From 5bd85195179972a40b2264c62fa43e0d71e79e53 Mon Sep 17 00:00:00 2001
From: Maxwell Jeffress <maxwelljeffress@proton.me>
Date: Mon, 25 Aug 2025 13:22:15 +1000
Subject: [PATCH] External library support

---
 src/main.cpp           | 44 ++++++++++++++++++++++++++++++++++++++++--
 tests/use/library.grnd |  3 +++
 tests/use/use.grnd     |  5 +++++
 3 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tests/use/library.grnd
 create mode 100644 tests/use/use.grnd

diff --git a/src/main.cpp b/src/main.cpp
index 3ab90f2..0c970ef 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,6 +41,8 @@
 #include <map>
 #include <stack>
 #include <fstream>
+#include <cstdlib>
+#include <filesystem>
 
 using namespace std;
 
@@ -402,9 +404,15 @@ string procFnName = "";
 
 bool inFunction = false;
 
-// Forward declaration for the call instruction
+// Forward declaration for the call instruction and use instruction
 Literal exec(vector<Instruction> in);
 
+// Forward declaration for the use instruction
+vector<Instruction> parser(vector<vector<string>> in);
+
+// Forward declaration for the use instruction
+vector<vector<string>> lexer(string in);
+
 /*
     exec function
     This function takes a list of instructions (see Instruction struct above and parser
@@ -1734,7 +1742,39 @@ Literal exec(vector<Instruction> in, bool executingFunction) {
                 }
                 break;
             case Instructions::Use:
-                cout << "Still to be implemented" << endl;
+                if (l.args.size() < 1) {
+                    error("Could not find all arguments for Use inbuilt");
+                }
+                {
+                    string useName;
+                    
+                    if (holds_alternative<Literal>(l.args[0])) {
+                        if (holds_alternative<string>(get<Literal>(l.args[0]).val)) {
+                            useName = get<string>(get<Literal>(l.args[0]).val) + ".grnd";
+                        } else {
+                            error("First argument for use requires a string literal");
+                        }
+                    } else {
+                        error("First argument for use requires a string literal");
+                    }
+
+                    string groundLibsDir = getenv("GROUND_LIBS");
+
+                    if (filesystem::exists(useName)) {
+                        
+                    } else if (groundLibsDir != "" && filesystem::exists(groundLibsDir + useName)) {
+                        useName = groundLibsDir + useName;
+                    } else {
+                        error("Could not find external Ground library in $GROUND_LIBS or current directory.");
+                    }
+
+                    ifstream file(useName);
+                    string lns;
+                    string in;
+                    while (getline(file, lns)) {
+                        in += lns += "\n";
+                    }
+                    Literal ret = exec(parser(lexer(in)), false);                }
                 break;
             case Instructions::Extern:
                 cout << "Still to be implemented" << endl;
diff --git a/tests/use/library.grnd b/tests/use/library.grnd
new file mode 100644
index 0000000..de99953
--- /dev/null
+++ b/tests/use/library.grnd
@@ -0,0 +1,3 @@
+fun -string !dingus
+return "Hello from the library"
+endfun
diff --git a/tests/use/use.grnd b/tests/use/use.grnd
new file mode 100644
index 0000000..1b5887a
--- /dev/null
+++ b/tests/use/use.grnd
@@ -0,0 +1,5 @@
+use "library"
+
+call !dingus &var
+
+stdlnout $var