1 files changed, 39 insertions, 30 deletions

diff --git a/src/frame.rs b/src/frame.rs
index e85256f5..2eac6879 100644
--- a/src/frame.rs
+++ b/src/frame.rs
@@ -2,6 +2,7 @@
 
 use std::fmt::{self, Debug, Formatter, Write};
 use std::num::NonZeroUsize;
+use std::str::FromStr;
 use std::sync::Arc;
 
 use crate::font::Font;
@@ -9,7 +10,7 @@ use crate::geom::{
     Abs, Align, Axes, Dir, Em, Numeric, Paint, Point, Shape, Size, Transform,
 };
 use crate::image::Image;
-use crate::model::{Dict, Value};
+use crate::model::{dict, Dict, Value};
 use crate::util::EcoString;
 
 /// A finished layout with elements at fixed positions.
@@ -396,7 +397,7 @@ pub struct Glyph {
     pub c: char,
 }
 
-/// A code for a natural language.
+/// An identifier for a natural language.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub struct Lang([u8; 3], u8);
 
@@ -404,19 +405,6 @@ impl Lang {
     /// The code for the english language.
     pub const ENGLISH: Self = Self(*b"en ", 2);
 
-    /// Construct a language from a two- or three-byte ISO 639-1/2/3 code.
-    pub fn from_str(iso: &str) -> Option<Self> {
-        let len = iso.len();
-        if matches!(len, 2 ..= 3) && iso.is_ascii() {
-            let mut bytes = [b' '; 3];
-            bytes[.. len].copy_from_slice(iso.as_bytes());
-            bytes.make_ascii_lowercase();
-            Some(Self(bytes, len as u8))
-        } else {
-            None
-        }
-    }
-
     /// Return the language code as an all lowercase string slice.
     pub fn as_str(&self) -> &str {
         std::str::from_utf8(&self.0[.. usize::from(self.1)]).unwrap_or_default()
@@ -432,28 +420,49 @@ impl Lang {
     }
 }
 
-/// A code for a region somewhere in the world.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
-pub struct Region([u8; 2]);
+impl FromStr for Lang {
+    type Err = &'static str;
 
-impl Region {
-    /// Construct a region from its two-byte ISO 3166-1 alpha-2 code.
-    pub fn from_str(iso: &str) -> Option<Self> {
-        if iso.is_ascii() {
-            let mut bytes: [u8; 2] = iso.as_bytes().try_into().ok()?;
-            bytes.make_ascii_uppercase();
-            Some(Self(bytes))
+    /// Construct a language from a two- or three-byte ISO 639-1/2/3 code.
+    fn from_str(iso: &str) -> Result<Self, Self::Err> {
+        let len = iso.len();
+        if matches!(len, 2 ..= 3) && iso.is_ascii() {
+            let mut bytes = [b' '; 3];
+            bytes[.. len].copy_from_slice(iso.as_bytes());
+            bytes.make_ascii_lowercase();
+            Ok(Self(bytes, len as u8))
         } else {
-            None
+            Err("expected two or three letter language code (ISO 639-1/2/3)")
         }
     }
+}
 
+/// An identifier for a region somewhere in the world.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub struct Region([u8; 2]);
+
+impl Region {
     /// Return the region code as an all uppercase string slice.
     pub fn as_str(&self) -> &str {
         std::str::from_utf8(&self.0).unwrap_or_default()
     }
 }
 
+impl FromStr for Region {
+    type Err = &'static str;
+
+    /// Construct a region from its two-byte ISO 3166-1 alpha-2 code.
+    fn from_str(iso: &str) -> Result<Self, Self::Err> {
+        if iso.len() == 2 && iso.is_ascii() {
+            let mut bytes: [u8; 2] = iso.as_bytes().try_into().unwrap();
+            bytes.make_ascii_uppercase();
+            Ok(Self(bytes))
+        } else {
+            Err("expected two letter region code (ISO 3166-1 alpha-2)")
+        }
+    }
+}
+
 /// A link destination.
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub enum Destination {
@@ -529,9 +538,9 @@ impl Role {
     pub fn is_weak(self) -> bool {
         // In Typst, all text is in a paragraph, so paragraph isn't very
         // descriptive.
-        match self {
-            Self::Paragraph | Self::GenericBlock | Self::GenericInline => true,
-            _ => false,
-        }
+        matches!(
+            self,
+            Self::Paragraph | Self::GenericBlock | Self::GenericInline
+        )
     }
 }