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argument.rs

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use crate::{
builtins::{PyBaseExceptionRef, PyTupleRef, PyTypeRef},
convert::ToPyObject,
AsObject, PyObjectRef, PyPayload, PyRef, PyResult, TryFromObject, VirtualMachine,
};
use indexmap::IndexMap;
use itertools::Itertools;
use std::ops::RangeInclusive;
pub trait IntoFuncArgs: Sized {
fn into_args(self, vm: &VirtualMachine) -> FuncArgs;
fn into_method_args(self, obj: PyObjectRef, vm: &VirtualMachine) -> FuncArgs {
let mut args = self.into_args(vm);
args.prepend_arg(obj);
args
}
}
impl<T> IntoFuncArgs for T
where
T: Into<FuncArgs>,
{
fn into_args(self, _vm: &VirtualMachine) -> FuncArgs {
self.into()
}
}
// A tuple of values that each implement `ToPyObject` represents a sequence of
// arguments that can be bound and passed to a built-in function.
macro_rules! into_func_args_from_tuple {
($(($n:tt, $T:ident)),*) => {
impl<$($T,)*> IntoFuncArgs for ($($T,)*)
where
$($T: ToPyObject,)*
{
#[inline]
fn into_args(self, vm: &VirtualMachine) -> FuncArgs {
let ($($n,)*) = self;
PosArgs::new(vec![$($n.to_pyobject(vm),)*]).into()
}
#[inline]
fn into_method_args(self, obj: PyObjectRef, vm: &VirtualMachine) -> FuncArgs {
let ($($n,)*) = self;
PosArgs::new(vec![obj, $($n.to_pyobject(vm),)*]).into()
}
}
};
}
into_func_args_from_tuple!((v1, T1));
into_func_args_from_tuple!((v1, T1), (v2, T2));
into_func_args_from_tuple!((v1, T1), (v2, T2), (v3, T3));
into_func_args_from_tuple!((v1, T1), (v2, T2), (v3, T3), (v4, T4));
into_func_args_from_tuple!((v1, T1), (v2, T2), (v3, T3), (v4, T4), (v5, T5));
/// The `FuncArgs` struct is one of the most used structs then creating
/// a rust function that can be called from python. It holds both positional
/// arguments, as well as keyword arguments passed to the function.
#[derive(Debug, Default, Clone)]
pub struct FuncArgs {
pub args: Vec<PyObjectRef>,
// sorted map, according to https://www.python.org/dev/peps/pep-0468/
pub kwargs: IndexMap<String, PyObjectRef>,
}
/// Conversion from vector of python objects to function arguments.
impl<A> From<A> for FuncArgs
where
A: Into<PosArgs>,
{
fn from(args: A) -> Self {
FuncArgs {
args: args.into().into_vec(),
kwargs: IndexMap::new(),
}
}
}
impl From<KwArgs> for FuncArgs {
fn from(kwargs: KwArgs) -> Self {
FuncArgs {
args: Vec::new(),
kwargs: kwargs.0,
}
}
}
impl FromArgs for FuncArgs {
fn from_args(_vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
Ok(std::mem::take(args))
}
}
impl FuncArgs {
pub fn new<A, K>(args: A, kwargs: K) -> Self
where
A: Into<PosArgs>,
K: Into<KwArgs>,
{
let PosArgs(args) = args.into();
let KwArgs(kwargs) = kwargs.into();
Self { args, kwargs }
}
pub fn with_kwargs_names<A, KW>(mut args: A, kwarg_names: KW) -> Self
where
A: ExactSizeIterator<Item = PyObjectRef>,
KW: ExactSizeIterator<Item = String>,
{
// last `kwarg_names.len()` elements of args in order of appearance in the call signature
let total_argc = args.len();
let kwargc = kwarg_names.len();
let posargc = total_argc - kwargc;
let posargs = args.by_ref().take(posargc).collect();
