From 104bc56bc12fd4adcce9505277cc92ec0d66968d Mon Sep 17 00:00:00 2001
From: Windel Bouwman <windel@windel.nl>
Date: Sun, 21 Oct 2018 23:33:06 +0200
Subject: [PATCH] Add hash builtin function.

---
 vm/src/builtins.rs      |  8 +++++++-
 vm/src/obj/objint.rs    |  8 ++++++++
 vm/src/obj/objobject.rs |  8 ++++++++
 vm/src/obj/objtuple.rs  | 20 ++++++++++++++++++++
 4 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/vm/src/builtins.rs b/vm/src/builtins.rs
index f97d962fc..df15bdee4 100644
--- a/vm/src/builtins.rs
+++ b/vm/src/builtins.rs
@@ -237,7 +237,12 @@ fn builtin_hasattr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     }
 }
 
-// builtin_hash
+fn builtin_hash(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(obj, None)]);
+
+    vm.call_method(obj, "__hash__", vec![])
+}
+
 // builtin_help
 // builtin_hex
 
@@ -522,6 +527,7 @@ pub fn make_module(ctx: &PyContext) -> PyObjectRef {
     dict.insert(String::from("float"), ctx.float_type());
     dict.insert(String::from("getattr"), ctx.new_rustfunc(builtin_getattr));
     dict.insert(String::from("hasattr"), ctx.new_rustfunc(builtin_hasattr));
+    dict.insert(String::from("hash"), ctx.new_rustfunc(builtin_hash));
     dict.insert(String::from("id"), ctx.new_rustfunc(builtin_id));
     dict.insert(String::from("int"), ctx.int_type());
     dict.insert(
diff --git a/vm/src/obj/objint.rs b/vm/src/obj/objint.rs
index 22835fa6a..9fcb321b2 100644
--- a/vm/src/obj/objint.rs
+++ b/vm/src/obj/objint.rs
@@ -99,6 +99,13 @@ fn int_eq(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.ctx.new_bool(result))
 }
 
+fn int_hash(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(zelf, Some(vm.ctx.int_type()))]);
+
+    // TODO: how to hash int?
+    Ok(zelf.clone())
+}
+
 fn int_abs(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(i, Some(vm.ctx.int_type()))]);
     Ok(vm.ctx.new_int(get_value(i).abs()))
@@ -283,6 +290,7 @@ pub fn init(context: &PyContext) {
     int_type.set_attr("__and__", context.new_rustfunc(int_and));
     int_type.set_attr("__divmod__", context.new_rustfunc(int_divmod));
     int_type.set_attr("__floordiv__", context.new_rustfunc(int_floordiv));
+    int_type.set_attr("__hash__", context.new_rustfunc(int_hash));
     int_type.set_attr("__new__", context.new_rustfunc(int_new));
     int_type.set_attr("__mod__", context.new_rustfunc(int_mod));
     int_type.set_attr("__mul__", context.new_rustfunc(int_mul));
diff --git a/vm/src/obj/objobject.rs b/vm/src/obj/objobject.rs
index dea6bc508..8e1aa37e1 100644
--- a/vm/src/obj/objobject.rs
+++ b/vm/src/obj/objobject.rs
@@ -49,6 +49,13 @@ fn object_ne(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     objbool::not(vm, &eq)
 }
 
+fn object_hash(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(_zelf, Some(vm.ctx.object()))]);
+
+    // For now default to non hashable
+    Err(vm.new_type_error("unhashable type".to_string()))
+}
+
 // TODO: is object the right place for delattr?
 fn object_delattr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(
@@ -91,6 +98,7 @@ pub fn init(context: &PyContext) {
     object.set_attr("__ne__", context.new_rustfunc(object_ne));
     object.set_attr("__delattr__", context.new_rustfunc(object_delattr));
     object.set_attr("__dict__", context.new_member_descriptor(object_dict));
+    object.set_attr("__hash__", context.new_rustfunc(object_hash));
     object.set_attr("__str__", context.new_rustfunc(object_str));
     object.set_attr("__repr__", context.new_rustfunc(object_repr));
 }
diff --git a/vm/src/obj/objtuple.rs b/vm/src/obj/objtuple.rs
index f449bbc69..b3479e086 100644
--- a/vm/src/obj/objtuple.rs
+++ b/vm/src/obj/objtuple.rs
@@ -3,6 +3,7 @@ use super::super::pyobject::{
 };
 use super::super::vm::VirtualMachine;
 use super::objbool;
+use super::objint;
 use super::objsequence::{get_item, seq_equal};
 use super::objstr;
 use super::objtype;
@@ -24,6 +25,24 @@ fn tuple_eq(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     Ok(vm.ctx.new_bool(result))
 }
 
+fn tuple_hash(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(zelf, Some(vm.ctx.tuple_type()))]);
+
+    let mut x: usize = 0x345678;
+    let elements = get_elements(zelf);
+    let len: usize = elements.len();
+    let mut mult = 0xf4243;
+
+    for elem in &elements {
+        let y: usize = objint::get_value(&vm.call_method(elem, "__hash__", vec![])?) as usize;
+        x = (x ^ y) * mult;
+        mult = mult + 82520 + len * 2;
+    }
+    x += 97531;
+
+    Ok(vm.ctx.new_int(x as i32))
+}
+
 fn tuple_len(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(zelf, Some(vm.ctx.tuple_type()))]);
     let elements = get_elements(zelf);
@@ -93,6 +112,7 @@ pub fn init(context: &PyContext) {
     tuple_type.set_attr("__eq__", context.new_rustfunc(tuple_eq));
     tuple_type.set_attr("__contains__", context.new_rustfunc(tuple_contains));
     tuple_type.set_attr("__getitem__", context.new_rustfunc(tuple_getitem));
+    tuple_type.set_attr("__hash__", context.new_rustfunc(tuple_hash));
     tuple_type.set_attr("__len__", context.new_rustfunc(tuple_len));
     tuple_type.set_attr("__repr__", context.new_rustfunc(tuple_repr));
 }