lean on string slice to prevent copies

mojoproject.toml

@@ -4,7 +4,7 @@ channels = ["conda-forge", "https://conda.modular.com/max-nightly"]
 description = "Experiments in porting over Golang stdlib into Mojo."
 name = "gojo"
 platforms = ["osx-arm64", "linux-64"]
-version = "0.1.6.nightly"
+version = "0.1.7.nightly"
 
 [tasks]
 tests = "bash scripts/tests.sh"

src/gojo/unicode/utf8/width.mojo

@@ -1,3 +1,4 @@
+from utils import StringSlice
 from collections import InlineArray
 from .table import Interval, narrow, combining, doublewidth, ambiguous, emoji, nonprint
 
@@ -73,7 +74,21 @@ struct Condition:
         """
         var width = 0
         for r in s:
-            width += self.rune_width(ord(String(r)))
+            width += self.rune_width(ord(r))
+        return width
+
+    fn string_width(self, s: StringSlice) -> Int:
+        """Return width as you can see.
+
+        Args:
+            s: The string to calculate the width of.
+
+        Returns:
+            The printable width of the string.
+        """
+        var width = 0
+        for r in s:
+            width += self.rune_width(ord(r))
         return width
 
 
@@ -119,6 +134,18 @@ fn string_width(s: String) -> Int:
     return DEFAULT_CONDITION.string_width(s)
 
 
+fn string_width(s: StringSlice) -> Int:
+    """Return width as you can see.
+
+    Args:
+        s: The string to calculate the width of.
+
+    Returns:
+        The printable width of the string.
+    """
+    return DEFAULT_CONDITION.string_width(s)
+
+
 fn rune_width(rune: UInt32) -> Int:
     """Return width as you can see.
 

src/recipe.yaml

@@ -5,7 +5,7 @@ context:
 
 package:
   name: "gojo"
-  version: 0.1.6.nightly
+  version: 0.1.7.nightly
 
 source:
   - path: .

test/test_unicode_width.mojo

@@ -5,22 +5,25 @@ import testing
 def test_string_width_east_asian():
     var s: String = "𡨸漢𡨸漢"
 
-    testing.assert_equal(string_width(s), 8)
+    testing.assert_equal(string_width(s), 8, msg="The length of 𡨸漢𡨸漢 should be 8.")
     for r in s:
-        testing.assert_equal(rune_width(ord(String(r))), 2)
+        testing.assert_equal(rune_width(ord(r)), 2, msg="The width of each character should be 2.")
+        testing.assert_equal(string_width(r), 2, msg="The width of each character should be 2.")
 
 
 def test_string_width_ascii():
     var ascii: String = "Hello, World!"
 
     testing.assert_equal(string_width(ascii), 13)
     for r in ascii:
-        testing.assert_equal(rune_width(ord(String(r))), 1)
+        testing.assert_equal(rune_width(ord(r)), 1, msg="The width of each character should be 1.")
+        testing.assert_equal(string_width(r), 1, msg="The width of each character should be 1.")
 
 
 def test_string_width_emoji():
     var s: String = "🔥🔥🔥🔥"
 
     testing.assert_equal(string_width(s), 8)
     for r in s:
-        testing.assert_equal(rune_width(ord(String(r))), 2)
+        testing.assert_equal(rune_width(ord(r)), 2, msg="The width of each character should be 2.")
+        testing.assert_equal(string_width(r), 2, msg="The width of each character should be 2.")