let kwargs = kwarg_names.zip_eq(args).collect::<IndexMap<_, _>>();
FuncArgs {
args: posargs,
kwargs,
}
}
pub fn prepend_arg(&mut self, item: PyObjectRef) {
self.args.reserve_exact(1);
self.args.insert(0, item)
}
pub fn shift(&mut self) -> PyObjectRef {
self.args.remove(0)
}
pub fn get_kwarg(&self, key: &str, default: PyObjectRef) -> PyObjectRef {
self.kwargs
.get(key)
.cloned()
.unwrap_or_else(|| default.clone())
}
pub fn get_optional_kwarg(&self, key: &str) -> Option<PyObjectRef> {
self.kwargs.get(key).cloned()
}
pub fn get_optional_kwarg_with_type(
&self,
key: &str,
ty: PyTypeRef,
vm: &VirtualMachine,
) -> PyResult<Option<PyObjectRef>> {
match self.get_optional_kwarg(key) {
Some(kwarg) => {
if kwarg.fast_isinstance(&ty) {
Ok(Some(kwarg))
} else {
let expected_ty_name = &ty.name();
let kwarg_class = kwarg.class();
let actual_ty_name = &kwarg_class.name();
Err(vm.new_type_error(format!(
"argument of type {} is required for named parameter `{}` (got: {})",
expected_ty_name, key, actual_ty_name
)))
}
}
None => Ok(None),
}
}
pub fn take_positional(&mut self) -> Option<PyObjectRef> {
if self.args.is_empty() {
None
} else {
Some(self.args.remove(0))
}
}
pub fn take_positional_keyword(&mut self, name: &str) -> Option<PyObjectRef> {
self.take_positional().or_else(|| self.take_keyword(name))
}
pub fn take_keyword(&mut self, name: &str) -> Option<PyObjectRef> {
self.kwargs.swap_remove(name)
}
pub fn remaining_keywords(&mut self) -> impl Iterator<Item = (String, PyObjectRef)> + '_ {
self.kwargs.drain(..)
}
/// Binds these arguments to their respective values.
///
/// If there is an insufficient number of arguments, there are leftover
/// arguments after performing the binding, or if an argument is not of
/// the expected type, a TypeError is raised.
///
/// If the given `FromArgs` includes any conversions, exceptions raised
/// during the conversion will halt the binding and return the error.
pub fn bind<T: FromArgs>(mut self, vm: &VirtualMachine) -> PyResult<T> {
let given_args = self.args.len();
let bound = T::from_args(vm, &mut self)
.map_err(|e| e.into_exception(T::arity(), given_args, vm))?;
if !self.args.is_empty() {
Err(vm.new_type_error(format!(
"Expected at most {} arguments ({} given)",
T::arity().end(),
given_args,
)))
} else if let Some(err) = self.check_kwargs_empty(vm) {
Err(err)
} else {
Ok(bound)
}
}
pub fn check_kwargs_empty(&self, vm: &VirtualMachine) -> Option<PyBaseExceptionRef> {
self.kwargs
.keys()
.next()
.map(|k| vm.new_type_error(format!("Unexpected keyword argument {}", k)))
}
}
/// An error encountered while binding arguments to the parameters of a Python
/// function call.
pub enum ArgumentError {
/// The call provided fewer positional arguments than the function requires.
TooFewArgs,
/// The call provided more positional arguments than the function accepts.
TooManyArgs,
/// The function doesn't accept a keyword argument with the given name.
InvalidKeywordArgument(String),
/// The function require a keyword argument with the given name, but one wasn't provided
RequiredKeywordArgument(String),
/// An exception was raised while binding arguments to the function
/// parameters.
