Split up `model` module

1 files changed, 87 insertions, 0 deletions

diff --git a/src/eval/module.rs b/src/eval/module.rs
new file mode 100644
index 00000000..e911d859
--- /dev/null
+++ b/src/eval/module.rs
@@ -0,0 +1,87 @@
+use std::fmt::{self, Debug, Formatter};
+use std::sync::Arc;
+
+use ecow::{eco_format, EcoString};
+
+use super::{Content, Scope, Value};
+use crate::diag::StrResult;
+
+/// An evaluated module, ready for importing or typesetting.
+#[derive(Clone, Hash)]
+pub struct Module(Arc<Repr>);
+
+/// The internal representation.
+#[derive(Clone, Hash)]
+struct Repr {
+    /// The module's name.
+    name: EcoString,
+    /// The top-level definitions that were bound in this module.
+    scope: Scope,
+    /// The module's layoutable contents.
+    content: Content,
+}
+
+impl Module {
+    /// Create a new module.
+    pub fn new(name: impl Into<EcoString>) -> Self {
+        Self(Arc::new(Repr {
+            name: name.into(),
+            scope: Scope::new(),
+            content: Content::empty(),
+        }))
+    }
+
+    /// Update the module's scope.
+    pub fn with_scope(mut self, scope: Scope) -> Self {
+        Arc::make_mut(&mut self.0).scope = scope;
+        self
+    }
+
+    /// Update the module's content.
+    pub fn with_content(mut self, content: Content) -> Self {
+        Arc::make_mut(&mut self.0).content = content;
+        self
+    }
+
+    /// Get the module's name.
+    pub fn name(&self) -> &EcoString {
+        &self.0.name
+    }
+
+    /// Access the module's scope.
+    pub fn scope(&self) -> &Scope {
+        &self.0.scope
+    }
+
+    /// Access the module's scope, mutably.
+    pub fn scope_mut(&mut self) -> &mut Scope {
+        &mut Arc::make_mut(&mut self.0).scope
+    }
+
+    /// Try to access a definition in the module.
+    pub fn get(&self, name: &str) -> StrResult<&Value> {
+        self.scope().get(&name).ok_or_else(|| {
+            eco_format!("module `{}` does not contain `{name}`", self.name())
+        })
+    }
+
+    /// Extract the module's content.
+    pub fn content(self) -> Content {
+        match Arc::try_unwrap(self.0) {
+            Ok(repr) => repr.content,
+            Err(arc) => arc.content.clone(),
+        }
+    }
+}
+
+impl Debug for Module {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "<module {}>", self.name())
+    }
+}
+
+impl PartialEq for Module {
+    fn eq(&self, other: &Self) -> bool {
+        Arc::ptr_eq(&self.0, &other.0)
+    }
+}