Basic SymbolElem addition

crates/typst-layout/src/math/mod.rs

@@ -17,7 +17,9 @@ use rustybuzz::Feature;
 use ttf_parser::Tag;
 use typst_library::diag::{bail, SourceResult};
 use typst_library::engine::Engine;
-use typst_library::foundations::{Content, NativeElement, Packed, Resolve, StyleChain};
+use typst_library::foundations::{
+    Content, NativeElement, Packed, Resolve, StyleChain, SymbolElem,
+};
 use typst_library::introspection::{Counter, Locator, SplitLocator, TagElem};
 use typst_library::layout::{
     Abs, AlignElem, Axes, BlockElem, BoxElem, Em, FixedAlignment, Fragment, Frame, HElem,
@@ -535,6 +537,12 @@ fn layout_realized(
         layout_h(elem, ctx, styles)?;
     } else if let Some(elem) = elem.to_packed::<TextElem>() {
         self::text::layout_text(elem, ctx, styles)?;
+    } else if let Some(elem) = elem.to_packed::<SymbolElem>() {
+        // This is a hack to avoid affecting layout that will be replaced in a
+        // later commit.
+        let text_elem = TextElem::new(elem.text.to_string().into());
+        let packed = Packed::new(text_elem);
+        self::text::layout_text(&packed, ctx, styles)?;
     } else if let Some(elem) = elem.to_packed::<BoxElem>() {
         layout_box(elem, ctx, styles)?;
     } else if elem.is::<AlignPointElem>() {

crates/typst-library/src/foundations/ops.rs

@@ -6,7 +6,9 @@ use ecow::eco_format;
 use typst_utils::Numeric;
 
 use crate::diag::{bail, HintedStrResult, StrResult};
-use crate::foundations::{format_str, Datetime, IntoValue, Regex, Repr, Value};
+use crate::foundations::{
+    format_str, Datetime, IntoValue, Regex, Repr, SymbolElem, Value,
+};
 use crate::layout::{Alignment, Length, Rel};
 use crate::text::TextElem;
 use crate::visualize::Stroke;
@@ -30,10 +32,10 @@ pub fn join(lhs: Value, rhs: Value) -> StrResult<Value> {
         (Symbol(a), Str(b)) => Str(format_str!("{a}{b}")),
         (Bytes(a), Bytes(b)) => Bytes(a + b),
         (Content(a), Content(b)) => Content(a + b),
-        (Content(a), Symbol(b)) => Content(a + TextElem::packed(b.get())),
+        (Content(a), Symbol(b)) => Content(a + SymbolElem::packed(b.get())),
         (Content(a), Str(b)) => Content(a + TextElem::packed(b)),
         (Str(a), Content(b)) => Content(TextElem::packed(a) + b),
-        (Symbol(a), Content(b)) => Content(TextElem::packed(a.get()) + b),
+        (Symbol(a), Content(b)) => Content(SymbolElem::packed(a.get()) + b),
         (Array(a), Array(b)) => Array(a + b),
         (Dict(a), Dict(b)) => Dict(a + b),
         (Args(a), Args(b)) => Args(a + b),
@@ -130,10 +132,10 @@ pub fn add(lhs: Value, rhs: Value) -> HintedStrResult<Value> {
         (Symbol(a), Str(b)) => Str(format_str!("{a}{b}")),
         (Bytes(a), Bytes(b)) => Bytes(a + b),
         (Content(a), Content(b)) => Content(a + b),
-        (Content(a), Symbol(b)) => Content(a + TextElem::packed(b.get())),
+        (Content(a), Symbol(b)) => Content(a + SymbolElem::packed(b.get())),
         (Content(a), Str(b)) => Content(a + TextElem::packed(b)),
         (Str(a), Content(b)) => Content(TextElem::packed(a) + b),
-        (Symbol(a), Content(b)) => Content(TextElem::packed(a.get()) + b),
+        (Symbol(a), Content(b)) => Content(SymbolElem::packed(a.get()) + b),
 
