Iterate over grapheme clusters instead of chars

Cargo.toml

@@ -29,6 +29,7 @@ rustybuzz = "0.4"
 serde = { version = "1", features = ["derive", "rc"] }
 ttf-parser = "0.12"
 unicode-bidi = "0.3.5"
+unicode-segmentation = "1.8"
 unicode-xid = "0.2"
 xi-unicode = "0.3"
 anyhow = { version = "1", optional = true }

src/eval/str.rs

@@ -3,6 +3,8 @@ use std::convert::TryFrom;
 use std::fmt::{self, Debug, Formatter, Write};
 use std::ops::{Add, AddAssign, Deref};
 
+use unicode_segmentation::UnicodeSegmentation;
+
 use crate::diag::StrResult;
 use crate::util::EcoString;
 
@@ -41,9 +43,9 @@ impl Str {
         self.0.as_str()
     }
 
-    /// Return an iterator over the chars as strings.
+    /// Return an iterator over the grapheme clusters as strings.
     pub fn iter(&self) -> impl Iterator<Item = Str> + '_ {
-        self.chars().map(Into::into)
+        self.graphemes(true).map(Into::into)
     }
 
     /// Repeat this string `n` times.

tests/typ/code/for.typ

@@ -58,15 +58,15 @@
 
 #test(out, (1, 2, 3, 4, 5, "a", 6, "b", 7))
 
-// Chars of string.
+// Grapheme clusters of string.
 #let first = true
-#let joined = for c in "abc" {
+#let joined = for c in "abc👩‍👩‍👦‍👦" {
   if not first { ", " }
   first = false
   c
 }
 
-#test(joined, "a, b, c")
+#test(joined, "a, b, c, 👩‍👩‍👦‍👦")
 
 // Return value.
 #test(for v in "" [], none)