From 28a9e389faf4be2f106bf64a94ae80ec3f2caef6 Mon Sep 17 00:00:00 2001
From: Maxwell Jeffress <maxwelljeffress@proton.me>
Date: Mon, 18 Aug 2025 09:36:35 +1000
Subject: [PATCH] Basic function calling support

---
 src/main.cpp         | 46 ++++++++++++++++++++++++++++++++++++--------
 tests/functions.grnd |  6 +++++-
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index d198867..7adeda2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -376,18 +376,20 @@ Types getType(string in) {
     return Types::Int;
 }
 
+bool processingFunction = false;
+string procFnName = "";
+
+bool inFunction = false;
+
+// Forward declaration for the call instruction
+Literal exec(vector<Instruction> in);
+
 /*
     exec function
     This function takes a list of instructions (see Instruction struct above and parser
     function below) and acts upon their properties. This is the main interpreter
     function for the program.
 */
-
-bool processingFunction = false;
-string procFnName = "";
-
-bool inFunction = false;
-
 Literal exec(vector<Instruction> in) {
     for (int i = 0; i < in.size(); i++) {
         Instruction l = in[i];
@@ -1508,6 +1510,10 @@ Literal exec(vector<Instruction> in) {
             case Instructions::Endfun:
                 error("No function is being defined. Cannot end function declaration here");
                 break;
+            /*
+                pusharg instruction
+                This instruction makes new arguments avaliable for functions.
+            */
             case Instructions::Pusharg:
                 if (l.args.size() < 1) {
                     error("Could not find all arguments required for Endfun inbuilt");
@@ -1518,9 +1524,33 @@ Literal exec(vector<Instruction> in) {
                     error("First argument of pusharg must be a literal");
                 }
                 break;
-            case Instructions::Local:
-                break;
+            /*
+                call instruction
+                This instruction calls a function, and makes the arguments avaliable for it.
+            */
             case Instructions::Call:
+                {
+                    if (l.args.size() < 2) {
+                        error("Could not find all arguments required for Call inbuilt");
+                    }
+                    
+                    FunctionRef ref;
+                    Direct returnRef;
+                    
+                    if (holds_alternative<FunctionRef>(l.args[0])) {
+                        ref = get<FunctionRef>(l.args[0]);
+                    } else {
+                        error("First argument of call must be a function reference");
+                    }
+
+                    if (holds_alternative<Direct>(l.args[1])) {
+                        returnRef = get<Direct>(l.args[1]);
+                    } else {
+                        error("Second argument of call must be a direct reference");
+                    }
+
+                    variables[returnRef.varName] = exec(functions[ref.fnName].instructions);                    
+                }
                 break;
             case Instructions::Use:
                 break;
diff --git a/tests/functions.grnd b/tests/functions.grnd
index 906f18d..f99555c 100644
--- a/tests/functions.grnd
+++ b/tests/functions.grnd
@@ -1,6 +1,10 @@
 fun -int !dingle -string &silly
-stdlnout &silly
+stdlnout "This is inside the function"
 return 10
 endfun
 
 stdlnout "This is outside the function"
+
+call !dingle &var
+
+stdlnout $var