RustPython · windelbouwman · Apr 17, 2019 · Mar 30, 2019 · Mar 30, 2019 · Mar 30, 2019
diff --git a/tests/snippets/builtin_slice.py b/tests/snippets/builtin_slice.py
@@ -11,6 +11,7 @@
 b = [1, 2]
 
 assert b[:] == [1, 2]
+assert b[slice(None)] == [1, 2]
 assert b[: 2 ** 100] == [1, 2]
 assert b[-2 ** 100 :] == [1, 2]
 assert b[2 ** 100 :] == []
@@ -60,6 +61,12 @@
 assert slice_c.stop == 5
 assert slice_c.step == 2
 
+a = object()
+slice_d = slice(a, "v", 1.0)
+assert slice_d.start is a
+assert slice_d.stop == "v"
+assert slice_d.step == 1.0
+
 
 class SubScript(object):
     def __getitem__(self, item):
@@ -74,6 +81,18 @@ def __setitem__(self, key, value):
 ss[:1] = 1
 
 
+class CustomIndex:
+    def __init__(self, x):
+        self.x = x
+
+    def __index__(self):
+        return self.x
+
+
+assert c[CustomIndex(1):CustomIndex(3)] == [1, 2]
+assert d[CustomIndex(1):CustomIndex(3)] == "23"
+
+
 def test_all_slices():
     """
     test all possible slices except big number

diff --git a/vm/src/frame.rs b/vm/src/frame.rs
@@ -2,8 +2,6 @@ use std::cell::RefCell;
 use std::fmt;
 use std::rc::Rc;
 
-use num_bigint::BigInt;
-
 use rustpython_parser::ast;
 
 use crate::builtins;
@@ -12,7 +10,6 @@ use crate::function::PyFuncArgs;
 use crate::obj::objbool;
 use crate::obj::objcode::PyCodeRef;
 use crate::obj::objdict::{PyDict, PyDictRef};
-use crate::obj::objint::PyInt;
 use crate::obj::objiter;
 use crate::obj::objlist;
 use crate::obj::objslice::PySlice;
@@ -435,26 +432,21 @@ impl Frame {
             }
             bytecode::Instruction::BuildSlice { size } => {
                 assert!(*size == 2 || *size == 3);
-                let elements = self.pop_multiple(*size);
-
-                let mut out: Vec<Option<BigInt>> = elements
-                    .into_iter()
-                    .map(|x| {
-                        if x.is(&vm.ctx.none()) {
-                            None
-                        } else if let Some(i) = x.payload::<PyInt>() {
-                            Some(i.as_bigint().clone())
-                        } else {
-                            panic!("Expect Int or None as BUILD_SLICE arguments")
-                        }
-                    })
-                    .collect();
 
-                let start = out[0].take();
-                let stop = out[1].take();
-                let step = if out.len() == 3 { out[2].take() } else { None };
+                let step = if *size == 3 {
+                    Some(self.pop_value())
+                } else {
+                    None
+                };
+                let stop = self.pop_value();
+                let start = self.pop_value();
 
-                let obj = PySlice { start, stop, step }.into_ref(vm);
+                let obj = PySlice {
+                    start: Some(start),
+                    stop,
+                    step,
+                }
+                .into_ref(vm);
                 self.push_value(obj.into_object());
                 Ok(None)
             }

diff --git a/vm/src/function.rs b/vm/src/function.rs
@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::mem;
 use std::ops::RangeInclusive;
 
 use crate::obj::objtype::{isinstance, PyClassRef};
@@ -48,6 +49,12 @@ impl From<(&Args, &KwArgs)> for PyFuncArgs {
     }
 }
 
+impl FromArgs for PyFuncArgs {
+    fn from_args(_vm: &VirtualMachine, args: &mut PyFuncArgs) -> Result<Self, ArgumentError> {
+        Ok(mem::replace(args, Default::default()))
+    }
+}
+
 impl PyFuncArgs {
     pub fn new(mut args: Vec<PyObjectRef>, kwarg_names: Vec<String>) -> PyFuncArgs {
         let mut kwargs = vec![];

diff --git a/vm/src/obj/objlist.rs b/vm/src/obj/objlist.rs
@@ -210,12 +210,12 @@ impl PyListRef {
     }
 
     fn setslice(self, slice: PySliceRef, sec: PyIterable, vm: &VirtualMachine) -> PyResult {
-        let step = slice.step.clone().unwrap_or_else(BigInt::one);
+        let step = slice.step_index(vm)?.unwrap_or_else(BigInt::one);
 
