
if (!validate_expr(item->context_expr, Load) ||
(item->optional_vars && !validate_expr(item->optional_vars, Store)))
return 0;
}
return validate_body(stmt->v.AsyncWith.body, "AsyncWith");
case Raise_kind:
if (stmt->v.Raise.exc) {
return validate_expr(stmt->v.Raise.exc, Load) &&
(!stmt->v.Raise.cause || validate_expr(stmt->v.Raise.cause, Load));
}
if (stmt->v.Raise.cause) {
PyErr_SetString(PyExc_ValueError, "Raise with cause but no exception");
return 0;
}
return 1;
case Try_kind:
if (!validate_body(stmt->v.Try.body, "Try"))
return 0;
if (!asdl_seq_LEN(stmt->v.Try.handlers) &&
!asdl_seq_LEN(stmt->v.Try.finalbody)) {
PyErr_SetString(PyExc_ValueError, "Try has neither except handlers nor finalbody");
return 0;
}
if (!asdl_seq_LEN(stmt->v.Try.handlers) &&
asdl_seq_LEN(stmt->v.Try.orelse)) {
PyErr_SetString(PyExc_ValueError, "Try has orelse but no except handlers");
return 0;
}
for (i = 0; i < asdl_seq_LEN(stmt->v.Try.handlers); i++) {
excepthandler_ty handler = asdl_seq_GET(stmt->v.Try.handlers, i);
if ((handler->v.ExceptHandler.type &&
!validate_expr(handler->v.ExceptHandler.type, Load)) ||
!validate_body(handler->v.ExceptHandler.body, "ExceptHandler"))
return 0;
}
return (!asdl_seq_LEN(stmt->v.Try.finalbody) ||
validate_stmts(stmt->v.Try.finalbody)) &&
(!asdl_seq_LEN(stmt->v.Try.orelse) ||
validate_stmts(stmt->v.Try.orelse));
case Assert_kind:
return validate_expr(stmt->v.Assert.test, Load) &&
(!stmt->v.Assert.msg || validate_expr(stmt->v.Assert.msg, Load));
case Import_kind:
return validate_nonempty_seq(stmt->v.Import.names, "names", "Import");
case ImportFrom_kind:
if (stmt->v.ImportFrom.level < 0) {
PyErr_SetString(PyExc_ValueError, "Negative ImportFrom level");
return 0;
}
return validate_nonempty_seq(stmt->v.ImportFrom.names, "names", "ImportFrom");
case Global_kind:
return validate_nonempty_seq(stmt->v.Global.names, "names", "Global");
case Nonlocal_kind:
return validate_nonempty_seq(stmt->v.Nonlocal.names, "names", "Nonlocal");
case Expr_kind:
return validate_expr(stmt->v.Expr.value, Load);
case AsyncFunctionDef_kind:
return validate_body(stmt->v.AsyncFunctionDef.body, "AsyncFunctionDef") &&
validate_arguments(stmt->v.AsyncFunctionDef.args) &&
validate_exprs(stmt->v.AsyncFunctionDef.decorator_list, Load, 0) &&
(!stmt->v.AsyncFunctionDef.returns ||
validate_expr(stmt->v.AsyncFunctionDef.returns, Load));
case Pass_kind:
case Break_kind:
case Continue_kind:
return 1;
default:
PyErr_SetString(PyExc_SystemError, "unexpected statement");
return 0;
}
}
static int
validate_stmts(asdl_seq *seq)
{
Py_ssize_t i;
for (i = 0; i < asdl_seq_LEN(seq); i++) {
stmt_ty stmt = asdl_seq_GET(seq, i);
if (stmt) {
if (!validate_stmt(stmt))
return 0;
}
else {
PyErr_SetString(PyExc_ValueError,
"None disallowed in statement list");
return 0;
}
}
return 1;
}
static int
validate_exprs(asdl_seq *exprs, expr_context_ty ctx, int null_ok)
{
Py_ssize_t i;
for (i = 0; i < asdl_seq_LEN(exprs); i++) {
expr_ty expr = asdl_seq_GET(exprs, i);
if (expr) {
if (!validate_expr(expr, ctx))
return 0;
}
else if (!null_ok) {
PyErr_SetString(PyExc_ValueError,
"None disallowed in expression list");
return 0;
}
}
return 1;
}
int
PyAST_Validate(mod_ty mod)
{
int res = 0;
switch (mod->kind) {
case Module_kind:
res = validate_stmts(mod->v.Module.body);
break;
case Interactive_kind:
res = validate_stmts(mod->v.Interactive.body);
break;
case Expression_kind:
res = validate_expr(mod->v.Expression.body, Load);
break;
default:
PyErr_SetString(PyExc_SystemError, "impossible module node");
res = 0;
break;
}
return res;
}
PyObject *
_PyAST_GetDocString(asdl_seq *body)
{
if (!asdl_seq_LEN(body)) {
return NULL;
}
stmt_ty st = (stmt_ty)asdl_seq_GET(body, 0);
if (st->kind != Expr_kind) {
return NULL;
}
expr_ty e = st->v.Expr.value;
if (e->kind == Constant_kind && PyUnicode_CheckExact(e->v.Constant.value)) {
return e->v.Constant.value;
}
return NULL;
}
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