Extension methods to help with Rust FFI strings and vecs

csharp_mod/SlangExtensions.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using StationeersIC10Editor;
+
+namespace Slang
+{
+    public static unsafe class SlangExtensions
+    {
+        // 1. Convert the Rust Byte Vector (Vec_uint8_t) to a C# String
+        public static string AsString(this Vec_uint8_t vec)
+        {
+            if (vec.ptr == null || vec.len == UIntPtr.Zero)
+            {
+                return string.Empty;
+            }
+
+            // Rust strings are UTF-8. Read bytes from raw pointer.
+            var toReturn = Encoding.UTF8.GetString(vec.ptr, (int)vec.len);
+
+            return toReturn;
+        }
+
+        public static void Drop(this Vec_uint8_t vec)
+        {
+            Ffi.free_string(vec);
+        }
+
+        // 2. Convert Rust Token Vector to C# List
+        public static List<Token> AsList(this Vec_FfiToken_t vec)
+        {
+            var list = new List<Token>((int)vec.len);
+            var currentPtr = vec.ptr;
+
+            // Iterate through the raw memory array
+            for (int i = 0; i < (int)vec.len; i++)
+            {
+                // Dereference pointer to get the struct at index i
+                FfiToken_t token = currentPtr[i];
+
+                var newToken = new Token(token.text.AsString(), token.column);
+                newToken.Error = token.error.AsString();
+
+                list.Add(newToken);
+            }
+
+            Ffi.free_ffi_token_vec(vec);
+
+            return list;
+        }
+    }
+}

csharp_mod/SlangGlue.cs

@@ -70,6 +70,18 @@ public unsafe struct Vec_FfiToken_t {
     public UIntPtr cap;
 }
 
+public unsafe partial class Ffi {
+    [DllImport(RustLib, ExactSpelling = true)] public static unsafe extern
+    void free_ffi_token_vec (
+        Vec_FfiToken_t v);
+}
+
+public unsafe partial class Ffi {
+    [DllImport(RustLib, ExactSpelling = true)] public static unsafe extern
+    void free_string (
+        Vec_uint8_t s);
+}
+
 public unsafe partial class Ffi {
     [DllImport(RustLib, ExactSpelling = true)] public static unsafe extern
     Vec_FfiToken_t tokenize_line (

rust_compiler/libs/compiler/src/test/branching.rs

@@ -155,4 +155,3 @@ fn test_spilled_variable_update_in_branch() -> anyhow::Result<()> {
 
     Ok(())
 }
-

rust_compiler/src/lib.rs

@@ -69,6 +69,16 @@ pub fn tokenize_line(input: safer_ffi::char_p::char_p_ref<'_>) -> safer_ffi::Vec
     tokens.into()
 }
 
+#[ffi_export]
+pub fn free_ffi_token_vec(v: safer_ffi::Vec<FfiToken>) {
+    drop(v)
+}
+
+#[ffi_export]
+pub fn free_string(s: safer_ffi::String) {
+    drop(s)
+}
+
 #[cfg(feature = "headers")]
 pub fn generate_headers() -> std::io::Result<()> {
     ::safer_ffi::headers::builder()