Use FromStr trait and formatting ✨

src/syntax/expr.rs

@@ -3,6 +3,7 @@
 use std::fmt::{self, Write, Debug, Formatter};
 use std::iter::FromIterator;
 use std::ops::Deref;
+use std::str::FromStr;
 use std::u8;
 
 use crate::error::Errors;
@@ -141,11 +142,16 @@ impl RgbaColor {
         RgbaColor { r, g, b, a, healed: true }
     }
 
+}
+
+impl FromStr for RgbaColor {
+    type Err = ParseColorError;
+
     /// Constructs a new color from a hex string like `7a03c2`.
     /// Do not specify a leading `#`.
-    pub fn from_str(hex_str: &str) -> Option<RgbaColor> {
+    fn from_str(hex_str: &str) -> Result<RgbaColor, Self::Err> {
         if !hex_str.is_ascii() {
-            return None;
+            return Err(ParseColorError);
         }
 
         let len = hex_str.len();
@@ -154,7 +160,7 @@ impl RgbaColor {
         let alpha = len == 4 || len == 8;
 
         if !long && !short {
-            return None;
+            return Err(ParseColorError);
         }
 
         let mut values: [u8; 4] = [255; 4];
@@ -164,7 +170,8 @@ impl RgbaColor {
             let pos = elem * item_len;
 
             let item = &hex_str[pos..(pos+item_len)];
-            values[elem] = u8::from_str_radix(item, 16).ok()?;
+            values[elem] = u8::from_str_radix(item, 16)
+                .map_err(|_| ParseColorError)?;
 
             if short {
                 // Duplicate number for shorthand notation, i.e. `a` -> `aa`
@@ -172,9 +179,7 @@ impl RgbaColor {
             }
         }
 
-        Some(
+        Ok(RgbaColor::new(values[0], values[1], values[2], values[3]))
-            RgbaColor::new(values[0], values[1], values[2], values[3])
-        )
     }
 }
 
@@ -182,23 +187,34 @@ impl Debug for RgbaColor {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         if f.alternate() {
             f.write_str("rgba(")?;
-            f.write_fmt(format_args!("r: {:02}, ", self.r))?;
+            write!(f, "r: {:02}, ", self.r)?;
-            f.write_fmt(format_args!("g: {:02}, ", self.g))?;
+            write!(f, "g: {:02}, ", self.g)?;
-            f.write_fmt(format_args!("b: {:02}, ", self.b))?;
+            write!(f, "b: {:02}, ", self.b)?;
-            f.write_fmt(format_args!("a: {:02}",   self.a))?;
+            write!(f, "a: {:02}",   self.a)?;
             f.write_char(')')?;
         } else {
             f.write_char('#')?;
-            f.write_fmt(format_args!("{:02x}", self.r))?;
+            write!(f, "{:02x}", self.r)?;
-            f.write_fmt(format_args!("{:02x}", self.g))?;
+            write!(f, "{:02x}", self.g)?;
-            f.write_fmt(format_args!("{:02x}", self.b))?;
+            write!(f, "{:02x}", self.b)?;
-            f.write_fmt(format_args!("{:02x}", self.a))?;
+            write!(f, "{:02x}", self.a)?;
         }
         if self.healed {
-            f.write_fmt(format_args!(" [healed]"))
+            f.write_fmt(format_args!(" [healed]"))?;
-        } else {
+        }
         Ok(())
     }
+}
+
+/// The error returned when parsing a [`RgbaColor`] from a string fails.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct ParseColorError;
+
+impl std::error::Error for ParseColorError {}
+
+impl fmt::Display for ParseColorError {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.write_str("invalid color")
     }
 }
 
@@ -296,7 +312,7 @@ impl Debug for Tuple {
 /// ```typst
 /// hsl(93, 10, 19.4)
 /// ```
-#[derive(Clone, PartialEq, Debug)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct NamedTuple {
     /// The name of the tuple and where it is in the user source.
     pub name: Spanned<Ident>,

src/syntax/parsing.rs

@@ -1,6 +1,7 @@
 //! Parsing of source code into syntax models.
 
 use std::iter::FromIterator;
+use std::str::FromStr;
 
 use crate::{Pass, Feedback};
 use super::func::{FuncHeader, FuncArgs, FuncArg};
@@ -253,12 +254,11 @@ impl<'s> FuncParser<'s> {
             Token::ExprSize(s) => take!(Expr::Size(s)),
             Token::ExprBool(b) => take!(Expr::Bool(b)),
             Token::ExprHex(s) => {
-                if let Some(color) = RgbaColor::from_str(s) {
+                if let Ok(color) = RgbaColor::from_str(s) {
                     take!(Expr::Color(color))
                 } else {
                     // Heal color by assuming black
-                    self.feedback.errors.push(err!(first.span;
+                    self.feedback.errors.push(err!(first.span; "invalid color"));
-                        "invalid color"));
                     take!(Expr::Color(RgbaColor::new_healed(0, 0, 0, 255)))
                 }
             },
@@ -284,9 +284,8 @@ impl<'s> FuncParser<'s> {
     /// Parse a tuple expression: `name(<expr>, ...)` with a given identifier.
     fn parse_named_tuple(&mut self, name: Spanned<Ident>) -> Spanned<NamedTuple> {
         let tuple = self.parse_tuple();
-        let start = name.span.start;
+        let span = Span::merge(name.span, tuple.span);
-        let end = tuple.span.end;
+        Spanned::new(NamedTuple::new(name, tuple), span)
-        Spanned::new(NamedTuple::new(name, tuple), Span::new(start, end))
     }
 
