Add sys.exc_info

Author: palaviv

tests/snippets/sysmod.py

@@ -38,3 +38,11 @@ def demo(x):
 demo(5)
 sys.settrace(None)
 
+assert sys.exc_info() == (None, None, None)
+
+try:
+	1/0
+except ZeroDivisionError as exc:
+	exc_info = sys.exc_info()
+	assert exc_info[0] == type(exc) == ZeroDivisionError
+	assert exc_info[1] == exc

vm/src/sysmodule.rs

@@ -4,7 +4,9 @@ use std::{env, mem};
 use crate::frame::FrameRef;
 use crate::function::{OptionalArg, PyFuncArgs};
 use crate::obj::objstr::PyStringRef;
-use crate::pyobject::{IntoPyObject, ItemProtocol, PyClassImpl, PyContext, PyObjectRef, PyResult};
+use crate::pyobject::{
+    IntoPyObject, ItemProtocol, PyClassImpl, PyContext, PyObjectRef, PyResult, TypeProtocol,
+};
 use crate::version;
 use crate::vm::{PySettings, VirtualMachine};
 
@@ -149,6 +151,17 @@ fn sys_intern(value: PyStringRef, _vm: &VirtualMachine) -> PyStringRef {
     value
 }
 
+fn sys_exc_info(vm: &VirtualMachine) -> PyResult {
+    Ok(vm.ctx.new_tuple(match vm.current_exception() {
+        Some(exception) => vec![
+            exception.class().into_object(),
+            exception.clone(),
+            vm.get_none(),
+        ],
+        None => vec![vm.get_none(), vm.get_none(), vm.get_none()],
+    }))
+}
+
 pub fn make_module(vm: &VirtualMachine, module: PyObjectRef, builtins: PyObjectRef) {
     let ctx = &vm.ctx;
 
@@ -309,6 +322,7 @@ settrace() -- set the global debug tracing function
       "setprofile" => ctx.new_rustfunc(sys_setprofile),
       "settrace" => ctx.new_rustfunc(sys_settrace),
       "version" => vm.new_str(version::get_version()),
+      "exc_info" => ctx.new_rustfunc(sys_exc_info),
     });
 
     modules.set_item("sys", module.clone(), vm).unwrap();