Upstream sharkdp/numbat state of the touched files before c69ba1b277

examples/tests/strings.nbt

@@ -1,19 +1,11 @@
 assert_eq(str_length(""), 0)
 assert_eq(str_length("foo"), 3)
 
-# Length and slicing operate on Unicode code points, not on UTF-8 bytes
-assert_eq(str_length("café"), 4)
-assert_eq(str_length("❤"), 1)
-
 assert_eq(str_slice(0, 5, "hello world"), "hello")
 assert_eq(str_slice(6, 11, "hello world"), "world")
 assert_eq(str_slice(0, 0, "hello world"), "")
 assert_eq(str_slice(0, 100, "hello world"), "")
 
-assert_eq(str_slice(0, 4, "café"), "café")
-assert_eq(str_slice(3, 4, "café"), "é")
-assert_eq(str_slice(0, 3, "café"), "caf")
-
 assert_eq(chr(65), "A")
 assert_eq(chr(97), "a")
 assert_eq(chr(0x2764), "❤")

numbat/src/ffi/strings.rs

@@ -12,7 +12,7 @@ pub fn str_length(
     mut args: Args,
     _return_type: &TypeScheme,
 ) -> Result<Value, Box<RuntimeErrorKind>> {
-    let len = string_arg!(args).chars().count();
+    let len = string_arg!(args).len();
     return_scalar!(len as f64)
 }
 
@@ -41,16 +41,9 @@ pub fn str_slice(
     let end = quantity_arg!(args).unsafe_value().to_f64() as usize;
     let input = string_arg!(args);
 
-    // Indices refer to code points, not bytes; out-of-range requests yield an
-    // empty string as before.
-    let characters = input.chars().collect::<Vec<char>>();
-    let output = if start <= end && end <= characters.len() {
-        characters[start..end].iter().collect::<String>()
-    } else {
-        String::new()
-    };
+    let output = input.get(start..end).unwrap_or_default();
 
-    return_string!(from = &output)
+    return_string!(borrowed = output)
 }
 
 pub fn chr(