     /// Parse an object expression: `{ <key>: <value>, ... }`.
@@ -548,20 +547,17 @@ mod tests {
     fn Str(text: &str) -> Expr { Expr::Str(text.to_string()) }
     fn Pt(points: f32) -> Expr { Expr::Size(Size::pt(points)) }
 
-    fn ClrS(color: &str) -> Expr {
-        Expr::Color(
-            RgbaColor::from_str(color).expect("Test color invalid")
-        )
-    }
-    fn ClrS_Healed() -> Expr {
-        let mut c = RgbaColor::from_str("000f")
-            .expect("Test color invalid");
-        c.healed = true;
-        Expr::Color(c)
-    }
     fn Clr(r: u8, g: u8, b: u8, a: u8) -> Expr {
         Expr::Color(RgbaColor::new(r, g, b, a))
     }
+    fn ClrStr(color: &str) -> Expr {
+        Expr::Color(RgbaColor::from_str(color).expect("invalid test color"))
+    }
+    fn ClrStrHealed() -> Expr {
+        let mut c = RgbaColor::from_str("000f").expect("invalid test color");
+        c.healed = true;
+        Expr::Color(c)
+    }
 
     fn T(text: &str) -> Node { Node::Text(text.to_string()) }
 
@@ -665,11 +661,11 @@ mod tests {
 
     #[test]
     fn parse_color_strings() {
-        assert_eq!(Clr(0xf6, 0x12, 0x43, 0xff), ClrS("f61243ff"));
+        assert_eq!(Clr(0xf6, 0x12, 0x43, 0xff), ClrStr("f61243ff"));
-        assert_eq!(Clr(0xb3, 0xd8, 0xb3, 0xff), ClrS("b3d8b3"));
+        assert_eq!(Clr(0xb3, 0xd8, 0xb3, 0xff), ClrStr("b3d8b3"));
-        assert_eq!(Clr(0xfc, 0xd2, 0xa9, 0xad), ClrS("fCd2a9AD"));
+        assert_eq!(Clr(0xfc, 0xd2, 0xa9, 0xad), ClrStr("fCd2a9AD"));
-        assert_eq!(Clr(0x22, 0x33, 0x33, 0xff), ClrS("233"));
+        assert_eq!(Clr(0x22, 0x33, 0x33, 0xff), ClrStr("233"));
-        assert_eq!(Clr(0x11, 0x11, 0x11, 0xbb), ClrS("111b"));
+        assert_eq!(Clr(0x11, 0x11, 0x11, 0xbb), ClrStr("111b"));
     }
 
     #[test]
@@ -816,7 +812,7 @@ mod tests {
         p!("[val: 3.14]"   => [func!("val": (Num(3.14)), {})]);
         p!("[val: 4.5cm]"  => [func!("val": (Sz(Size::cm(4.5))), {})]);
         p!("[val: 12e1pt]" => [func!("val": (Pt(12e1)), {})]);
-        p!("[val: #f7a20500]" => [func!("val": (ClrS("f7a20500")), {})]);
+        p!("[val: #f7a20500]" => [func!("val": (ClrStr("f7a20500")), {})]);
 
         // Unclosed string.
         p!("[val: \"hello]" => [func!("val": (Str("hello]")), {})], [
@@ -825,16 +821,16 @@ mod tests {
         ]);
 
         //Invalid colors
-        p!("[val: #12345]" => [func!("val": (ClrS_Healed()), {})], [
+        p!("[val: #12345]" => [func!("val": (ClrStrHealed()), {})], [
             (0:6, 0:12, "invalid color"),
         ]);
-        p!("[val: #a5]" => [func!("val": (ClrS_Healed()), {})], [
+        p!("[val: #a5]" => [func!("val": (ClrStrHealed()), {})], [
             (0:6, 0:9, "invalid color"),
         ]);
-        p!("[val: #14b2ah]" => [func!("val": (ClrS_Healed()), {})], [
+        p!("[val: #14b2ah]" => [func!("val": (ClrStrHealed()), {})], [
             (0:6, 0:13, "invalid color"),
         ]);
-        p!("[val: #f075ff011]" => [func!("val": (ClrS_Healed()), {})], [
+        p!("[val: #f075ff011]" => [func!("val": (ClrStrHealed()), {})], [
             (0:6, 0:16, "invalid color"),
         ]);
     }
@@ -881,7 +877,7 @@ mod tests {
         );
         p!("[val: items(\"fire\", #f93a6d)]" =>
             [func!("val": (named_tuple!(
-                "items", Str("fire"), ClrS("f93a6d")
+                "items", Str("fire"), ClrStr("f93a6d")
             )), {})]
         );
 

src/syntax/tokens.rs

@@ -389,12 +389,10 @@ impl<'s> Tokens<'s> {
     fn parse_hex_value(&mut self) -> Token<'s> {
         // This will parse more than the permissable 0-9, a-f, A-F character
         // ranges to provide nicer error messages later.
-        let payload = self.read_string_until(
+        ExprHex(self.read_string_until(
             |n| !n.is_ascii_alphanumeric(),
             false, 0, 0
-        ).0;
+        ).0)
-
-        ExprHex(payload)
     }
 
     fn parse_expr(&mut self, text: &'s str) -> Token<'s> {