From 803ae9309f54eaffff1340a81d06ede1969e26b1 Mon Sep 17 00:00:00 2001
From: Laurenz <laurmaedje@gmail.com>
Date: Tue, 18 Jul 2023 21:53:42 +0200
Subject: [PATCH] Support `scope` argument for `eval`

---
 .../typst-library/src/compute/foundations.rs  |  23 +++++++++++++++++-
 crates/typst/src/eval/mod.rs                  |   4 ++-
 crates/typst/src/eval/scope.rs                |  11 +++++++--
 tests/ref/compute/foundations.png             | Bin 0 -> 2344 bytes
 tests/typ/compute/foundations.typ             |  12 ++++++++-
 5 files changed, 45 insertions(+), 5 deletions(-)
 create mode 100644 tests/ref/compute/foundations.png

diff --git a/crates/typst-library/src/compute/foundations.rs b/crates/typst-library/src/compute/foundations.rs
index ecac3ffad..b76631138 100644
--- a/crates/typst-library/src/compute/foundations.rs
+++ b/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)
 }
diff --git a/crates/typst/src/eval/mod.rs b/crates/typst/src/eval/mod.rs
index 6f684a7bd..f72eeaa4f 100644
--- a/crates/typst/src/eval/mod.rs
+++ b/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 {
diff --git a/crates/typst/src/eval/scope.rs b/crates/typst/src/eval/scope.rs
index f3e137151..b8d5b75a0 100644
--- a/crates/typst/src/eval/scope.rs
+++ b/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"
+                )
             }
         }
     }
diff --git a/tests/ref/compute/foundations.png b/tests/ref/compute/foundations.png
new file mode 100644
index 0000000000000000000000000000000000000000..5d6ba7441a7ca4f992779f6e61b304476fbb7cd7
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diff --git a/tests/typ/compute/foundations.typ b/tests/typ/compute/foundations.typ
index 9c7b13cab..3da2e6019 100644
--- a/tests/typ/compute/foundations.typ
+++ b/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