User-defined symbols

library/src/compute/construct.rs

@@ -240,6 +240,67 @@ castable! {
     },
 }
 
+/// # Symbol
+/// Create a custom symbol with modifiers.
+///
+/// ## Example
+/// ```
+/// #let envelope = symbol(
+///   "🖂",
+///   ("stamped", "🖃"),
+///   ("stamped.pen", "🖆"),
+///   ("lightning", "🖄"),
+///   ("fly", "🖅"),
+/// )
+///
+/// #envelope
+/// #envelope.stamped
+/// #envelope.stamped.pen
+/// #envelope.lightning
+/// #envelope.fly
+/// ```
+///
+/// ## Parameters
+/// - variants: Variant (positional, variadic)
+///   The variants of the symbol.
+///
+///   Can be a just a string consisting of a single character for the
+///   modifierless variant or an array with two strings specifying the modifiers
+///   and the symbol. Individual modifiers should be separated by dots. When
+///   displaying a symbol, Typst selects the first from the variants that have
+///   all attached modifiers and the minimum number of other modifiers.
+///
+/// - returns: symbol
+///
+/// ## Category
+/// construct
+#[func]
+pub fn symbol(args: &mut Args) -> SourceResult<Value> {
+    let mut list: Vec<(EcoString, char)> = vec![];
+    for Spanned { v, span } in args.all::<Spanned<Variant>>()? {
+        if list.iter().any(|(prev, _)| &v.0 == prev) {
+            bail!(span, "duplicate variant");
+        }
+        list.push((v.0, v.1));
+    }
+    Ok(Value::Symbol(Symbol::runtime(list)))
+}
+
+/// A value that can be cast to a symbol.
+struct Variant(EcoString, char);
+
+castable! {
+    Variant,
+    c: char => Self(EcoString::new(), c),
+    array: Array => {
+        let mut iter = array.into_iter();
+        match (iter.next(), iter.next(), iter.next()) {
+            (Some(a), Some(b), None) => Self(a.cast()?, b.cast()?),
+            _ => Err("point array must contain exactly two entries")?,
+        }
+    },
+}
+
 /// # String
 /// Convert a value to a string.
 ///

library/src/lib.rs

@@ -101,6 +101,7 @@ fn global(sym: Module, math: Module) -> Module {
     global.def_func::<compute::LumaFunc>("luma");
     global.def_func::<compute::RgbFunc>("rgb");
     global.def_func::<compute::CmykFunc>("cmyk");
+    global.def_func::<compute::SymbolFunc>("symbol");
     global.def_func::<compute::StrFunc>("str");
     global.def_func::<compute::LabelFunc>("label");
     global.def_func::<compute::RegexFunc>("regex");

src/model/symbol.rs

@@ -1,6 +1,7 @@
 use std::cmp::Reverse;
 use std::collections::BTreeSet;
 use std::fmt::{self, Debug, Display, Formatter, Write};
+use std::sync::Arc;
 
 use crate::diag::StrResult;
 use crate::util::EcoString;
@@ -38,7 +39,8 @@ pub struct Symbol {
 #[derive(Clone, Eq, PartialEq, Hash)]
 enum Repr {
     Single(char),
-    List(&'static [(&'static str, char)]),
+    Static(&'static [(&'static str, char)]),
+    Runtime(Arc<Vec<(EcoString, char)>>),
 }
 
 impl Symbol {
@@ -47,12 +49,22 @@ impl Symbol {
         Self { repr: Repr::Single(c), modifiers: EcoString::new() }
     }
 
-    /// Create a symbol with variants.
+    /// Create a symbol with a static variant list.
     #[track_caller]
     pub fn list(list: &'static [(&'static str, char)]) -> Self {
         debug_assert!(!list.is_empty());
         Self {
-            repr: Repr::List(list),
+            repr: Repr::Static(list),
+            modifiers: EcoString::new(),
+        }
+    }
+
+    /// Create a symbol with a runtime variant list.
+    #[track_caller]
+    pub fn runtime(list: Vec<(EcoString, char)>) -> Self {
+        debug_assert!(!list.is_empty());
+        Self {
+            repr: Repr::Runtime(Arc::new(list)),
             modifiers: EcoString::new(),
         }
     }
@@ -61,7 +73,7 @@ impl Symbol {
     pub fn get(&self) -> char {
         match self.repr {
             Repr::Single(c) => c,
-            Repr::List(list) => find(list, &self.modifiers).unwrap(),
+            _ => find(self.variants(), &self.modifiers).unwrap(),
         }
     }
 
