Support scope argument for eval

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

@@ -218,9 +218,30 @@ pub fn eval(
     #[named]
     #[default(EvalMode::Code)]
     mode: EvalMode,
+    /// A scope of definitions that are made available.
+    ///
+    /// ```example
+    /// #eval("x + 1", scope: (x: 2)) \
+    /// #eval(
+    ///   "abc/xyz",
+    ///   mode: "math",
+    ///   scope: (
+    ///     abc: $a + b + c$,
+    ///     xyz: $x + y + z$,
+    ///   ),
+    /// )
+    /// ```
+    #[named]
+    #[default]
+    scope: Dict,
     /// The virtual machine.
     vm: &mut Vm,
 ) -> SourceResult<Value> {
     let Spanned { v: text, span } = source;
-    typst::eval::eval_string(vm.world(), &text, mode, span)
+    let dict = scope;
+    let mut scope = Scope::new();
+    for (key, value) in dict {
+        scope.define(key, value);
+    }
+    typst::eval::eval_string(vm.world(), &text, span, mode, scope)
 }

crates/typst/src/eval/mod.rs

@@ -145,8 +145,9 @@ pub fn eval(
 pub fn eval_string(
     world: Tracked<dyn World + '_>,
     string: &str,
-    mode: EvalMode,
     span: Span,
+    mode: EvalMode,
+    scope: Scope,
 ) -> SourceResult<Value> {
     let mut root = match mode {
         EvalMode::Code => parse_code(string),
@@ -179,6 +180,7 @@ pub fn eval_string(
     let id = FileId::detached();
     let scopes = Scopes::new(Some(world.library()));
     let mut vm = Vm::new(vt, route.track(), id, scopes);
+    vm.scopes.scopes.push(scope);
 
     // Evaluate the code.
     let result = match mode {

crates/typst/src/eval/scope.rs

@@ -72,7 +72,11 @@ impl<'a> Scopes<'a> {
 #[cold]
 fn unknown_variable(var: &str) -> EcoString {
     if var.contains('-') {
-        eco_format!("unknown variable: {} - if you meant to use subtraction, try adding spaces around the minus sign.", var)
+        eco_format!(
+            "unknown variable: {} - if you meant to use subtraction, \
+             try adding spaces around the minus sign.",
+            var
+        )
     } else {
         eco_format!("unknown variable: {}", var)
     }
@@ -171,7 +175,10 @@ impl Slot {
         match self.kind {
             Kind::Normal => Ok(&mut self.value),
             Kind::Captured => {
-                bail!("variables from outside the function are read-only and cannot be modified")
+                bail!(
+                    "variables from outside the function are \
+                     read-only and cannot be modified"
+                )
             }
         }
     }

tests/typ/compute/foundations.typ

@@ -73,7 +73,17 @@
 #test(type(10 / 3), "float")
 
 ---
-#eval("[_Hello" + " World!_]")
+// Test the eval function.
+#test(eval("1 + 2"), 3)
+#test(eval("1 + x", scope: (x: 3)), 4)
+#test(eval("let x = x + 1; x + 1", scope: (x: 1)), 3)
+
+---
+// Test evaluation in other modes.
+// Ref: true
+#eval("[_Hello" + " World!_]") \
+#eval("_Hello" + " World!_", mode: "markup") \
+#eval("RR_1^NN", mode: "math", scope: (RR: math.NN, NN: math.RR))
 
 ---
 // Error: 7-12 expected identifier