Exception(PyBaseExceptionRef),
}
impl From<PyBaseExceptionRef> for ArgumentError {
fn from(ex: PyBaseExceptionRef) -> Self {
ArgumentError::Exception(ex)
}
}
impl ArgumentError {
fn into_exception(
self,
arity: RangeInclusive<usize>,
num_given: usize,
vm: &VirtualMachine,
) -> PyBaseExceptionRef {
match self {
ArgumentError::TooFewArgs => vm.new_type_error(format!(
"Expected at least {} arguments ({} given)",
arity.start(),
num_given
)),
ArgumentError::TooManyArgs => vm.new_type_error(format!(
"Expected at most {} arguments ({} given)",
arity.end(),
num_given
)),
ArgumentError::InvalidKeywordArgument(name) => {
vm.new_type_error(format!("{} is an invalid keyword argument", name))
}
ArgumentError::RequiredKeywordArgument(name) => {
vm.new_type_error(format!("Required keyqord only argument {}", name))
}
ArgumentError::Exception(ex) => ex,
}
}
}
/// Implemented by any type that can be accepted as a parameter to a built-in
/// function.
///
pub trait FromArgs: Sized {
/// The range of positional arguments permitted by the function signature.
///
/// Returns an empty range if not applicable.
fn arity() -> RangeInclusive<usize> {
0..=0
}
/// Extracts this item from the next argument(s).
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError>;
}
pub trait FromArgOptional {
type Inner: TryFromObject;
fn from_inner(x: Self::Inner) -> Self;
}
impl<T: TryFromObject> FromArgOptional for OptionalArg<T> {
type Inner = T;
fn from_inner(x: T) -> Self {
Self::Present(x)
}
}
impl<T: TryFromObject> FromArgOptional for T {
type Inner = Self;
fn from_inner(x: Self) -> Self {
x
}
}
/// A map of keyword arguments to their values.
///
/// A built-in function with a `KwArgs` parameter is analogous to a Python
/// function with `**kwargs`. All remaining keyword arguments are extracted
/// (and hence the function will permit an arbitrary number of them).
///
/// `KwArgs` optionally accepts a generic type parameter to allow type checks
/// or conversions of each argument.
///
/// Note:
///
/// KwArgs is only for functions that accept arbitrary keyword arguments. For
/// functions that accept only *specific* named arguments, a rust struct with
/// an appropriate FromArgs implementation must be created.
#[derive(Clone)]
pub struct KwArgs<T = PyObjectRef>(IndexMap<String, T>);
impl<T> KwArgs<T> {
pub fn new(map: IndexMap<String, T>) -> Self {
KwArgs(map)
}
pub fn pop_kwarg(&mut self, name: &str) -> Option<T> {
self.0.remove(name)
}
}
impl<T> FromIterator<(String, T)> for KwArgs<T> {
fn from_iter<I: IntoIterator<Item = (String, T)>>(iter: I) -> Self {
KwArgs(iter.into_iter().collect())
}
}
impl<T> Default for KwArgs<T> {
fn default() -> Self {
KwArgs(IndexMap::new())
}
}
impl<T> FromArgs for KwArgs<T>
where
T: TryFromObject,
{
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
let mut kwargs = IndexMap::new();
for (name, value) in args.remaining_keywords() {
kwargs.insert(name, value.try_into_value(vm)?);
}
Ok(KwArgs(kwargs))
}
}
impl<T> IntoIterator for KwArgs<T> {
type Item = (String, T);
type IntoIter = indexmap::map::IntoIter<String, T>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
/// A list of positional argument values.
///
/// A built-in function with a `PosArgs` parameter is analogous to a Python
/// function with `*args`. All remaining positional arguments are extracted
/// (and hence the function will permit an arbitrary number of them).
///
/// `PosArgs` optionally accepts a generic type parameter to allow type checks
/// or conversions of each argument.