         if step.is_zero() {
             Err(vm.new_value_error("slice step cannot be zero".to_string()))
         } else if step.is_positive() {
-            let range = self.get_slice_range(&slice.start, &slice.stop);
+            let range = self.get_slice_range(&slice.start_index(vm)?, &slice.stop_index(vm)?);
             if range.start < range.end {
                 match step.to_i32() {
                     Some(1) => self._set_slice(range, sec, vm),
@@ -237,14 +237,14 @@ impl PyListRef {
         } else {
             // calculate the range for the reverse slice, first the bounds needs to be made
             // exclusive around stop, the lower number
-            let start = &slice.start.as_ref().map(|x| {
+            let start = &slice.start_index(vm)?.as_ref().map(|x| {
                 if *x == (-1).to_bigint().unwrap() {
                     self.get_len() + BigInt::one() //.to_bigint().unwrap()
                 } else {
                     x + 1
                 }
             });
-            let stop = &slice.stop.as_ref().map(|x| {
+            let stop = &slice.stop_index(vm)?.as_ref().map(|x| {
                 if *x == (-1).to_bigint().unwrap() {
                     self.get_len().to_bigint().unwrap()
                 } else {
@@ -552,9 +552,9 @@ impl PyListRef {
     }
 
     fn delslice(self, slice: PySliceRef, vm: &VirtualMachine) -> PyResult {
-        let start = &slice.start;
-        let stop = &slice.stop;
-        let step = slice.step.clone().unwrap_or_else(BigInt::one);
+        let start = slice.start_index(vm)?;
+        let stop = slice.stop_index(vm)?;
+        let step = slice.step_index(vm)?.unwrap_or_else(BigInt::one);
 
         if step.is_zero() {
             Err(vm.new_value_error("slice step cannot be zero".to_string()))

diff --git a/vm/src/obj/objrange.rs b/vm/src/obj/objrange.rs
@@ -273,7 +273,7 @@ impl PyRange {
                 }
             }
             RangeIndex::Slice(slice) => {
-                let new_start = if let Some(int) = slice.start.as_ref() {
+                let new_start = if let Some(int) = slice.start_index(vm)? {
                     if let Some(i) = self.get(int) {
                         PyInt::new(i).into_ref(vm)
                     } else {
@@ -283,7 +283,7 @@ impl PyRange {
                     self.start.clone()
                 };
 
-                let new_end = if let Some(int) = slice.stop.as_ref() {
+                let new_end = if let Some(int) = slice.stop_index(vm)? {
                     if let Some(i) = self.get(int) {
                         PyInt::new(i).into_ref(vm)
                     } else {
@@ -293,7 +293,7 @@ impl PyRange {
                     self.stop.clone()
                 };
 
-                let new_step = if let Some(int) = slice.step.as_ref() {
+                let new_step = if let Some(int) = slice.step_index(vm)? {
                     PyInt::new(int * self.step.as_bigint()).into_ref(vm)
                 } else {
                     self.step.clone()

diff --git a/vm/src/obj/objsequence.rs b/vm/src/obj/objsequence.rs
@@ -65,14 +65,15 @@ pub trait PySliceableSequence {
     where
         Self: Sized,
     {
-        // TODO: we could potentially avoid this copy and use slice
-        match slice.payload() {
-            Some(PySlice { start, stop, step }) => {
-                let step = step.clone().unwrap_or_else(BigInt::one);
+        match slice.clone().downcast::<PySlice>() {
+            Ok(slice) => {
+                let start = slice.start_index(vm)?;
+                let stop = slice.stop_index(vm)?;
+                let step = slice.step_index(vm)?.unwrap_or_else(BigInt::one);
                 if step.is_zero() {
                     Err(vm.new_value_error("slice step cannot be zero".to_string()))
                 } else if step.is_positive() {
-                    let range = self.get_slice_range(start, stop);
+                    let range = self.get_slice_range(&start, &stop);
                     if range.start < range.end {
                         #[allow(clippy::range_plus_one)]
                         match step.to_i32() {

diff --git a/vm/src/obj/objslice.rs b/vm/src/obj/objslice.rs
@@ -1,18 +1,16 @@
-use num_bigint::BigInt;
-
-use crate::function::PyFuncArgs;
-use crate::pyobject::{PyContext, PyObjectRef, PyRef, PyResult, PyValue};
+use crate::function::{OptionalArg, PyFuncArgs};
+use crate::pyobject::{IdProtocol, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TypeProtocol};
 use crate::vm::VirtualMachine;
 
-use super::objint;
-use crate::obj::objtype::PyClassRef;
+use crate::obj::objint::PyInt;
+use crate::obj::objtype::{class_has_attr, PyClassRef};
+use num_bigint::BigInt;
 
 #[derive(Debug)]
 pub struct PySlice {
-    // TODO: should be private
-    pub start: Option<BigInt>,
-    pub stop: Option<BigInt>,
-    pub step: Option<BigInt>,
+    pub start: Option<PyObjectRef>,
+    pub stop: PyObjectRef,
+    pub step: Option<PyObjectRef>,
 }
 
 impl PyValue for PySlice {
@@ -23,52 +21,35 @@ impl PyValue for PySlice {
 
 pub type PySliceRef = PyRef<PySlice>;
 