@@ -71,10 +83,7 @@ impl Symbol {
             self.modifiers.push('.');
         }
         self.modifiers.push_str(modifier);
-        if match self.repr {
-            Repr::Single(_) => true,
-            Repr::List(list) => find(list, &self.modifiers).is_none(),
-        } {
+        if find(self.variants(), &self.modifiers).is_none() {
             Err("unknown modifier")?
         }
         Ok(self)
@@ -82,21 +91,19 @@ impl Symbol {
 
     /// The characters that are covered by this symbol.
     pub fn variants(&self) -> impl Iterator<Item = (&str, char)> {
-        let (first, slice) = match self.repr {
-            Repr::Single(c) => (Some(("", c)), [].as_slice()),
-            Repr::List(list) => (None, list),
-        };
-        first.into_iter().chain(slice.iter().copied())
+        match &self.repr {
+            Repr::Single(c) => Variants::Single(Some(*c).into_iter()),
+            Repr::Static(list) => Variants::Static(list.iter()),
+            Repr::Runtime(list) => Variants::Runtime(list.iter()),
+        }
     }
 
     /// Possible modifiers.
     pub fn modifiers(&self) -> impl Iterator<Item = &str> + '_ {
         let mut set = BTreeSet::new();
-        if let Repr::List(list) = self.repr {
-            for modifier in list.iter().flat_map(|(name, _)| name.split('.')) {
-                if !modifier.is_empty() && !contained(&self.modifiers, modifier) {
-                    set.insert(modifier);
-                }
+        for modifier in self.variants().flat_map(|(name, _)| name.split('.')) {
+            if !modifier.is_empty() && !contained(&self.modifiers, modifier) {
+                set.insert(modifier);
             }
         }
         set.into_iter()
@@ -115,13 +122,35 @@ impl Display for Symbol {
     }
 }
 
+/// Iterator over variants.
+enum Variants<'a> {
+    Single(std::option::IntoIter<char>),
+    Static(std::slice::Iter<'static, (&'static str, char)>),
+    Runtime(std::slice::Iter<'a, (EcoString, char)>),
+}
+
+impl<'a> Iterator for Variants<'a> {
+    type Item = (&'a str, char);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            Self::Single(iter) => Some(("", iter.next()?)),
+            Self::Static(list) => list.next().copied(),
+            Self::Runtime(list) => list.next().map(|(s, c)| (s.as_str(), *c)),
+        }
+    }
+}
+
 /// Find the best symbol from the list.
-fn find(list: &[(&str, char)], modifiers: &str) -> Option<char> {
+fn find<'a>(
+    variants: impl Iterator<Item = (&'a str, char)>,
+    modifiers: &str,
+) -> Option<char> {
     let mut best = None;
     let mut best_score = None;
 
     // Find the best table entry with this name.
-    'outer: for candidate in list {
+    'outer: for candidate in variants {
         for modifier in parts(modifiers) {
             if !contained(candidate.0, modifier) {
                 continue 'outer;

tests/typ/compute/construct.typ

@@ -41,6 +41,23 @@
 // Error: 21-26 expected integer or ratio, found boolean
 #rgb(10%, 20%, 30%, false)
 
+---
+// Ref: true
+#let envelope = symbol(
+  "🖂",
+  ("stamped", "🖃"),
+  ("stamped.pen", "🖆"),
+  ("lightning", "🖄"),
+  ("fly", "🖅"),
+)
+
+#envelope
+#envelope.stamped
+#envelope.pen
+#envelope.stamped.pen
+#envelope.lightning
+#envelope.fly
+
 ---
 // Test conversion to string.
 #test(str(123), "123")