#[derive(Clone)]
pub struct PosArgs<T = PyObjectRef>(Vec<T>);
impl<T> PosArgs<T> {
pub fn new(args: Vec<T>) -> Self {
Self(args)
}
pub fn into_vec(self) -> Vec<T> {
self.0
}
pub fn iter(&self) -> std::slice::Iter<T> {
self.0.iter()
}
}
impl<T> From<Vec<T>> for PosArgs<T> {
fn from(v: Vec<T>) -> Self {
Self(v)
}
}
impl From<()> for PosArgs<PyObjectRef> {
fn from(_args: ()) -> Self {
Self(Vec::new())
}
}
impl<T> AsRef<[T]> for PosArgs<T> {
fn as_ref(&self) -> &[T] {
&self.0
}
}
impl<T: PyPayload> PosArgs<PyRef<T>> {
pub fn into_tuple(self, vm: &VirtualMachine) -> PyTupleRef {
vm.ctx
.new_tuple(self.0.into_iter().map(Into::into).collect())
}
}
impl<T> FromArgs for PosArgs<T>
where
T: TryFromObject,
{
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
let mut varargs = Vec::new();
while let Some(value) = args.take_positional() {
varargs.push(value.try_into_value(vm)?);
}
Ok(PosArgs(varargs))
}
}
impl<T> IntoIterator for PosArgs<T> {
type Item = T;
type IntoIter = std::vec::IntoIter<T>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl<T> FromArgs for T
where
T: TryFromObject,
{
fn arity() -> RangeInclusive<usize> {
1..=1
}
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
let value = args.take_positional().ok_or(ArgumentError::TooFewArgs)?;
Ok(value.try_into_value(vm)?)
}
}
/// An argument that may or may not be provided by the caller.
///
/// This style of argument is not possible in pure Python.
#[derive(Debug, result_like::OptionLike, is_macro::Is)]
pub enum OptionalArg<T = PyObjectRef> {
Present(T),
Missing,
}
impl OptionalArg<PyObjectRef> {
pub fn unwrap_or_none(self, vm: &VirtualMachine) -> PyObjectRef {
self.unwrap_or_else(|| vm.ctx.none())
}
}
pub type OptionalOption<T = PyObjectRef> = OptionalArg<Option<T>>;
impl<T> OptionalOption<T> {
#[inline]
pub fn flatten(self) -> Option<T> {
self.into_option().flatten()
}
}
impl<T> FromArgs for OptionalArg<T>
where
T: TryFromObject,
{
fn arity() -> RangeInclusive<usize> {
0..=1
}
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
let r = if let Some(value) = args.take_positional() {
OptionalArg::Present(value.try_into_value(vm)?)
} else {
OptionalArg::Missing
};
Ok(r)
}
}
// For functions that accept no arguments. Implemented explicitly instead of via
// macro below to avoid unused warnings.
impl FromArgs for () {
fn from_args(_vm: &VirtualMachine, _args: &mut FuncArgs) -> Result<Self, ArgumentError> {
Ok(())
}
}
// A tuple of types that each implement `FromArgs` represents a sequence of
// arguments that can be bound and passed to a built-in function.
//
// Technically, a tuple can contain tuples, which can contain tuples, and so on,
// so this actually represents a tree of values to be bound from arguments, but
// in practice this is only used for the top-level parameters.
macro_rules! tuple_from_py_func_args {
($($T:ident),+) => {
impl<$($T),+> FromArgs for ($($T,)+)
where
$($T: FromArgs),+
{
fn arity() -> RangeInclusive<usize> {
let mut min = 0;
let mut max = 0;
$(
let (start, end) = $T::arity().into_inner();
min += start;
max += end;
)+
min..=max
}
fn from_args(vm: &VirtualMachine, args: &mut FuncArgs) -> Result<Self, ArgumentError> {
Ok(($($T::from_args(vm, args)?,)+))
}
}
};
}
// Implement `FromArgs` for up to 7-tuples, allowing built-in functions to bind
// up to 7 top-level parameters (note that `PosArgs`, `KwArgs`, nested tuples, etc.
// count as 1, so this should actually be more than enough).
tuple_from_py_func_args!(A);
tuple_from_py_func_args!(A, B);
tuple_from_py_func_args!(A, B, C);
tuple_from_py_func_args!(A, B, C, D);
tuple_from_py_func_args!(A, B, C, D, E);
tuple_from_py_func_args!(A, B, C, D, E, F);
tuple_from_py_func_args!(A, B, C, D, E, F, G);
tuple_from_py_func_args!(A, B, C, D, E, F, G, H);
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