From 1ff88fb662d1b1623efa6542b50b00d65ea439b2 Mon Sep 17 00:00:00 2001
From: HyeockJinKim <kherootz@gmail.com>
Date: Sat, 21 Sep 2019 01:10:02 +0900
Subject: [PATCH] Fix __eq__ of range

__eq__ compare length, start, step of range

Fixes #1389
---
 vm/src/obj/objrange.rs | 46 ++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 13 deletions(-)

diff --git a/vm/src/obj/objrange.rs b/vm/src/obj/objrange.rs
index eed66687a..6a9a09d69 100644
--- a/vm/src/obj/objrange.rs
+++ b/vm/src/obj/objrange.rs
@@ -104,6 +104,20 @@ impl PyRange {
         let result = start + step * index;
         Some(result)
     }
+
+    #[inline]
+    fn length(&self) -> PyInt {
+        let start = self.start.as_bigint();
+        let stop = self.stop.as_bigint();
+        let step = self.step.as_bigint();
+
+        match step.sign() {
+            Sign::Plus if start < stop => PyInt::new((stop - start - 1usize) / step + 1),
+            Sign::Minus if start > stop => PyInt::new((start - stop - 1usize) / (-step) + 1),
+            Sign::Plus | Sign::Minus => PyInt::new(0),
+            Sign::NoSign => unreachable!(),
+        }
+    }
 }
 
 pub fn get_value(obj: &PyObjectRef) -> PyRange {
@@ -201,16 +215,7 @@ impl PyRange {
 
     #[pymethod(name = "__len__")]
     fn len(&self, _vm: &VirtualMachine) -> PyInt {
-        let start = self.start.as_bigint();
-        let stop = self.stop.as_bigint();
-        let step = self.step.as_bigint();
-
-        match step.sign() {
-            Sign::Plus if start < stop => PyInt::new((stop - start - 1usize) / step + 1),
-            Sign::Minus if start > stop => PyInt::new((start - stop - 1usize) / (-step) + 1),
-            Sign::Plus | Sign::Minus => PyInt::new(0),
-            Sign::NoSign => unreachable!(),
-        }
+        self.length()
     }
 
     #[pymethod(name = "__repr__")]
@@ -243,9 +248,24 @@ impl PyRange {
     fn eq(&self, rhs: PyObjectRef, vm: &VirtualMachine) -> bool {
         if objtype::isinstance(&rhs, &vm.ctx.range_type()) {
             let rhs = get_value(&rhs);
-            self.start.as_bigint() == rhs.start.as_bigint()
-                && self.stop.as_bigint() == rhs.stop.as_bigint()
-                && self.step.as_bigint() == rhs.step.as_bigint()
+
+            if self.length().as_bigint() != rhs.length().as_bigint() {
+                return false;
+            }
+
+            if self.length().as_bigint().is_zero() {
+                return true;
+            }
+
+            if self.start.as_bigint() != rhs.start.as_bigint() {
+                return false;
+            }
+            let step = self.step.as_bigint();
+            if step.is_one() || step == rhs.step.as_bigint() {
+                return true;
+            }
+
+            false
         } else {
             false
         }