From 6cb8b665a224a3e56f496b06f843702abbe61a8e Mon Sep 17 00:00:00 2001
From: Jeong YunWon <jeong@youknowone.org>
Date: Wed, 11 Mar 2020 04:52:35 +0900
Subject: [PATCH] Fix str.expandtab() for newlines

---
 Lib/test/string_tests.py |  2 --
 vm/src/obj/objstr.rs     | 35 ++++++++++++++++++++++++-----------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/Lib/test/string_tests.py b/Lib/test/string_tests.py
index 4af8a70ee..121a9dca6 100644
--- a/Lib/test/string_tests.py
+++ b/Lib/test/string_tests.py
@@ -327,8 +327,6 @@ class BaseTest:
         self.checkequal('HELLO', 'HELLO', 'upper')
         self.checkraises(TypeError, 'hello', 'upper', 42)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_expandtabs(self):
         self.checkequal('abc\rab      def\ng       hi', 'abc\rab\tdef\ng\thi',
                         'expandtabs')
diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
index e3b186cf4..46a6ab41f 100644
--- a/vm/src/obj/objstr.rs
+++ b/vm/src/obj/objstr.rs
@@ -184,6 +184,12 @@ struct SplitLineArgs {
     keepends: OptionalArg<bool>,
 }
 
+#[derive(FromArgs)]
+struct ExpandtabsArgs {
+    #[pyarg(positional_or_keyword, optional = true)]
+    tabsize: OptionalArg<usize>,
+}
+
 #[pyimpl(flags(BASETYPE))]
 impl PyString {
     #[pyslot]
@@ -1079,21 +1085,28 @@ impl PyString {
     }
 
     #[pymethod]
-    fn expandtabs(&self, tab_stop: OptionalArg<usize>) -> String {
-        let tab_stop = tab_stop.into_option().unwrap_or(8 as usize);
+    fn expandtabs(&self, args: ExpandtabsArgs) -> String {
+        let tab_stop = args.tabsize.unwrap_or(8);
         let mut expanded_str = String::with_capacity(self.value.len());
         let mut tab_size = tab_stop;
         let mut col_count = 0 as usize;
         for ch in self.value.chars() {
-            // 0x0009 is tab
-            if ch == 0x0009 as char {
-                let num_spaces = tab_size - col_count;
-                col_count += num_spaces;
-                let expand = " ".repeat(num_spaces);
-                expanded_str.push_str(&expand);
-            } else {
-                expanded_str.push(ch);
-                col_count += 1;
+            match ch {
+                '\t' => {
+                    let num_spaces = tab_size - col_count;
+                    col_count += num_spaces;
+                    let expand = " ".repeat(num_spaces);
+                    expanded_str.push_str(&expand);
+                }
+                '\r' | '\n' => {
+                    expanded_str.push(ch);
+                    col_count = 0;
+                    tab_size = 0;
+                }
+                _ => {
+                    expanded_str.push(ch);
+                    col_count += 1;
+                }
             }
             if col_count >= tab_size {
                 tab_size += tab_stop;