1 files changed, 135 insertions, 0 deletions
diff --git a/crates/typst-library/src/math/lr.rs b/crates/typst-library/src/math/lr.rs
new file mode 100644
index 00000000..07ab0dd4
--- /dev/null
+++ b/crates/typst-library/src/math/lr.rs
@@ -0,0 +1,135 @@
+use crate::foundations::{elem, func, Content, NativeElement, Smart};
+use crate::layout::{Length, Rel};
+use crate::math::Mathy;
+use crate::text::TextElem;
+
+/// Scales delimiters.
+///
+/// While matched delimiters scale by default, this can be used to scale
+/// unmatched delimiters and to control the delimiter scaling more precisely.
+#[elem(title = "Left/Right", Mathy)]
+pub struct LrElem {
+    /// The size of the brackets, relative to the height of the wrapped content.
+    pub size: Smart<Rel<Length>>,
+
+    /// The delimited content, including the delimiters.
+    #[required]
+    #[parse(
+        let mut arguments = args.all::<Content>()?.into_iter();
+        let mut body = arguments.next().unwrap_or_default();
+        arguments.for_each(|arg| body += TextElem::packed(',') + arg);
+        body
+    )]
+    pub body: Content,
+}
+
+/// Scales delimiters vertically to the nearest surrounding `{lr()}` group.
+///
+/// ```example
+/// $ { x mid(|) sum_(i=1)^n w_i|f_i (x)| < 1 } $
+/// ```
+#[elem(Mathy)]
+pub struct MidElem {
+    /// The content to be scaled.
+    #[required]
+    pub body: Content,
+}
+
+/// Floors an expression.
+///
+/// ```example
+/// $ floor(x/2) $
+/// ```
+#[func]
+pub fn floor(
+    /// The size of the brackets, relative to the height of the wrapped content.
+    #[named]
+    size: Option<Smart<Rel<Length>>>,
+    /// The expression to floor.
+    body: Content,
+) -> Content {
+    delimited(body, '⌊', '⌋', size)
+}
+
+/// Ceils an expression.
+///
+/// ```example
+/// $ ceil(x/2) $
+/// ```
+#[func]
+pub fn ceil(
+    /// The size of the brackets, relative to the height of the wrapped content.
+    #[named]
+    size: Option<Smart<Rel<Length>>>,
+    /// The expression to ceil.
+    body: Content,
+) -> Content {
+    delimited(body, '⌈', '⌉', size)
+}
+
+/// Rounds an expression.
+///
+/// ```example
+/// $ round(x/2) $
+/// ```
+#[func]
+pub fn round(
+    /// The size of the brackets, relative to the height of the wrapped content.
+    #[named]
+    size: Option<Smart<Rel<Length>>>,
+    /// The expression to round.
+    body: Content,
+) -> Content {
+    delimited(body, '⌊', '⌉', size)
+}
+
+/// Takes the absolute value of an expression.
+///
+/// ```example
+/// $ abs(x/2) $
+/// ```
+#[func]
+pub fn abs(
+    /// The size of the brackets, relative to the height of the wrapped content.
+    #[named]
+    size: Option<Smart<Rel<Length>>>,
+    /// The expression to take the absolute value of.
+    body: Content,
+) -> Content {
+    delimited(body, '|', '|', size)
+}
+
+/// Takes the norm of an expression.
+///
+/// ```example
+/// $ norm(x/2) $
+/// ```
+#[func]
+pub fn norm(
+    /// The size of the brackets, relative to the height of the wrapped content.
+    #[named]
+    size: Option<Smart<Rel<Length>>>,
+    /// The expression to take the norm of.
+    body: Content,
+) -> Content {
+    delimited(body, '‖', '‖', size)
+}
+
+fn delimited(
+    body: Content,
+    left: char,
+    right: char,
+    size: Option<Smart<Rel<Length>>>,
+) -> Content {
+    let span = body.span();
+    let mut elem = LrElem::new(Content::sequence([
+        TextElem::packed(left),
+        body,
+        TextElem::packed(right),
+    ]));
+    // Push size only if size is provided
+    if let Some(size) = size {
+        elem.push_size(size);
+    }
+    elem.pack().spanned(span)
+}