From 217c572a343e982a0ee1ab5b1e4e9b64b1013678 Mon Sep 17 00:00:00 2001
From: Kishan Goli <kishangoli@ucsb.edu>
Date: Tue, 19 May 2026 21:34:58 -0700
Subject: [PATCH] bindgen implementation

---
 crates/vdb-ffi/Cargo.toml      |  3 +++
 crates/vdb-ffi/build.rs        | 23 +++++++++++++++++++++++
 crates/vdb-ffi/src/bindings.rs | 24 ------------------------
 crates/vdb-ffi/src/engine.rs   |  6 ++----
 crates/vdb-ffi/src/lib.rs      |  6 +++++-
 5 files changed, 33 insertions(+), 29 deletions(-)
 create mode 100644 crates/vdb-ffi/build.rs
 delete mode 100644 crates/vdb-ffi/src/bindings.rs

diff --git a/crates/vdb-ffi/Cargo.toml b/crates/vdb-ffi/Cargo.toml
index a8dd816..c0445f0 100644
--- a/crates/vdb-ffi/Cargo.toml
+++ b/crates/vdb-ffi/Cargo.toml
@@ -5,3 +5,6 @@ edition = "2021"
 
 [lib]
 path = "src/lib.rs"
+
+[build-dependencies]
+bindgen = "0.72"
diff --git a/crates/vdb-ffi/build.rs b/crates/vdb-ffi/build.rs
new file mode 100644
index 0000000..c87be6e
--- /dev/null
+++ b/crates/vdb-ffi/build.rs
@@ -0,0 +1,23 @@
+use std::{env, path::PathBuf};
+
+fn main() {
+    println!("cargo:rerun-if-changed=../../cpp/vector_engine_ffi.h");
+
+    let bindings = bindgen::Builder::default()
+        .header("../../cpp/vector_engine_ffi.h")
+        .clang_arg("-xc++")
+        .clang_arg("-std=c++17")
+        .clang_arg("-I../../cpp")
+        .allowlist_type("NativeVectorEngine")
+        .allowlist_type("NativeSearchResults")
+        .allowlist_function("native_.*")
+        .layout_tests(false)
+        .generate()
+        .expect("failed to generate FFI bindings with bindgen");
+
+    let out_dir = PathBuf::from(env::var("OUT_DIR").expect("OUT_DIR was not set"));
+
+    bindings
+        .write_to_file(out_dir.join("bindings.rs"))
+        .expect("failed to write generated bindings");
+}
diff --git a/crates/vdb-ffi/src/bindings.rs b/crates/vdb-ffi/src/bindings.rs
deleted file mode 100644
index 41594b2..0000000
--- a/crates/vdb-ffi/src/bindings.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-#[repr(C)]
-pub struct NativeVectorEngine {
-    _private: [u8; 0], // rust short hand for declaring "opaque" struct
-}
-
-#[repr(C)]
-pub struct NativeSearchResults {
-    _private: [u8; 0],
-}
-
-unsafe extern "C" {
-    pub fn native_vector_engine_new() -> *mut NativeVectorEngine;
-    pub fn native_vector_engine_free(engine: *mut NativeVectorEngine);
-
-    pub fn native_vector_engine_insert( engine: *mut NativeVectorEngine, id: *const std::os::raw::c_char, vector: *const f32, len: usize, );
-
-    pub fn native_vector_engine_delete( engine: *mut NativeVectorEngine, id: *const std::os::raw::c_char, ) -> bool;
-    pub fn native_vector_engine_search( engine: *const NativeVectorEngine, query: *const f32, len: usize, k: usize, ) -> *mut NativeSearchResults;
-    pub fn native_search_results_len(results: *const NativeSearchResults) -> usize;
-    
-    pub fn native_search_results_id_at( results: *const NativeSearchResults, index: usize, ) -> *const std::os::raw::c_char;
-    pub fn native_search_results_score_at( results: *const NativeSearchResults, index: usize, ) -> f32;
-    pub fn native_search_results_free(results: *mut NativeSearchResults);
-}
diff --git a/crates/vdb-ffi/src/engine.rs b/crates/vdb-ffi/src/engine.rs
index df892cd..4aead3d 100644
--- a/crates/vdb-ffi/src/engine.rs
+++ b/crates/vdb-ffi/src/engine.rs
@@ -73,10 +73,8 @@ impl FfiSearchResults {
     pub fn id_at(&self, index: usize) -> String {
         let id_ptr = unsafe { native_search_results_id_at(self.handle, index) };
 
-        unsafe { CStr::from_ptr(id_ptr) }
-            .to_str()
-            .expect("native search result ID must be valid")
-            .to_string()
+        unsafe { CStr::from_ptr(id_ptr) }.to_str().expect("native search result ID must be valid").to_string()
+        // first converting pointer to rust CStr, then rust string
     }
 
     pub fn score_at(&self, index: usize) -> f32 {
diff --git a/crates/vdb-ffi/src/lib.rs b/crates/vdb-ffi/src/lib.rs
index 8c4f91f..6ca15a5 100644
--- a/crates/vdb-ffi/src/lib.rs
+++ b/crates/vdb-ffi/src/lib.rs
@@ -1,4 +1,8 @@
-mod bindings;
 mod engine;
 
+#[allow(non_camel_case_types, non_snake_case, non_upper_case_globals)]
+mod bindings {
+    include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+}
+
 pub use engine::{FfiSearchResults, FfiVectorEngine};