1 files changed, 145 insertions, 0 deletions
diff --git a/crates/typst-library/src/model/document.rs b/crates/typst-library/src/model/document.rs
new file mode 100644
index 00000000..b693d785
--- /dev/null
+++ b/crates/typst-library/src/model/document.rs
@@ -0,0 +1,145 @@
+use ecow::EcoString;
+
+use crate::diag::{bail, HintedStrResult, SourceResult};
+use crate::engine::Engine;
+use crate::foundations::{
+    cast, elem, Args, Array, Construct, Content, Datetime, Fields, Smart, StyleChain,
+    Styles, Value,
+};
+use crate::introspection::Introspector;
+use crate::layout::Page;
+
+/// The root element of a document and its metadata.
+///
+/// All documents are automatically wrapped in a `document` element. You cannot
+/// create a document element yourself. This function is only used with
+/// [set rules]($styling/#set-rules) to specify document metadata. Such a set
+/// rule must not occur inside of any layout container.
+///
+/// ```example
+/// #set document(title: [Hello])
+///
+/// This has no visible output, but
+/// embeds metadata into the PDF!
+/// ```
+///
+/// Note that metadata set with this function is not rendered within the
+/// document. Instead, it is embedded in the compiled PDF file.
+#[elem(Construct)]
+pub struct DocumentElem {
+    /// The document's title. This is often rendered as the title of the
+    /// PDF viewer window.
+    ///
+    /// While this can be arbitrary content, PDF viewers only support plain text
+    /// titles, so the conversion might be lossy.
+    #[ghost]
+    pub title: Option<Content>,
+
+    /// The document's authors.
+    #[ghost]
+    pub author: Author,
+
+    /// The document's keywords.
+    #[ghost]
+    pub keywords: Keywords,
+
+    /// The document's creation date.
+    ///
+    /// If this is `{auto}` (default), Typst uses the current date and time.
+    /// Setting it to `{none}` prevents Typst from embedding any creation date
+    /// into the PDF metadata.
+    ///
+    /// The year component must be at least zero in order to be embedded into a
+    /// PDF.
+    ///
+    /// If you want to create byte-by-byte reproducible PDFs, set this to
+    /// something other than `{auto}`.
+    #[ghost]
+    pub date: Smart<Option<Datetime>>,
+}
+
+impl Construct for DocumentElem {
+    fn construct(_: &mut Engine, args: &mut Args) -> SourceResult<Content> {
+        bail!(args.span, "can only be used in set rules")
+    }
+}
+
+/// A list of authors.
+#[derive(Debug, Default, Clone, PartialEq, Hash)]
+pub struct Author(Vec<EcoString>);
+
+cast! {
+    Author,
+    self => self.0.into_value(),
+    v: EcoString => Self(vec![v]),
+    v: Array => Self(v.into_iter().map(Value::cast).collect::<HintedStrResult<_>>()?),
+}
+
+/// A list of keywords.
+#[derive(Debug, Default, Clone, PartialEq, Hash)]
+pub struct Keywords(Vec<EcoString>);
+
+cast! {
+    Keywords,
+    self => self.0.into_value(),
+    v: EcoString => Self(vec![v]),
+    v: Array => Self(v.into_iter().map(Value::cast).collect::<HintedStrResult<_>>()?),
+}
+
+/// A finished document with metadata and page frames.
+#[derive(Debug, Default, Clone)]
+pub struct Document {
+    /// The document's finished pages.
+    pub pages: Vec<Page>,
+    /// Details about the document.
+    pub info: DocumentInfo,
+    /// Provides the ability to execute queries on the document.
+    pub introspector: Introspector,
+}
+
+/// Details about the document.
+#[derive(Debug, Default, Clone, PartialEq, Hash)]
+pub struct DocumentInfo {
+    /// The document's title.
+    pub title: Option<EcoString>,
+    /// The document's author.
+    pub author: Vec<EcoString>,
+    /// The document's keywords.
+    pub keywords: Vec<EcoString>,
+    /// The document's creation date.
+    pub date: Smart<Option<Datetime>>,
+}
+
+impl DocumentInfo {
+    /// Populate this document info with details from the given styles.
+    ///
+    /// Document set rules are a bit special, so we need to do this manually.
+    pub fn populate(&mut self, styles: &Styles) {
+        let chain = StyleChain::new(styles);
+        let has = |field| styles.has::<DocumentElem>(field as _);
+        if has(<DocumentElem as Fields>::Enum::Title) {
+            self.title =
+                DocumentElem::title_in(chain).map(|content| content.plain_text());
+        }
+        if has(<DocumentElem as Fields>::Enum::Author) {
+            self.author = DocumentElem::author_in(chain).0;
+        }
+        if has(<DocumentElem as Fields>::Enum::Keywords) {
+            self.keywords = DocumentElem::keywords_in(chain).0;
+        }
+        if has(<DocumentElem as Fields>::Enum::Date) {
+            self.date = DocumentElem::date_in(chain);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_document_is_send_and_sync() {
+        fn ensure_send_and_sync<T: Send + Sync>() {}
+        ensure_send_and_sync::<Document>();
+    }
+}