         (Array(a), Array(b)) => Array(a + b),
         (Dict(a), Dict(b)) => Dict(a + b),

crates/typst-library/src/foundations/symbol.rs

@@ -9,7 +9,10 @@ use typst_syntax::{is_ident, Span, Spanned};
 use typst_utils::hash128;
 
 use crate::diag::{bail, SourceResult, StrResult};
-use crate::foundations::{cast, func, scope, ty, Array, Func, NativeFunc, Repr as _};
+use crate::foundations::{
+    cast, elem, func, scope, ty, Array, Content, Func, NativeElement, NativeFunc, Packed,
+    PlainText, Repr as _,
+};
 
 /// A Unicode symbol.
 ///
@@ -425,3 +428,31 @@ fn parts(modifiers: &str) -> impl Iterator<Item = &str> {
 fn contained(modifiers: &str, m: &str) -> bool {
     parts(modifiers).any(|part| part == m)
 }
+
+/// A single character.
+#[elem(Repr, PlainText)]
+pub struct SymbolElem {
+    /// The symbol's character.
+    #[required]
+    pub text: char, // This is called `text` for consistency with `TextElem`.
+}
+
+impl SymbolElem {
+    /// Create a new packed symbol element.
+    pub fn packed(text: impl Into<char>) -> Content {
+        Self::new(text.into()).pack()
+    }
+}
+
+impl PlainText for Packed<SymbolElem> {
+    fn plain_text(&self, text: &mut EcoString) {
+        text.push(self.text);
+    }
+}
+
+impl crate::foundations::Repr for SymbolElem {
+    /// Use a custom repr that matches normal content.
+    fn repr(&self) -> EcoString {
+        eco_format!("[{}]", self.text)
+    }
+}

crates/typst-library/src/foundations/value.rs

@@ -16,7 +16,7 @@ use crate::foundations::{
     fields, ops, repr, Args, Array, AutoValue, Bytes, CastInfo, Content, Datetime,
     Decimal, Dict, Duration, Fold, FromValue, Func, IntoValue, Label, Module,
     NativeElement, NativeType, NoneValue, Plugin, Reflect, Repr, Resolve, Scope, Str,
-    Styles, Symbol, Type, Version,
+    Styles, Symbol, SymbolElem, Type, Version,
 };
 use crate::layout::{Abs, Angle, Em, Fr, Length, Ratio, Rel};
 use crate::text::{RawContent, RawElem, TextElem};
@@ -209,7 +209,7 @@ impl Value {
             Self::Decimal(v) => TextElem::packed(eco_format!("{v}")),
             Self::Str(v) => TextElem::packed(v),
             Self::Version(v) => TextElem::packed(eco_format!("{v}")),
-            Self::Symbol(v) => TextElem::packed(v.get()),
+            Self::Symbol(v) => SymbolElem::packed(v.get()),
             Self::Content(v) => v,
             Self::Module(module) => module.content(),
             _ => RawElem::new(RawContent::Text(self.repr()))
@@ -656,7 +656,7 @@ primitive! { Duration: "duration", Duration }
 primitive! { Content: "content",
     Content,
     None => Content::empty(),
-    Symbol(v) => TextElem::packed(v.get()),
+    Symbol(v) => SymbolElem::packed(v.get()),
     Str(v) => TextElem::packed(v)
 }
 primitive! { Styles: "styles", Styles }

crates/typst-library/src/math/accent.rs

@@ -1,8 +1,7 @@
 use crate::diag::bail;
-use crate::foundations::{cast, elem, func, Content, NativeElement, Value};
+use crate::foundations::{cast, elem, func, Content, NativeElement, SymbolElem};
 use crate::layout::{Length, Rel};
 use crate::math::Mathy;
-use crate::text::TextElem;
 
