Rename compute to eval ✏

1 files changed, 35 insertions, 0 deletions

diff --git a/src/eval/scope.rs b/src/eval/scope.rs
new file mode 100644
index 00000000..8e6576d1
--- /dev/null
+++ b/src/eval/scope.rs
@@ -0,0 +1,35 @@
+//! Mapping from identifiers to functions.
+
+use std::collections::HashMap;
+use std::fmt::{self, Debug, Formatter};
+
+use super::value::FuncValue;
+
+/// A map from identifiers to functions.
+pub struct Scope {
+    functions: HashMap<String, FuncValue>,
+}
+
+impl Scope {
+    // Create a new empty scope with a fallback function that is invoked when no
+    // match is found.
+    pub fn new() -> Self {
+        Self { functions: HashMap::new() }
+    }
+
+    /// Associate the given name with the function.
+    pub fn insert(&mut self, name: impl Into<String>, function: FuncValue) {
+        self.functions.insert(name.into(), function);
+    }
+
+    /// Return the function with the given name if there is one.
+    pub fn func(&self, name: &str) -> Option<&FuncValue> {
+        self.functions.get(name)
+    }
+}
+
+impl Debug for Scope {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.debug_set().entries(self.functions.keys()).finish()
+    }
+}