-fn slice_new(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
-    no_kwargs!(vm, args);
-    let (cls, start, stop, step): (
-        &PyObjectRef,
-        Option<&PyObjectRef>,
-        Option<&PyObjectRef>,
-        Option<&PyObjectRef>,
-    ) = match args.args.len() {
-        0 | 1 => Err(vm.new_type_error("slice() must have at least one arguments.".to_owned())),
-        2 => {
-            arg_check!(
-                vm,
-                args,
-                required = [
-                    (cls, Some(vm.ctx.type_type())),
-                    (stop, Some(vm.ctx.int_type()))
-                ]
-            );
-            Ok((cls, None, Some(stop), None))
+fn slice_new(cls: PyClassRef, args: PyFuncArgs, vm: &VirtualMachine) -> PyResult<PySliceRef> {
+    let slice: PySlice = match args.args.len() {
+        0 => {
+            return Err(vm.new_type_error("slice() must have at least one arguments.".to_owned()));
+        }
+        1 => {
+            let stop = args.bind(vm)?;
+            PySlice {
+                start: None,
+                stop,
+                step: None,
+            }
         }
         _ => {
-            arg_check!(
-                vm,
-                args,
-                required = [
-                    (cls, Some(vm.ctx.type_type())),
-                    (start, Some(vm.ctx.int_type())),
-                    (stop, Some(vm.ctx.int_type()))
-                ],
-                optional = [(step, Some(vm.ctx.int_type()))]
-            );
-            Ok((cls, Some(start), Some(stop), step))
+            let (start, stop, step): (PyObjectRef, PyObjectRef, OptionalArg<PyObjectRef>) =
+                args.bind(vm)?;
+            PySlice {
+                start: Some(start),
+                stop,
+                step: step.into_option(),
+            }
         }
-    }?;
-    PySlice {
-        start: start.map(|x| objint::get_value(x).clone()),
-        stop: stop.map(|x| objint::get_value(x).clone()),
-        step: step.map(|x| objint::get_value(x).clone()),
-    }
-    .into_ref_with_type(vm, cls.clone().downcast().unwrap())
-    .map(PyRef::into_object)
+    };
+    slice.into_ref_with_type(vm, cls)
 }
 
-fn get_property_value(vm: &VirtualMachine, value: &Option<BigInt>) -> PyObjectRef {
+fn get_property_value(vm: &VirtualMachine, value: &Option<PyObjectRef>) -> PyObjectRef {
     if let Some(value) = value {
-        vm.ctx.new_int(value.clone())
+        value.clone()
     } else {
         vm.get_none()
     }
@@ -79,13 +60,57 @@ impl PySliceRef {
         get_property_value(vm, &self.start)
     }
 
-    fn stop(self, vm: &VirtualMachine) -> PyObjectRef {
-        get_property_value(vm, &self.stop)
+    fn stop(self, _vm: &VirtualMachine) -> PyObjectRef {
+        self.stop.clone()
     }
 
     fn step(self, vm: &VirtualMachine) -> PyObjectRef {
         get_property_value(vm, &self.step)
     }
+
+    pub fn start_index(&self, vm: &VirtualMachine) -> PyResult<Option<BigInt>> {
+        if let Some(obj) = &self.start {
+            to_index_value(vm, obj)
+        } else {
+            Ok(None)
+        }
+    }
+
+    pub fn stop_index(&self, vm: &VirtualMachine) -> PyResult<Option<BigInt>> {
+        to_index_value(vm, &self.stop)
+    }
+
+    pub fn step_index(&self, vm: &VirtualMachine) -> PyResult<Option<BigInt>> {
+        if let Some(obj) = &self.step {
+            to_index_value(vm, obj)
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+fn to_index_value(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<Option<BigInt>> {
+    if obj.is(&vm.ctx.none) {
+        return Ok(None);
+    }
+
+    if let Some(val) = obj.payload::<PyInt>() {
+        Ok(Some(val.as_bigint().clone()))
+    } else {
+        let cls = obj.class();
+        if class_has_attr(&cls, "__index__") {
+            let index_result = vm.call_method(obj, "__index__", vec![])?;
+            if let Some(val) = index_result.payload::<PyInt>() {
+                Ok(Some(val.as_bigint().clone()))
+            } else {
+                Err(vm.new_type_error("__index__ method returned non integer".to_string()))
+            }
+        } else {
+            Err(vm.new_type_error(
+                "slice indices must be integers or None or have an __index__ method".to_string(),
+            ))
+        }
+    }
 }
 
 pub fn init(context: &PyContext) {