 /// Attaches an accent to a base.
 ///
@@ -142,8 +141,8 @@ cast! {
     Accent,
     self => self.0.into_value(),
     v: char => Self::new(v),
-    v: Content => match v.to_packed::<TextElem>() {
+    v: Content => match v.to_packed::<SymbolElem>() {
-        Some(elem) => Value::Str(elem.text.clone().into()).cast()?,
+        Some(elem) => Self::new(elem.text),
-        None => bail!("expected text"),
+        None => bail!("expected a symbol"),
     },
 }

crates/typst-realize/src/lib.rs

@@ -16,7 +16,7 @@ use typst_library::engine::Engine;
 use typst_library::foundations::{
     Content, Context, ContextElem, Element, NativeElement, Recipe, RecipeIndex, Selector,
     SequenceElem, Show, ShowSet, Style, StyleChain, StyleVec, StyledElem, Styles,
-    Synthesize, Transformation,
+    SymbolElem, Synthesize, Transformation,
 };
 use typst_library::html::{tag, HtmlElem};
 use typst_library::introspection::{Locatable, SplitLocator, Tag, TagElem};
@@ -221,7 +221,7 @@ impl<'a, 'x, 'y, 'z, 's> Grouped<'a, 'x, 'y, 'z, 's> {
 /// Handles an arbitrary piece of content during realization.
 fn visit<'a>(
     s: &mut State<'a, '_, '_, '_>,
-    content: &'a Content,
+    mut content: &'a Content,
     styles: StyleChain<'a>,
 ) -> SourceResult<()> {
     // Tags can always simply be pushed.
@@ -230,6 +230,12 @@ fn visit<'a>(
         return Ok(());
     }
 
+    if let Some(elem) = content.to_packed::<SymbolElem>() {
+        // This is a hack to avoid affecting layout that will be replaced in a
+        // later commit.
+        content = Box::leak(Box::new(TextElem::packed(elem.text.to_string())));
+    }
+
     // Transformations for math content based on the realization kind. Needs
     // to happen before show rules.
     if visit_math_rules(s, content, styles)? {

tests/suite/foundations/content.typ

@@ -50,12 +50,14 @@
 `raw` <myraw>
 
 --- content-fields-complex ---
-// Integrated test for content fields.
+// Integrated test for content fields. The idea is to parse a normal looking
+// equation and symbolically evaluate it with the given variable values.
+
 #let compute(equation, ..vars) = {
   let vars = vars.named()
   let f(elem) = {
     let func = elem.func()
-    if func == text {
+    if elem.has("text") {
       let text = elem.text
       if regex("^\d+$") in text {
         int(text)
@@ -74,7 +76,7 @@
       elem
         .children
         .filter(v => v != [ ])
-        .split[+]
+        .split($+$.body)
         .map(xs => xs.fold(1, (prod, v) => prod * f(v)))
         .fold(0, (sum, v) => sum + v)
     }
@@ -83,13 +85,15 @@
   [With ]
   vars
     .pairs()
-    .map(p => $#p.first() = #p.last()$)
+    .map(((name, value)) => $name = value$)
     .join(", ", last: " and ")
   [ we have:]
   $ equation = result $
 }
 
 #compute($x y + y^2$, x: 2, y: 3)
+// This should generate the same output as:
+// With $x = 2$ and $y = 3$ we have: $ x y + y^2 = 15 $
 
 --- content-label-has-method ---
 // Test whether the label is accessible through the `has` method.

tests/suite/math/symbols.typ

@@ -2,7 +2,7 @@
 
 --- math-symbol-basic ---
 #let sym = symbol("s", ("basic", "s"))
-#test($sym.basic$, $#"s"$)
+#test($sym.basic$, $s$)
 
 --- math-symbol-underscore ---
 #let sym = symbol("s", ("test_underscore", "s"))
@@ -16,7 +16,7 @@ $sym.test-dash$
 
 --- math-symbol-double ---
 #let sym = symbol("s", ("test.basic", "s"))
-#test($sym.test.basic$, $#"s"$)
+#test($sym.test.basic$, $s$)
 
 --- math-symbol-double-underscore ---
 #let sym = symbol("s", ("one.test_underscore", "s"))