Add function calling

Signed-off-by: Marcel Müller <neikos@neikos.email>

src/eval/mod.rs

@@ -7,6 +7,7 @@ use crate::Context;
 use crate::emit::Instruction;
 use crate::emit::VMInstructions;
 use crate::emit::VariableSlot;
+use crate::functions::FunctionMap;
 use crate::input::NomoInput;
 use crate::value::NomoValue;
 
@@ -69,7 +70,11 @@ impl Scope {
     clippy::unnecessary_to_owned,
     reason = "We cannot do the suggested way as the lifetimes would not match up"
 )]
-pub fn execute(vm: &VMInstructions, global_context: &Context) -> Result<String, EvaluationError> {
+pub fn execute(
+    available_functions: &FunctionMap,
+    vm: &VMInstructions,
+    global_context: &Context,
+) -> Result<String, EvaluationError> {
     let mut output = String::new();
 
     let mut scopes = Scope {
@@ -208,7 +213,17 @@ pub fn execute(vm: &VMInstructions, global_context: &Context) -> Result<String,
 
                 scopes.insert_into_slot(*result_slot, result.unwrap());
             }
-            Instruction::FunctionCall { .. } => todo!(),
+            Instruction::FunctionCall { name, args, slot } => {
+                let args = args.iter().map(|slot| scopes.get(slot)).cloned().collect();
+
+                let value = available_functions
+                    .get(name.as_str())
+                    .unwrap()
+                    .call(args)
+                    .unwrap();
+
+                scopes.insert_into_slot(*slot, value);
+            }
         }
 
         ip += 1;
@@ -221,6 +236,8 @@ pub fn execute(vm: &VMInstructions, global_context: &Context) -> Result<String,
 mod tests {
     use crate::Context;
     use crate::eval::execute;
+    use crate::functions::FunctionMap;
+    use crate::functions::NomoFunctionError;
 
     #[test]
     fn check_simple_variable_interpolation() {
@@ -234,7 +251,7 @@ mod tests {
 
         let mut context = Context::new();
         context.insert("world", "World");
-        let output = execute(&emit, &context);
+        let output = execute(&FunctionMap::default(), &emit, &context);
 
         insta::assert_debug_snapshot!(output, @r#"
         Ok(
@@ -242,4 +259,31 @@ mod tests {
         )
         "#);
     }
+
+    #[test]
+    fn check_method_call() {
+        let input = "Hello {{= foo(world) }}";
+
+        let parsed = crate::parser::parse(input.into()).unwrap();
+
+        let ast = crate::ast::parse(parsed.tokens()).unwrap();
+
+        let emit = crate::emit::emit_machine(ast);
+
+        let mut context = Context::new();
+        context.insert("world", "World");
+        let mut function_map = FunctionMap::default();
+
+        function_map.register("foo", |arg: String| -> Result<String, NomoFunctionError> {
+            Ok(arg.to_uppercase())
+        });
+
+        let output = execute(&function_map, &emit, &context);
+
+        insta::assert_debug_snapshot!(output, @r#"
+        Ok(
+            "Hello WORLD",
+        )
+        "#);
+    }
 }